rb_equal_opt: fully static call data

This changeset reduces the generated binary of rb_equal_opt from 129 bytes to 17 bytes on my machine, according to nm(1).
author: 卜部昌平 <shyouhei@ruby-lang.org> 2020-05-29 16:04:53 +0900
committer: 卜部昌平 <shyouhei@ruby-lang.org> 2020-06-09 09:52:46 +0900
commit: 8f3d4090f037ae35fc9ba6380ee284aec837201f (patch)
tree: fcdc79400e8c8f05d99e018bde2f3002b3fa2c08 /benchmark/vm_poly_method.yml
parent: 77293cef91a9aa424c086ae05f03211d9a8a87d3 (diff)
0 files changed, 0 insertions, 0 deletions
diff --git a/.appveyor.yml b/.appveyor.yml
index 6803edff9b..05ff204541 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -26,8 +26,9 @@ environment:
     # is limited, and compatibility issues that happen only in newer versions are rare.
     # You may test some other stuff on GitHub Actions instead.
     - build: vs
-      vs: 120
+      vs: 120 # Visual Studio 2013
       ssl: OpenSSL-v111
+      # The worker image name. This is NOT the Visual Studio version we're using here.
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       GEMS_FOR_TEST: ""
   RELINE_TEST_ENCODING: "UTF-8"
@@ -47,6 +48,7 @@ for:
     - cd C:\Tools\vcpkg
     - git pull -q
     - .\bootstrap-vcpkg.bat
+    - ps: Start-FileDownload 'https://github.com/microsoft/vcpkg-tool/releases/download/2023-08-09/vcpkg.exe' -FileName 'C:\Tools\vcpkg\vcpkg.exe'
     - cd %APPVEYOR_BUILD_FOLDER%
     - vcpkg --triplet %Platform%-windows install --x-use-aria2 libffi libyaml readline zlib
     - CALL SET vcvars=%%^VS%VS%COMNTOOLS^%%..\..\VC\vcvarsall.bat
@@ -75,6 +77,7 @@ for:
     - attrib +r /s /d
     - mkdir %Platform%-mswin_%vs%
   build_script:
+    - set HAVE_GIT=no
     - cd %APPVEYOR_BUILD_FOLDER%
     - cd %Platform%-mswin_%vs%
     - >-
@@ -91,7 +94,7 @@ for:
     - nmake -l "TESTOPTS=-v -q" btest
     - nmake -l "TESTOPTS=-v -q" test-basic
     - >-
-      nmake -l "TESTOPTS=-v --timeout-scale=3.0
+      nmake -l "TESTOPTS=--timeout-scale=3.0
       --excludes=../test/excludes/_appveyor -j%JOBS%
       --exclude win32ole
       --exclude test_bignum
@@ -102,7 +105,7 @@ for:
     # separately execute tests without -j which may crash worker with -j.
     - >-
       nmake -l
-      "TESTOPTS=-v --timeout-scale=3.0 --excludes=../test/excludes/_appveyor"
+      "TESTOPTS=--timeout-scale=3.0 --excludes=../test/excludes/_appveyor"
       TESTS="
       ../test/win32ole
       ../test/ruby/test_bignum.rb
diff --git a/.cirrus.yml b/.cirrus.yml
deleted file mode 100644
index 6c47159921..0000000000
--- a/.cirrus.yml
+++ /dev/null
@@ -1,133 +0,0 @@
-# This CI is used to test Arm cases. We can set the maximum 16 tasks.
-# The entire testing design is inspired from .github/workflows/compilers.yml.
-
-# By default, Cirrus mounts an empty volume to `/tmp`
-# which triggers all sorts of warnings like "system temporary path is world-writable: /tmp".
-# Lets workaround it by specifying a custom volume mount point.
-env:
-  CIRRUS_VOLUME: /cirrus-ci-volume
-  LANG: C.UTF-8
-
-task:
-  name: Arm64 Graviton2 / $CC
-  skip: "changesIncludeOnly('doc/**', '**.{md,rdoc,ronn,[1-8]}', '.document')"
-  arm_container:
-    # We use the arm64 images at https://github.com/ruby/ruby-ci-image/pkgs/container/ruby-ci-image .
-    image: ghcr.io/ruby/ruby-ci-image:$CC
-    # Define the used cpu core in each matrix task. We can use total 16 cpu
-    # cores in entire matrix. [cpu] = [total cpu: 16] / [number of tasks]
-    cpu: 8
-    # We can request maximum 4 GB per cpu.
-    # [memory per task] = [memory per cpu: 4 GB] * [cpu]
-    memory: 32G
-  env:
-    CIRRUS_CLONE_DEPTH: 50
-    optflags: '-O1'
-    debugflags: '-ggdb3'
-    RUBY_PREFIX: /tmp/ruby-prefix
-    RUBY_DEBUG: ci rgengc
-    RUBY_TESTOPTS: >-
-      -q
-      --color=always
-      --tty=no
-    matrix:
-      CC: clang-12
-      CC: gcc-11
-  id_script: id
-  set_env_script:
-    # Set `GNUMAKEFLAGS`, because the flags are GNU make specific. Note using
-    # the `make` environment variable used in compilers.yml causes some rubygems
-    # tests to fail.
-    # https://github.com/rubygems/rubygems/issues/4921
-    - echo "GNUMAKEFLAGS=-s -j$((1 + $CIRRUS_CPU))" >> "$CIRRUS_ENV"
-    - cat "$CIRRUS_ENV"
-  # Arm containers are executed in AWS's EKS, and it's not yet supporting IPv6
-  # See https://github.com/aws/containers-roadmap/issues/835
-  disable_ipv6_script: sudo ./tool/disable_ipv6.sh
-  autogen_script: ./autogen.sh
-  configure_script: >-
-    ./configure -C
-    --enable-debug-env
-    --disable-install-doc
-    --with-ext=-test-/cxxanyargs,+
-    --prefix="$RUBY_PREFIX"
-  make_extract-extlibs_script: make extract-extlibs
-  make_incs_script: make incs
-  make_script: make
-  make_leaked-globals_script: make leaked-globals
-  make_test_script: make test
-  make_install_script: make install
-  install_gems_for_test_script: $RUBY_PREFIX/bin/gem install --no-doc timezone tzinfo
-  make_test-tool_script: make test-tool
-  make_test-all_script: make test-all
-  make_test-spec_script: make test-spec
-
-# The following is to test YJIT on ARM64 CPUs available on Cirrus CI
-yjit_task:
-  name: Arm64 Graviton2 / $CC YJIT
-  auto_cancellation: $CIRRUS_BRANCH != 'master'
-  skip: "changesIncludeOnly('doc/**', '**.{md,rdoc,ronn,[1-8]}', '.document')"
-  arm_container:
-    # We use the arm64 images at https://github.com/ruby/ruby-ci-image/pkgs/container/ruby-ci-image .
-    image: ghcr.io/ruby/ruby-ci-image:$CC
-    # Define the used cpu core in each matrix task. We can use total 16 cpu
-    # cores in entire matrix. [cpu] = [total cpu: 16] / [number of tasks]
-    cpu: 8
-    # We can request maximum 4 GB per cpu.
-    # [memory per task] = [memory per cpu: 4 GB] * [cpu]
-    memory: 32G
-  env:
-    CIRRUS_CLONE_DEPTH: 50
-    optflags: '-O1'
-    debugflags: '-ggdb3'
-    RUBY_PREFIX: /tmp/ruby-prefix
-    RUBY_DEBUG: ci rgengc
-    RUBY_TESTOPTS: >-
-      -q
-      --color=always
-      --tty=no
-    matrix:
-      - CC: clang-12
-        configure: --enable-yjit=dev
-        rustup_init: --default-toolchain=1.58.0
-      - CC: gcc-11
-        configure: --enable-yjit
-  id_script: id
-  set_env_script:
-    # Set `GNUMAKEFLAGS`, because the flags are GNU make specific. Note using
-    # the `make` environment variable used in compilers.yml causes some rubygems
-    # tests to fail.
-    # https://github.com/rubygems/rubygems/issues/4921
-    - echo "GNUMAKEFLAGS=-s -j$((1 + $CIRRUS_CPU))" >> "$CIRRUS_ENV"
-    - echo RUST_BACKTRACE=1 >> "$CIRRUS_ENV"
-    - cat "$CIRRUS_ENV"
-  # Arm containers are executed in AWS's EKS, and it's not yet supporting IPv6
-  # See https://github.com/aws/containers-roadmap/issues/835
-  disable_ipv6_script: sudo ./tool/disable_ipv6.sh
-  install_rust_script:
-    - sudo apt-get update -y
-    - sudo apt-get install -y curl
-    - "curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y $rustup_init"
-  autogen_script: ./autogen.sh
-  configure_script: >-
-    source $HOME/.cargo/env && ./configure -C
-    --enable-debug-env
-    --disable-install-doc
-    --with-ext=-test-/cxxanyargs,+
-    --prefix="$RUBY_PREFIX"
-    $configure
-  make_miniruby_script: source $HOME/.cargo/env && make miniruby
-  make_bindgen_script: |
-    if [[ "$CC" = "clang-12" ]]; then
-      source $HOME/.cargo/env && make yjit-bindgen
-    else
-      echo "only running bindgen on clang image"
-    fi
-  boot_miniruby_script: ./miniruby --yjit-call-threshold=1 -e0
-  test_dump_insns_script: ./miniruby --yjit-call-threshold=1 --yjit-dump-insns -e0
-  output_stats_script: ./miniruby --yjit-call-threshold=1 --yjit-stats -e0
-  full_build_script: source $HOME/.cargo/env && make
-  cargo_test_script: source $HOME/.cargo/env && cd yjit && cargo test
-  make_test_script: source $HOME/.cargo/env && make test RUN_OPTS="--yjit-call-threshold=1 --yjit-verify-ctx"
-  make_test_all_script: source $HOME/.cargo/env && make test-all RUN_OPTS="--yjit-call-threshold=1 --yjit-verify-ctx" TESTOPTS="$RUBY_TESTOPTS"
-  make_test_spec_script: source $HOME/.cargo/env && make test-spec RUN_OPTS="--yjit-call-threshold=1 --yjit-verify-ctx"
diff --git a/.github/auto_request_review.yml b/.github/auto_request_review.yml
deleted file mode 100644
index d058b6ca00..0000000000
--- a/.github/auto_request_review.yml
+++ /dev/null
@@ -1,9 +0,0 @@
-files:
-  'yjit*': [team:yjit]
-  'yjit/**/*': [team:yjit]
-  'doc/yjit/*': [team:yjit]
-  'bootstraptest/test_yjit*': [team:yjit]
-  'test/ruby/test_yjit*': [team:yjit]
-  '.github/workflows/yjit*': [team:yjit]
-options:
-  ignore_draft: true
diff --git a/.github/workflows/auto_request_review.yml b/.github/workflows/auto_request_review.yml
deleted file mode 100644
index 340aae4391..0000000000
--- a/.github/workflows/auto_request_review.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-name: Auto Request Review
-on:
-  pull_request_target:
-    types: [opened, ready_for_review, reopened]
-
-permissions:
-  contents: read
-
-jobs:
-  auto-request-review:
-    name: Auto Request Review
-    runs-on: ubuntu-latest
-    if: ${{ github.repository == 'ruby/ruby' }}
-    steps:
-      - name: Request review based on files changes and/or groups the author belongs to
-        uses: necojackarc/auto-request-review@5f91f424cabb3211c669e49e79da8363f7df395b # v0.10.0
-        with:
-          # scope: public_repo
-          token: ${{ secrets.MATZBOT_GITHUB_TOKEN }}
diff --git a/.github/workflows/baseruby.yml b/.github/workflows/baseruby.yml
index 3b21225491..ebaafe3bf0 100644
--- a/.github/workflows/baseruby.yml
+++ b/.github/workflows/baseruby.yml
@@ -33,7 +33,7 @@ permissions:
 jobs:
   baseruby:
     name: BASERUBY
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     strategy:
       matrix:
@@ -48,12 +48,12 @@ jobs:
           - ruby-3.1
 
     steps:
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: .downloaded-cache
           key: downloaded-cache
-      - uses: ruby/setup-ruby@4b2d1d631efa087f8896c15a0c6023dc2f483198 # v1.128.0
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler: none
@@ -65,7 +65,7 @@ jobs:
       - run: make incs
       - run: make all
       - run: make test
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/bundled_gems.yml b/.github/workflows/bundled_gems.yml
index d81059f298..070c0fa1dd 100644
--- a/.github/workflows/bundled_gems.yml
+++ b/.github/workflows/bundled_gems.yml
@@ -41,9 +41,9 @@ jobs:
           echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
           echo "TODAY=$(date +%F)" >> $GITHUB_ENV
 
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: .downloaded-cache
           key: downloaded-cache-${{ github.sha }}
@@ -151,7 +151,7 @@ jobs:
           GIT_COMMITTER_NAME: git
         if: ${{ github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull') && steps.show.outcome == 'failure' }}
 
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/check_dependencies.yml b/.github/workflows/check_dependencies.yml
index fcac6ffc97..79b2916feb 100644
--- a/.github/workflows/check_dependencies.yml
+++ b/.github/workflows/check_dependencies.yml
@@ -33,7 +33,7 @@ jobs:
   update-deps:
     strategy:
       matrix:
-        os: [ubuntu-20.04]
+        os: [ubuntu-22.04]
       fail-fast: true
     runs-on: ${{ matrix.os }}
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
@@ -46,15 +46,14 @@ jobs:
         if: ${{ contains(matrix.os, 'ubuntu') }}
       - name: Install libraries
         run: |
-          brew upgrade
           brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline
         if: ${{ contains(matrix.os, 'macos') }}
       - name: git config
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: .downloaded-cache
           key: downloaded-cache
@@ -64,7 +63,7 @@ jobs:
       - run: make all golf
       - run: ruby tool/update-deps --fix
       - run: git diff --no-ext-diff --ignore-submodules --exit-code
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/cirrus-notify.yml b/.github/workflows/cirrus-notify.yml
deleted file mode 100644
index bd99a71ecd..0000000000
--- a/.github/workflows/cirrus-notify.yml
+++ /dev/null
@@ -1,46 +0,0 @@
-on:
-  check_suite:
-    type: ['completed']
-name: Cirrus CI failure notification
-
-permissions:
-  contents: read
-
-jobs:
-  cirrus-notify:
-    name: After Cirrus CI Failure
-    if: >-
-      github.event.check_suite.app.name == 'Cirrus CI'
-      && github.event.check_suite.conclusion != 'success'
-      && github.event.check_suite.conclusion != 'cancelled'
-      && github.event.check_suite.conclusion != 'skipped'
-      && github.event.check_suite.head_branch == 'master'
-    runs-on: ubuntu-latest
-    steps:
-      - uses: octokit/request-action@8cd8f5d6738d122de9213dc5cf87e116c40f5fae # v2.x
-        id: get_failed_check_run
-        with:
-          route: GET /repos/${{ github.repository }}/check-suites/${{ github.event.check_suite.id }}/check-runs?status=completed
-          mediaType: '{"previews": ["antiope"]}'
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      - name: Dump GitHub context
-        env:
-          GITHUB_CONTEXT: ${{ toJson(github) }}
-        run: echo "$GITHUB_CONTEXT"
-      - name: Dump check_runs
-        env:
-          CHECK_RUNS: ${{ steps.get_failed_check_run.outputs.data }}
-        run: echo "$CHECK_RUNS"
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
-        with:
-          payload: |
-            {
-              "ci": "Cirrus CI",
-              "env": "Cirrus CI",
-              "url": "${{ fromJson(steps.get_failed_check_run.outputs.data).check_runs[0].html_url }}",
-              "commit": "${{ github.event.check_suite.head_commit.id }}",
-              "branch": "${{ github.event.check_suite.head_branch }}"
-            }
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index b86bec4224..8dba76fbe2 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -49,9 +49,9 @@ jobs:
         sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
 
     - name: Checkout repository
-      uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
-    - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+    - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
       with:
         path: .downloaded-cache
         key: downloaded-cache
@@ -63,6 +63,7 @@ jobs:
       uses: github/codeql-action/init@959cbb7472c4d4ad70cdfe6f4976053fe48ab394 # v2.1.37
       with:
         config-file: ./.github/codeql/codeql-config.yml
+        trap-caching: false
 
     - name: Set ENV
       run: echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 82171c16a3..caf12cc0f4 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -80,27 +80,13 @@ jobs:
           - { name: gcc-9,     env: { default_cc: gcc-9 } }
           - { name: gcc-8,     env: { default_cc: gcc-8 } }
           - { name: gcc-7,     env: { default_cc: gcc-7 } }
-          - { name: gcc-6,     env: { default_cc: gcc-6 } }
-          - { name: gcc-5,     env: { default_cc: gcc-5 } }
-          - { name: gcc-4.8,   env: { default_cc: gcc-4.8 } }
-          - name: 'gcc-11 LTO'
-            container: gcc-11
+          - name: 'gcc-13 LTO'
+            container: gcc-13
             env:
-              default_cc: 'gcc-11 -flto=auto -ffat-lto-objects'
+              default_cc: 'gcc-13 -flto=auto -ffat-lto-objects -Werror=lto-type-mismatch'
               optflags: '-O2'
             shared: disable
             # check: true
-          - name: 'gcc-11 annocheck'
-            container: gcc-11
-            env:
-              # Minimal flags to pass the check.
-              default_cc: 'gcc-11 -O2 -fcf-protection -Wa,--generate-missing-build-notes=yes'
-              LDFLAGS: '-Wl,-z,now'
-              # FIXME: Drop skipping options
-              # https://bugs.ruby-lang.org/issues/18061
-              # https://sourceware.org/annobin/annobin.html/Test-pie.html
-              TEST_ANNOCHECK_OPTS: "--skip-pie"
-            check: true
           - { name: clang-16,  env: { default_cc: clang-16 } }
           - { name: clang-15,  env: { default_cc: clang-15 } }
           - { name: clang-14,  env: { default_cc: clang-14 } }
@@ -108,17 +94,15 @@ jobs:
           - { name: clang-12,  env: { default_cc: clang-12 } }
           - { name: clang-11,  env: { default_cc: clang-11 } }
           - { name: clang-10,  env: { default_cc: clang-10 } }
-          - { name: clang-9,   env: { default_cc: clang-9 } }
-          - { name: clang-8,   env: { default_cc: clang-8 } }
-          - { name: clang-7,   env: { default_cc: clang-7 } }
-          - { name: clang-6.0, env: { default_cc: clang-6.0 } }
-          - { name: clang-5.0, env: { default_cc: clang-5.0 } }
-          - { name: clang-4.0, env: { default_cc: clang-4.0 } }
-          - { name: clang-3.9, env: { default_cc: clang-3.9 } }
-          - name: 'clang-14 LTO'
-            container: clang-14
+          # llvm-objcopy<=9 doesn't have --wildcard. It compiles, but leaves Rust symbols in libyjit.o.
+          - { name: clang-9,   env: { default_cc: clang-9,   append_configure: '--disable-yjit' } }
+          - { name: clang-8,   env: { default_cc: clang-8,   append_configure: '--disable-yjit' } }
+          - { name: clang-7,   env: { default_cc: clang-7,   append_configure: '--disable-yjit' } }
+          - { name: clang-6.0, env: { default_cc: clang-6.0, append_configure: '--disable-yjit' } }
+          - name: 'clang-16 LTO'
+            container: clang-16
             env:
-              default_cc: 'clang-14 -flto=auto'
+              default_cc: 'clang-16 -flto=auto'
               optflags: '-O2'
             shared: disable
             # check: true
@@ -184,7 +168,11 @@ jobs:
 #         - { name: VM_CHECK_MODE,                  env: { cppflags: '-DVM_CHECK_MODE' } }
 
           - { name: USE_EMBED_CI=0,                 env: { cppflags: '-DUSE_EMBED_CI=0' } }
-          - { name: USE_FLONUM=0,                   env: { cppflags: '-DUSE_FLONUM=0' } }
+          - name: USE_FLONUM=0,
+            env:
+              cppflags: '-DUSE_FLONUM=0'
+              # yjit requires FLONUM for the pointer tagging scheme
+              append_configure: '--disable-yjit'
 #         - { name: USE_GC_MALLOC_OBJ_INFO_DETAILS, env: { cppflags: '-DUSE_GC_MALLOC_OBJ_INFO_DETAILS' } }
           - { name: USE_LAZY_LOAD,                  env: { cppflags: '-DUSE_LAZY_LOAD' } }
 #         - { name: USE_RINCGC=0,                   env: { cppflags: '-DUSE_RINCGC=0' } }
@@ -237,10 +225,10 @@ jobs:
       - name: setenv
         run: |
           echo "GNUMAKEFLAGS=-sj$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
@@ -274,7 +262,7 @@ jobs:
       - run: make test-annocheck
         if: ${{ matrix.entry.check && endsWith(matrix.entry.name, 'annocheck') }}
 
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 6f04fd34e9..d8dc58b119 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -35,8 +35,9 @@ jobs:
       matrix:
         test_task: ["check"] # "test-bundler-parallel", "test-bundled-gems"
         os:
-          - macos-11
-          - macos-12
+          - macos-13
+          - macos-14
+          - macos-15
       fail-fast: false
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
@@ -49,22 +50,21 @@ jobs:
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
       - name: Install libraries
         run: |
-          brew upgrade
           brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline bison
         working-directory: src
       - name: Set ENV
         run: |
           echo "MAKEFLAGS=-j$((1 + $(sysctl -n hw.activecpu)))" >> $GITHUB_ENV
-          echo "PATH="/usr/local/opt/bison/bin:$PATH"" >> $GITHUB_ENV
+          echo "PATH="/usr/local/opt/bison/bin:/opt/homebrew/opt/bison/bin:$PATH"" >> $GITHUB_ENV
       - run: ./autogen.sh
         working-directory: src
       - name: Run configure
@@ -94,7 +94,7 @@ jobs:
           PRECHECK_BUNDLED_GEMS: "no"
         if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
         continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/mingw.yml b/.github/workflows/mingw.yml
index ba3886218a..0df917d3d8 100644
--- a/.github/workflows/mingw.yml
+++ b/.github/workflows/mingw.yml
@@ -65,15 +65,15 @@ jobs:
           git config --global core.eol lf
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
       - name: Set up Ruby & MSYS2
-        uses: ruby/setup-ruby@4b2d1d631efa087f8896c15a0c6023dc2f483198 # v1.128.0
+        uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
         with:
           ruby-version: ${{ matrix.base_ruby }}
       - name: set env
@@ -159,7 +159,7 @@ jobs:
           make ${{ StartsWith(matrix.test_task, 'spec/') && matrix.test_task || 'test-spec' }}
         if: ${{matrix.test_task == 'check' || matrix.test_task == 'test-spec' || StartsWith(matrix.test_task, 'spec/')}}
 
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/mjit-bindgen.yml b/.github/workflows/mjit-bindgen.yml
index 553306a4f7..26f8a1b2aa 100644
--- a/.github/workflows/mjit-bindgen.yml
+++ b/.github/workflows/mjit-bindgen.yml
@@ -36,7 +36,7 @@ jobs:
         include:
           - task: mjit-bindgen
       fail-fast: false
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
       - run: mkdir build
@@ -52,21 +52,21 @@ jobs:
           build-essential \
           libssl-dev libyaml-dev libreadline6-dev \
           zlib1g-dev libncurses5-dev libffi-dev \
-          libclang1-10 \
+          libclang1-14 \
           bison autoconf
           sudo apt-get install -q -y pkg-config || :
       - name: Set up Ruby
-        uses: ruby/setup-ruby@4b2d1d631efa087f8896c15a0c6023dc2f483198 # v1.128.0
+        uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
         with:
           ruby-version: '3.1'
       - name: git config
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
@@ -85,7 +85,7 @@ jobs:
       - run: make ${{ matrix.task }}
       - run: git diff --exit-code
         working-directory: src
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/mjit.yml b/.github/workflows/mjit.yml
index 8812d759d1..6f7181489a 100644
--- a/.github/workflows/mjit.yml
+++ b/.github/workflows/mjit.yml
@@ -57,10 +57,10 @@ jobs:
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
@@ -94,7 +94,7 @@ jobs:
           unset GNUMAKEFLAGS
           make -s test-spec RUN_OPTS="$RUN_OPTS"
         timeout-minutes: 60
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
new file mode 100644
index 0000000000..5d4474d978
--- /dev/null
+++ b/.github/workflows/publish.yml
@@ -0,0 +1,18 @@
+name: Start release workflow
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  notify:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Build release package
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/actions/dispatches \
+            -d '{"event_type": "${{ github.ref }}"}'
diff --git a/.github/workflows/scorecards.yml b/.github/workflows/scorecards.yml
index 5e2397e693..c12a95362d 100644
--- a/.github/workflows/scorecards.yml
+++ b/.github/workflows/scorecards.yml
@@ -32,12 +32,12 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
 
       - name: "Run analysis"
-        uses: ossf/scorecard-action@e38b1902ae4f44df626f11ba0734b14fb91f8f86 # v2.1.2
+        uses: ossf/scorecard-action@ea651e62978af7915d09fe2e282747c798bf2dab # v2.4.1
         with:
           results_file: results.sarif
           results_format: sarif
@@ -59,7 +59,7 @@ jobs:
       # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
       # format to the repository Actions tab.
       - name: "Upload artifact"
-        uses: actions/upload-artifact@83fd05a356d7e2593de66fc9913b3002723633cb # v3.1.1
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: SARIF file
           path: results.sarif
diff --git a/.github/workflows/spec_guards.yml b/.github/workflows/spec_guards.yml
index cc142b6d05..4521195a2b 100644
--- a/.github/workflows/spec_guards.yml
+++ b/.github/workflows/spec_guards.yml
@@ -6,13 +6,10 @@ on:
       - 'spec/**'
       - '!spec/*.md'
   pull_request:
-    paths-ignore:
+    paths:
       - 'spec/**'
       - '!spec/*.md'
   merge_group:
-    paths-ignore:
-      - 'spec/**'
-      - '!spec/*.md'
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
@@ -24,28 +21,42 @@ permissions:
 jobs:
   rubyspec:
     name: Rubyspec
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.head_commit.message, 'Document')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.title, 'Document')
+      || contains(github.event.pull_request.labels.*.name, 'Document')
+      || (github.event_name == 'push' && github.actor == 'dependabot[bot]')
+      )}}
+
     strategy:
       matrix:
         # Specs from ruby/spec should still run on all supported Ruby versions.
         # This also ensures the needed ruby_version_is guards are there, see spec/README.md.
         ruby:
-          - ruby-2.7
           - ruby-3.1
+          - ruby-3.2
 
     steps:
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
-      - uses: ruby/setup-ruby@4b2d1d631efa087f8896c15a0c6023dc2f483198 # v1.128.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler: none
+
       - run: gem install webrick
+
       - run: ruby ../mspec/bin/mspec
         working-directory: spec/ruby
         env:
           CHECK_LEAKS: true
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
@@ -57,4 +68,4 @@ jobs:
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 637042426a..4fbca1170e 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -53,7 +53,7 @@ jobs:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
       RUBY_DEBUG: ci
       SETARCH: ${{ matrix.arch && format('setarch {0}', matrix.arch) }}
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
       - run: mkdir build
@@ -79,10 +79,10 @@ jobs:
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
@@ -127,7 +127,7 @@ jobs:
           TESTS: ${{ matrix.skipped_tests }}
         if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
         continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
index 1e907a0232..27920b5821 100644
--- a/.github/workflows/wasm.yml
+++ b/.github/workflows/wasm.yml
@@ -50,7 +50,7 @@ jobs:
       WASI_SDK_VERSION_MINOR: 0
       BINARYEN_VERSION: 109
       WASMTIME_VERSION: v0.33.0
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
       - run: mkdir build
@@ -59,7 +59,7 @@ jobs:
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
       - name: Install libraries
@@ -91,6 +91,18 @@ jobs:
           echo "WASI_SDK_PATH=/opt/wasi-sdk" >> $GITHUB_ENV
       - run: ./autogen.sh
         working-directory: src
+
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          ruby-version: '3.0'
+          bundler: none
+
+      - name: Download config.guess with wasi version
+        run: |
+          rm tool/config.guess tool/config.sub
+          ruby tool/downloader.rb -d tool -e gnu config.guess config.sub
+        working-directory: src
+
       - name: Run configure
         run: |
           ../src/configure \
@@ -115,7 +127,7 @@ jobs:
           ruby ./bootstraptest/runner.rb --ruby="$(which wasmtime) run $PWD/../build/ruby --mapdir /::./ -- " --verbose "--sets=$NO_THREAD_TESTS"
         working-directory: src
 
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index afee80a468..c2bd4881c2 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -34,85 +34,68 @@ jobs:
     strategy:
       matrix:
         include:
-          - vs: 2019
           - vs: 2022
+            vcvers: -vcvars_ver=14.2
       fail-fast: false
-    runs-on: windows-${{ matrix.vs < 2022 && '2019' || matrix.vs }}
+    runs-on: windows-${{ matrix.vs }}
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     name: VisualStudio ${{ matrix.vs }}
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
       PATCH: C:\msys64\usr\bin\patch.exe
-      OS_VER: windows-${{ matrix.vs < 2022 && '2019' || matrix.vs }}
+      OS_VER: windows-${{ matrix.vs }}
     steps:
       - run: md build
         working-directory:
-      - uses: msys2/setup-msys2@d40200dc2db4c351366b048a9565ad82919e1c24 # v2
+      - uses: msys2/setup-msys2@61f9e5e925871ba6c9e3e8da24ede83ea27fa91f # v2.27.0
         id: setup-msys2
         with:
           update: true
-          install: >-
-            patch
-        if: ${{ env.OS_VER != 'windows-2019' }}
+          install: bison patch
       - name: patch path
         shell: msys2 {0}
         run: echo PATCH=$(cygpath -wa $(command -v patch)) >> $GITHUB_ENV
         if: ${{ steps.setup-msys2.outcome == 'success' }}
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
-        with:
-          path: C:\vcpkg\downloads
-          key: ${{ runner.os }}-vcpkg-download-${{ env.OS_VER }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-download-${{ env.OS_VER }}-
-            ${{ runner.os }}-vcpkg-download-
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: C:\vcpkg\installed
-          key: ${{ runner.os }}-vcpkg-installed-${{ matrix.os }}-${{ github.sha }}
+          key: ${{ runner.os }}-vcpkg-installed-windows-${{ matrix.vs }}-${{ github.sha }}
           restore-keys: |
-            ${{ runner.os }}-vcpkg-installed-${{ matrix.os }}-
-            ${{ runner.os }}-vcpkg-installed-
+            ${{ runner.os }}-vcpkg-installed-windows-${{ matrix.vs }}-
+            ${{ runner.os }}-vcpkg-installed-windows-
       - name: Install libraries with vcpkg
         run: |
+          iex "& {$(irm get.scoop.sh)} -RunAsAdmin"
+          Join-Path (Resolve-Path ~).Path "scoop\shims" >> $Env:GITHUB_PATH
+          scoop install cmake@3.31.6
           vcpkg --triplet x64-windows install libffi libyaml openssl readline zlib
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
-        with:
-          path: C:\Users\runneradmin\AppData\Local\Temp\chocolatey
-          key: ${{ runner.os }}-chocolatey-${{ env.OS_VER }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-chocolatey-${{ env.OS_VER }}-
-            ${{ runner.os }}-chocolatey-
-      - name: Install libraries with chocolatey
-        run: |
-          # Using Choco-Install for retries, but it doesn't detect failures properly
-          # if you pass multiple package names in a single command.
-          Choco-Install -PackageName winflexbison3
-        shell: pwsh
+        shell:
+          pwsh
       - name: git config
         run: |
           git config --global core.autocrlf false
           git config --global core.eol lf
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
       - name: setup env
         # %TEMP% is inconsistent with %TMP% and test-all expects they are consistent.
         # https://github.com/actions/virtual-environments/issues/712#issuecomment-613004302
+        # msys2/setup-msys2 installs MSYS2 to D:/a/_temp/msys64/usr/bin
         run: |
-          set VS=${{ matrix.vs }}
-          set VCVARS=${{ matrix.vcvars }}
+          set Path=D:/a/_temp/msys64/usr/bin;%Path%
           if not "%VCVARS%" == "" goto :vcset
-            set VCVARS="C:\Program Files (x86)\Microsoft Visual Studio\%VS%\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-            if not exist %VCVARS% set VCVARS="C:\Program Files\Microsoft Visual Studio\%VS%\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
+            set VCVARS="C:\Program Files (x86)\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
+            if not exist %VCVARS% set VCVARS="C:\Program Files\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
           :vcset
           set | C:\msys64\usr\bin\sort > old.env
-          call %VCVARS%
+          call %VCVARS% ${{ matrix.vcvers || ''}}
           set TMP=%USERPROFILE%\AppData\Local\Temp
           set TEMP=%USERPROFILE%\AppData\Local\Temp
           set /a TEST_JOBS=(15 * %NUMBER_OF_PROCESSORS% / 10) > nul
@@ -137,7 +120,7 @@ jobs:
       - run: nmake extract-extlibs
       - run: nmake
         env:
-          YACC: win_bison
+          YACC: bison.exe
       - run: nmake test
         timeout-minutes: 5
       - run: nmake test-spec
@@ -146,7 +129,7 @@ jobs:
         env:
           RUBY_TESTOPTS: -j${{env.TEST_JOBS}} --job-status=normal
         timeout-minutes: 60
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.github/workflows/yjit-ubuntu.yml b/.github/workflows/yjit-ubuntu.yml
index be869d681d..0b7b9046e9 100644
--- a/.github/workflows/yjit-ubuntu.yml
+++ b/.github/workflows/yjit-ubuntu.yml
@@ -33,9 +33,9 @@ jobs:
   cargo:
     name: Rust cargo test
     # GitHub Action's image seems to already contain a Rust 1.58.0.
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       # For now we can't run cargo test --offline because it complains about the
       # capstone dependency, even though the dependency is optional
       #- run: cargo test --offline
@@ -52,9 +52,10 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - test_task: "yjit-bindgen"
-            hint: "To fix: use patch in logs"
-            configure: "--with-gcc=clang-12 --enable-yjit=dev"
+          - test_task: 'yjit-bindgen'
+            hint: 'To fix: use patch in logs'
+            configure: '--with-gcc=clang-14 --enable-yjit=dev'
+            libclang_path: '/usr/lib/llvm-14/lib/libclang.so.1'
 
           - test_task: "check"
             # YJIT should be automatically built in release mode on x86-64 Linux with rustc present
@@ -84,7 +85,7 @@ jobs:
       YJIT_BENCH_OPTS: ${{ matrix.yjit_bench_opts }}
       RUBY_DEBUG: ci
       BUNDLE_JOBS: 8 # for yjit-bench
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
       - run: mkdir build
@@ -101,10 +102,10 @@ jobs:
         run: |
           git config --global advice.detachedHead 0
           git config --global init.defaultBranch garbage
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
           path: src/.downloaded-cache
           key: downloaded-cache
@@ -142,6 +143,7 @@ jobs:
           RUBY_TESTOPTS: "-q --tty=no"
           TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
           PRECHECK_BUNDLED_GEMS: "no"
+          LIBCLANG_PATH: ${{ matrix.libclang_path }}
         continue-on-error: ${{ matrix.test_task == 'yjit-bench' }}
       - name: Show ${{ github.event.pull_request.base.ref }} GitHub URL for yjit-bench comparison
         run: echo "https://github.com/${BASE_REPO}/commit/${BASE_SHA}"
@@ -149,7 +151,7 @@ jobs:
           BASE_REPO: ${{ github.event.pull_request.base.repo.full_name }}
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
         if: ${{ matrix.test_task == 'yjit-bench' && startsWith(github.event_name, 'pull') }}
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 665feba914..0000000000
--- a/.travis.yml
+++ /dev/null
@@ -1,235 +0,0 @@
-# -*- YAML -*-
-# Copyright (C) 2011 Urabe, Shyouhei.  All rights reserved.
-#
-# This file is  a part of the programming language  Ruby.  Permission is hereby
-# granted,  to either  redistribute  or  modify this  file,  provided that  the
-# conditions  mentioned in  the file  COPYING are  met.  Consult  the  file for
-# details.
-
-# We only manage non-amd64 free pipelines.
-# https://docs.travis-ci.com/user/billing-overview/
-
-language: c
-
-os: linux
-
-if: commit_message !~ /\[DOC\]/
-
-dist: focal
-
-git:
-  quiet: true
-
-cache:
-  ccache: true
-  directories:
-    - $HOME/config_2nd
-    - $HOME/.downloaded-cache
-
-env:
-  global:
-    # The tests skipped in `make test-all`.
-    - TEST_ALL_SKIPPED_TESTS=
-    # The tests executed separately by `make test-all`.
-    - TEST_ALL_SEPARATED_TESTS=
-    # Reset timestamps early
-    - _=$(touch NEWS && find . -type f -exec touch -r NEWS {} +)
-    - CONFIGURE_TTY=no
-    - CCACHE_COMPILERCHECK=none
-    - CCACHE_NOCOMPRESS=1
-    - CCACHE_MAXSIZE=512Mi
-    - NPROC="`nproc`"
-    # JOBS and SETARCH are overridden when necessary; see below.
-    - JOBS=-j$((1+${NPROC}))
-    - SETARCH=
-    - RUBY_PREFIX=/tmp/ruby-prefix
-    - GEMS_FOR_TEST='timezone tzinfo'
-    # https://github.com/travis-ci/travis-build/blob/e411371dda21430a60f61b8f3f57943d2fe4d344/lib/travis/build/bash/travis_apt_get_options.bash#L7
-    - travis_apt_get_options='--allow-downgrades --allow-remove-essential --allow-change-held-packages'
-    - travis_apt_get_options="-yq --no-install-suggests --no-install-recommends $travis_apt_get_options"
-    # -O1 is faster than -O3 in our tests.
-    - optflags=-O1
-    # -g0 disables backtraces when SEGV.  Do not set that.
-    - debugflags=-ggdb3
-
-.org.ruby-lang.ci.matrix-definitions:
-
-  - &gcc-10
-    compiler: gcc-10
-    before_install:
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${TRAVIS_ROOT}/var/lib/apt/lists/'* && exec apt-get update -yq"
-      - >-
-        tool/travis_retry.sh sudo -E apt-get $travis_apt_get_options install
-        ccache
-        gcc-10
-        g++-10
-        libffi-dev
-        libncurses-dev
-        libncursesw5-dev
-        libreadline-dev
-        libssl-dev
-        libyaml-dev
-        openssl
-        zlib1g-dev
-
-  # --------
-
-  - &arm64-linux
-    name: arm64-linux
-    arch: arm64
-    <<: *gcc-10
-
-  - &ppc64le-linux
-    name: ppc64le-linux
-    arch: ppc64le
-    <<: *gcc-10
-
-  - &s390x-linux
-    name: s390x-linux
-    arch: s390x
-    <<: *gcc-10
-
-  - &arm32-linux
-    name: arm32-linux
-    arch: arm64
-    # https://packages.ubuntu.com/focal/crossbuild-essential-armhf
-    compiler: arm-linux-gnueabihf-gcc
-    env:
-      - SETARCH='setarch linux32 --verbose --32bit'
-      # The "TestReadline#test_interrupt_in_other_thread" started failing on arm32
-      # from https://www.travis-ci.com/github/ruby/ruby/jobs/529005145
-      - TEST_ALL_SKIPPED_TESTS=test_interrupt_in_other_thread
-    before_install:
-      - sudo dpkg --add-architecture armhf
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${TRAVIS_ROOT}/var/lib/apt/lists/'* && exec apt-get update -yq"
-      - >-
-        tool/travis_retry.sh sudo -E apt-get $travis_apt_get_options install
-        ccache
-        crossbuild-essential-armhf
-        libc6:armhf
-        libstdc++-10-dev:armhf
-        libffi-dev:armhf
-        libncurses-dev:armhf
-        libncursesw5-dev:armhf
-        libreadline-dev:armhf
-        libssl-dev:armhf
-        libyaml-dev:armhf
-        linux-libc-dev:armhf
-        zlib1g-dev:armhf
-
-matrix:
-  include:
-    # Build every commit (Allowed Failures):
-    - <<: *arm32-linux
-    # Comment out as the 2nd arm64 pipeline is unstable.
-    # - <<: *arm64-linux
-    - <<: *ppc64le-linux
-    - <<: *s390x-linux
-  allow_failures:
-    # We see multiple errors indicating errors on the Travis environment itself in a short while:
-    # https://app.travis-ci.com/github/ruby/ruby/jobs/544382885
-    # https://app.travis-ci.com/github/ruby/ruby/jobs/544361370
-    # It's not a fault of Ruby's arm32 support but just Travis arm32 seems unsable.
-    - name: arm32-linux
-    # - name: arm64-linux
-    # We see "Some worker was crashed." in about 40% of recent ppc64le-linux jobs
-    # e.g. https://app.travis-ci.com/github/ruby/ruby/jobs/530959548
-    - name: ppc64le-linux
-    # Tentatively disable, because often hungs up **after** all tests
-    # have finished successfully and saving caches.
-    - name: s390x-linux
-  fast_finish: true
-
-before_script:
-  - . tool/ci_functions.sh
-  - |-
-    if [ -n "${TEST_ALL_SKIPPED_TESTS}" ]; then
-      TEST_ALL_OPTS="${TEST_ALL_OPTS} $(ci_to_excluded_test_opts "${TEST_ALL_SKIPPED_TESTS}")"
-      if [ -z "${TEST_ALL_SEPARATED_TESTS}" ]; then
-        TEST_ALL_SEPARATED_TESTS="${TEST_ALL_SKIPPED_TESTS}"
-      fi
-    fi
-  - |-
-    if [ -n "${TEST_ALL_SEPARATED_TESTS}" ]; then
-      TEST_ALL_OPTS_SEPARATED="$(ci_to_included_test_opts "${TEST_ALL_SEPARATED_TESTS}")"
-    fi
-  - echo TEST_ALL_OPTS="${TEST_ALL_OPTS}" TEST_ALL_OPTS_SEPARATED="${TEST_ALL_OPTS_SEPARATED}"
-  - rm -fr .ext autom4te.cache
-  - |-
-    [ -d ~/.downloaded-cache ] ||
-    mkdir ~/.downloaded-cache
-  - ln -s ~/.downloaded-cache
-  - "> config.status"
-  - "> .rbconfig.time"
-  - sed -f tool/prereq.status template/Makefile.in common.mk > Makefile
-  - make -s $JOBS up
-  - make -s $JOBS srcs
-  - rm -f config.status Makefile rbconfig.rb .rbconfig.time
-  - |-
-    if [ -d ~/config_2nd ]; then
-      cp -pr ~/config_2nd build
-    else
-      mkdir build
-    fi
-  - mkdir config_1st config_2nd gems/src
-  - chmod -R a-w .
-  - chmod -R u+w build config_1st config_2nd gems/src
-  - cd build
-  - |-
-    case "$CC" in
-    gcc*)   CC="ccache $CC${GCC_FLAGS:+ }$GCC_FLAGS -fno-diagnostics-color";;
-    clang*) CC="ccache $CC${GCC_FLAGS:+ }$GCC_FLAGS -fno-color-diagnostics";;
-    esac
-  - |-
-    [ ! -f config.cache ] ||
-    [ "$CC" = "`sed -n s/^ac_cv_prog_CC=//p config.cache`" ] ||
-    (set -x; exec rm config.cache)
-  - $SETARCH ../configure -C --disable-install-doc --prefix=$RUBY_PREFIX $CONFIG_FLAG
-  - cp -pr config.cache config.status .ext/include ../config_1st
-  - $SETARCH make reconfig
-  - cp -pr config.cache config.status .ext/include ../config_2nd
-  - (cd .. && exec diff -ru config_1st config_2nd)
-  - chmod u+w ..
-  - rm -rf ~/config_2nd
-  - mv ../config_2nd ~
-  - chmod u-w ..
-  - $SETARCH make -s $JOBS
-  - make -s install
-  - |-
-    [ -z "${GEMS_FOR_TEST}" ] ||
-    $RUBY_PREFIX/bin/gem install --no-document $GEMS_FOR_TEST
-  - echo "raise 'do not load ~/.irbrc in test'" > ~/.irbrc
-
-script:
-  - $SETARCH make -s test -o showflags TESTOPTS="${TESTOPTS=$JOBS -q --tty=no}"
-  - ../tool/travis_wait.sh $SETARCH make -s test-all -o exts TESTOPTS="$JOBS -q --tty=no ${TEST_ALL_OPTS}" RUBYOPT="-w"
-  # Run the failing tests separately returning ok status to check if it works,
-  # visualize them.
-  - |
-    if [ -n "${TEST_ALL_OPTS_SEPARATED}" ]; then
-      $SETARCH make -s test-all -o exts TESTOPTS="$JOBS -v --tty=no ${TEST_ALL_OPTS_SEPARATED}" RUBYOPT="-w" || :
-    fi
-  - $SETARCH make -s test-spec MSPECOPT=-ff # not using `-j` because sometimes `mspec -j` silently dies
-  - $SETARCH make -s -o showflags leaked-globals
-
-# We enable Travis on the specific branches or forked repositories here.
-if: (repo = ruby/ruby AND (branch = master OR branch =~ /^ruby_\d_\d$/)) OR repo != ruby/ruby
-
-# We want to be notified when something happens.
-notifications:
-  irc:
-    channels:
-      - "chat.freenode.net#ruby-core"
-    on_success: change # [always|never|change] # default: always
-    on_failure: always # [always|never|change] # default: always
-    template:
-      - "%{message} by @%{author}: See %{build_url}"
-
-  webhooks:
-    urls:
-      - secure: mRsoS/UbqDkKkW5p3AEqM27d4SZnV6Gsylo3bm8T/deltQzTsGzZwrm7OIBXZv0UFZdE68XmPlyHfZFLSP2V9QZ7apXMf9/vw0GtcSe1gchtnjpAPF6lYBn7nMCbVPPx9cS0dwL927fjdRM1vj7IKZ2bk4F0lAJ25R25S6teqdk= # ruby-lang slack: ruby/simpler-alerts-bot (travis)
-    on_success: never
-    on_failure: always
-
-  email:
-    - jaruga@ruby-lang.org
diff --git a/NEWS.md b/NEWS.md
index 33a7b85c47..f6c3c6fc97 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -510,7 +510,7 @@ Note: We're only listing outstanding class updates.
     * json 2.6.3
     * logger 1.5.3
     * mutex_m 0.1.2
-    * net-http 0.3.2
+    * net-http 0.4.0
     * net-protocol 0.2.1
     * nkf 0.1.2
     * open-uri 0.3.0
diff --git a/README.ja.md b/README.ja.md
index bb69c09055..93c0131690 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -4,7 +4,6 @@
 [![Actions Status: Windows](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
 [![AppVeyor status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
 [![Travis Status](https://app.travis-ci.com/ruby/ruby.svg?branch=master)](https://app.travis-ci.com/ruby/ruby)
-[![Cirrus Status](https://api.cirrus-ci.com/github/ruby/ruby.svg)](https://cirrus-ci.com/github/ruby/ruby/master)
 
 # Rubyとは
 
diff --git a/README.md b/README.md
index 35ef2d9e89..c445448c71 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,6 @@
 [![Actions Status: Windows](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
 [![AppVeyor status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
 [![Travis Status](https://app.travis-ci.com/ruby/ruby.svg?branch=master)](https://app.travis-ci.com/ruby/ruby)
-[![Cirrus Status](https://api.cirrus-ci.com/github/ruby/ruby.svg)](https://cirrus-ci.com/github/ruby/ruby/master)
 
 # What is Ruby?
 
diff --git a/addr2line.c b/addr2line.c
index f7d5b0239b..e5f25293e2 100644
--- a/addr2line.c
+++ b/addr2line.c
@@ -1145,18 +1145,24 @@ resolve_strx(DebugInfoReader *reader, uint64_t idx)
 }
 
 static void
+debug_info_reader_read_addr_value(DebugInfoReader *reader, DebugInfoValue *v)
+{
+    if (reader->address_size == 4) {
+        set_uint_value(v, read_uint32(&reader->p));
+    } else if (reader->address_size == 8) {
+        set_uint_value(v, read_uint64(&reader->p));
+    } else {
+        fprintf(stderr,"unknown address_size:%d", reader->address_size);
+        abort();
+    }
+}
+
+static void
 debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoValue *v)
 {
     switch (form) {
       case DW_FORM_addr:
-        if (reader->address_size == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->address_size == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
-        } else {
-            fprintf(stderr,"unknown address_size:%d", reader->address_size);
-            abort();
-        }
+        debug_info_reader_read_addr_value(reader, v);
         break;
       case DW_FORM_block2:
         v->size = read_uint16(&reader->p);
@@ -1208,13 +1214,19 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         set_uint_value(v, read_uleb128(reader));
         break;
       case DW_FORM_ref_addr:
-        if (reader->format == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->format == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
+        if (reader->current_version <= 2) {
+            // DWARF Version 2 specifies that references have
+            // the same size as an address on the target system
+            debug_info_reader_read_addr_value(reader, v);
         } else {
-            fprintf(stderr,"unknown format:%d", reader->format);
-            abort();
+            if (reader->format == 4) {
+                set_uint_value(v, read_uint32(&reader->p));
+            } else if (reader->format == 8) {
+                set_uint_value(v, read_uint64(&reader->p));
+            } else {
+                fprintf(stderr,"unknown format:%d", reader->format);
+                abort();
+            }
         }
         break;
       case DW_FORM_ref1:
diff --git a/array.c b/array.c
index 654c79a44d..b76e9a64a3 100644
--- a/array.c
+++ b/array.c
@@ -3736,8 +3736,8 @@ rb_ary_bsearch_index(VALUE ary)
             const VALUE zero = INT2FIX(0);
             switch (rb_cmpint(rb_funcallv(v, id_cmp, 1, &zero), v, zero)) {
               case 0: return INT2FIX(mid);
-              case 1: smaller = 1; break;
-              case -1: smaller = 0;
+              case 1: smaller = 0; break;
+              case -1: smaller = 1;
             }
         }
         else {
diff --git a/bignum.c b/bignum.c
index 8ef19e9751..cb2c3b6f07 100644
--- a/bignum.c
+++ b/bignum.c
@@ -4586,11 +4586,14 @@ big_shift3(VALUE x, int lshift_p, size_t shift_numdigits, int shift_numbits)
 
     if (lshift_p) {
         if (LONG_MAX < shift_numdigits) {
-            rb_raise(rb_eArgError, "too big number");
+          too_big:
+            rb_raise(rb_eRangeError, "shift width too big");
         }
         s1 = shift_numdigits;
         s2 = shift_numbits;
+        if ((size_t)s1 != shift_numdigits) goto too_big;
         xn = BIGNUM_LEN(x);
+        if (LONG_MAX/SIZEOF_BDIGIT <= xn+s1) goto too_big;
         z = bignew(xn+s1+1, BIGNUM_SIGN(x));
         zds = BDIGITS(z);
         BDIGITS_ZERO(zds, s1);
diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index 9d9143d265..5c655b8f25 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1,3 +1,33 @@
+# Regression test for yielding with autosplat to block with
+# optional parameters. https://github.com/Shopify/yjit/issues/313
+assert_equal '[:a, :b, :a, :b]', %q{
+  def yielder(arg) = yield(arg) + yield(arg)
+
+  yielder([:a, :b]) do |c = :c, d = :d|
+    [c, d]
+  end
+}
+
+# Regression test for GC mishap while doing shape transition
+assert_equal '[:ok]', %q{
+  # [Bug #19601]
+  class RegressionTest
+    def initialize
+      @a = @b = @fourth_ivar_does_shape_transition = nil
+    end
+
+    def extender
+      @first_extended_ivar = [:ok]
+    end
+  end
+
+  GC.stress = true
+
+  # Used to crash due to GC run in rb_ensure_iv_list_size()
+  # not marking the newly allocated [:ok].
+  RegressionTest.new.extender.itself
+}
+
 assert_equal 'true', %q{
   # regression test for tracking type of locals for too long
   def local_setting_cmp(five)
@@ -221,6 +251,8 @@ assert_equal 'string', %q{
 
 # Check that exceptions work when getting global variable
 assert_equal 'rescued', %q{
+  Warning[:deprecated] = true
+
   module Warning
     def warn(message)
       raise
@@ -1141,6 +1173,38 @@ assert_equal '42', %q{
   run
 }
 
+# splatting an empty array on a specialized method
+assert_equal 'ok', %q{
+  def run
+    "ok".to_s(*[])
+  end
+
+  run
+  run
+}
+
+# splatting an single element array on a specialized method
+assert_equal '[1]', %q{
+  def run
+    [].<<(*[1])
+  end
+
+  run
+  run
+}
+
+# specialized method with wrong args
+assert_equal 'ok', %q{
+  def run(x)
+    "bad".to_s(123) if x
+  rescue
+    :ok
+  end
+
+  run(false)
+  run(true)
+}
+
 # getinstancevariable on Symbol
 assert_equal '[nil, nil]', %q{
   # @foo to exercise the getinstancevariable instruction
@@ -3456,3 +3520,11 @@ assert_equal 'ok', %q{
 
   cw(4)
 }
+
+assert_normal_exit %{
+  class Bug20997
+    def foo(&) = self.class.name(&)
+
+    new.foo
+  end
+}
diff --git a/class.c b/class.c
index 847c4d0a57..cf0b7b821f 100644
--- a/class.c
+++ b/class.c
@@ -404,6 +404,30 @@ class_init_copy_check(VALUE clone, VALUE orig)
     }
 }
 
+struct cvc_table_copy_ctx {
+    VALUE clone;
+    struct rb_id_table * new_table;
+};
+
+static enum rb_id_table_iterator_result
+cvc_table_copy(ID id, VALUE val, void *data) {
+    struct cvc_table_copy_ctx *ctx = (struct cvc_table_copy_ctx *)data;
+    struct rb_cvar_class_tbl_entry * orig_entry;
+    orig_entry = (struct rb_cvar_class_tbl_entry *)val;
+
+    struct rb_cvar_class_tbl_entry *ent;
+
+    ent = ALLOC(struct rb_cvar_class_tbl_entry);
+    ent->class_value = ctx->clone;
+    ent->cref = orig_entry->cref;
+    ent->global_cvar_state = orig_entry->global_cvar_state;
+    rb_id_table_insert(ctx->new_table, id, (VALUE)ent);
+
+    RB_OBJ_WRITTEN(ctx->clone, Qundef, ent->cref);
+
+    return ID_TABLE_CONTINUE;
+}
+
 static void
 copy_tables(VALUE clone, VALUE orig)
 {
@@ -411,6 +435,17 @@ copy_tables(VALUE clone, VALUE orig)
         rb_free_const_table(RCLASS_CONST_TBL(clone));
         RCLASS_CONST_TBL(clone) = 0;
     }
+    if (RCLASS_CVC_TBL(orig)) {
+        struct rb_id_table *rb_cvc_tbl = RCLASS_CVC_TBL(orig);
+        struct rb_id_table *rb_cvc_tbl_dup = rb_id_table_create(rb_id_table_size(rb_cvc_tbl));
+
+        struct cvc_table_copy_ctx ctx;
+        ctx.clone = clone;
+        ctx.new_table = rb_cvc_tbl_dup;
+        rb_id_table_foreach(rb_cvc_tbl, cvc_table_copy, &ctx);
+        RCLASS_CVC_TBL(clone) = rb_cvc_tbl_dup;
+    }
+    rb_id_table_free(RCLASS_M_TBL(clone));
     RCLASS_M_TBL(clone) = 0;
     if (!RB_TYPE_P(clone, T_ICLASS)) {
         st_data_t id;
@@ -923,7 +958,7 @@ rb_define_class_under(VALUE outer, const char *name, VALUE super)
 }
 
 VALUE
-rb_define_class_id_under(VALUE outer, ID id, VALUE super)
+rb_define_class_id_under_no_pin(VALUE outer, ID id, VALUE super)
 {
     VALUE klass;
 
@@ -940,8 +975,6 @@ rb_define_class_id_under(VALUE outer, ID id, VALUE super)
                      " (%"PRIsVALUE" is given but was %"PRIsVALUE")",
                      outer, rb_id2str(id), RCLASS_SUPER(klass), super);
         }
-        /* Class may have been defined in Ruby and not pin-rooted */
-        rb_vm_add_root_module(klass);
 
         return klass;
     }
@@ -953,12 +986,19 @@ rb_define_class_id_under(VALUE outer, ID id, VALUE super)
     rb_set_class_path_string(klass, outer, rb_id2str(id));
     rb_const_set(outer, id, klass);
     rb_class_inherited(super, klass);
-    rb_vm_add_root_module(klass);
 
     return klass;
 }
 
 VALUE
+rb_define_class_id_under(VALUE outer, ID id, VALUE super)
+{
+    VALUE klass = rb_define_class_id_under_no_pin(outer, id, super);
+    rb_vm_add_root_module(klass);
+    return klass;
+}
+
+VALUE
 rb_module_s_alloc(VALUE klass)
 {
     VALUE mod = class_alloc(T_MODULE, klass);
@@ -1105,8 +1145,8 @@ rb_include_module(VALUE klass, VALUE module)
             iclass = iclass->next;
         }
 
-        int do_include = 1;
         while (iclass) {
+            int do_include = 1;
             VALUE check_class = iclass->klass;
             /* During lazy sweeping, iclass->klass could be a dead object that
              * has not yet been swept. */
@@ -1173,7 +1213,7 @@ static int
 do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super, bool check_cyclic)
 {
     VALUE p, iclass, origin_stack = 0;
-    int method_changed = 0, add_subclass;
+    int method_changed = 0;
     long origin_len;
     VALUE klass_origin = RCLASS_ORIGIN(klass);
     VALUE original_klass = klass;
@@ -1237,7 +1277,6 @@ do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super
         iclass = rb_include_class_new(module, super_class);
         c = RCLASS_SET_SUPER(c, iclass);
         RCLASS_SET_INCLUDER(iclass, klass);
-        add_subclass = TRUE;
         if (module != RCLASS_ORIGIN(module)) {
             if (!origin_stack) origin_stack = rb_ary_hidden_new(2);
             VALUE origin[2] = {iclass, RCLASS_ORIGIN(module)};
@@ -1248,14 +1287,11 @@ do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super
             RCLASS_SET_ORIGIN(RARRAY_AREF(origin_stack, (origin_len -= 2)), iclass);
             RICLASS_SET_ORIGIN_SHARED_MTBL(iclass);
             rb_ary_resize(origin_stack, origin_len);
-            add_subclass = FALSE;
         }
 
-        if (add_subclass) {
-            VALUE m = module;
-            if (BUILTIN_TYPE(m) == T_ICLASS) m = METACLASS_OF(m);
-            rb_module_add_to_subclasses_list(m, iclass);
-        }
+        VALUE m = module;
+        if (BUILTIN_TYPE(m) == T_ICLASS) m = METACLASS_OF(m);
+        rb_module_add_to_subclasses_list(m, iclass);
 
         if (BUILTIN_TYPE(klass) == T_MODULE && FL_TEST(klass, RMODULE_IS_REFINEMENT)) {
             VALUE refined_class =
diff --git a/common.mk b/common.mk
index 3798f82bc6..126053c9c8 100644
--- a/common.mk
+++ b/common.mk
@@ -43,7 +43,7 @@ RUN_OPTS      = --disable-gems
 
 # GITPULLOPTIONS = --no-tags
 
-INCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(srcdir) -I$(UNICODE_HDR_DIR)
+INCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(srcdir) -I$(UNICODE_HDR_DIR) $(incflags)
 
 GEM_HOME =
 GEM_PATH =
@@ -790,7 +790,8 @@ $(arch:noarch=ignore)-fake.rb: $(srcdir)/template/fake.rb.in $(tooldir)/generic_
 	$(ECHO) generating $@
 	$(Q) $(CPP) -DRUBY_EXPORT $(INCFLAGS) $(CPPFLAGS) "$(srcdir)/version.c" | \
 	$(BOOTSTRAPRUBY) "$(tooldir)/generic_erb.rb" -o $@ "$(srcdir)/template/fake.rb.in" \
-		i=- srcdir="$(srcdir)" BASERUBY="$(BASERUBY)"
+	    i=- srcdir="$(srcdir)" BASERUBY="$(BASERUBY)" \
+	    LIBPATHENV="$(LIBPATHENV)" PRELOADENV="$(PRELOADENV)" LIBRUBY_SO="$(LIBRUBY_SO)"
 
 noarch-fake.rb: # prerequisite of yes-fake
 	$(Q) exit > $@
@@ -1436,7 +1437,7 @@ no-test-bundled-gems-prepare: no-test-bundled-gems-precheck
 yes-test-bundled-gems-prepare: yes-test-bundled-gems-precheck
 	$(ACTIONS_GROUP)
 	$(XRUBY) -C "$(srcdir)" bin/gem install --no-document \
-		--install-dir .bundle --conservative "bundler" "minitest:~> 5" "test-unit" "rake" "hoe" "yard" "pry" "packnga" "rexml" "json-schema" "test-unit-rr"
+		--install-dir .bundle --conservative "bundler" "minitest:~> 5" "test-unit" "rake" "hoe" "rexml" "json-schema:5.1.0" "test-unit-rr"
 	$(ACTIONS_ENDGROUP)
 
 PREPARE_BUNDLED_GEMS = test-bundled-gems-prepare
@@ -3220,8 +3221,13 @@ compile.$(OBJEXT): {$(VPATH)}vm_callinfo.h
 compile.$(OBJEXT): {$(VPATH)}vm_core.h
 compile.$(OBJEXT): {$(VPATH)}vm_debug.h
 compile.$(OBJEXT): {$(VPATH)}vm_opts.h
+complex.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
+complex.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
+complex.$(OBJEXT): $(CCAN_DIR)/list/list.h
+complex.$(OBJEXT): $(CCAN_DIR)/str/str.h
 complex.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 complex.$(OBJEXT): $(top_srcdir)/internal/array.h
+complex.$(OBJEXT): $(top_srcdir)/internal/basic_operators.h
 complex.$(OBJEXT): $(top_srcdir)/internal/bignum.h
 complex.$(OBJEXT): $(top_srcdir)/internal/bits.h
 complex.$(OBJEXT): $(top_srcdir)/internal/class.h
@@ -3229,6 +3235,7 @@ complex.$(OBJEXT): $(top_srcdir)/internal/compilers.h
 complex.$(OBJEXT): $(top_srcdir)/internal/complex.h
 complex.$(OBJEXT): $(top_srcdir)/internal/fixnum.h
 complex.$(OBJEXT): $(top_srcdir)/internal/gc.h
+complex.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 complex.$(OBJEXT): $(top_srcdir)/internal/math.h
 complex.$(OBJEXT): $(top_srcdir)/internal/numeric.h
 complex.$(OBJEXT): $(top_srcdir)/internal/object.h
@@ -3239,6 +3246,7 @@ complex.$(OBJEXT): $(top_srcdir)/internal/variable.h
 complex.$(OBJEXT): $(top_srcdir)/internal/vm.h
 complex.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 complex.$(OBJEXT): {$(VPATH)}assert.h
+complex.$(OBJEXT): {$(VPATH)}atomic.h
 complex.$(OBJEXT): {$(VPATH)}backward/2/assume.h
 complex.$(OBJEXT): {$(VPATH)}backward/2/attributes.h
 complex.$(OBJEXT): {$(VPATH)}backward/2/bool.h
@@ -3396,11 +3404,18 @@ complex.$(OBJEXT): {$(VPATH)}internal/value_type.h
 complex.$(OBJEXT): {$(VPATH)}internal/variable.h
 complex.$(OBJEXT): {$(VPATH)}internal/warning_push.h
 complex.$(OBJEXT): {$(VPATH)}internal/xmalloc.h
+complex.$(OBJEXT): {$(VPATH)}method.h
 complex.$(OBJEXT): {$(VPATH)}missing.h
+complex.$(OBJEXT): {$(VPATH)}node.h
 complex.$(OBJEXT): {$(VPATH)}ruby_assert.h
+complex.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 complex.$(OBJEXT): {$(VPATH)}shape.h
 complex.$(OBJEXT): {$(VPATH)}st.h
 complex.$(OBJEXT): {$(VPATH)}subst.h
+complex.$(OBJEXT): {$(VPATH)}thread_$(THREAD_MODEL).h
+complex.$(OBJEXT): {$(VPATH)}thread_native.h
+complex.$(OBJEXT): {$(VPATH)}vm_core.h
+complex.$(OBJEXT): {$(VPATH)}vm_opts.h
 cont.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
 cont.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
 cont.$(OBJEXT): $(CCAN_DIR)/list/list.h
@@ -5889,8 +5904,13 @@ enum.$(OBJEXT): {$(VPATH)}st.h
 enum.$(OBJEXT): {$(VPATH)}subst.h
 enum.$(OBJEXT): {$(VPATH)}symbol.h
 enum.$(OBJEXT): {$(VPATH)}util.h
+enumerator.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
+enumerator.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
+enumerator.$(OBJEXT): $(CCAN_DIR)/list/list.h
+enumerator.$(OBJEXT): $(CCAN_DIR)/str/str.h
 enumerator.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/array.h
+enumerator.$(OBJEXT): $(top_srcdir)/internal/basic_operators.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/bignum.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/bits.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/class.h
@@ -5911,6 +5931,7 @@ enumerator.$(OBJEXT): $(top_srcdir)/internal/struct.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/vm.h
 enumerator.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 enumerator.$(OBJEXT): {$(VPATH)}assert.h
+enumerator.$(OBJEXT): {$(VPATH)}atomic.h
 enumerator.$(OBJEXT): {$(VPATH)}backward/2/assume.h
 enumerator.$(OBJEXT): {$(VPATH)}backward/2/attributes.h
 enumerator.$(OBJEXT): {$(VPATH)}backward/2/bool.h
@@ -6077,13 +6098,20 @@ enumerator.$(OBJEXT): {$(VPATH)}internal/value_type.h
 enumerator.$(OBJEXT): {$(VPATH)}internal/variable.h
 enumerator.$(OBJEXT): {$(VPATH)}internal/warning_push.h
 enumerator.$(OBJEXT): {$(VPATH)}internal/xmalloc.h
+enumerator.$(OBJEXT): {$(VPATH)}method.h
 enumerator.$(OBJEXT): {$(VPATH)}missing.h
+enumerator.$(OBJEXT): {$(VPATH)}node.h
 enumerator.$(OBJEXT): {$(VPATH)}onigmo.h
 enumerator.$(OBJEXT): {$(VPATH)}oniguruma.h
 enumerator.$(OBJEXT): {$(VPATH)}ruby_assert.h
+enumerator.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 enumerator.$(OBJEXT): {$(VPATH)}shape.h
 enumerator.$(OBJEXT): {$(VPATH)}st.h
 enumerator.$(OBJEXT): {$(VPATH)}subst.h
+enumerator.$(OBJEXT): {$(VPATH)}thread_$(THREAD_MODEL).h
+enumerator.$(OBJEXT): {$(VPATH)}thread_native.h
+enumerator.$(OBJEXT): {$(VPATH)}vm_core.h
+enumerator.$(OBJEXT): {$(VPATH)}vm_opts.h
 error.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
 error.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
 error.$(OBJEXT): $(CCAN_DIR)/list/list.h
@@ -7052,6 +7080,7 @@ goruby.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+goruby.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 goruby.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
@@ -8889,8 +8918,13 @@ main.$(OBJEXT): {$(VPATH)}missing.h
 main.$(OBJEXT): {$(VPATH)}st.h
 main.$(OBJEXT): {$(VPATH)}subst.h
 main.$(OBJEXT): {$(VPATH)}vm_debug.h
+marshal.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
+marshal.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
+marshal.$(OBJEXT): $(CCAN_DIR)/list/list.h
+marshal.$(OBJEXT): $(CCAN_DIR)/str/str.h
 marshal.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/array.h
+marshal.$(OBJEXT): $(top_srcdir)/internal/basic_operators.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/bignum.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/bits.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/class.h
@@ -8900,6 +8934,7 @@ marshal.$(OBJEXT): $(top_srcdir)/internal/error.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/fixnum.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/gc.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/hash.h
+marshal.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/numeric.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/object.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/serial.h
@@ -8912,6 +8947,7 @@ marshal.$(OBJEXT): $(top_srcdir)/internal/variable.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/vm.h
 marshal.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 marshal.$(OBJEXT): {$(VPATH)}assert.h
+marshal.$(OBJEXT): {$(VPATH)}atomic.h
 marshal.$(OBJEXT): {$(VPATH)}backward/2/assume.h
 marshal.$(OBJEXT): {$(VPATH)}backward/2/attributes.h
 marshal.$(OBJEXT): {$(VPATH)}backward/2/bool.h
@@ -8927,6 +8963,7 @@ marshal.$(OBJEXT): {$(VPATH)}constant.h
 marshal.$(OBJEXT): {$(VPATH)}defines.h
 marshal.$(OBJEXT): {$(VPATH)}encindex.h
 marshal.$(OBJEXT): {$(VPATH)}encoding.h
+marshal.$(OBJEXT): {$(VPATH)}id.h
 marshal.$(OBJEXT): {$(VPATH)}id_table.h
 marshal.$(OBJEXT): {$(VPATH)}intern.h
 marshal.$(OBJEXT): {$(VPATH)}internal.h
@@ -8967,6 +9004,7 @@ marshal.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+marshal.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 marshal.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
@@ -9082,13 +9120,21 @@ marshal.$(OBJEXT): {$(VPATH)}internal/xmalloc.h
 marshal.$(OBJEXT): {$(VPATH)}io.h
 marshal.$(OBJEXT): {$(VPATH)}marshal.c
 marshal.$(OBJEXT): {$(VPATH)}marshal.rbinc
+marshal.$(OBJEXT): {$(VPATH)}method.h
 marshal.$(OBJEXT): {$(VPATH)}missing.h
+marshal.$(OBJEXT): {$(VPATH)}node.h
 marshal.$(OBJEXT): {$(VPATH)}onigmo.h
 marshal.$(OBJEXT): {$(VPATH)}oniguruma.h
+marshal.$(OBJEXT): {$(VPATH)}ruby_assert.h
+marshal.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 marshal.$(OBJEXT): {$(VPATH)}shape.h
 marshal.$(OBJEXT): {$(VPATH)}st.h
 marshal.$(OBJEXT): {$(VPATH)}subst.h
+marshal.$(OBJEXT): {$(VPATH)}thread_$(THREAD_MODEL).h
+marshal.$(OBJEXT): {$(VPATH)}thread_native.h
 marshal.$(OBJEXT): {$(VPATH)}util.h
+marshal.$(OBJEXT): {$(VPATH)}vm_core.h
+marshal.$(OBJEXT): {$(VPATH)}vm_opts.h
 math.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 math.$(OBJEXT): $(top_srcdir)/internal/bignum.h
 math.$(OBJEXT): $(top_srcdir)/internal/class.h
@@ -9513,6 +9559,7 @@ miniinit.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+miniinit.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 miniinit.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
@@ -10480,8 +10527,13 @@ numeric.$(OBJEXT): {$(VPATH)}shape.h
 numeric.$(OBJEXT): {$(VPATH)}st.h
 numeric.$(OBJEXT): {$(VPATH)}subst.h
 numeric.$(OBJEXT): {$(VPATH)}util.h
+object.$(OBJEXT): $(CCAN_DIR)/check_type/check_type.h
+object.$(OBJEXT): $(CCAN_DIR)/container_of/container_of.h
+object.$(OBJEXT): $(CCAN_DIR)/list/list.h
+object.$(OBJEXT): $(CCAN_DIR)/str/str.h
 object.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 object.$(OBJEXT): $(top_srcdir)/internal/array.h
+object.$(OBJEXT): $(top_srcdir)/internal/basic_operators.h
 object.$(OBJEXT): $(top_srcdir)/internal/bignum.h
 object.$(OBJEXT): $(top_srcdir)/internal/bits.h
 object.$(OBJEXT): $(top_srcdir)/internal/class.h
@@ -10490,6 +10542,7 @@ object.$(OBJEXT): $(top_srcdir)/internal/error.h
 object.$(OBJEXT): $(top_srcdir)/internal/eval.h
 object.$(OBJEXT): $(top_srcdir)/internal/fixnum.h
 object.$(OBJEXT): $(top_srcdir)/internal/gc.h
+object.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 object.$(OBJEXT): $(top_srcdir)/internal/inits.h
 object.$(OBJEXT): $(top_srcdir)/internal/numeric.h
 object.$(OBJEXT): $(top_srcdir)/internal/object.h
@@ -10502,6 +10555,7 @@ object.$(OBJEXT): $(top_srcdir)/internal/variable.h
 object.$(OBJEXT): $(top_srcdir)/internal/vm.h
 object.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 object.$(OBJEXT): {$(VPATH)}assert.h
+object.$(OBJEXT): {$(VPATH)}atomic.h
 object.$(OBJEXT): {$(VPATH)}backward/2/assume.h
 object.$(OBJEXT): {$(VPATH)}backward/2/attributes.h
 object.$(OBJEXT): {$(VPATH)}backward/2/bool.h
@@ -10670,18 +10724,26 @@ object.$(OBJEXT): {$(VPATH)}internal/variable.h
 object.$(OBJEXT): {$(VPATH)}internal/warning_push.h
 object.$(OBJEXT): {$(VPATH)}internal/xmalloc.h
 object.$(OBJEXT): {$(VPATH)}kernel.rbinc
+object.$(OBJEXT): {$(VPATH)}method.h
 object.$(OBJEXT): {$(VPATH)}missing.h
 object.$(OBJEXT): {$(VPATH)}nilclass.rbinc
+object.$(OBJEXT): {$(VPATH)}node.h
 object.$(OBJEXT): {$(VPATH)}object.c
 object.$(OBJEXT): {$(VPATH)}onigmo.h
 object.$(OBJEXT): {$(VPATH)}oniguruma.h
 object.$(OBJEXT): {$(VPATH)}probes.dmyh
 object.$(OBJEXT): {$(VPATH)}probes.h
+object.$(OBJEXT): {$(VPATH)}ruby_assert.h
+object.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 object.$(OBJEXT): {$(VPATH)}shape.h
 object.$(OBJEXT): {$(VPATH)}st.h
 object.$(OBJEXT): {$(VPATH)}subst.h
+object.$(OBJEXT): {$(VPATH)}thread_$(THREAD_MODEL).h
+object.$(OBJEXT): {$(VPATH)}thread_native.h
 object.$(OBJEXT): {$(VPATH)}util.h
 object.$(OBJEXT): {$(VPATH)}variable.h
+object.$(OBJEXT): {$(VPATH)}vm_core.h
+object.$(OBJEXT): {$(VPATH)}vm_opts.h
 pack.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 pack.$(OBJEXT): $(top_srcdir)/internal/array.h
 pack.$(OBJEXT): $(top_srcdir)/internal/bits.h
@@ -11095,6 +11157,7 @@ proc.$(OBJEXT): $(top_srcdir)/internal/compilers.h
 proc.$(OBJEXT): $(top_srcdir)/internal/error.h
 proc.$(OBJEXT): $(top_srcdir)/internal/eval.h
 proc.$(OBJEXT): $(top_srcdir)/internal/gc.h
+proc.$(OBJEXT): $(top_srcdir)/internal/hash.h
 proc.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 proc.$(OBJEXT): $(top_srcdir)/internal/object.h
 proc.$(OBJEXT): $(top_srcdir)/internal/proc.h
@@ -14344,6 +14407,7 @@ signal.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+signal.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 signal.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
@@ -14834,6 +14898,7 @@ st.$(OBJEXT): {$(VPATH)}internal/variable.h
 st.$(OBJEXT): {$(VPATH)}internal/warning_push.h
 st.$(OBJEXT): {$(VPATH)}internal/xmalloc.h
 st.$(OBJEXT): {$(VPATH)}missing.h
+st.$(OBJEXT): {$(VPATH)}ruby_assert.h
 st.$(OBJEXT): {$(VPATH)}st.c
 st.$(OBJEXT): {$(VPATH)}st.h
 st.$(OBJEXT): {$(VPATH)}subst.h
@@ -15099,6 +15164,7 @@ string.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+string.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 string.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
@@ -15540,6 +15606,7 @@ symbol.$(OBJEXT): {$(VPATH)}internal/attr/nodiscard.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/noexcept.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/noinline.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/nonnull.h
+symbol.$(OBJEXT): {$(VPATH)}internal/attr/nonstring.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/noreturn.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/pure.h
 symbol.$(OBJEXT): {$(VPATH)}internal/attr/restrict.h
diff --git a/compile.c b/compile.c
index da89d0e0ca..0452305923 100644
--- a/compile.c
+++ b/compile.c
@@ -1243,6 +1243,32 @@ new_adjust_body(rb_iseq_t *iseq, LABEL *label, int line)
     return adjust;
 }
 
+static void
+iseq_insn_each_markable_object(INSN *insn, void (*func)(VALUE *, VALUE), VALUE data)
+{
+    const char *types = insn_op_types(insn->insn_id);
+    for (int j = 0; types[j]; j++) {
+        char type = types[j];
+        switch (type) {
+          case TS_CDHASH:
+          case TS_ISEQ:
+          case TS_VALUE:
+          case TS_IC: // constant path array
+          case TS_CALLDATA: // ci is stored.
+            func(&OPERAND_AT(insn, j), data);
+            break;
+          default:
+            break;
+        }
+    }
+}
+
+static void
+iseq_insn_each_object_write_barrier(VALUE *obj_ptr, VALUE iseq)
+{
+    RB_OBJ_WRITTEN(iseq, Qundef, *obj_ptr);
+}
+
 static INSN *
 new_insn_core(rb_iseq_t *iseq, const NODE *line_node,
               int insn_id, int argc, VALUE *argv)
@@ -1260,6 +1286,9 @@ new_insn_core(rb_iseq_t *iseq, const NODE *line_node,
     iobj->operands = argv;
     iobj->operand_size = argc;
     iobj->sc_state = 0;
+
+    iseq_insn_each_markable_object(iobj, iseq_insn_each_object_write_barrier, (VALUE)iseq);
+
     return iobj;
 }
 
@@ -2631,9 +2660,11 @@ iseq_set_exception_table(rb_iseq_t *iseq)
     struct iseq_catch_table_entry *entry;
 
     ISEQ_BODY(iseq)->catch_table = NULL;
-    if (NIL_P(ISEQ_COMPILE_DATA(iseq)->catch_table_ary)) return COMPILE_OK;
-    tlen = (int)RARRAY_LEN(ISEQ_COMPILE_DATA(iseq)->catch_table_ary);
-    tptr = RARRAY_CONST_PTR_TRANSIENT(ISEQ_COMPILE_DATA(iseq)->catch_table_ary);
+
+    VALUE catch_table_ary = ISEQ_COMPILE_DATA(iseq)->catch_table_ary;
+    if (NIL_P(catch_table_ary)) return COMPILE_OK;
+    tlen = (int)RARRAY_LEN(catch_table_ary);
+    tptr = RARRAY_CONST_PTR_TRANSIENT(catch_table_ary);
 
     if (tlen > 0) {
         struct iseq_catch_table *table = xmalloc(iseq_catch_table_bytes(tlen));
@@ -2669,6 +2700,8 @@ iseq_set_exception_table(rb_iseq_t *iseq)
         RB_OBJ_WRITE(iseq, &ISEQ_COMPILE_DATA(iseq)->catch_table_ary, 0); /* free */
     }
 
+    RB_GC_GUARD(catch_table_ary);
+
     return COMPILE_OK;
 }
 
@@ -2807,7 +2840,6 @@ remove_unreachable_chunk(rb_iseq_t *iseq, LINK_ELEMENT *i)
                 break;
             }
             else if ((lab = find_destination((INSN *)i)) != 0) {
-                if (lab->unremovable) break;
                 unref_counts[lab->label_no]++;
             }
         }
@@ -2824,8 +2856,7 @@ remove_unreachable_chunk(rb_iseq_t *iseq, LINK_ELEMENT *i)
             /* do nothing */
         }
         else if (IS_ADJUST(i)) {
-            LABEL *dest = ((ADJUST *)i)->label;
-            if (dest && dest->unremovable) return 0;
+            return 0;
         }
         end = i;
     } while ((i = i->next) != 0);
@@ -4589,7 +4620,12 @@ compile_array_1(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *node)
     }
     else {
         CHECK(COMPILE_(ret, "array element", node, FALSE));
-        ADD_INSN1(ret, node, newarray, INT2FIX(1));
+        if (keyword_node_p(node)) {
+            ADD_INSN1(ret, node, newarraykwsplat, INT2FIX(1));
+        }
+        else {
+            ADD_INSN1(ret, node, newarray, INT2FIX(1));
+        }
     }
 
     return 1;
@@ -5040,12 +5076,17 @@ compile_massign_lhs(rb_iseq_t *iseq, LINK_ANCHOR *const pre, LINK_ANCHOR *const
 
         CHECK(COMPILE_POPPED(pre, "masgn lhs (NODE_ATTRASGN)", node));
 
+        bool safenav_call = false;
         LINK_ELEMENT *insn_element = LAST_ELEMENT(pre);
         iobj = (INSN *)get_prev_insn((INSN *)insn_element); /* send insn */
         ASSUME(iobj);
-        ELEM_REMOVE(LAST_ELEMENT(pre));
-        ELEM_REMOVE((LINK_ELEMENT *)iobj);
-        pre->last = iobj->link.prev;
+        ELEM_REMOVE(insn_element);
+        if (!IS_INSN_ID(iobj, send)) {
+            safenav_call = true;
+            iobj = (INSN *)get_prev_insn(iobj);
+            ELEM_INSERT_NEXT(&iobj->link, insn_element);
+        }
+        (pre->last = iobj->link.prev)->next = 0;
 
         const struct rb_callinfo *ci = (struct rb_callinfo *)OPERAND_AT(iobj, 0);
         int argc = vm_ci_argc(ci) + 1;
@@ -5064,7 +5105,9 @@ compile_massign_lhs(rb_iseq_t *iseq, LINK_ANCHOR *const pre, LINK_ANCHOR *const
             return COMPILE_NG;
         }
 
-        ADD_ELEM(lhs, (LINK_ELEMENT *)iobj);
+        iobj->link.prev = lhs->last;
+        lhs->last->next = &iobj->link;
+        for (lhs->last = &iobj->link; lhs->last->next; lhs->last = lhs->last->next);
         if (vm_ci_flag(ci) & VM_CALL_ARGS_SPLAT) {
             int argc = vm_ci_argc(ci);
             ci = ci_argc_set(iseq, ci, argc - 1);
@@ -5073,9 +5116,11 @@ compile_massign_lhs(rb_iseq_t *iseq, LINK_ANCHOR *const pre, LINK_ANCHOR *const
             INSERT_BEFORE_INSN1(iobj, line_node, newarray, INT2FIX(1));
             INSERT_BEFORE_INSN(iobj, line_node, concatarray);
         }
-        ADD_INSN(lhs, line_node, pop);
-        if (argc != 1) {
+        if (!safenav_call) {
             ADD_INSN(lhs, line_node, pop);
+            if (argc != 1) {
+                ADD_INSN(lhs, line_node, pop);
+            }
         }
         for (int i=0; i < argc; i++) {
             ADD_INSN(post, line_node, pop);
@@ -7612,7 +7657,6 @@ compile_next(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node, in
         add_ensure_iseq(ret, iseq, 0);
         ADD_INSNL(ret, line_node, jump, ISEQ_COMPILE_DATA(iseq)->end_label);
         ADD_ADJUST_RESTORE(ret, splabel);
-        splabel->unremovable = FALSE;
 
         if (!popped) {
             ADD_INSN(ret, line_node, putnil);
@@ -9277,7 +9321,8 @@ compile_attrasgn(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node
     /* optimization shortcut
      *   obj["literal"] = value -> opt_aset_with(obj, "literal", value)
      */
-    if (mid == idASET && !private_recv_p(node) && node->nd_args &&
+    if (!ISEQ_COMPILE_DATA(iseq)->in_masgn &&
+        mid == idASET && !private_recv_p(node) && node->nd_args &&
         nd_type_p(node->nd_args, NODE_LIST) && node->nd_args->nd_alen == 2 &&
         nd_type_p(node->nd_args->nd_head, NODE_STR) &&
         ISEQ_COMPILE_DATA(iseq)->current_block == NULL &&
@@ -9475,7 +9520,10 @@ iseq_compile_each0(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const no
       }
 
       case NODE_MASGN:{
+        bool prev_in_masgn = ISEQ_COMPILE_DATA(iseq)->in_masgn;
+        ISEQ_COMPILE_DATA(iseq)->in_masgn = true;
         compile_massign(iseq, ret, node, popped);
+        ISEQ_COMPILE_DATA(iseq)->in_masgn = prev_in_masgn;
         break;
       }
 
@@ -9717,7 +9765,12 @@ iseq_compile_each0(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const no
       case NODE_LIT:{
         debugp_param("lit", node->nd_lit);
         if (!popped) {
-            ADD_INSN1(ret, node, putobject, node->nd_lit);
+            if (UNLIKELY(node->nd_lit == rb_mRubyVMFrozenCore)) {
+                ADD_INSN1(ret, node, putspecialobject, INT2FIX(VM_SPECIAL_OBJECT_VMCORE)); // [Bug #20569]
+            }
+            else {
+                ADD_INSN1(ret, node, putobject, node->nd_lit);
+            }
             RB_OBJ_WRITTEN(iseq, Qundef, node->nd_lit);
         }
         break;
@@ -10735,6 +10788,12 @@ iseq_build_kw(rb_iseq_t *iseq, VALUE params, VALUE keywords)
     return keyword;
 }
 
+static void
+iseq_insn_each_object_mark(VALUE *obj_ptr, VALUE _)
+{
+    rb_gc_mark(*obj_ptr);
+}
+
 void
 rb_iseq_mark_insn_storage(struct iseq_compile_data_storage *storage)
 {
@@ -10761,29 +10820,7 @@ rb_iseq_mark_insn_storage(struct iseq_compile_data_storage *storage)
             iobj = (INSN *)&storage->buff[pos];
 
             if (iobj->operands) {
-                int j;
-                const char *types = insn_op_types(iobj->insn_id);
-
-                for (j = 0; types[j]; j++) {
-                    char type = types[j];
-                    switch (type) {
-                      case TS_CDHASH:
-                      case TS_ISEQ:
-                      case TS_VALUE:
-                      case TS_IC: // constant path array
-                      case TS_CALLDATA: // ci is stored.
-                        {
-                            VALUE op = OPERAND_AT(iobj, j);
-
-                            if (!SPECIAL_CONST_P(op)) {
-                                rb_gc_mark(op);
-                            }
-                        }
-                        break;
-                      default:
-                        break;
-                    }
-                }
+                iseq_insn_each_markable_object(iobj, iseq_insn_each_object_mark, (VALUE)0);
             }
             pos += (int)size;
         }
diff --git a/complex.c b/complex.c
index 57962f9013..a227cb0a58 100644
--- a/complex.c
+++ b/complex.c
@@ -2116,8 +2116,11 @@ nucomp_convert(VALUE klass, VALUE a1, VALUE a2, int raise)
             return a1;
         /* should raise exception for consistency */
         if (!k_numeric_p(a1)) {
-            if (!raise)
-                return rb_protect(to_complex, a1, NULL);
+            if (!raise) {
+                a1 = rb_protect(to_complex, a1, NULL);
+                rb_set_errinfo(Qnil);
+                return a1;
+            }
             return to_complex(a1);
         }
     }
diff --git a/configure.ac b/configure.ac
index 151a0da970..220392d120 100644
--- a/configure.ac
+++ b/configure.ac
@@ -214,15 +214,23 @@ AS_CASE(["/${rb_CC} "],
 [*clang*],            [
     # Ditto for LLVM.  Note however that llvm-as is a LLVM-IR to LLVM bitcode
     # assembler that does not target your machine native binary.
-    : ${LD:="${CC}"}         # ... try -fuse-ld=lld ?
-    RUBY_CHECK_PROG_FOR_CC([AR],      [s/clang/llvm-ar/])
-#   RUBY_CHECK_PROG_FOR_CC([AS],      [s/clang/llvm-as/])
+
+    # Xcode has its own version tools that may be incompatible with
+    # genuine LLVM tools, use the tools in the same directory.
+
+    AS_IF([$rb_CC -E -dM -xc - < /dev/null | grep -F __apple_build_version__ > /dev/null],
+          [llvm_prefix=], [llvm_prefix=llvm-])
+    # AC_PREPROC_IFELSE cannot be used before AC_USE_SYSTEM_EXTENSIONS
+
+    RUBY_CHECK_PROG_FOR_CC([LD],      [s/clang/ld/]) # ... maybe try lld ?
+    RUBY_CHECK_PROG_FOR_CC([AR],      [s/clang/${llvm_prefix}ar/])
+#   RUBY_CHECK_PROG_FOR_CC([AS],      [s/clang/${llvm_prefix}as/])
     RUBY_CHECK_PROG_FOR_CC([CXX],     [s/clang/clang++/])
-    RUBY_CHECK_PROG_FOR_CC([NM],      [s/clang/llvm-nm/])
-    RUBY_CHECK_PROG_FOR_CC([OBJCOPY], [s/clang/llvm-objcopy/])
-    RUBY_CHECK_PROG_FOR_CC([OBJDUMP], [s/clang/llvm-objdump/])
-    RUBY_CHECK_PROG_FOR_CC([RANLIB],  [s/clang/llvm-ranlib/])
-    RUBY_CHECK_PROG_FOR_CC([STRIP],   [s/clang/llvm-strip/])
+    RUBY_CHECK_PROG_FOR_CC([NM],      [s/clang/${llvm_prefix}nm/])
+    RUBY_CHECK_PROG_FOR_CC([OBJCOPY], [s/clang/${llvm_prefix}objcopy/])
+    RUBY_CHECK_PROG_FOR_CC([OBJDUMP], [s/clang/${llvm_prefix}objdump/])
+    RUBY_CHECK_PROG_FOR_CC([RANLIB],  [s/clang/${llvm_prefix}ranlib/])
+    RUBY_CHECK_PROG_FOR_CC([STRIP],   [s/clang/${llvm_prefix}strip/])
 ])
 AS_UNSET(rb_CC)
 AS_UNSET(rb_dummy)
@@ -967,9 +975,10 @@ AS_IF([test "x$OPT_DIR" != x], [
     LDFLAGS="${LDFLAGS:+$LDFLAGS }$val"
     DLDFLAGS="${DLDFLAGS:+$DLDFLAGS }$val"
     LDFLAGS_OPTDIR="$val"
-    CPPFLAGS="${CPPFLAGS:+$CPPFLAGS }"`echo "$OPT_DIR" | tr "${PATH_SEPARATOR}" '\012' |
+    INCFLAGS="${INCFLAGS:+$INCFLAGS }"`echo "$OPT_DIR" | tr "${PATH_SEPARATOR}" '\012' |
         sed '/^$/d;s|^|-I|;s|$|/include|' | tr '\012' ' ' | sed 's/ *$//'`
 ])
+AC_SUBST(incflags, "$INCFLAGS")
 
 test -z "${ac_env_CFLAGS_set}" -a -n "${cflags+set}" && eval CFLAGS="\"$cflags $ARCH_FLAG\""
 test -z "${ac_env_CXXFLAGS_set}" -a -n "${cxxflags+set}" && eval CXXFLAGS="\"$cxxflags $ARCH_FLAG\""
@@ -1194,8 +1203,6 @@ main()
 		ac_cv_func_gmtime_r=yes
 		rb_cv_large_fd_select=yes
 		ac_cv_type_struct_timeval=yes
-                ac_cv_func_clock_gettime=yes
-                ac_cv_func_clock_getres=yes
 		ac_cv_func_malloc_usable_size=no
 		ac_cv_type_off_t=yes
 		ac_cv_sizeof_off_t=8
@@ -1341,6 +1348,8 @@ AC_CHECK_HEADERS(syscall.h)
 AC_CHECK_HEADERS(time.h)
 AC_CHECK_HEADERS(ucontext.h)
 AC_CHECK_HEADERS(utime.h)
+AC_CHECK_HEADERS(stdatomic.h)
+
 AS_CASE("$target_cpu", [x64|x86_64|i[3-6]86*], [
   AC_CHECK_HEADERS(x86intrin.h)
 ])
@@ -1357,6 +1366,8 @@ AC_ARG_WITH([jemalloc],
   [with_jemalloc=$withval], [with_jemalloc=no])
 AS_IF([test "x$with_jemalloc" != xno],[
   # find jemalloc header first
+  save_CPPFLAGS="${CPPFLAGS}"
+  CPPFLAGS="${INCFLAGS} ${CPPFLAGS}"
   malloc_header=
   AC_CHECK_HEADER(jemalloc/jemalloc.h, [malloc_header=jemalloc/jemalloc.h], [
     AC_CHECK_HEADER(jemalloc.h, [malloc_header=jemalloc.h])
@@ -1388,6 +1399,8 @@ AS_IF([test "x$with_jemalloc" != xno],[
       done
     done
   ])
+  CPPFLAGS="${save_CPPFLAGS}"
+  unset save_CPPFLAGS
   with_jemalloc=${rb_cv_jemalloc_library}
   AS_CASE(["$with_jemalloc"],
   [no],
@@ -1998,6 +2011,7 @@ AC_CHECK_FUNCS(_longjmp)		# used for AC_ARG_WITH(setjmp-type)
 test x$ac_cv_func__longjmp = xno && ac_cv_func__setjmp=no
 AC_CHECK_FUNCS(arc4random_buf)
 AC_CHECK_FUNCS(atan2l atan2f)
+AC_CHECK_DECLS(atomic_signal_fence, [], [], [#include <stdatomic.h>])
 AC_CHECK_FUNCS(chmod)
 AC_CHECK_FUNCS(chown)
 AC_CHECK_FUNCS(chroot)
@@ -3052,7 +3066,7 @@ AC_SUBST(EXTOBJS)
 	[darwin*], [	: ${LDSHARED='$(CC) -dynamic -bundle'}
 			: ${DLDSHARED='$(CC) -dynamiclib'}
 			: ${LDFLAGS=""}
-			: ${LIBPATHENV=DYLD_FALLBACK_LIBRARY_PATH}
+			: ${LIBPATHENV=DYLD_LIBRARY_PATH}
 			: ${PRELOADENV=DYLD_INSERT_LIBRARIES}
                         AS_IF([test x"$enable_shared" = xyes], [
                             # Resolve symbols from libruby.dylib when --enable-shared
diff --git a/cont.c b/cont.c
index a1cb1c8ba0..5375d1945b 100644
--- a/cont.c
+++ b/cont.c
@@ -1255,6 +1255,8 @@ jit_cont_new(rb_execution_context_t *ec)
 static void
 jit_cont_free(struct rb_jit_cont *cont)
 {
+    if (!cont) return;
+
     rb_native_mutex_lock(&jit_cont_lock);
     if (cont == first_jit_cont) {
         first_jit_cont = cont->next;
@@ -2095,7 +2097,7 @@ rb_fiber_storage_get(VALUE self)
 static int
 fiber_storage_validate_each(VALUE key, VALUE value, VALUE _argument)
 {
-    rb_check_id(&key);
+    Check_Type(key, T_SYMBOL);
 
     return ST_CONTINUE;
 }
@@ -2167,8 +2169,7 @@ rb_fiber_storage_set(VALUE self, VALUE value)
 static VALUE
 rb_fiber_storage_aref(VALUE class, VALUE key)
 {
-    ID id = rb_check_id(&key);
-    if (!id) return Qnil;
+    Check_Type(key, T_SYMBOL);
 
     VALUE storage = fiber_storage_get(fiber_current());
 
@@ -2190,8 +2191,7 @@ rb_fiber_storage_aref(VALUE class, VALUE key)
 static VALUE
 rb_fiber_storage_aset(VALUE class, VALUE key, VALUE value)
 {
-    ID id = rb_check_id(&key);
-    if (!id) return Qnil;
+    Check_Type(key, T_SYMBOL);
 
     VALUE storage = fiber_storage_get(fiber_current());
 
@@ -2339,7 +2339,7 @@ rb_fiber_initialize(int argc, VALUE* argv, VALUE self)
 VALUE
 rb_fiber_new_storage(rb_block_call_func_t func, VALUE obj, VALUE storage)
 {
-    return fiber_initialize(fiber_alloc(rb_cFiber), rb_proc_new(func, obj), rb_fiber_pool_default(Qnil), 1, storage);
+    return fiber_initialize(fiber_alloc(rb_cFiber), rb_proc_new(func, obj), rb_fiber_pool_default(Qnil), 0, storage);
 }
 
 VALUE
@@ -2799,7 +2799,8 @@ rb_fiber_blocking(VALUE class)
     // If we are already blocking, this is essentially a no-op:
     if (fiber->blocking) {
         return rb_yield(fiber_value);
-    } else {
+    }
+    else {
         return rb_ensure(fiber_blocking_yield, fiber_value, fiber_blocking_ensure, fiber_value);
     }
 }
diff --git a/coroutine/asyncify/Context.h b/coroutine/asyncify/Context.h
index 7dba829a1d..71791a4004 100644
--- a/coroutine/asyncify/Context.h
+++ b/coroutine/asyncify/Context.h
@@ -13,6 +13,7 @@
 
 #include <stddef.h>
 #include <stdio.h>
+#include <stdint.h>
 #include "wasm/asyncify.h"
 #include "wasm/machine.h"
 #include "wasm/fiber.h"
@@ -47,10 +48,13 @@ static inline void coroutine_initialize_main(struct coroutine_context * context)
 
 static inline void coroutine_initialize(struct coroutine_context *context, coroutine_start start, void *stack, size_t size)
 {
-    if (ASYNCIFY_CORO_DEBUG) fprintf(stderr, "[%s] entry (context = %p, stack = %p ... %p)\n", __func__, context, stack, (char *)stack + size);
+    // Linear stack pointer must be always aligned down to 16 bytes.
+    // https://github.com/WebAssembly/tool-conventions/blob/c74267a5897c1bdc9aa60adeaf41816387d3cd12/BasicCABI.md#the-linear-stack
+    uintptr_t sp = ((uintptr_t)stack + size) & ~0xF;
+    if (ASYNCIFY_CORO_DEBUG) fprintf(stderr, "[%s] entry (context = %p, stack = %p ... %p)\n", __func__, context, stack, (char *)sp);
     rb_wasm_init_context(&context->fc, coroutine_trampoline, start, context);
     // record the initial stack pointer position to restore it after resumption
-    context->current_sp = (char *)stack + size;
+    context->current_sp = (char *)sp;
     context->stack_base = stack;
     context->size = size;
 }
diff --git a/cygwin/GNUmakefile.in b/cygwin/GNUmakefile.in
index 43e92a27f0..f342d2fcf7 100644
--- a/cygwin/GNUmakefile.in
+++ b/cygwin/GNUmakefile.in
@@ -2,6 +2,9 @@ gnumake = yes
 
 include Makefile
 
+MUNICODE_FLAG := $(if $(filter mingw%,$(target_os)),-municode)
+override EXE_LDFLAGS += $(MUNICODE_FLAG)
+
 DLLWRAP = @DLLWRAP@ --target=$(target_os) --driver-name="$(CC)"
 windres-cpp := $(CPP) -xc
 windres-cpp := --preprocessor=$(firstword $(windres-cpp)) \
@@ -63,7 +66,7 @@ $(PROGRAM): $(RUBY_INSTALL_NAME).res.$(OBJEXT)
 $(WPROGRAM): $(RUBYW_INSTALL_NAME).res.$(OBJEXT)
 	@rm -f $@
 	$(ECHO) linking $@
-	$(Q) $(PURIFY) $(CC) -mwindows -e $(SYMBOL_PREFIX)mainCRTStartup $(LDFLAGS) $(XLDFLAGS) \
+	$(Q) $(PURIFY) $(CC) $(MUNICODE_FLAG) -mwindows -e $(SYMBOL_PREFIX)mainCRTStartup $(LDFLAGS) $(XLDFLAGS) \
 	  $(MAINOBJ) $(EXTOBJS) $(LIBRUBYARG) $(LIBS) -o $@
 $(STUBPROGRAM): $(RUBY_INSTALL_NAME).res.$(OBJEXT)
 
diff --git a/doc/.document b/doc/.document
index 5ef2d99651..f589dda07c 100644
--- a/doc/.document
+++ b/doc/.document
@@ -6,3 +6,4 @@ NEWS
 syntax
 optparse
 rdoc
+yjit
diff --git a/doc/net-http/examples.rdoc b/doc/net-http/examples.rdoc
index dd4acecda6..c1366e7ad1 100644
--- a/doc/net-http/examples.rdoc
+++ b/doc/net-http/examples.rdoc
@@ -10,9 +10,10 @@ Many code examples here use these example websites:
 
 Some examples also assume these variables:
 
-  uri = URI('https://jsonplaceholder.typicode.com')
+  uri = URI('https://jsonplaceholder.typicode.com/')
   uri.freeze # Examples may not modify.
   hostname = uri.hostname # => "jsonplaceholder.typicode.com"
+  path = uri.path         # => "/"
   port = uri.port         # => 443
 
 So that example requests may be written as:
diff --git a/doc/net-http/included_getters.rdoc b/doc/net-http/included_getters.rdoc
new file mode 100644
index 0000000000..7ac327f4b4
--- /dev/null
+++ b/doc/net-http/included_getters.rdoc
@@ -0,0 +1,3 @@
+This class also includes (indirectly) module Net::HTTPHeader,
+which gives access to its
+{methods for getting headers}[rdoc-ref:Net::HTTPHeader@Getters].
diff --git a/doc/yjit/yjit.md b/doc/yjit/yjit.md
index 0ab6b99ded..67b2ffa5f0 100644
--- a/doc/yjit/yjit.md
+++ b/doc/yjit/yjit.md
@@ -9,9 +9,9 @@ YJIT - Yet Another Ruby JIT
 ===========================
 
 YJIT is a lightweight, minimalistic Ruby JIT built inside CRuby.
-It lazily compiles code using a Basic Block Versioning (BBV) architecture. The target use case is that of servers running
-Ruby on Rails, an area where MJIT has not yet managed to deliver speedups.
-YJIT is currently supported for macOS and Linux on x86-64 and arm64/aarch64 CPUs.
+It lazily compiles code using a Basic Block Versioning (BBV) architecture.
+The target use case is that of servers running Ruby on Rails.
+YJIT is currently supported for macOS, Linux and BSD on x86-64 and arm64/aarch64 CPUs.
 This project is open source and falls under the same license as CRuby.
 
 <p align="center"><b>
@@ -20,6 +20,8 @@ This project is open source and falls under the same license as CRuby.
  </b></p>
 
 If you wish to learn more about the approach taken, here are some conference talks and publications:
+- RubyKaigi 2022 keynote: [Stories from developing YJIT](https://www.youtube.com/watch?v=EMchdR9C8XM)
+- RubyKaigi 2022 talk: [Building a Lightweight IR and Backend for YJIT](https://www.youtube.com/watch?v=BbLGqTxTRp0)
 - RubyKaigi 2021 talk: [YJIT: Building a New JIT Compiler Inside CRuby](https://www.youtube.com/watch?v=PBVLf3yfMs8)
 - Blog post: [YJIT: Building a New JIT Compiler Inside CRuby](https://pointersgonewild.com/2021/06/02/yjit-building-a-new-jit-compiler-inside-cruby/)
 - VMIL 2021 paper: [YJIT: A Basic Block Versioning JIT Compiler for CRuby](https://dl.acm.org/doi/10.1145/3486606.3486781)
@@ -52,8 +54,7 @@ series = {VMIL 2021}
 
 ## Current Limitations
 
-YJIT may not be suitable for certain applications. It currently only supports macOS and Linux on x86-64 and arm64/aarch64 CPUs. YJIT will use more memory than the Ruby interpreter because the JIT compiler needs to generate machine code in memory and maintain additional state
-information.
+YJIT may not be suitable for certain applications. It currently only supports macOS and Linux on x86-64 and arm64/aarch64 CPUs. YJIT will use more memory than the Ruby interpreter because the JIT compiler needs to generate machine code in memory and maintain additional state information.
 You can change how much executable memory is allocated using [YJIT's command-line options](#command-line-options). There is a slight performance tradeoff because allocating less executable memory could result in the generated machine code being collected more often.
 
 ## Installation
@@ -80,22 +81,31 @@ git clone https://github.com/ruby/ruby yjit
 cd yjit
 ```
 
-The YJIT `ruby` binary can be built with either GCC or Clang. It can be built either in dev (debug) mode or in release mode. For maximum performance, compile YJIT in release mode with GCC. More detailed build instructions are provided in the [Ruby README](https://github.com/ruby/ruby#how-to-compile-and-install).
+The YJIT `ruby` binary can be built with either GCC or Clang. It can be built either in dev (debug) mode or in release mode. For maximum performance, compile YJIT in release mode with GCC. More detailed build instructions are provided in the [Ruby README](https://github.com/ruby/ruby#how-to-build).
 
 ```sh
 # Configure in release mode for maximum performance, build and install
 ./autogen.sh
 ./configure --enable-yjit --prefix=$HOME/.rubies/ruby-yjit --disable-install-doc
-make -j install
+make -j && make install
 ```
 
 or
 
 ```sh
-# Configure in dev (debug) mode for development, build and install
+# Configure in lower-performance dev (debug) mode for development, build and install
 ./autogen.sh
 ./configure --enable-yjit=dev --prefix=$HOME/.rubies/ruby-yjit --disable-install-doc
-make -j install
+make -j && make install
+```
+
+Dev mode includes extended YJIT statistics, but can be slow. For only statistics you can configure in stats mode:
+
+```sh
+# Configure in extended-stats mode without slow runtime checks, build and install
+./autogen.sh
+./configure --enable-yjit=stats --prefix=$HOME/.rubies/ruby-yjit --disable-install-doc
+make -j && make install
 ```
 
 On macOS, you may need to specify where to find some libraries:
@@ -107,7 +117,7 @@ brew install openssl readline libyaml
 # Configure in dev (debug) mode for development, build and install
 ./autogen.sh
 ./configure --enable-yjit=dev --prefix=$HOME/.rubies/ruby-yjit --disable-install-doc --with-opt-dir="$(brew --prefix openssl):$(brew --prefix readline):$(brew --prefix libyaml)"
-make -j install
+make -j && make install
 ```
 
 Typically configure will choose the default C compiler. To specify the C compiler, use
@@ -155,11 +165,9 @@ YJIT supports all command-line options supported by upstream CRuby, but also add
 
 - `--yjit`: enable YJIT (disabled by default)
 - `--yjit-call-threshold=N`: number of calls after which YJIT begins to compile a function (default 30)
-- `--yjit-exec-mem-size=N`: size of the executable memory block to allocate, in MiB (default 128 MiB)
-- `--yjit-stats`: produce statistics after the execution of a program
-- `--yjit-trace-exits`: produce a Marshal dump of backtraces from specific exits. Automatically enables `--yjit-stats` (must configure and build with `--enable-yjit=stats` to use this)
-- `--yjit-max-versions=N`: maximum number of versions to generate per basic block (default 4)
-- `--yjit-greedy-versioning`: greedy versioning mode (disabled by default, may increase code size)
+- `--yjit-exec-mem-size=N`: size of the executable memory block to allocate, in MiB (default 64 MiB)
+- `--yjit-stats`: print statistics after the execution of a program (incurs a run-time cost)
+- `--yjit-trace-exits`: produce a Marshal dump of backtraces from specific exits. Automatically enables `--yjit-stats`
 
 Note that there is also an environment variable `RUBY_YJIT_ENABLE` which can be used to enable YJIT.
 This can be useful for some deployment scripts where specifying an extra command-line option to Ruby is not practical.
@@ -168,26 +176,77 @@ This can be useful for some deployment scripts where specifying an extra command
 
 We have collected a set of benchmarks and implemented a simple benchmarking harness in the [yjit-bench](https://github.com/Shopify/yjit-bench) repository. This benchmarking harness is designed to disable CPU frequency scaling, set process affinity and disable address space randomization so that the variance between benchmarking runs will be as small as possible. Please kindly note that we are at an early stage in this project.
 
-### Performance Tips
+## Performance Tips for Production Deployments
+
+While YJIT options default to what we think would work well for most workloads,
+they might not necessarily be the best configuration for your application.
+
+This section covers tips on improving YJIT performance in case YJIT does not
+speed up your application in production.
+
+### Increasing --yjit-exec-mem-size
+
+When JIT code size (`RubyVM::YJIT.runtime_stats[:code_region_size]`) reaches this value,
+YJIT triggers "code GC" that frees all JIT code and starts recompiling everything.
+Compiling code takes some time, so scheduling code GC too frequently slows down your application.
+Increasing `--yjit-exec-mem-size` may speed up your application if `RubyVM::YJIT.runtime_stats[:code_gc_count]` is not 0 or 1.
+
+### Running workers as long as possible
+
+It's helpful to call the same code as many times as possible before a process restarts.
+If a process is killed too frequently, the time taken for compiling methods may outweigh
+the speedup obtained by compiling them.
 
-This section contains tips on writing Ruby code that will run as fast as possible on YJIT. Some of this advice is based on current limitations of YJIT, while other advice is broadly applicable. It probably won't be practical to apply these tips everywhere in your codebase, but you can profile your code using a tool such as [stackprof](https://github.com/tmm1/stackprof) and refactor the specific methods that make up the largest fractions of the execution time.
+You should monitor the number of requests each process has served.
+If you're periodically killing worker processes, e.g. with `unicorn-worker-killer` or `puma_worker_killer`,
+you may want to reduce the killing frequency or increase the limit.
 
-- Use exceptions for error recovery only, not as part of normal control-flow
+## Saving YJIT Memory Usage
+
+YJIT allocates memory for JIT code and metadata. Enabling YJIT generally results in more memory usage.
+
+This section goes over tips on minimizing YJIT memory usage in case it uses more than your capacity.
+
+### Increasing --yjit-call-threshold
+
+As of Ruby 3.2, `--yjit-call-threshold` defaults to 30. With this default, some applications end up
+compiling methods that are used only during the application boot. Increasing this option may help
+you reduce the size of JIT code and metadata. It's worth trying different values like `--yjit-call-threshold=100`.
+
+Note that increasing the value too much may result in compiling code too late.
+You should monitor how many requests each worker processes before it's restarted. For example,
+if each process only handles 1000 requests, `--yjit-call-threshold=1000` might be too large for your application.
+
+### Decreasing --yjit-exec-mem-size
+
+`--yjit-exec-mem-size` specifies the JIT code size, but YJIT also uses memory for its metadata,
+which often consumes more memory than JIT code. Generally, YJIT adds memory overhead by roughly
+3-4x of `--yjit-exec-mem-size` in production as of Ruby 3.2. You should multiply that by the number
+of worker processes to estimate the worst case memory overhead.
+
+Running code GC adds overhead, but it could be still faster than recovering from a whole process killed by OOM.
+
+## Code Optimization Tips
+
+This section contains tips on writing Ruby code that will run as fast as possible on YJIT. Some of this advice is based on current limitations of YJIT, while other advice is broadly applicable. It probably won't be practical to apply these tips everywhere in your codebase. You should ideally start by profiling your application using a tool such as [stackprof](https://github.com/tmm1/stackprof) so that you can determine which methods make up most of the execution time. You can then refactor the specific methods that make up the largest fractions of the execution time. We do not recommend modifying your entire codebase based on the current limitations of YJIT.
+
+- Avoid using `OpenStruct`
 - Avoid redefining basic integer operations (i.e. +, -, <, >, etc.)
 - Avoid redefining the meaning of `nil`, equality, etc.
 - Avoid allocating objects in the hot parts of your code
-- Use while loops if you can, instead of `integer.times`
 - Minimize layers of indirection
   - Avoid classes that wrap objects if you can
   - Avoid methods that just call another method, trivial one liner methods
-- CRuby method calls are costly. Favor larger methods over smaller methods.
 - Try to write code so that the same variables always have the same type
+- Use `while` loops if you can, instead of C methods like `Array#each`
+  - This is not idiomatic Ruby, but could help in hot methods
+- CRuby method calls are costly. Avoid things such as methods that only return a value from a hash or return a constant.
 
 You can also use the `--yjit-stats` command-line option to see which bytecodes cause YJIT to exit, and refactor your code to avoid using these instructions in the hottest methods of your code.
 
 ### Other Statistics
 
-If you compile Ruby with `RUBY_DEBUG` and/or `YJIT_STATS` defined and run with `--yjit --yjit-stats`, YJIT will track and return performance statistics in `RubyVM::YJIT.runtime_stats`.
+If you run `ruby` with `--yjit --yjit-stats`, YJIT will track and return performance statistics in `RubyVM::YJIT.runtime_stats`.
 
 ```rb
 $ RUBYOPT="--yjit --yjit-stats" irb
@@ -205,16 +264,24 @@ irb(main):001:0> RubyVM::YJIT.runtime_stats
 
 Some of the counters include:
 
-:exec_instruction - how many Ruby bytecode instructions have been executed
-:binding_allocations - number of bindings allocated
-:binding_set - number of variables set via a binding
-:vm_insns_count - number of instructions executed by the Ruby interpreter
-:compiled_iseq_count - number of bytecode sequences compiled
+* :exec_instruction - how many Ruby bytecode instructions have been executed
+* :binding_allocations - number of bindings allocated
+* :binding_set - number of variables set via a binding
+* :code_gc_count - number of garbage collections of compiled code since process start
+* :vm_insns_count - number of instructions executed by the Ruby interpreter
+* :compiled_iseq_count - number of bytecode sequences compiled
+* :inline_code_size - size in bytes of compiled YJIT blocks
+* :outline_code_size - size in bytes of YJIT error-handling compiled code
+* :side_exit_count - number of side exits taken at runtime
+* :total_exit_count - number of exits, including side exits, taken at runtime
+* :avg_len_in_yjit - avg. number of instructions in compiled blocks before exiting to interpreter
 
 Counters starting with "exit_" show reasons for YJIT code taking a side exit (return to the interpreter.) See yjit_hacking.md for more details.
 
 Performance counter names are not guaranteed to remain the same between Ruby versions. If you're curious what one does, it's usually best to search the source code for it &mdash; but it may change in a later Ruby version.
 
+The printed text after a --yjit-stats run includes other information that may be named differently than the information in runtime_stats.
+
 ## Contributing
 
 We welcome open source contributors. You should feel free to open new issues to report bugs or just to ask questions.
@@ -242,8 +309,6 @@ The YJIT source code is divided between:
 - `yjit/src/options.rs`: handling of command-line options
 - `yjit/bindgen/src/main.rs`: C bindings exposed to the Rust codebase through bindgen
 - `yjit/src/cruby.rs`: C bindings manually exposed to the Rust codebase
-- `misc/test_yjit_asm.sh`: script to compile and run the in-memory assembler tests
-- `misc/yjit_asm_tests.c`: tests for the in-memory assembler
 
 The core of CRuby's interpreter logic is found in:
 - `insns.def`: defines Ruby's bytecode instructions (gets compiled into `vm.inc`)
diff --git a/enc/Makefile.in b/enc/Makefile.in
index dd8ca1b528..9d0c367134 100644
--- a/enc/Makefile.in
+++ b/enc/Makefile.in
@@ -51,7 +51,7 @@ optflags = @optflags@
 debugflags = @debugflags@
 warnflags = @warnflags@
 CCDLFLAGS = @CCDLFLAGS@
-INCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(top_srcdir)
+INCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(top_srcdir) @incflags@
 DEFS = @DEFS@
 CPPFLAGS = @CPPFLAGS@ -DONIG_ENC_REGISTER=rb_enc_register
 LDFLAGS = @LDFLAGS@
diff --git a/enc/cesu_8.c b/enc/cesu_8.c
index decbb928f4..75f62df280 100644
--- a/enc/cesu_8.c
+++ b/enc/cesu_8.c
@@ -42,6 +42,8 @@
 #define VALID_CODE_LIMIT  0x0010ffff
 
 #define utf8_islead(c)     ((UChar )((c) & 0xc0) != 0x80)
+#define utf16_is_high_surrogate(v) ((v >> 10) == 0x36)
+#define utf16_is_low_surrogate(v)  ((v >> 10) == 0x37)
 
 static const int EncLen_CESU8[] = {
   1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
@@ -283,6 +285,12 @@ is_mbc_newline(const UChar* p, const UChar* end, OnigEncoding enc)
   return 0;
 }
 
+static int
+utf8_decode_3byte_sequence(const UChar* p)
+{
+    return ((p[0] & 0xF) << 12) | ((p[1] & 0x3f) << 6) | (p[2] & 0x3f);
+}
+
 static OnigCodePoint
 mbc_to_code(const UChar* p, const UChar* end, OnigEncoding enc)
 {
@@ -295,11 +303,11 @@ mbc_to_code(const UChar* p, const UChar* end, OnigEncoding enc)
     case 2:
       return ((p[0] & 0x1F)  << 6) | (p[1] & 0x3f);
     case 3:
-      return ((p[0] & 0xF) << 12) | ((p[1] & 0x3f) << 6) | (p[2] & 0x3f);
+      return utf8_decode_3byte_sequence(p);
     case 6:
       {
-          int high = ((p[0] & 0xF) << 12) | ((p[1] & 0x3f) << 6) | (p[2] & 0x3f);
-          int low  = ((p[3] & 0xF) << 12) | ((p[4] & 0x3f) << 6) | (p[5] & 0x3f);
+          int high = utf8_decode_3byte_sequence(p);
+          int low  = utf8_decode_3byte_sequence(p + 3);
           return ((high & 0x03ff) << 10) + (low & 0x03ff) + 0x10000;
       }
   }
@@ -410,7 +418,6 @@ get_ctype_code_range(OnigCtype ctype, OnigCodePoint *sb_out,
   return onigenc_unicode_ctype_code_range(ctype, ranges);
 }
 
-
 static UChar*
 left_adjust_char_head(const UChar* start, const UChar* s, const UChar* end, OnigEncoding enc ARG_UNUSED)
 {
@@ -420,6 +427,14 @@ left_adjust_char_head(const UChar* start, const UChar* s, const UChar* end, Onig
   p = s;
 
   while (!utf8_islead(*p) && p > start) p--;
+
+  if (p > start && s - p == 2 && utf16_is_low_surrogate(utf8_decode_3byte_sequence(p))) {
+    const UChar *p_surrogate_pair = p - 1;
+    while (!utf8_islead(*p_surrogate_pair) && p_surrogate_pair > start) p_surrogate_pair--;
+    if (p - p_surrogate_pair == 3 && utf16_is_high_surrogate(utf8_decode_3byte_sequence(p_surrogate_pair))) {
+      return (UChar* )p_surrogate_pair;
+    }
+  }
   return (UChar* )p;
 }
 
diff --git a/enc/depend b/enc/depend
index 60c5a3ebb2..973ad93010 100644
--- a/enc/depend
+++ b/enc/depend
@@ -7018,6 +7018,7 @@ enc/trans/iso2022.$(OBJEXT): internal/attr/nodiscard.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/noexcept.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/noinline.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/nonnull.h
+enc/trans/iso2022.$(OBJEXT): internal/attr/nonstring.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/noreturn.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/pure.h
 enc/trans/iso2022.$(OBJEXT): internal/attr/restrict.h
diff --git a/encoding.c b/encoding.c
index 39a47f2b8c..2f4b47bdfa 100644
--- a/encoding.c
+++ b/encoding.c
@@ -1556,7 +1556,14 @@ enc_set_default_encoding(struct default_encoding *def, VALUE encoding, const cha
         if (NIL_P(encoding)) {
             def->index = -1;
             def->enc = 0;
-            st_insert(enc_table->names, (st_data_t)strdup(name),
+            char *name_dup = strdup(name);
+
+            st_data_t existing_name = (st_data_t)name_dup;
+            if (st_delete(enc_table->names, &existing_name, NULL)) {
+                xfree((void *)existing_name);
+            }
+
+            st_insert(enc_table->names, (st_data_t)name_dup,
                       (st_data_t)UNSPECIFIED_ENCODING);
         }
         else {
diff --git a/enum.c b/enum.c
index 391de0b337..b3c715e0a1 100644
--- a/enum.c
+++ b/enum.c
@@ -4459,7 +4459,7 @@ sum_iter(VALUE i, struct enum_sum_memo *memo)
     }
     else switch (TYPE(memo->v)) {
       default:      sum_iter_some_value(i, memo);    return;
-      case T_FLOAT: sum_iter_Kahan_Babuska(i, memo); return;
+      case T_FLOAT:
       case T_FIXNUM:
       case T_BIGNUM:
       case T_RATIONAL:
diff --git a/enumerator.c b/enumerator.c
index f6b3aae1f7..d587b63d32 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -164,7 +164,10 @@ static VALUE sym_each, sym_cycle, sym_yield;
 
 static VALUE lazy_use_super_method;
 
+extern ID ruby_static_id_cause;
+
 #define id_call idCall
+#define id_cause ruby_static_id_cause
 #define id_each idEach
 #define id_eqq idEqq
 #define id_initialize idInitialize
@@ -807,8 +810,16 @@ get_next_values(VALUE obj, struct enumerator *e)
 {
     VALUE curr, vs;
 
-    if (e->stop_exc)
-        rb_exc_raise(e->stop_exc);
+    if (e->stop_exc) {
+        VALUE exc = e->stop_exc;
+        VALUE result = rb_attr_get(exc, id_result);
+        VALUE mesg = rb_attr_get(exc, idMesg);
+        if (!NIL_P(mesg)) mesg = rb_str_dup(mesg);
+        VALUE stop_exc = rb_exc_new_str(rb_eStopIteration, mesg);
+        rb_ivar_set(stop_exc, id_cause, exc);
+        rb_ivar_set(stop_exc, id_result, result);
+        rb_exc_raise(stop_exc);
+    }
 
     curr = rb_fiber_current();
 
diff --git a/error.c b/error.c
index 8aa081c198..726f57a4c0 100644
--- a/error.c
+++ b/error.c
@@ -420,7 +420,7 @@ rb_warn(const char *fmt, ...)
 void
 rb_category_warn(rb_warning_category_t category, const char *fmt, ...)
 {
-    if (!NIL_P(ruby_verbose)) {
+    if (!NIL_P(ruby_verbose) && rb_warning_category_enabled_p(category)) {
         with_warning_string(mesg, 0, fmt) {
             rb_warn_category(mesg, rb_warning_category_to_name(category));
         }
@@ -452,7 +452,7 @@ rb_warning(const char *fmt, ...)
 void
 rb_category_warning(rb_warning_category_t category, const char *fmt, ...)
 {
-    if (RTEST(ruby_verbose)) {
+    if (RTEST(ruby_verbose) && rb_warning_category_enabled_p(category)) {
         with_warning_string(mesg, 0, fmt) {
             rb_warn_category(mesg, rb_warning_category_to_name(category));
         }
@@ -1818,7 +1818,9 @@ name_err_init_attr(VALUE exc, VALUE recv, VALUE method)
     cfp = rb_vm_get_ruby_level_next_cfp(ec, cfp);
     rb_ivar_set(exc, id_name, method);
     err_init_recv(exc, recv);
-    if (cfp) rb_ivar_set(exc, id_iseq, rb_iseqw_new(cfp->iseq));
+    if (cfp && VM_FRAME_TYPE(cfp) != VM_FRAME_MAGIC_DUMMY) {
+        rb_ivar_set(exc, id_iseq, rb_iseqw_new(cfp->iseq));
+    }
     return exc;
 }
 
diff --git a/eval.c b/eval.c
index ff17ad343c..a61dfb1289 100644
--- a/eval.c
+++ b/eval.c
@@ -647,6 +647,10 @@ rb_ec_setup_exception(const rb_execution_context_t *ec, VALUE mesg, VALUE cause)
         cause = get_ec_errinfo(ec);
     }
     if (cause != mesg) {
+        if (THROW_DATA_P(cause)) {
+            cause = Qnil;
+        }
+
         rb_ivar_set(mesg, id_cause, cause);
     }
 }
@@ -1773,6 +1777,16 @@ rb_obj_extend(int argc, VALUE *argv, VALUE obj)
     return obj;
 }
 
+VALUE
+rb_top_main_class(const char *method)
+{
+    VALUE klass = GET_THREAD()->top_wrapper;
+
+    if (!klass) return rb_cObject;
+    rb_warning("main.%s in the wrapped load is effective only in wrapper module", method);
+    return klass;
+}
+
 /*
  *  call-seq:
  *     include(module, ...)   -> self
@@ -1785,13 +1799,7 @@ rb_obj_extend(int argc, VALUE *argv, VALUE obj)
 static VALUE
 top_include(int argc, VALUE *argv, VALUE self)
 {
-    rb_thread_t *th = GET_THREAD();
-
-    if (th->top_wrapper) {
-        rb_warning("main.include in the wrapped load is effective only in wrapper module");
-        return rb_mod_include(argc, argv, th->top_wrapper);
-    }
-    return rb_mod_include(argc, argv, rb_cObject);
+    return rb_mod_include(argc, argv, rb_top_main_class("include"));
 }
 
 /*
diff --git a/eval_error.c b/eval_error.c
index 948a205dd9..9806683000 100644
--- a/eval_error.c
+++ b/eval_error.c
@@ -455,7 +455,12 @@ exiting_split(VALUE errinfo, volatile int *exitcode, volatile int *sigstatus)
 
     if (NIL_P(errinfo)) return 0;
 
-    if (rb_obj_is_kind_of(errinfo, rb_eSystemExit)) {
+    if (THROW_DATA_P(errinfo)) {
+        int throw_state = ((const struct vm_throw_data *)errinfo)->throw_state;
+        ex = throw_state & VM_THROW_STATE_MASK;
+        result |= EXITING_WITH_STATUS;
+    }
+    else if (rb_obj_is_kind_of(errinfo, rb_eSystemExit)) {
         ex = sysexit_status(errinfo);
         result |= EXITING_WITH_STATUS;
     }
diff --git a/ext/-test-/string/fstring.c b/ext/-test-/string/fstring.c
index 2374319fe3..64f079251d 100644
--- a/ext/-test-/string/fstring.c
+++ b/ext/-test-/string/fstring.c
@@ -12,13 +12,13 @@ bug_s_fstring(VALUE self, VALUE str)
 VALUE
 bug_s_rb_enc_interned_str(VALUE self, VALUE encoding)
 {
-    return rb_enc_interned_str("foo", 3, RDATA(encoding)->data);
+    return rb_enc_interned_str("foo", 3, NIL_P(encoding) ? NULL : RDATA(encoding)->data);
 }
 
 VALUE
 bug_s_rb_enc_str_new(VALUE self, VALUE encoding)
 {
-    return rb_enc_str_new("foo", 3, RDATA(encoding)->data);
+    return rb_enc_str_new("foo", 3, NIL_P(encoding) ? NULL : RDATA(encoding)->data);
 }
 
 void
diff --git a/ext/-test-/string/set_len.c b/ext/-test-/string/set_len.c
index 219cea404c..049da2cdb5 100644
--- a/ext/-test-/string/set_len.c
+++ b/ext/-test-/string/set_len.c
@@ -7,8 +7,18 @@ bug_str_set_len(VALUE str, VALUE len)
     return str;
 }
 
+static VALUE
+bug_str_append(VALUE str, VALUE addendum)
+{
+    StringValue(addendum);
+    rb_str_modify_expand(str, RSTRING_LEN(addendum));
+    memcpy(RSTRING_END(str), RSTRING_PTR(addendum), RSTRING_LEN(addendum));
+    return str;
+}
+
 void
 Init_string_set_len(VALUE klass)
 {
     rb_define_method(klass, "set_len", bug_str_set_len, 1);
+    rb_define_method(klass, "append", bug_str_append, 1);
 }
diff --git a/ext/extmk.rb b/ext/extmk.rb
index cab9a519c1..4e77a7167b 100755
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -136,6 +136,14 @@ def extract_makefile(makefile, keep = true)
   true
 end
 
+def create_makefile(target, srcprefix = nil)
+  if $static and target.include?("/")
+    base = File.basename(target)
+    $defs << "-DInit_#{base}=Init_#{target.tr('/', '_')}"
+  end
+  super
+end
+
 def extmake(target, basedir = 'ext', maybestatic = true)
   FileUtils.mkpath target unless File.directory?(target)
   begin
@@ -163,8 +171,6 @@ def extmake(target, basedir = 'ext', maybestatic = true)
     $mdir = target
     $srcdir = File.join($top_srcdir, basedir, $mdir)
     $preload = nil
-    $objs = []
-    $srcs = []
     $extso = []
     makefile = "./Makefile"
     static = $static
@@ -198,7 +204,7 @@ def extmake(target, basedir = 'ext', maybestatic = true)
       begin
 	$extconf_h = nil
 	ok &&= extract_makefile(makefile)
-	old_objs = $objs
+	old_objs = $objs || []
 	old_cleanfiles = $distcleanfiles | $cleanfiles
 	conf = ["#{$srcdir}/makefile.rb", "#{$srcdir}/extconf.rb"].find {|f| File.exist?(f)}
 	if (!ok || ($extconf_h && !File.exist?($extconf_h)) ||
@@ -261,6 +267,8 @@ def extmake(target, basedir = 'ext', maybestatic = true)
     unless $destdir.to_s.empty? or $mflags.defined?("DESTDIR")
       args += ["DESTDIR=" + relative_from($destdir, "../"+prefix)]
     end
+    $objs ||= []
+    $srcs ||= []
     if $static and ok and !$objs.empty? and !noinstall
       args += ["static"]
       $extlist.push [(maybestatic ? $static : false), target, $target, $preload]
@@ -549,7 +557,13 @@ extend Module.new {
   end
 
   def create_makefile(*args, &block)
-    return super unless @gemname
+    unless @gemname
+      if $static and (target = args.first).include?("/")
+        base = File.basename(target)
+        $defs << "-DInit_#{base}=Init_#{target.tr('/', '_')}"
+      end
+      return super
+    end
     super(*args) do |conf|
       conf.find do |s|
         s.sub!(%r(^(srcdir *= *)\$\(top_srcdir\)/\.bundle/gems/[^/]+(?=/))) {
diff --git a/ext/io/console/depend b/ext/io/console/depend
index 06ccdde70d..36747ef583 100644
--- a/ext/io/console/depend
+++ b/ext/io/console/depend
@@ -185,7 +185,7 @@ win32_vk.inc: win32_vk.list
 	-e 'n=$$F[1] and (n.strip!; /\AVK_/=~n) and' \
 	-e   'puts(%[#ifndef #{n}\n# define #{n} UNDEFINED_VK\n#endif])' \
 	$< && \
-	gperf --ignore-case -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k* $< \
+	gperf --ignore-case -L ANSI-C -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k* $< \
 	| sed -f $(top_srcdir)/tool/gperf.sed \
 	) > $(@F)
 
diff --git a/ext/io/console/win32_vk.inc b/ext/io/console/win32_vk.inc
index cbec7bef15..d15b1219fb 100644
--- a/ext/io/console/win32_vk.inc
+++ b/ext/io/console/win32_vk.inc
@@ -480,7 +480,7 @@
 # define VK_OEM_CLEAR UNDEFINED_VK
 #endif
 /* ANSI-C code produced by gperf version 3.1 */
-/* Command-line: gperf --ignore-case -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k'*' win32_vk.list  */
+/* Command-line: gperf --ignore-case -L ANSI-C -E -C -P -p -j1 -i 1 -g -o -t -K ofs -N console_win32_vk -k'*' win32_vk.list  */
 
 #if !((' ' == 32) && ('!' == 33) && ('"' == 34) && ('#' == 35) \
       && ('%' == 37) && ('&' == 38) && ('\'' == 39) && ('(' == 40) \
@@ -509,18 +509,17 @@
 #error "gperf generated tables don't work with this execution character set. Please report a bug to <bug-gperf@gnu.org>."
 #endif
 
-#define gperf_offsetof(s, n) (short)offsetof(struct s##_t, s##_str##n)
 #line 1 "win32_vk.list"
 
 struct vktable {short ofs; unsigned short vk;};
-static const struct vktable *console_win32_vk(/*const char *, unsigned int*/);
+static const struct vktable *console_win32_vk(const char *, size_t);
 #line 5 "win32_vk.list"
 struct vktable;
 /* maximum key range = 245, duplicates = 0 */
 
 #ifndef GPERF_DOWNCASE
 #define GPERF_DOWNCASE 1
-static unsigned char gperf_downcase[256] =
+static const unsigned char gperf_downcase[256] =
   {
       0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,
      15,  16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,
@@ -1007,368 +1006,368 @@ console_win32_vk (register const char *str, register size_t len)
       {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1},
       {-1}, {-1}, {-1},
 #line 40 "win32_vk.list"
-      {gperf_offsetof(stringpool, 12), VK_UP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str12, VK_UP},
 #line 52 "win32_vk.list"
-      {gperf_offsetof(stringpool, 13), VK_APPS},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str13, VK_APPS},
 #line 159 "win32_vk.list"
-      {gperf_offsetof(stringpool, 14), VK_CRSEL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str14, VK_CRSEL},
 #line 34 "win32_vk.list"
-      {gperf_offsetof(stringpool, 15), VK_SPACE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str15, VK_SPACE},
 #line 95 "win32_vk.list"
-      {gperf_offsetof(stringpool, 16), VK_SCROLL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str16, VK_SCROLL},
 #line 29 "win32_vk.list"
-      {gperf_offsetof(stringpool, 17), VK_ESCAPE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str17, VK_ESCAPE},
 #line 9 "win32_vk.list"
-      {gperf_offsetof(stringpool, 18), VK_CANCEL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str18, VK_CANCEL},
 #line 32 "win32_vk.list"
-      {gperf_offsetof(stringpool, 19), VK_ACCEPT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str19, VK_ACCEPT},
 #line 66 "win32_vk.list"
-      {gperf_offsetof(stringpool, 20), VK_SEPARATOR},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str20, VK_SEPARATOR},
 #line 43 "win32_vk.list"
-      {gperf_offsetof(stringpool, 21), VK_SELECT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str21, VK_SELECT},
 #line 18 "win32_vk.list"
-      {gperf_offsetof(stringpool, 22), VK_CONTROL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str22, VK_CONTROL},
 #line 166 "win32_vk.list"
-      {gperf_offsetof(stringpool, 23), VK_OEM_CLEAR},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str23, VK_OEM_CLEAR},
 #line 145 "win32_vk.list"
-      {gperf_offsetof(stringpool, 24), VK_OEM_RESET},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str24, VK_OEM_RESET},
 #line 155 "win32_vk.list"
-      {gperf_offsetof(stringpool, 25), VK_OEM_AUTO},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str25, VK_OEM_AUTO},
 #line 151 "win32_vk.list"
-      {gperf_offsetof(stringpool, 26), VK_OEM_CUSEL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str26, VK_OEM_CUSEL},
       {-1},
 #line 22 "win32_vk.list"
-      {gperf_offsetof(stringpool, 28), VK_KANA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str28, VK_KANA},
 #line 127 "win32_vk.list"
-      {gperf_offsetof(stringpool, 29), VK_OEM_PLUS},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str29, VK_OEM_PLUS},
 #line 35 "win32_vk.list"
-      {gperf_offsetof(stringpool, 30), VK_PRIOR},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str30, VK_PRIOR},
 #line 152 "win32_vk.list"
-      {gperf_offsetof(stringpool, 31), VK_OEM_ATTN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str31, VK_OEM_ATTN},
 #line 20 "win32_vk.list"
-      {gperf_offsetof(stringpool, 32), VK_PAUSE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str32, VK_PAUSE},
 #line 13 "win32_vk.list"
-      {gperf_offsetof(stringpool, 33), VK_BACK},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str33, VK_BACK},
 #line 144 "win32_vk.list"
-      {gperf_offsetof(stringpool, 34), VK_PACKET},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str34, VK_PACKET},
 #line 105 "win32_vk.list"
-      {gperf_offsetof(stringpool, 35), VK_RCONTROL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str35, VK_RCONTROL},
 #line 104 "win32_vk.list"
-      {gperf_offsetof(stringpool, 36), VK_LCONTROL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str36, VK_LCONTROL},
 #line 37 "win32_vk.list"
-      {gperf_offsetof(stringpool, 37), VK_END},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str37, VK_END},
 #line 38 "win32_vk.list"
-      {gperf_offsetof(stringpool, 38), VK_HOME},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str38, VK_HOME},
 #line 44 "win32_vk.list"
-      {gperf_offsetof(stringpool, 39), VK_PRINT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str39, VK_PRINT},
 #line 94 "win32_vk.list"
-      {gperf_offsetof(stringpool, 40), VK_NUMLOCK},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str40, VK_NUMLOCK},
 #line 39 "win32_vk.list"
-      {gperf_offsetof(stringpool, 41), VK_LEFT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str41, VK_LEFT},
 #line 25 "win32_vk.list"
-      {gperf_offsetof(stringpool, 42), VK_JUNJA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str42, VK_JUNJA},
 #line 19 "win32_vk.list"
-      {gperf_offsetof(stringpool, 43), VK_MENU},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str43, VK_MENU},
 #line 150 "win32_vk.list"
-      {gperf_offsetof(stringpool, 44), VK_OEM_WSCTRL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str44, VK_OEM_WSCTRL},
 #line 156 "win32_vk.list"
-      {gperf_offsetof(stringpool, 45), VK_OEM_ENLW},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str45, VK_OEM_ENLW},
 #line 36 "win32_vk.list"
-      {gperf_offsetof(stringpool, 46), VK_NEXT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str46, VK_NEXT},
 #line 51 "win32_vk.list"
-      {gperf_offsetof(stringpool, 47), VK_RWIN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str47, VK_RWIN},
 #line 50 "win32_vk.list"
-      {gperf_offsetof(stringpool, 48), VK_LWIN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str48, VK_LWIN},
 #line 21 "win32_vk.list"
-      {gperf_offsetof(stringpool, 49), VK_CAPITAL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str49, VK_CAPITAL},
 #line 49 "win32_vk.list"
-      {gperf_offsetof(stringpool, 50), VK_HELP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str50, VK_HELP},
 #line 164 "win32_vk.list"
-      {gperf_offsetof(stringpool, 51), VK_NONAME},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str51, VK_NONAME},
 #line 8 "win32_vk.list"
-      {gperf_offsetof(stringpool, 52), VK_RBUTTON},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str52, VK_RBUTTON},
 #line 7 "win32_vk.list"
-      {gperf_offsetof(stringpool, 53), VK_LBUTTON},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str53, VK_LBUTTON},
 #line 96 "win32_vk.list"
-      {gperf_offsetof(stringpool, 54), VK_OEM_NEC_EQUAL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str54, VK_OEM_NEC_EQUAL},
       {-1},
 #line 47 "win32_vk.list"
-      {gperf_offsetof(stringpool, 56), VK_INSERT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str56, VK_INSERT},
 #line 27 "win32_vk.list"
-      {gperf_offsetof(stringpool, 57), VK_HANJA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str57, VK_HANJA},
       {-1}, {-1},
 #line 46 "win32_vk.list"
-      {gperf_offsetof(stringpool, 60), VK_SNAPSHOT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str60, VK_SNAPSHOT},
 #line 158 "win32_vk.list"
-      {gperf_offsetof(stringpool, 61), VK_ATTN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str61, VK_ATTN},
 #line 14 "win32_vk.list"
-      {gperf_offsetof(stringpool, 62), VK_TAB},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str62, VK_TAB},
 #line 157 "win32_vk.list"
-      {gperf_offsetof(stringpool, 63), VK_OEM_BACKTAB},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str63, VK_OEM_BACKTAB},
 #line 143 "win32_vk.list"
-      {gperf_offsetof(stringpool, 64), VK_ICO_CLEAR},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str64, VK_ICO_CLEAR},
 #line 30 "win32_vk.list"
-      {gperf_offsetof(stringpool, 65), VK_CONVERT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str65, VK_CONVERT},
 #line 16 "win32_vk.list"
-      {gperf_offsetof(stringpool, 66), VK_RETURN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str66, VK_RETURN},
 #line 146 "win32_vk.list"
-      {gperf_offsetof(stringpool, 67), VK_OEM_JUMP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str67, VK_OEM_JUMP},
       {-1}, {-1}, {-1},
 #line 111 "win32_vk.list"
-      {gperf_offsetof(stringpool, 71), VK_BROWSER_STOP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str71, VK_BROWSER_STOP},
 #line 26 "win32_vk.list"
-      {gperf_offsetof(stringpool, 72), VK_FINAL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str72, VK_FINAL},
 #line 163 "win32_vk.list"
-      {gperf_offsetof(stringpool, 73), VK_ZOOM},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str73, VK_ZOOM},
 #line 28 "win32_vk.list"
-      {gperf_offsetof(stringpool, 74), VK_KANJI},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str74, VK_KANJI},
 #line 48 "win32_vk.list"
-      {gperf_offsetof(stringpool, 75), VK_DELETE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str75, VK_DELETE},
 #line 128 "win32_vk.list"
-      {gperf_offsetof(stringpool, 76), VK_OEM_COMMA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str76, VK_OEM_COMMA},
 #line 67 "win32_vk.list"
-      {gperf_offsetof(stringpool, 77), VK_SUBTRACT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str77, VK_SUBTRACT},
       {-1},
 #line 10 "win32_vk.list"
-      {gperf_offsetof(stringpool, 79), VK_MBUTTON},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str79, VK_MBUTTON},
 #line 78 "win32_vk.list"
-      {gperf_offsetof(stringpool, 80), VK_F9},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str80, VK_F9},
 #line 17 "win32_vk.list"
-      {gperf_offsetof(stringpool, 81), VK_SHIFT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str81, VK_SHIFT},
 #line 103 "win32_vk.list"
-      {gperf_offsetof(stringpool, 82), VK_RSHIFT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str82, VK_RSHIFT},
 #line 102 "win32_vk.list"
-      {gperf_offsetof(stringpool, 83), VK_LSHIFT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str83, VK_LSHIFT},
 #line 65 "win32_vk.list"
-      {gperf_offsetof(stringpool, 84), VK_ADD},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str84, VK_ADD},
 #line 31 "win32_vk.list"
-      {gperf_offsetof(stringpool, 85), VK_NONCONVERT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str85, VK_NONCONVERT},
 #line 160 "win32_vk.list"
-      {gperf_offsetof(stringpool, 86), VK_EXSEL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str86, VK_EXSEL},
 #line 126 "win32_vk.list"
-      {gperf_offsetof(stringpool, 87), VK_OEM_1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str87, VK_OEM_1},
 #line 138 "win32_vk.list"
-      {gperf_offsetof(stringpool, 88), VK_OEM_AX},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str88, VK_OEM_AX},
 #line 108 "win32_vk.list"
-      {gperf_offsetof(stringpool, 89), VK_BROWSER_BACK},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str89, VK_BROWSER_BACK},
 #line 137 "win32_vk.list"
-      {gperf_offsetof(stringpool, 90), VK_OEM_8},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str90, VK_OEM_8},
 #line 129 "win32_vk.list"
-      {gperf_offsetof(stringpool, 91), VK_OEM_MINUS},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str91, VK_OEM_MINUS},
 #line 162 "win32_vk.list"
-      {gperf_offsetof(stringpool, 92), VK_PLAY},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str92, VK_PLAY},
 #line 131 "win32_vk.list"
-      {gperf_offsetof(stringpool, 93), VK_OEM_2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str93, VK_OEM_2},
 #line 15 "win32_vk.list"
-      {gperf_offsetof(stringpool, 94), VK_CLEAR},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str94, VK_CLEAR},
 #line 99 "win32_vk.list"
-      {gperf_offsetof(stringpool, 95), VK_OEM_FJ_TOUROKU},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str95, VK_OEM_FJ_TOUROKU},
 #line 147 "win32_vk.list"
-      {gperf_offsetof(stringpool, 96), VK_OEM_PA1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str96, VK_OEM_PA1},
 #line 140 "win32_vk.list"
-      {gperf_offsetof(stringpool, 97), VK_ICO_HELP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str97, VK_ICO_HELP},
 #line 112 "win32_vk.list"
-      {gperf_offsetof(stringpool, 98), VK_BROWSER_SEARCH},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str98, VK_BROWSER_SEARCH},
 #line 53 "win32_vk.list"
-      {gperf_offsetof(stringpool, 99), VK_SLEEP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str99, VK_SLEEP},
       {-1},
 #line 70 "win32_vk.list"
-      {gperf_offsetof(stringpool, 101), VK_F1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str101, VK_F1},
 #line 148 "win32_vk.list"
-      {gperf_offsetof(stringpool, 102), VK_OEM_PA2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str102, VK_OEM_PA2},
 #line 154 "win32_vk.list"
-      {gperf_offsetof(stringpool, 103), VK_OEM_COPY},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str103, VK_OEM_COPY},
 #line 77 "win32_vk.list"
-      {gperf_offsetof(stringpool, 104), VK_F8},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str104, VK_F8},
 #line 88 "win32_vk.list"
-      {gperf_offsetof(stringpool, 105), VK_F19},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str105, VK_F19},
 #line 41 "win32_vk.list"
-      {gperf_offsetof(stringpool, 106), VK_RIGHT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str106, VK_RIGHT},
 #line 71 "win32_vk.list"
-      {gperf_offsetof(stringpool, 107), VK_F2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str107, VK_F2},
 #line 135 "win32_vk.list"
-      {gperf_offsetof(stringpool, 108), VK_OEM_6},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str108, VK_OEM_6},
 #line 87 "win32_vk.list"
-      {gperf_offsetof(stringpool, 109), VK_F18},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str109, VK_F18},
       {-1},
 #line 117 "win32_vk.list"
-      {gperf_offsetof(stringpool, 111), VK_VOLUME_UP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str111, VK_VOLUME_UP},
       {-1}, {-1},
 #line 120 "win32_vk.list"
-      {gperf_offsetof(stringpool, 114), VK_MEDIA_STOP},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str114, VK_MEDIA_STOP},
 #line 130 "win32_vk.list"
-      {gperf_offsetof(stringpool, 115), VK_OEM_PERIOD},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str115, VK_OEM_PERIOD},
       {-1},
 #line 161 "win32_vk.list"
-      {gperf_offsetof(stringpool, 117), VK_EREOF},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str117, VK_EREOF},
       {-1}, {-1}, {-1},
 #line 114 "win32_vk.list"
-      {gperf_offsetof(stringpool, 121), VK_BROWSER_HOME},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str121, VK_BROWSER_HOME},
 #line 75 "win32_vk.list"
-      {gperf_offsetof(stringpool, 122), VK_F6},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str122, VK_F6},
       {-1},
 #line 110 "win32_vk.list"
-      {gperf_offsetof(stringpool, 124), VK_BROWSER_REFRESH},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str124, VK_BROWSER_REFRESH},
       {-1},
 #line 165 "win32_vk.list"
-      {gperf_offsetof(stringpool, 126), VK_PA1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str126, VK_PA1},
 #line 142 "win32_vk.list"
-      {gperf_offsetof(stringpool, 127), VK_PROCESSKEY},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str127, VK_PROCESSKEY},
 #line 68 "win32_vk.list"
-      {gperf_offsetof(stringpool, 128), VK_DECIMAL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str128, VK_DECIMAL},
 #line 132 "win32_vk.list"
-      {gperf_offsetof(stringpool, 129), VK_OEM_3},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str129, VK_OEM_3},
 #line 107 "win32_vk.list"
-      {gperf_offsetof(stringpool, 130), VK_RMENU},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str130, VK_RMENU},
 #line 106 "win32_vk.list"
-      {gperf_offsetof(stringpool, 131), VK_LMENU},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str131, VK_LMENU},
 #line 98 "win32_vk.list"
-      {gperf_offsetof(stringpool, 132), VK_OEM_FJ_MASSHOU},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str132, VK_OEM_FJ_MASSHOU},
 #line 54 "win32_vk.list"
-      {gperf_offsetof(stringpool, 133), VK_NUMPAD0},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str133, VK_NUMPAD0},
 #line 24 "win32_vk.list"
-      {gperf_offsetof(stringpool, 134), VK_HANGUL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str134, VK_HANGUL},
 #line 63 "win32_vk.list"
-      {gperf_offsetof(stringpool, 135), VK_NUMPAD9},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str135, VK_NUMPAD9},
 #line 23 "win32_vk.list"
-      {gperf_offsetof(stringpool, 136), VK_HANGEUL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str136, VK_HANGEUL},
 #line 134 "win32_vk.list"
-      {gperf_offsetof(stringpool, 137), VK_OEM_5},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str137, VK_OEM_5},
 #line 149 "win32_vk.list"
-      {gperf_offsetof(stringpool, 138), VK_OEM_PA3},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str138, VK_OEM_PA3},
 #line 115 "win32_vk.list"
-      {gperf_offsetof(stringpool, 139), VK_VOLUME_MUTE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str139, VK_VOLUME_MUTE},
 #line 133 "win32_vk.list"
-      {gperf_offsetof(stringpool, 140), VK_OEM_4},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str140, VK_OEM_4},
 #line 122 "win32_vk.list"
-      {gperf_offsetof(stringpool, 141), VK_LAUNCH_MAIL},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str141, VK_LAUNCH_MAIL},
 #line 97 "win32_vk.list"
-      {gperf_offsetof(stringpool, 142), VK_OEM_FJ_JISHO},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str142, VK_OEM_FJ_JISHO},
 #line 72 "win32_vk.list"
-      {gperf_offsetof(stringpool, 143), VK_F3},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str143, VK_F3},
 #line 101 "win32_vk.list"
-      {gperf_offsetof(stringpool, 144), VK_OEM_FJ_ROYA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str144, VK_OEM_FJ_ROYA},
 #line 100 "win32_vk.list"
-      {gperf_offsetof(stringpool, 145), VK_OEM_FJ_LOYA},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str145, VK_OEM_FJ_LOYA},
       {-1},
 #line 42 "win32_vk.list"
-      {gperf_offsetof(stringpool, 147), VK_DOWN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str147, VK_DOWN},
       {-1},
 #line 153 "win32_vk.list"
-      {gperf_offsetof(stringpool, 149), VK_OEM_FINISH},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str149, VK_OEM_FINISH},
       {-1},
 #line 74 "win32_vk.list"
-      {gperf_offsetof(stringpool, 151), VK_F5},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str151, VK_F5},
       {-1},
 #line 136 "win32_vk.list"
-      {gperf_offsetof(stringpool, 153), VK_OEM_7},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str153, VK_OEM_7},
 #line 73 "win32_vk.list"
-      {gperf_offsetof(stringpool, 154), VK_F4},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str154, VK_F4},
 #line 86 "win32_vk.list"
-      {gperf_offsetof(stringpool, 155), VK_F17},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str155, VK_F17},
 #line 55 "win32_vk.list"
-      {gperf_offsetof(stringpool, 156), VK_NUMPAD1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str156, VK_NUMPAD1},
 #line 141 "win32_vk.list"
-      {gperf_offsetof(stringpool, 157), VK_ICO_00},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str157, VK_ICO_00},
       {-1},
 #line 62 "win32_vk.list"
-      {gperf_offsetof(stringpool, 159), VK_NUMPAD8},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str159, VK_NUMPAD8},
       {-1}, {-1},
 #line 56 "win32_vk.list"
-      {gperf_offsetof(stringpool, 162), VK_NUMPAD2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str162, VK_NUMPAD2},
       {-1},
 #line 124 "win32_vk.list"
-      {gperf_offsetof(stringpool, 164), VK_LAUNCH_APP1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str164, VK_LAUNCH_APP1},
 #line 109 "win32_vk.list"
-      {gperf_offsetof(stringpool, 165), VK_BROWSER_FORWARD},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str165, VK_BROWSER_FORWARD},
       {-1},
 #line 76 "win32_vk.list"
-      {gperf_offsetof(stringpool, 167), VK_F7},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str167, VK_F7},
       {-1}, {-1},
 #line 125 "win32_vk.list"
-      {gperf_offsetof(stringpool, 170), VK_LAUNCH_APP2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str170, VK_LAUNCH_APP2},
 #line 64 "win32_vk.list"
-      {gperf_offsetof(stringpool, 171), VK_MULTIPLY},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str171, VK_MULTIPLY},
       {-1}, {-1},
 #line 45 "win32_vk.list"
-      {gperf_offsetof(stringpool, 174), VK_EXECUTE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str174, VK_EXECUTE},
       {-1},
 #line 113 "win32_vk.list"
-      {gperf_offsetof(stringpool, 176), VK_BROWSER_FAVORITES},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str176, VK_BROWSER_FAVORITES},
 #line 60 "win32_vk.list"
-      {gperf_offsetof(stringpool, 177), VK_NUMPAD6},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str177, VK_NUMPAD6},
       {-1},
 #line 85 "win32_vk.list"
-      {gperf_offsetof(stringpool, 179), VK_F16},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str179, VK_F16},
       {-1}, {-1},
 #line 79 "win32_vk.list"
-      {gperf_offsetof(stringpool, 182), VK_F10},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str182, VK_F10},
       {-1}, {-1},
 #line 116 "win32_vk.list"
-      {gperf_offsetof(stringpool, 185), VK_VOLUME_DOWN},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str185, VK_VOLUME_DOWN},
       {-1}, {-1},
 #line 89 "win32_vk.list"
-      {gperf_offsetof(stringpool, 188), VK_F20},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str188, VK_F20},
 #line 119 "win32_vk.list"
-      {gperf_offsetof(stringpool, 189), VK_MEDIA_PREV_TRACK},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str189, VK_MEDIA_PREV_TRACK},
       {-1},
 #line 33 "win32_vk.list"
-      {gperf_offsetof(stringpool, 191), VK_MODECHANGE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str191, VK_MODECHANGE},
       {-1}, {-1}, {-1}, {-1}, {-1},
 #line 83 "win32_vk.list"
-      {gperf_offsetof(stringpool, 197), VK_F14},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str197, VK_F14},
 #line 57 "win32_vk.list"
-      {gperf_offsetof(stringpool, 198), VK_NUMPAD3},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str198, VK_NUMPAD3},
 #line 11 "win32_vk.list"
-      {gperf_offsetof(stringpool, 199), VK_XBUTTON1},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str199, VK_XBUTTON1},
       {-1}, {-1}, {-1},
 #line 93 "win32_vk.list"
-      {gperf_offsetof(stringpool, 203), VK_F24},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str203, VK_F24},
       {-1},
 #line 12 "win32_vk.list"
-      {gperf_offsetof(stringpool, 205), VK_XBUTTON2},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str205, VK_XBUTTON2},
 #line 59 "win32_vk.list"
-      {gperf_offsetof(stringpool, 206), VK_NUMPAD5},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str206, VK_NUMPAD5},
       {-1}, {-1},
 #line 58 "win32_vk.list"
-      {gperf_offsetof(stringpool, 209), VK_NUMPAD4},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str209, VK_NUMPAD4},
       {-1}, {-1}, {-1}, {-1}, {-1},
 #line 121 "win32_vk.list"
-      {gperf_offsetof(stringpool, 215), VK_MEDIA_PLAY_PAUSE},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str215, VK_MEDIA_PLAY_PAUSE},
       {-1},
 #line 123 "win32_vk.list"
-      {gperf_offsetof(stringpool, 217), VK_LAUNCH_MEDIA_SELECT},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str217, VK_LAUNCH_MEDIA_SELECT},
 #line 80 "win32_vk.list"
-      {gperf_offsetof(stringpool, 218), VK_F11},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str218, VK_F11},
       {-1},
 #line 139 "win32_vk.list"
-      {gperf_offsetof(stringpool, 220), VK_OEM_102},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str220, VK_OEM_102},
 #line 118 "win32_vk.list"
-      {gperf_offsetof(stringpool, 221), VK_MEDIA_NEXT_TRACK},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str221, VK_MEDIA_NEXT_TRACK},
 #line 61 "win32_vk.list"
-      {gperf_offsetof(stringpool, 222), VK_NUMPAD7},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str222, VK_NUMPAD7},
       {-1},
 #line 90 "win32_vk.list"
-      {gperf_offsetof(stringpool, 224), VK_F21},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str224, VK_F21},
       {-1},
 #line 82 "win32_vk.list"
-      {gperf_offsetof(stringpool, 226), VK_F13},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str226, VK_F13},
       {-1}, {-1},
 #line 81 "win32_vk.list"
-      {gperf_offsetof(stringpool, 229), VK_F12},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str229, VK_F12},
       {-1}, {-1},
 #line 92 "win32_vk.list"
-      {gperf_offsetof(stringpool, 232), VK_F23},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str232, VK_F23},
       {-1}, {-1},
 #line 91 "win32_vk.list"
-      {gperf_offsetof(stringpool, 235), VK_F22},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str235, VK_F22},
       {-1}, {-1}, {-1}, {-1}, {-1}, {-1},
 #line 84 "win32_vk.list"
-      {gperf_offsetof(stringpool, 242), VK_F15},
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str242, VK_F15},
       {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1}, {-1},
       {-1}, {-1}, {-1}, {-1},
 #line 69 "win32_vk.list"
-      {gperf_offsetof(stringpool, 256), VK_DIVIDE}
+      {(int)(size_t)&((struct stringpool_t *)0)->stringpool_str256, VK_DIVIDE}
     };
 
   if (len <= MAX_WORD_LENGTH && len >= MIN_WORD_LENGTH)
diff --git a/ext/io/console/win32_vk.list b/ext/io/console/win32_vk.list
index 7909a4d1f0..5df3d6da57 100644
--- a/ext/io/console/win32_vk.list
+++ b/ext/io/console/win32_vk.list
@@ -1,6 +1,6 @@
 %{
 struct vktable {short ofs; unsigned short vk;};
-static const struct vktable *console_win32_vk(/*!ANSI{*/const char *, unsigned int/*}!ANSI*/);
+static const struct vktable *console_win32_vk(const char *, size_t);
 %}
 struct vktable
 %%
diff --git a/ext/io/wait/extconf.rb b/ext/io/wait/extconf.rb
index eecdcce99f..c6230b7783 100644
--- a/ext/io/wait/extconf.rb
+++ b/ext/io/wait/extconf.rb
@@ -5,7 +5,7 @@ if RUBY_VERSION < "2.6"
   File.write("Makefile", dummy_makefile($srcdir).join(""))
 else
   target = "io/wait"
-  have_func("rb_io_wait")
+  have_func("rb_io_wait", "ruby/io.h")
   unless macro_defined?("DOSISH", "#include <ruby.h>")
     have_header(ioctl_h = "sys/ioctl.h") or ioctl_h = nil
     fionread = %w[sys/ioctl.h sys/filio.h sys/socket.h].find do |h|
diff --git a/ext/json/parser/extconf.rb b/ext/json/parser/extconf.rb
index feb586e1b4..4723a02aee 100644
--- a/ext/json/parser/extconf.rb
+++ b/ext/json/parser/extconf.rb
@@ -1,8 +1,8 @@
 # frozen_string_literal: false
 require 'mkmf'
 
-have_func("rb_enc_raise", "ruby.h")
-have_func("rb_enc_interned_str", "ruby.h")
+have_func("rb_enc_raise", "ruby/encoding.h")
+have_func("rb_enc_interned_str", "ruby/encoding.h")
 
 # checking if String#-@ (str_uminus) dedupes... '
 begin
diff --git a/ext/objspace/depend b/ext/objspace/depend
index de5fa6c6a3..52797664e0 100644
--- a/ext/objspace/depend
+++ b/ext/objspace/depend
@@ -158,12 +158,14 @@ object_tracing.o: $(hdrdir)/ruby/missing.h
 object_tracing.o: $(hdrdir)/ruby/ruby.h
 object_tracing.o: $(hdrdir)/ruby/st.h
 object_tracing.o: $(hdrdir)/ruby/subst.h
+object_tracing.o: $(top_srcdir)/gc.h
 object_tracing.o: $(top_srcdir)/internal.h
 object_tracing.o: object_tracing.c
 object_tracing.o: objspace.h
 objspace.o: $(RUBY_EXTCONF_H)
 objspace.o: $(arch_hdrdir)/ruby/config.h
 objspace.o: $(hdrdir)/ruby/assert.h
+objspace.o: $(hdrdir)/ruby/atomic.h
 objspace.o: $(hdrdir)/ruby/backward.h
 objspace.o: $(hdrdir)/ruby/backward/2/assume.h
 objspace.o: $(hdrdir)/ruby/backward/2/attributes.h
@@ -336,10 +338,16 @@ objspace.o: $(hdrdir)/ruby/regex.h
 objspace.o: $(hdrdir)/ruby/ruby.h
 objspace.o: $(hdrdir)/ruby/st.h
 objspace.o: $(hdrdir)/ruby/subst.h
+objspace.o: $(hdrdir)/ruby/thread_native.h
+objspace.o: $(top_srcdir)/ccan/check_type/check_type.h
+objspace.o: $(top_srcdir)/ccan/container_of/container_of.h
+objspace.o: $(top_srcdir)/ccan/list/list.h
+objspace.o: $(top_srcdir)/ccan/str/str.h
 objspace.o: $(top_srcdir)/gc.h
 objspace.o: $(top_srcdir)/id_table.h
 objspace.o: $(top_srcdir)/internal.h
 objspace.o: $(top_srcdir)/internal/array.h
+objspace.o: $(top_srcdir)/internal/basic_operators.h
 objspace.o: $(top_srcdir)/internal/class.h
 objspace.o: $(top_srcdir)/internal/compilers.h
 objspace.o: $(top_srcdir)/internal/gc.h
@@ -348,10 +356,17 @@ objspace.o: $(top_srcdir)/internal/imemo.h
 objspace.o: $(top_srcdir)/internal/sanitizers.h
 objspace.o: $(top_srcdir)/internal/serial.h
 objspace.o: $(top_srcdir)/internal/static_assert.h
+objspace.o: $(top_srcdir)/internal/vm.h
 objspace.o: $(top_srcdir)/internal/warnings.h
+objspace.o: $(top_srcdir)/method.h
 objspace.o: $(top_srcdir)/node.h
+objspace.o: $(top_srcdir)/ruby_assert.h
+objspace.o: $(top_srcdir)/ruby_atomic.h
 objspace.o: $(top_srcdir)/shape.h
 objspace.o: $(top_srcdir)/symbol.h
+objspace.o: $(top_srcdir)/thread_pthread.h
+objspace.o: $(top_srcdir)/vm_core.h
+objspace.o: $(top_srcdir)/vm_opts.h
 objspace.o: objspace.c
 objspace.o: {$(VPATH)}id.h
 objspace_dump.o: $(RUBY_EXTCONF_H)
diff --git a/ext/objspace/object_tracing.c b/ext/objspace/object_tracing.c
index 0bf866a8f1..8c54d51eab 100644
--- a/ext/objspace/object_tracing.c
+++ b/ext/objspace/object_tracing.c
@@ -13,6 +13,7 @@
 
 **********************************************************************/
 
+#include "gc.h"
 #include "internal.h"
 #include "ruby/debug.h"
 #include "objspace.h"
@@ -121,6 +122,10 @@ freeobj_i(VALUE tpval, void *data)
     st_data_t v;
     struct allocation_info *info;
 
+    /* Modifying the st table can cause allocations, which can trigger GC.
+     * Since freeobj_i is called during GC, it must not trigger another GC. */
+    VALUE gc_disabled = rb_gc_disable_no_rest();
+
     if (arg->keep_remains) {
         if (st_lookup(arg->object_table, obj, &v)) {
             info = (struct allocation_info *)v;
@@ -135,6 +140,8 @@ freeobj_i(VALUE tpval, void *data)
             ruby_xfree(info);
         }
     }
+
+    if (gc_disabled == Qfalse) rb_gc_enable();
 }
 
 static int
diff --git a/ext/openssl/ossl_pkey_ec.c b/ext/openssl/ossl_pkey_ec.c
index a59849f719..92842f95ac 100644
--- a/ext/openssl/ossl_pkey_ec.c
+++ b/ext/openssl/ossl_pkey_ec.c
@@ -483,7 +483,7 @@ static VALUE ossl_ec_key_check_key(VALUE self)
 #ifdef HAVE_EVP_PKEY_CHECK
     EVP_PKEY *pkey;
     EVP_PKEY_CTX *pctx;
-    EC_KEY *ec;
+    const EC_KEY *ec;
 
     GetPKey(self, pkey);
     GetEC(self, ec);
diff --git a/ext/ripper/lib/ripper/lexer.rb b/ext/ripper/lib/ripper/lexer.rb
index 6a3c04af30..a0f1cbeaa8 100644
--- a/ext/ripper/lib/ripper/lexer.rb
+++ b/ext/ripper/lib/ripper/lexer.rb
@@ -242,7 +242,12 @@ class Ripper
     end
 
     def on_error2(mesg, elem)
-      @errors.push Elem.new(elem.pos, __callee__, elem.tok, elem.state, mesg)
+      if elem
+        elem = Elem.new(elem.pos, __callee__, elem.tok, elem.state, mesg)
+      else
+        elem = Elem.new([lineno(), column()], __callee__, token(), state(), mesg)
+      end
+      @errors.push elem
     end
     PARSER_EVENTS.grep(/_error\z/) do |e|
       arity = PARSER_EVENT_TABLE.fetch(e)
diff --git a/ext/socket/raddrinfo.c b/ext/socket/raddrinfo.c
index 269edc4dad..45b4cad38f 100644
--- a/ext/socket/raddrinfo.c
+++ b/ext/socket/raddrinfo.c
@@ -287,8 +287,9 @@ numeric_getaddrinfo(const char *node, const char *service,
 void
 rb_freeaddrinfo(struct rb_addrinfo *ai)
 {
-    if (!ai->allocated_by_malloc)
-        freeaddrinfo(ai->ai);
+    if (!ai->allocated_by_malloc) {
+        if (ai->ai) freeaddrinfo(ai->ai);
+    }
     else {
         struct addrinfo *ai1, *ai2;
         ai1 = ai->ai;
diff --git a/ext/strscan/extconf.rb b/ext/strscan/extconf.rb
index b53b63e455..3c311d2364 100644
--- a/ext/strscan/extconf.rb
+++ b/ext/strscan/extconf.rb
@@ -2,7 +2,8 @@
 require 'mkmf'
 if RUBY_ENGINE == 'ruby'
   $INCFLAGS << " -I$(top_srcdir)" if $extmk
-  have_func("onig_region_memsize", "ruby.h")
+  have_func("onig_region_memsize(NULL)")
+  have_func("rb_reg_onig_match", "ruby/re.h")
   create_makefile 'strscan'
 else
   File.write('Makefile', dummy_makefile("").join)
diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index 9b646ab678..16d669d8a5 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -22,7 +22,7 @@ extern size_t onig_region_memsize(const struct re_registers *regs);
 
 #include <stdbool.h>
 
-#define STRSCAN_VERSION "3.0.5"
+#define STRSCAN_VERSION "3.0.7"
 
 /* =======================================================================
                          Data Type Definitions
@@ -539,6 +539,68 @@ adjust_register_position(struct strscanner *p, long position)
     }
 }
 
+/* rb_reg_onig_match is available in Ruby 3.3 and later. */
+#ifndef HAVE_RB_REG_ONIG_MATCH
+static OnigPosition
+rb_reg_onig_match(VALUE re, VALUE str,
+                  OnigPosition (*match)(regex_t *reg, VALUE str, struct re_registers *regs, void *args),
+                  void *args, struct re_registers *regs)
+{
+    regex_t *reg = rb_reg_prepare_re(re, str);
+
+    bool tmpreg = reg != RREGEXP_PTR(re);
+    if (!tmpreg) RREGEXP(re)->usecnt++;
+
+    OnigPosition result = match(reg, str, regs, args);
+
+    if (!tmpreg) RREGEXP(re)->usecnt--;
+    if (tmpreg) {
+        if (RREGEXP(re)->usecnt) {
+            onig_free(reg);
+        }
+        else {
+            onig_free(RREGEXP_PTR(re));
+            RREGEXP_PTR(re) = reg;
+        }
+    }
+
+    if (result < 0) {
+        if (result != ONIG_MISMATCH) {
+            rb_raise(ScanError, "regexp buffer overflow");
+        }
+    }
+
+    return result;
+}
+#endif
+
+static OnigPosition
+strscan_match(regex_t *reg, VALUE str, struct re_registers *regs, void *args_ptr)
+{
+    struct strscanner *p = (struct strscanner *)args_ptr;
+
+    return onig_match(reg,
+                      match_target(p),
+                      (UChar* )(CURPTR(p) + S_RESTLEN(p)),
+                      (UChar* )CURPTR(p),
+                      regs,
+                      ONIG_OPTION_NONE);
+}
+
+static OnigPosition
+strscan_search(regex_t *reg, VALUE str, struct re_registers *regs, void *args_ptr)
+{
+    struct strscanner *p = (struct strscanner *)args_ptr;
+
+    return onig_search(reg,
+                       match_target(p),
+                       (UChar *)(CURPTR(p) + S_RESTLEN(p)),
+                       (UChar *)CURPTR(p),
+                       (UChar *)(CURPTR(p) + S_RESTLEN(p)),
+                       regs,
+                       ONIG_OPTION_NONE);
+}
+
 static VALUE
 strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly)
 {
@@ -560,47 +622,14 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly
     }
 
     if (RB_TYPE_P(pattern, T_REGEXP)) {
-        regex_t *rb_reg_prepare_re(VALUE re, VALUE str);
-        regex_t *re;
-        long ret;
-        int tmpreg;
-
         p->regex = pattern;
-        re = rb_reg_prepare_re(pattern, p->str);
-        tmpreg = re != RREGEXP_PTR(pattern);
-        if (!tmpreg) RREGEXP(pattern)->usecnt++;
-
-        if (headonly) {
-            ret = onig_match(re,
-                             match_target(p),
-                             (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                             (UChar* )CURPTR(p),
-                             &(p->regs),
-                             ONIG_OPTION_NONE);
-        }
-        else {
-            ret = onig_search(re,
-                              match_target(p),
-                              (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                              (UChar* )CURPTR(p),
-                              (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                              &(p->regs),
-                              ONIG_OPTION_NONE);
-        }
-        if (!tmpreg) RREGEXP(pattern)->usecnt--;
-        if (tmpreg) {
-            if (RREGEXP(pattern)->usecnt) {
-                onig_free(re);
-            }
-            else {
-                onig_free(RREGEXP_PTR(pattern));
-                RREGEXP_PTR(pattern) = re;
-            }
-        }
+        OnigPosition ret = rb_reg_onig_match(pattern,
+                                             p->str,
+                                             headonly ? strscan_match : strscan_search,
+                                             (void *)p,
+                                             &(p->regs));
 
-        if (ret == -2) rb_raise(ScanError, "regexp buffer overflow");
-        if (ret < 0) {
-            /* not matched */
+        if (ret == ONIG_MISMATCH) {
             return Qnil;
         }
     }
@@ -1038,8 +1067,9 @@ strscan_empty_p(VALUE self)
  * This method is obsolete; use #eos? instead.
  *
  *   s = StringScanner.new('test string')
- *   s.eos?              # These two
- *   s.rest?             # are opposites.
+ *   # These two are opposites
+ *   s.eos? # => false
+ *   s.rest? # => true
  */
 static VALUE
 strscan_rest_p(VALUE self)
@@ -1501,7 +1531,9 @@ strscan_named_captures(VALUE self)
     named_captures_data data;
     data.self = self;
     data.captures = rb_hash_new();
-    onig_foreach_name(RREGEXP_PTR(p->regex), named_captures_iter, &data);
+    if (!RB_NIL_P(p->regex)) {
+        onig_foreach_name(RREGEXP_PTR(p->regex), named_captures_iter, &data);
+    }
 
     return data.captures;
 }
diff --git a/ext/win32/lib/win32/registry.rb b/ext/win32/lib/win32/registry.rb
index b5b99ff684..bda8bb012f 100644
--- a/ext/win32/lib/win32/registry.rb
+++ b/ext/win32/lib/win32/registry.rb
@@ -69,7 +69,11 @@ For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/pr
   WCHAR_NUL = "\0".encode(WCHAR).freeze
   WCHAR_CR = "\r".encode(WCHAR).freeze
   WCHAR_SIZE = WCHAR_NUL.bytesize
-  LOCALE = Encoding.find(Encoding.locale_charmap)
+  begin
+    LOCALE = Encoding.find(Encoding.locale_charmap)
+  rescue ArgumentError
+    LOCALE = Encoding::UTF_8
+  end
 
   class Registry
 
@@ -740,14 +744,11 @@ For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/pr
     # method returns.
     #
     def write(name, type, data)
-      termsize = 0
       case type
       when REG_SZ, REG_EXPAND_SZ
-        data = data.encode(WCHAR)
-        termsize = WCHAR_SIZE
+        data = data.encode(WCHAR) << WCHAR_NUL
       when REG_MULTI_SZ
         data = data.to_a.map {|s| s.encode(WCHAR)}.join(WCHAR_NUL) << WCHAR_NUL
-        termsize = WCHAR_SIZE
       when REG_BINARY, REG_NONE
         data = data.to_s
       when REG_DWORD
@@ -759,7 +760,7 @@ For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/pr
       else
         raise TypeError, "Unsupported type #{Registry.type2name(type)}"
       end
-      API.SetValue(@hkey, name, type, data, data.bytesize + termsize)
+      API.SetValue(@hkey, name, type, data, data.bytesize)
     end
 
     #
diff --git a/gc.c b/gc.c
index 54400e4f6b..919d57989a 100644
--- a/gc.c
+++ b/gc.c
@@ -2474,6 +2474,7 @@ rb_objspace_set_event_hook(const rb_event_flag_t event)
 static void
 gc_event_hook_body(rb_execution_context_t *ec, rb_objspace_t *objspace, const rb_event_flag_t event, VALUE data)
 {
+    if (UNLIKELY(!ec->cfp)) return;
     const VALUE *pc = ec->cfp->pc;
     if (pc && VM_FRAME_RUBYFRAME_P(ec->cfp)) {
         /* increment PC because source line is calculated with PC-1 */
@@ -2795,6 +2796,12 @@ newobj_alloc(rb_objspace_t *objspace, rb_ractor_t *cr, size_t size_pool_idx, boo
     return obj;
 }
 
+static void
+newobj_zero_slot(VALUE obj)
+{
+    memset((char *)obj + sizeof(struct RBasic), 0, rb_gc_obj_slot_size(obj) - sizeof(struct RBasic));
+}
+
 ALWAYS_INLINE(static VALUE newobj_slowpath(VALUE klass, VALUE flags, rb_objspace_t *objspace, rb_ractor_t *cr, int wb_protected, size_t size_pool_idx));
 
 static inline VALUE
@@ -2825,7 +2832,7 @@ newobj_slowpath(VALUE klass, VALUE flags, rb_objspace_t *objspace, rb_ractor_t *
 #endif
         newobj_init(klass, flags, wb_protected, objspace, obj);
 
-        gc_event_hook_prep(objspace, RUBY_INTERNAL_EVENT_NEWOBJ, obj, newobj_fill(obj, 0, 0, 0));
+        gc_event_hook_prep(objspace, RUBY_INTERNAL_EVENT_NEWOBJ, obj, newobj_zero_slot(obj));
     }
     RB_VM_LOCK_LEAVE_CR_LEV(cr, &lev);
 
@@ -3455,7 +3462,7 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
       case T_OBJECT:
         if (rb_shape_obj_too_complex(obj)) {
             RB_DEBUG_COUNTER_INC(obj_obj_too_complex);
-            rb_id_table_free(ROBJECT_IV_HASH(obj));
+            st_free_table(ROBJECT_IV_HASH(obj));
         }
         else if (RANY(obj)->as.basic.flags & ROBJECT_EMBED) {
             RB_DEBUG_COUNTER_INC(obj_obj_embed);
@@ -3655,7 +3662,7 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
         cc_table_free(objspace, obj, FALSE);
         rb_class_remove_from_module_subclasses(obj);
         rb_class_remove_from_super_subclasses(obj);
-#if !USE_RVARGC
+#if !RCLASS_EXT_EMBEDDED
         xfree(RCLASS_EXT(obj));
 #endif
 
@@ -4351,16 +4358,20 @@ run_finalizer(rb_objspace_t *objspace, VALUE obj, VALUE table)
         VALUE objid;
         VALUE final;
         rb_control_frame_t *cfp;
+        VALUE *sp;
         long finished;
     } saved;
+
     rb_execution_context_t * volatile ec = GET_EC();
 #define RESTORE_FINALIZER() (\
         ec->cfp = saved.cfp, \
+        ec->cfp->sp = saved.sp, \
         ec->errinfo = saved.errinfo)
 
     saved.errinfo = ec->errinfo;
     saved.objid = rb_obj_id(obj);
     saved.cfp = ec->cfp;
+    saved.sp = ec->cfp->sp;
     saved.finished = 0;
     saved.final = Qundef;
 
@@ -4882,7 +4893,7 @@ obj_memsize_of(VALUE obj, int use_all_types)
     switch (BUILTIN_TYPE(obj)) {
       case T_OBJECT:
         if (rb_shape_obj_too_complex(obj)) {
-            size += rb_id_table_memsize(ROBJECT_IV_HASH(obj));
+            size += rb_st_memsize(ROBJECT_IV_HASH(obj));
         }
         else if (!(RBASIC(obj)->flags & ROBJECT_EMBED)) {
             size += ROBJECT_IV_CAPACITY(obj) * sizeof(VALUE);
@@ -7208,6 +7219,8 @@ gc_mark_imemo(rb_objspace_t *objspace, VALUE obj)
     }
 }
 
+static void mark_cvc_tbl(rb_objspace_t *objspace, VALUE klass);
+
 static void
 gc_mark_children(rb_objspace_t *objspace, VALUE obj)
 {
@@ -7254,6 +7267,7 @@ gc_mark_children(rb_objspace_t *objspace, VALUE obj)
         if (!RCLASS_EXT(obj)) break;
 
         mark_m_tbl(objspace, RCLASS_M_TBL(obj));
+        mark_cvc_tbl(objspace, obj);
         cc_table_mark(objspace, obj);
         for (attr_index_t i = 0; i < RCLASS_IV_COUNT(obj); i++) {
             gc_mark(objspace, RCLASS_IVPTR(obj)[i]);
@@ -7323,7 +7337,7 @@ gc_mark_children(rb_objspace_t *objspace, VALUE obj)
         {
             rb_shape_t *shape = rb_shape_get_shape_by_id(ROBJECT_SHAPE_ID(obj));
             if (rb_shape_obj_too_complex(obj)) {
-                mark_m_tbl(objspace, ROBJECT_IV_HASH(obj));
+                mark_tbl_no_pin(objspace, ROBJECT_IV_HASH(obj));
             }
             else {
                 const VALUE * const ptr = ROBJECT_IVPTR(obj);
@@ -9267,10 +9281,23 @@ rb_gc_register_address(VALUE *addr)
     rb_objspace_t *objspace = &rb_objspace;
     struct gc_list *tmp;
 
+    VALUE obj = *addr;
+
     tmp = ALLOC(struct gc_list);
     tmp->next = global_list;
     tmp->varptr = addr;
     global_list = tmp;
+
+    /*
+     * Because some C extensions have assignment-then-register bugs,
+     * we guard `obj` here so that it would not get swept defensively.
+     */
+    RB_GC_GUARD(obj);
+    if (0 && !SPECIAL_CONST_P(obj)) {
+	rb_warn("Object is assigned to registering address already: %"PRIsVALUE,
+		rb_obj_class(obj));
+	rb_print_backtrace();
+    }
 }
 
 void
@@ -10111,15 +10138,13 @@ gc_ref_update_array(rb_objspace_t * objspace, VALUE v)
     }
 }
 
-static void update_m_tbl(rb_objspace_t *objspace, struct rb_id_table *tbl);
-
 static void
 gc_ref_update_object(rb_objspace_t *objspace, VALUE v)
 {
     VALUE *ptr = ROBJECT_IVPTR(v);
 
     if (rb_shape_obj_too_complex(v)) {
-        update_m_tbl(objspace, ROBJECT_IV_HASH(v));
+        rb_gc_update_tbl_refs(ROBJECT_IV_HASH(v));
         return;
     }
 
@@ -10467,9 +10492,14 @@ static enum rb_id_table_iterator_result
 update_cvc_tbl_i(VALUE cvc_entry, void *data)
 {
     struct rb_cvar_class_tbl_entry *entry;
+    rb_objspace_t * objspace = (rb_objspace_t *)data;
 
     entry = (struct rb_cvar_class_tbl_entry *)cvc_entry;
 
+    if (entry->cref) {
+        TYPED_UPDATE_IF_MOVED(objspace, rb_cref_t *, entry->cref);
+    }
+
     entry->class_value = rb_gc_location(entry->class_value);
 
     return ID_TABLE_CONTINUE;
@@ -10485,6 +10515,28 @@ update_cvc_tbl(rb_objspace_t *objspace, VALUE klass)
 }
 
 static enum rb_id_table_iterator_result
+mark_cvc_tbl_i(VALUE cvc_entry, void *data)
+{
+    struct rb_cvar_class_tbl_entry *entry;
+
+    entry = (struct rb_cvar_class_tbl_entry *)cvc_entry;
+
+    RUBY_ASSERT(entry->cref == 0 || (BUILTIN_TYPE((VALUE)entry->cref) == T_IMEMO && IMEMO_TYPE_P(entry->cref, imemo_cref)));
+    rb_gc_mark((VALUE) entry->cref);
+
+    return ID_TABLE_CONTINUE;
+}
+
+static void
+mark_cvc_tbl(rb_objspace_t *objspace, VALUE klass)
+{
+    struct rb_id_table *tbl = RCLASS_CVC_TBL(klass);
+    if (tbl) {
+        rb_id_table_foreach_values(tbl, mark_cvc_tbl_i, objspace);
+    }
+}
+
+static enum rb_id_table_iterator_result
 update_const_table(VALUE value, void *data)
 {
     rb_const_entry_t *ce = (rb_const_entry_t *)value;
@@ -12279,18 +12331,23 @@ objspace_malloc_fixup(rb_objspace_t *objspace, void *mem, size_t size)
         }                                                    \
     } while (0)
 
+static void
+check_malloc_not_in_gc(rb_objspace_t *objspace, const char *msg)
+{
+    if (UNLIKELY(malloc_during_gc_p(objspace))) {
+        dont_gc_on();
+        during_gc = false;
+        rb_bug("Cannot %s during GC", msg);
+    }
+}
+
 /* these shouldn't be called directly.
  * objspace_* functions do not check allocation size.
  */
 static void *
 objspace_xmalloc0(rb_objspace_t *objspace, size_t size)
 {
-    if (UNLIKELY(malloc_during_gc_p(objspace))) {
-        rb_warn("malloc during GC detected, this could cause crashes if it triggers another GC");
-#if RGENGC_CHECK_MODE || RUBY_DEBUG
-        rb_bug("Cannot malloc during GC");
-#endif
-    }
+    check_malloc_not_in_gc(objspace, "malloc");
 
     void *mem;
 
@@ -12309,12 +12366,7 @@ xmalloc2_size(const size_t count, const size_t elsize)
 static void *
 objspace_xrealloc(rb_objspace_t *objspace, void *ptr, size_t new_size, size_t old_size)
 {
-    if (UNLIKELY(malloc_during_gc_p(objspace))) {
-        rb_warn("realloc during GC detected, this could cause crashes if it triggers another GC");
-#if RGENGC_CHECK_MODE || RUBY_DEBUG
-        rb_bug("Cannot realloc during GC");
-#endif
-    }
+    check_malloc_not_in_gc(objspace, "realloc");
 
     void *mem;
 
@@ -12614,8 +12666,16 @@ ruby_xrealloc2_body(void *ptr, size_t n, size_t size)
 void
 ruby_sized_xfree(void *x, size_t size)
 {
-    if (x) {
-        objspace_xfree(&rb_objspace, x, size);
+    if (LIKELY(x)) {
+        /* It's possible for a C extension's pthread destructor function set by pthread_key_create
+         * to be called after ruby_vm_destruct and attempt to free memory. Fall back to mimfree in
+         * that case. */
+        if (LIKELY(GET_VM())) {
+            objspace_xfree(&rb_objspace, x, size);
+        }
+        else {
+            ruby_mimfree(x);
+        }
     }
 }
 
@@ -12809,12 +12869,47 @@ wmap_mark_map(st_data_t key, st_data_t val, st_data_t arg)
 }
 #endif
 
+static int
+wmap_replace_ref(st_data_t *key, st_data_t *value, st_data_t _argp, int existing)
+{
+    *key = rb_gc_location((VALUE)*key);
+
+    VALUE *values = (VALUE *)*value;
+    VALUE size = values[0];
+
+    for (VALUE index = 1; index <= size; index++) {
+        values[index] = rb_gc_location(values[index]);
+    }
+
+    return ST_CONTINUE;
+}
+
+static int
+wmap_foreach_replace(st_data_t key, st_data_t value, st_data_t _argp, int error)
+{
+    if (rb_gc_location((VALUE)key) != (VALUE)key) {
+        return ST_REPLACE;
+    }
+
+    VALUE *values = (VALUE *)value;
+    VALUE size = values[0];
+
+    for (VALUE index = 1; index <= size; index++) {
+        VALUE val = values[index];
+        if (rb_gc_location(val) != val) {
+            return ST_REPLACE;
+        }
+    }
+
+    return ST_CONTINUE;
+}
+
 static void
 wmap_compact(void *ptr)
 {
     struct weakmap *w = ptr;
     if (w->wmap2obj) rb_gc_update_tbl_refs(w->wmap2obj);
-    if (w->obj2wmap) rb_gc_update_tbl_refs(w->obj2wmap);
+    if (w->obj2wmap) st_foreach_with_replace(w->obj2wmap, wmap_foreach_replace, wmap_replace_ref, (st_data_t)NULL);
     w->final = rb_gc_location(w->final);
 }
 
@@ -12912,25 +13007,40 @@ wmap_live_p(rb_objspace_t *objspace, VALUE obj)
 }
 
 static int
-wmap_final_func(st_data_t *key, st_data_t *value, st_data_t arg, int existing)
+wmap_remove_inverse_ref(st_data_t *key, st_data_t *val, st_data_t arg, int existing)
 {
-    VALUE wmap, *ptr, size, i, j;
     if (!existing) return ST_STOP;
-    wmap = (VALUE)arg, ptr = (VALUE *)*value;
-    for (i = j = 1, size = ptr[0]; i <= size; ++i) {
-        if (ptr[i] != wmap) {
-            ptr[j++] = ptr[i];
-        }
-    }
-    if (j == 1) {
-        ruby_sized_xfree(ptr, i * sizeof(VALUE));
+
+    VALUE old_ref = (VALUE)arg;
+
+    VALUE *values = (VALUE *)*val;
+    VALUE size = values[0];
+
+    if (size == 1) {
+        // fast path, we only had one backref
+        RUBY_ASSERT(values[1] == old_ref);
+        ruby_sized_xfree(values, 2 * sizeof(VALUE));
         return ST_DELETE;
     }
-    if (j < i) {
-        SIZED_REALLOC_N(ptr, VALUE, j + 1, i);
-        ptr[0] = j;
-        *value = (st_data_t)ptr;
+
+    bool found = false;
+    VALUE index = 1;
+    for (; index <= size; index++) {
+        if (values[index] == old_ref) {
+            found = true;
+            break;
+        }
+    }
+    if (!found) return ST_STOP;
+
+    if (size > index) {
+        MEMMOVE(&values[index], &values[index + 1], VALUE, size - index);
     }
+
+    size -= 1;
+    values[0] = size;
+    SIZED_REALLOC_N(values, VALUE, size + 1, size + 2);
+    *val = (st_data_t)values;
     return ST_CONTINUE;
 }
 
@@ -12963,7 +13073,7 @@ wmap_finalize(RB_BLOCK_CALL_FUNC_ARGLIST(objid, self))
     wmap = (st_data_t)obj;
     if (st_delete(w->wmap2obj, &wmap, &orig)) {
         wmap = (st_data_t)obj;
-        st_update(w->obj2wmap, orig, wmap_final_func, wmap);
+        st_update(w->obj2wmap, orig, wmap_remove_inverse_ref, wmap);
     }
     return self;
 }
@@ -13179,6 +13289,14 @@ wmap_aset_update(st_data_t *key, st_data_t *val, st_data_t arg, int existing)
     VALUE size, *ptr, *optr;
     if (existing) {
         size = (ptr = optr = (VALUE *)*val)[0];
+
+        for (VALUE index = 1; index <= size; index++) {
+            if (ptr[index] == (VALUE)arg) {
+                // The reference was already registered.
+                return ST_STOP;
+            }
+        }
+
         ++size;
         SIZED_REALLOC_N(ptr, VALUE, size + 1, size);
     }
@@ -13194,6 +13312,23 @@ wmap_aset_update(st_data_t *key, st_data_t *val, st_data_t arg, int existing)
     return ST_CONTINUE;
 }
 
+struct wmap_aset_replace_args {
+    VALUE new_value;
+    VALUE old_value;
+};
+
+static int
+wmap_aset_replace_value(st_data_t *key, st_data_t *val, st_data_t _args, int existing)
+{
+    struct wmap_aset_replace_args *args = (struct wmap_aset_replace_args *)_args;
+
+    if (existing) {
+        args->old_value = *val;
+    }
+    *val = (st_data_t)args->new_value;
+    return ST_CONTINUE;
+}
+
 /* Creates a weak reference from the given key to the given value */
 static VALUE
 wmap_aset(VALUE self, VALUE key, VALUE value)
@@ -13208,8 +13343,25 @@ wmap_aset(VALUE self, VALUE key, VALUE value)
         define_final0(key, w->final);
     }
 
-    st_update(w->obj2wmap, (st_data_t)value, wmap_aset_update, key);
-    st_insert(w->wmap2obj, (st_data_t)key, (st_data_t)value);
+    struct wmap_aset_replace_args aset_args = {
+        .new_value = value,
+        .old_value = Qundef,
+    };
+    st_update(w->wmap2obj, (st_data_t)key, wmap_aset_replace_value, (st_data_t)&aset_args);
+
+    // If the value is unchanged, we have nothing to do.
+    if (value != aset_args.old_value) {
+        if (!UNDEF_P(aset_args.old_value) && FL_ABLE(aset_args.old_value)) {
+            // That key existed and had an inverse reference, we need to clear the outdated inverse reference.
+            st_update(w->obj2wmap, (st_data_t)aset_args.old_value, wmap_remove_inverse_ref, key);
+        }
+
+        if (FL_ABLE(value)) {
+            // If the value has no finalizer, we don't need to keep the inverse reference
+            st_update(w->obj2wmap, (st_data_t)value, wmap_aset_update, key);
+        }
+    }
+
     return nonspecial_obj_id(value);
 }
 
@@ -14159,7 +14311,7 @@ rb_raw_obj_info_buitin_type(char *const buff, const size_t buff_size, const VALU
                 {
                     const rb_method_entry_t *me = &RANY(obj)->as.imemo.ment;
 
-                    APPEND_F(":%s (%s%s%s%s) type:%s alias:%d owner:%p defined_class:%p",
+                    APPEND_F(":%s (%s%s%s%s) type:%s aliased:%d owner:%p defined_class:%p",
                              rb_id2name(me->called_id),
                              METHOD_ENTRY_VISI(me) == METHOD_VISI_PUBLIC ?  "pub" :
                              METHOD_ENTRY_VISI(me) == METHOD_VISI_PRIVATE ? "pri" : "pro",
@@ -14167,7 +14319,7 @@ rb_raw_obj_info_buitin_type(char *const buff, const size_t buff_size, const VALU
                              METHOD_ENTRY_CACHED(me) ? ",cc" : "",
                              METHOD_ENTRY_INVALIDATED(me) ? ",inv" : "",
                              me->def ? rb_method_type_name(me->def->type) : "NULL",
-                             me->def ? me->def->alias_count : -1,
+                             me->def ? me->def->aliased : -1,
                              (void *)me->owner, // obj_info(me->owner),
                              (void *)me->defined_class); //obj_info(me->defined_class)));
 
diff --git a/gc.h b/gc.h
index b2356444c6..23218c1a9e 100644
--- a/gc.h
+++ b/gc.h
@@ -116,8 +116,6 @@ int ruby_get_stack_grow_direction(volatile VALUE *addr);
 const char *rb_obj_info(VALUE obj);
 const char *rb_raw_obj_info(char *const buff, const size_t buff_size, VALUE obj);
 
-VALUE rb_gc_disable_no_rest(void);
-
 struct rb_thread_struct;
 
 size_t rb_size_pool_slot_size(unsigned char pool_id);
@@ -142,6 +140,8 @@ void rb_objspace_each_objects_without_setup(
 
 size_t rb_gc_obj_slot_size(VALUE obj);
 
+VALUE rb_gc_disable_no_rest(void);
+
 RUBY_SYMBOL_EXPORT_END
 
 #endif /* RUBY_GC_H */
diff --git a/gems/bundled_gems b/gems/bundled_gems
index 6dac400cb8..d37d869d41 100644
--- a/gems/bundled_gems
+++ b/gems/bundled_gems
@@ -1,14 +1,14 @@
 # gem-name version-to-bundle repository-url [optional-commit-hash-to-test-or-defaults-to-v-version]
-minitest        5.16.3  https://github.com/seattlerb/minitest
+minitest        5.25.1  https://github.com/seattlerb/minitest
 power_assert    2.0.3   https://github.com/ruby/power_assert
 rake            13.0.6  https://github.com/ruby/rake
 test-unit       3.5.7   https://github.com/test-unit/test-unit
-rexml           3.2.5   https://github.com/ruby/rexml
-rss             0.2.9   https://github.com/ruby/rss
-net-ftp         0.2.0   https://github.com/ruby/net-ftp
-net-imap        0.3.4   https://github.com/ruby/net-imap
+rexml           3.3.9   https://github.com/ruby/rexml
+rss             0.3.1   https://github.com/ruby/rss
+net-ftp         0.2.1   https://github.com/ruby/net-ftp
+net-imap        0.3.9   https://github.com/ruby/net-imap
 net-pop         0.1.2   https://github.com/ruby/net-pop
-net-smtp        0.3.3   https://github.com/ruby/net-smtp
+net-smtp        0.3.4   https://github.com/ruby/net-smtp
 matrix          0.4.2   https://github.com/ruby/matrix
 prime           0.1.2   https://github.com/ruby/prime
 rbs             2.8.2   https://github.com/ruby/rbs
diff --git a/gems/lib/core_assertions.rb b/gems/lib/core_assertions.rb
new file mode 100644
index 0000000000..7334063885
--- /dev/null
+++ b/gems/lib/core_assertions.rb
@@ -0,0 +1 @@
+require_relative "../../tool/lib/core_assertions.rb"
diff --git a/gems/lib/envutil.rb b/gems/lib/envutil.rb
new file mode 100644
index 0000000000..d684c22cf2
--- /dev/null
+++ b/gems/lib/envutil.rb
@@ -0,0 +1 @@
+require_relative "../../tool/lib/envutil.rb"
diff --git a/tool/dummy-rake-compiler/rake/extensiontask.rb b/gems/lib/rake/extensiontask.rb
index 62b7ff8018..fdbe8d8874 100644
--- a/tool/dummy-rake-compiler/rake/extensiontask.rb
+++ b/gems/lib/rake/extensiontask.rb
@@ -1,8 +1,11 @@
+require "rake/tasklib" unless defined?(Rake::TaskLib)
+
 module Rake
   class ExtensionTask < TaskLib
     def initialize(...)
-      task :compile do
+      task :compile do |args|
         puts "Dummy `compile` task defined in #{__FILE__}"
+        puts "#{args.name} => #{args.prereqs.join(' ')}"
       end
     end
   end
diff --git a/hash.c b/hash.c
index 5204d8b018..d2dce30624 100644
--- a/hash.c
+++ b/hash.c
@@ -221,7 +221,7 @@ obj_any_hash(VALUE obj)
     return FIX2LONG(hval);
 }
 
-static st_index_t
+st_index_t
 rb_any_hash(VALUE a)
 {
     return any_hash(a, obj_any_hash);
@@ -361,6 +361,9 @@ const struct st_hash_type rb_hashtype_ident = {
     rb_ident_hash,
 };
 
+#define RHASH_IDENTHASH_P(hash) (RHASH_TYPE(hash) == &identhash)
+#define RHASH_STRING_KEY_P(hash, key) (!RHASH_IDENTHASH_P(hash) && (rb_obj_class(key) == rb_cString))
+
 typedef st_index_t st_hash_t;
 
 /*
@@ -767,31 +770,39 @@ ar_free_and_clear_table(VALUE hash)
     HASH_ASSERT(RHASH_TRANSIENT_P(hash) == 0);
 }
 
-static void
-ar_try_convert_table(VALUE hash)
-{
-    if (!RHASH_AR_TABLE_P(hash)) return;
-
-    const unsigned size = RHASH_AR_TABLE_SIZE(hash);
+void rb_st_add_direct_with_hash(st_table *tab, st_data_t key, st_data_t value, st_hash_t hash); // st.c
 
-    st_table *new_tab;
-    st_index_t i;
+enum ar_each_key_type {
+    ar_each_key_copy,
+    ar_each_key_cmp,
+    ar_each_key_insert,
+};
 
-    if (size < RHASH_AR_TABLE_MAX_SIZE) {
-        return;
+static inline int
+ar_each_key(ar_table *ar, int max, enum ar_each_key_type type, st_data_t *dst_keys, st_table *new_tab, st_hash_t *hashes)
+{
+    for (int i = 0; i < max; i++) {
+        ar_table_pair *pair = &ar->pairs[i];
+
+        switch (type) {
+          case ar_each_key_copy:
+            dst_keys[i] = pair->key;
+            break;
+          case ar_each_key_cmp:
+            if (dst_keys[i] != pair->key) return 1;
+            break;
+          case ar_each_key_insert:
+            if (UNDEF_P(pair->key)) continue; // deleted entry
+            rb_st_add_direct_with_hash(new_tab, pair->key, pair->val, hashes[i]);
+            break;
+        }
     }
 
-    new_tab = st_init_table_with_size(&objhash, size * 2);
-
-    for (i = 0; i < RHASH_AR_TABLE_MAX_BOUND; i++) {
-        ar_table_pair *pair = RHASH_AR_TABLE_REF(hash, i);
-        st_add_direct(new_tab, pair->key, pair->val);
-    }
-    ar_free_and_clear_table(hash);
-    RHASH_ST_TABLE_SET(hash, new_tab);
-    return;
+    return 0;
 }
 
+
+
 static st_table *
 ar_force_convert_table(VALUE hash, const char *file, int line)
 {
@@ -802,22 +813,32 @@ ar_force_convert_table(VALUE hash, const char *file, int line)
     }
 
     if (RHASH_AR_TABLE(hash)) {
-        unsigned i, bound = RHASH_AR_TABLE_BOUND(hash);
-
-#if defined(RHASH_CONVERT_TABLE_DEBUG) && RHASH_CONVERT_TABLE_DEBUG
-        rb_obj_info_dump(hash);
-        fprintf(stderr, "force_convert: %s:%d\n", file, line);
-        RB_DEBUG_COUNTER_INC(obj_hash_force_convert);
-#endif
+        ar_table *ar = RHASH_AR_TABLE(hash);
+        st_hash_t hashes[RHASH_AR_TABLE_MAX_SIZE];
+        unsigned int bound, size;
+
+        // prepare hash values
+        do {
+            st_data_t keys[RHASH_AR_TABLE_MAX_SIZE];
+            bound = RHASH_AR_TABLE_BOUND(hash);
+            size = RHASH_AR_TABLE_SIZE(hash);
+            ar_each_key(ar, bound, ar_each_key_copy, keys, NULL, NULL);
+
+            for (unsigned int i = 0; i < bound; i++) {
+                // do_hash calls #hash method and it can modify hash object
+                hashes[i] = UNDEF_P(keys[i]) ? 0 : ar_do_hash(keys[i]);
+            }
 
-        new_tab = st_init_table_with_size(&objhash, RHASH_AR_TABLE_SIZE(hash));
+            // check if modified
+            if (UNLIKELY(!RHASH_AR_TABLE_P(hash))) return RHASH_ST_TABLE(hash);
+            if (UNLIKELY(RHASH_AR_TABLE_BOUND(hash) != bound)) continue;
+            if (UNLIKELY(ar_each_key(ar, bound, ar_each_key_cmp, keys, NULL, NULL))) continue;
+        } while (0);
 
-        for (i = 0; i < bound; i++) {
-            if (ar_cleared_entry(hash, i)) continue;
 
-            ar_table_pair *pair = RHASH_AR_TABLE_REF(hash, i);
-            st_add_direct(new_tab, pair->key, pair->val);
-        }
+        // make st
+        new_tab = st_init_table_with_size(&objhash, size);
+        ar_each_key(ar, bound, ar_each_key_insert, NULL, new_tab, hashes);
         ar_free_and_clear_table(hash);
     }
     else {
@@ -1409,13 +1430,19 @@ iter_lev_in_ivar_set(VALUE hash, int lev)
     rb_ivar_set_internal(hash, id_hash_iter_lev, INT2FIX(lev));
 }
 
-static int
+static inline int
 iter_lev_in_flags(VALUE hash)
 {
     unsigned int u = (unsigned int)((RBASIC(hash)->flags >> RHASH_LEV_SHIFT) & RHASH_LEV_MAX);
     return (int)u;
 }
 
+static inline void
+iter_lev_in_flags_set(VALUE hash, int lev)
+{
+    RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((VALUE)lev << RHASH_LEV_SHIFT));
+}
+
 static int
 RHASH_ITER_LEV(VALUE hash)
 {
@@ -1439,7 +1466,7 @@ hash_iter_lev_inc(VALUE hash)
     }
     else {
         lev += 1;
-        RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((VALUE)lev << RHASH_LEV_SHIFT));
+        iter_lev_in_flags_set(hash, lev);
         if (lev == RHASH_LEV_MAX) {
             iter_lev_in_ivar_set(hash, lev);
         }
@@ -1457,7 +1484,7 @@ hash_iter_lev_dec(VALUE hash)
     }
     else {
         HASH_ASSERT(lev > 0);
-        RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((lev-1) << RHASH_LEV_SHIFT));
+        iter_lev_in_flags_set(hash, lev - 1);
     }
 }
 
@@ -1536,6 +1563,16 @@ rb_hash_foreach(VALUE hash, rb_foreach_func *func, VALUE farg)
     hash_verify(hash);
 }
 
+void rb_st_compact_table(st_table *tab);
+
+static void
+compact_after_delete(VALUE hash)
+{
+    if (RHASH_ITER_LEV(hash) == 0 && RHASH_ST_TABLE_P(hash)) {
+        rb_st_compact_table(RHASH_ST_TABLE(hash));
+    }
+}
+
 static VALUE
 hash_alloc_flags(VALUE klass, VALUE flags, VALUE ifnone)
 {
@@ -1708,7 +1745,7 @@ rb_hash_stlike_update(VALUE hash, st_data_t key, st_update_callback_func *func,
     if (RHASH_AR_TABLE_P(hash)) {
         int result = ar_update(hash, key, func, arg);
         if (result == -1) {
-            ar_try_convert_table(hash);
+            ar_force_convert_table(hash, __FILE__, __LINE__);
         }
         else {
             return result;
@@ -2463,6 +2500,7 @@ rb_hash_delete_m(VALUE hash, VALUE key)
     val = rb_hash_delete_entry(hash, key);
 
     if (!UNDEF_P(val)) {
+        compact_after_delete(hash);
         return val;
     }
     else {
@@ -2583,6 +2621,7 @@ rb_hash_delete_if(VALUE hash)
     rb_hash_modify_check(hash);
     if (!RHASH_TABLE_EMPTY_P(hash)) {
         rb_hash_foreach(hash, delete_if_i, hash);
+        compact_after_delete(hash);
     }
     return hash;
 }
@@ -2646,6 +2685,7 @@ rb_hash_reject(VALUE hash)
     result = hash_dup_with_compare_by_id(hash);
     if (!RHASH_EMPTY_P(hash)) {
         rb_hash_foreach(result, delete_if_i, result);
+        compact_after_delete(result);
     }
     return result;
 }
@@ -2705,6 +2745,7 @@ rb_hash_except(int argc, VALUE *argv, VALUE hash)
         key = argv[i];
         rb_hash_delete(result, key);
     }
+    compact_after_delete(result);
 
     return result;
 }
@@ -2802,6 +2843,7 @@ rb_hash_select(VALUE hash)
     result = hash_dup_with_compare_by_id(hash);
     if (!RHASH_EMPTY_P(hash)) {
         rb_hash_foreach(result, keep_if_i, result);
+        compact_after_delete(result);
     }
     return result;
 }
@@ -2893,6 +2935,7 @@ rb_hash_clear(VALUE hash)
     }
     else {
         st_clear(RHASH_ST_TABLE(hash));
+        compact_after_delete(hash);
     }
 
     return hash;
@@ -2966,7 +3009,7 @@ rb_hash_aset(VALUE hash, VALUE key, VALUE val)
         ar_alloc_table(hash);
     }
 
-    if (RHASH_TYPE(hash) == &identhash || rb_obj_class(key) != rb_cString) {
+    if (!RHASH_STRING_KEY_P(hash, key)) {
         RHASH_UPDATE_ITER(hash, iter_lev, key, hash_aset, val);
     }
     else {
@@ -3338,6 +3381,7 @@ rb_hash_transform_keys_bang(int argc, VALUE *argv, VALUE hash)
         rb_ary_clear(pairs);
         rb_hash_clear(new_keys);
     }
+    compact_after_delete(hash);
     return hash;
 }
 
@@ -3388,6 +3432,7 @@ rb_hash_transform_values(VALUE hash)
 
     if (!RHASH_EMPTY_P(hash)) {
         rb_hash_stlike_foreach_with_replace(result, transform_values_foreach_func, transform_values_foreach_replace, result);
+        compact_after_delete(result);
     }
 
     return result;
@@ -3924,18 +3969,9 @@ rb_hash_invert(VALUE hash)
 }
 
 static int
-rb_hash_update_callback(st_data_t *key, st_data_t *value, struct update_arg *arg, int existing)
-{
-    *value = arg->arg;
-    return ST_CONTINUE;
-}
-
-NOINSERT_UPDATE_CALLBACK(rb_hash_update_callback)
-
-static int
 rb_hash_update_i(VALUE key, VALUE value, VALUE hash)
 {
-    RHASH_UPDATE(hash, key, rb_hash_update_callback, value);
+    rb_hash_aset(hash, key, value);
     return ST_CONTINUE;
 }
 
@@ -3947,6 +3983,9 @@ rb_hash_update_block_callback(st_data_t *key, st_data_t *value, struct update_ar
     if (existing) {
         newvalue = (st_data_t)rb_yield_values(3, (VALUE)*key, (VALUE)*value, (VALUE)newvalue);
     }
+    else if (RHASH_STRING_KEY_P(arg->hash, *key) && !RB_OBJ_FROZEN(*key)) {
+        *key = rb_hash_key_str(*key);
+    }
     *value = newvalue;
     return ST_CONTINUE;
 }
@@ -4199,7 +4238,7 @@ rb_hash_assoc(VALUE hash, VALUE key)
     table = RHASH_ST_TABLE(hash);
     orighash = table->type;
 
-    if (orighash != &identhash) {
+    if (!RHASH_IDENTHASH_P(hash)) {
         VALUE value;
         struct reset_hash_type_arg ensure_arg;
         struct st_hash_type assochash;
@@ -4459,7 +4498,7 @@ rb_hash_compare_by_id(VALUE hash)
 MJIT_FUNC_EXPORTED VALUE
 rb_hash_compare_by_id_p(VALUE hash)
 {
-    return RBOOL(RHASH_ST_TABLE_P(hash) && RHASH_ST_TABLE(hash)->type == &identhash);
+    return RBOOL(RHASH_IDENTHASH_P(hash));
 }
 
 VALUE
@@ -4777,7 +4816,7 @@ rb_hash_add_new_element(VALUE hash, VALUE key, VALUE val)
         if (ret != -1) {
             return ret;
         }
-        ar_try_convert_table(hash);
+        ar_force_convert_table(hash, __FILE__, __LINE__);
     }
     tbl = RHASH_TBL_RAW(hash);
     return st_update(tbl, (st_data_t)key, add_new_i, (st_data_t)args);
@@ -4956,7 +4995,7 @@ env_name(volatile VALUE *s)
 static VALUE env_aset(VALUE nm, VALUE val);
 
 static void
-reset_by_modified_env(const char *nam)
+reset_by_modified_env(const char *nam, const char *val)
 {
     /*
      * ENV['TZ'] = nil has a special meaning.
@@ -4965,7 +5004,7 @@ reset_by_modified_env(const char *nam)
      * This hack might works only on Linux glibc.
      */
     if (ENVMATCH(nam, TZ_ENV)) {
-        ruby_reset_timezone();
+        ruby_reset_timezone(val);
     }
 }
 
@@ -4973,7 +5012,7 @@ static VALUE
 env_delete(VALUE name)
 {
     const char *nam = env_name(name);
-    reset_by_modified_env(nam);
+    reset_by_modified_env(nam, NULL);
     VALUE val = getenv_with_lock(nam);
 
     if (!NIL_P(val)) {
@@ -5433,7 +5472,7 @@ env_aset(VALUE nm, VALUE val)
     get_env_ptr(value, val);
 
     ruby_setenv(name, value);
-    reset_by_modified_env(name);
+    reset_by_modified_env(name, value);
     return val;
 }
 
@@ -5988,24 +6027,23 @@ env_to_s(VALUE _)
 static VALUE
 env_inspect(VALUE _)
 {
-    VALUE i;
     VALUE str = rb_str_buf_new2("{");
+    rb_encoding *enc = env_encoding();
 
     ENV_LOCK();
     {
         char **env = GET_ENVIRON(environ);
         while (*env) {
-            char *s = strchr(*env, '=');
+            const char *s = strchr(*env, '=');
 
             if (env != environ) {
                 rb_str_buf_cat2(str, ", ");
             }
             if (s) {
-                rb_str_buf_cat2(str, "\"");
-                rb_str_buf_cat(str, *env, s-*env);
-                rb_str_buf_cat2(str, "\"=>");
-                i = rb_inspect(rb_str_new2(s+1));
-                rb_str_buf_append(str, i);
+                rb_str_buf_append(str, rb_str_inspect(env_enc_str_new(*env, s-*env, enc)));
+                rb_str_buf_cat2(str, "=>");
+                s++;
+                rb_str_buf_append(str, rb_str_inspect(env_enc_str_new(s, strlen(s), enc)));
             }
             env++;
         }
diff --git a/include/ruby/internal/anyargs.h b/include/ruby/internal/anyargs.h
index e3e1b6166d..e4c6d155cc 100644
--- a/include/ruby/internal/anyargs.h
+++ b/include/ruby/internal/anyargs.h
@@ -84,12 +84,15 @@
 
 #elif defined(_WIN32) || defined(__CYGWIN__)
 # /* Skip due to [Bug #16134] */
+# define RBIMPL_CAST_FN_PTR 1
 
 #elif ! RBIMPL_HAS_ATTRIBUTE(transparent_union)
 # /* :TODO: improve here, please find a way to support. */
+# define RBIMPL_CAST_FN_PTR 1
 
 #elif ! defined(HAVE_VA_ARGS_MACRO)
 # /* :TODO: improve here, please find a way to support. */
+# define RBIMPL_CAST_FN_PTR 1
 
 #else
 # /** @cond INTERNAL_MACRO */
@@ -348,6 +351,25 @@ RBIMPL_ANYARGS_DECL(rb_define_method, VALUE, const char *)
 
 #endif /* __cplusplus */
 
+#if defined(RBIMPL_CAST_FN_PTR) && !defined(__cplusplus)
+/* In C23, K&R style prototypes are gone and so `void foo(ANYARGS)` became
+ * equivalent to `void foo(void)` unlike in earlier versions. This is a problem
+ * for rb_define_* functions since that makes all valid functions one can pass
+ * trip -Wincompatible-pointer-types, which we treat as errors. This is mostly
+ * not a problem for the __builtin_choose_expr path, but outside of that we
+ * need to add a cast for compatibility.
+ */
+#define rb_define_method(klass, mid, func, arity)           rb_define_method((klass), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_method_id(klass, mid, func, arity)        rb_define_method_id((klass), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_singleton_method(obj, mid, func, arity)   rb_define_singleton_method((obj), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_protected_method(klass, mid, func, arity) rb_define_protected_method((klass), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_private_method(klass, mid, func, arity)   rb_define_private_method((klass), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_module_function(mod, mid, func, arity)    rb_define_module_function((mod), (mid), (VALUE (*)(ANYARGS))(func), (arity))
+#define rb_define_global_function(mid, func, arity)         rb_define_global_function((mid), (VALUE (*)(ANYARGS))(func), (arity))
+
+#undef RBIMPL_CAST_FN_PTR
+#endif /* defined(RBIMPL_CAST_FN_PTR) && !defined(__cplusplus) */
+
 /**
  * This  macro is  to properly  cast  a function  parameter of  *_define_method
  * family.  It  has been  around since  1.x era so  you can  maximise backwards
diff --git a/include/ruby/internal/attr/nonstring.h b/include/ruby/internal/attr/nonstring.h
new file mode 100644
index 0000000000..de26e926d4
--- /dev/null
+++ b/include/ruby/internal/attr/nonstring.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_NONSTRING_H                        /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NONSTRING_H
+/**
+ * @file
+ * @author     Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright  This  file  is   a  part  of  the   programming  language  Ruby.
+ *             Permission  is hereby  granted,  to  either redistribute  and/or
+ *             modify this file, provided that  the conditions mentioned in the
+ *             file COPYING are met.  Consult the file for details.
+ * @warning    Symbols   prefixed  with   either  `RBIMPL`   or  `rbimpl`   are
+ *             implementation details.   Don't take  them as canon.  They could
+ *             rapidly appear then vanish.  The name (path) of this header file
+ *             is also an  implementation detail.  Do not expect  it to persist
+ *             at the place it is now.  Developers are free to move it anywhere
+ *             anytime at will.
+ * @note       To  ruby-core:  remember  that   this  header  can  be  possibly
+ *             recursively included  from extension  libraries written  in C++.
+ *             Do not  expect for  instance `__VA_ARGS__` is  always available.
+ *             We assume C99  for ruby itself but we don't  assume languages of
+ *             extension libraries.  They could be written in C++98.
+ * @brief      Defines #RBIMPL_ATTR_NONSTRING.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((nonstring))` */
+#if RBIMPL_HAS_ATTRIBUTE(nonstring)
+# define RBIMPL_ATTR_NONSTRING() __attribute__((nonstring))
+#else
+# define RBIMPL_ATTR_NONSTRING() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NONSTRING_H */
diff --git a/include/ruby/internal/gc.h b/include/ruby/internal/gc.h
index 66fc14e511..054e4b0f9c 100644
--- a/include/ruby/internal/gc.h
+++ b/include/ruby/internal/gc.h
@@ -26,10 +26,15 @@
 RBIMPL_SYMBOL_EXPORT_BEGIN()
 
 /**
- * Inform the garbage collector that `valptr` points to a live Ruby object that
- * should not be moved. Note that extensions should use this API on global
- * constants instead of assuming constants defined in Ruby are always alive.
- * Ruby code can remove global constants.
+ * Inform the garbage  collector that the global or static  variable pointed by
+ * `valptr` stores  a live  Ruby object  that should not  be moved.   Note that
+ * extensions  should use  this API  on  global constants  instead of  assuming
+ * constants defined  in Ruby are  always alive.   Ruby code can  remove global
+ * constants.
+ *
+ * Because this  registration itself has  a possibility  to trigger a  GC, this
+ * function  must be  called  before any  GC-able objects  is  assigned to  the
+ * address pointed by `valptr`.
  */
 void rb_gc_register_address(VALUE *valptr);
 
diff --git a/include/ruby/io/buffer.h b/include/ruby/io/buffer.h
index 88e5598066..e4b855d8e7 100644
--- a/include/ruby/io/buffer.h
+++ b/include/ruby/io/buffer.h
@@ -56,14 +56,10 @@ enum rb_io_buffer_endian {
     RB_IO_BUFFER_LITTLE_ENDIAN = 4,
     RB_IO_BUFFER_BIG_ENDIAN = 8,
 
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-    RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_LITTLE_ENDIAN,
-#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#if defined(WORDS_BIGENDIAN)
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_BIG_ENDIAN,
-#elif REG_DWORD == REG_DWORD_LITTLE_ENDIAN
+#else
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_LITTLE_ENDIAN,
-#elif REG_DWORD == REG_DWORD_BIG_ENDIAN
-    RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_BIG_ENDIAN,
 #endif
 
     RB_IO_BUFFER_NETWORK_ENDIAN = RB_IO_BUFFER_BIG_ENDIAN
diff --git a/include/ruby/st.h b/include/ruby/st.h
index 1e4bb80686..f35ab43603 100644
--- a/include/ruby/st.h
+++ b/include/ruby/st.h
@@ -98,6 +98,8 @@ struct st_table {
 
 enum st_retval {ST_CONTINUE, ST_STOP, ST_DELETE, ST_CHECK, ST_REPLACE};
 
+size_t rb_st_table_size(const struct st_table *tbl);
+#define st_table_size rb_st_table_size
 st_table *rb_st_init_table(const struct st_hash_type *);
 #define st_init_table rb_st_init_table
 st_table *rb_st_init_table_with_size(const struct st_hash_type *, st_index_t);
diff --git a/include/ruby/win32.h b/include/ruby/win32.h
index 197eb8a802..18de3a17d8 100644
--- a/include/ruby/win32.h
+++ b/include/ruby/win32.h
@@ -125,8 +125,15 @@ typedef unsigned int uintptr_t;
 #define O_SHARE_DELETE 0x20000000 /* for rb_w32_open(), rb_w32_wopen() */
 
 typedef int clockid_t;
+#if defined(__MINGW32__)
+#undef CLOCK_PROCESS_CPUTIME_ID
+#undef CLOCK_THREAD_CPUTIME_ID
+#undef CLOCK_REALTIME_COARSE
+#endif
+#if defined(HAVE_CLOCK_GETTIME) && !defined(CLOCK_REALTIME)
 #define CLOCK_REALTIME  0
 #define CLOCK_MONOTONIC 1
+#endif
 
 #undef utime
 #undef lseek
diff --git a/internal/class.h b/internal/class.h
index 5731a5bc33..63917e867f 100644
--- a/internal/class.h
+++ b/internal/class.h
@@ -15,6 +15,9 @@
 #include "ruby/intern.h"        /* for rb_alloc_func_t */
 #include "ruby/ruby.h"          /* for struct RBasic */
 #include "shape.h"
+#include "ruby_assert.h"
+#include "vm_core.h"
+#include "method.h"             /* for rb_cref_t */
 
 #ifdef RCLASS_SUPER
 # undef RCLASS_SUPER
@@ -29,6 +32,7 @@ struct rb_subclass_entry {
 struct rb_cvar_class_tbl_entry {
     uint32_t index;
     rb_serial_t global_cvar_state;
+    const rb_cref_t * cref;
     VALUE class_value;
 };
 
@@ -115,6 +119,7 @@ void rb_class_foreach_subclass(VALUE klass, void (*f)(VALUE, VALUE), VALUE);
 void rb_class_detach_subclasses(VALUE);
 void rb_class_detach_module_subclasses(VALUE);
 void rb_class_remove_from_module_subclasses(VALUE);
+VALUE rb_define_class_id_under_no_pin(VALUE outer, ID id, VALUE super);
 VALUE rb_obj_methods(int argc, const VALUE *argv, VALUE obj);
 VALUE rb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj);
 VALUE rb_obj_private_methods(int argc, const VALUE *argv, VALUE obj);
diff --git a/internal/eval.h b/internal/eval.h
index 73bb656d96..e594d8516d 100644
--- a/internal/eval.h
+++ b/internal/eval.h
@@ -21,6 +21,7 @@ extern ID ruby_static_id_status;
 VALUE rb_refinement_module_get_refined_class(VALUE module);
 void rb_class_modify_check(VALUE);
 NORETURN(VALUE rb_f_raise(int argc, VALUE *argv));
+VALUE rb_top_main_class(const char *method);
 
 /* eval_error.c */
 VALUE rb_get_backtrace(VALUE info);
diff --git a/internal/hash.h b/internal/hash.h
index 657e5eff3c..64832c9610 100644
--- a/internal/hash.h
+++ b/internal/hash.h
@@ -73,6 +73,7 @@ VALUE rb_hash_default_value(VALUE hash, VALUE key);
 VALUE rb_hash_set_default_proc(VALUE hash, VALUE proc);
 long rb_dbl_long_hash(double d);
 st_table *rb_init_identtable(void);
+st_index_t rb_any_hash(VALUE a);
 VALUE rb_to_hash_type(VALUE obj);
 VALUE rb_hash_key_str(VALUE);
 VALUE rb_hash_values(VALUE hash);
diff --git a/internal/time.h b/internal/time.h
index a3bf0587ec..e21b3574f6 100644
--- a/internal/time.h
+++ b/internal/time.h
@@ -28,7 +28,10 @@ struct timeval rb_time_timeval(VALUE);
 RUBY_SYMBOL_EXPORT_BEGIN
 /* time.c (export) */
 void ruby_reset_leap_second_info(void);
-void ruby_reset_timezone(void);
+#ifdef RBIMPL_ATTR_DEPRECATED_INTERNAL_ONLY
+RBIMPL_ATTR_DEPRECATED_INTERNAL_ONLY()
+#endif
+void ruby_reset_timezone(const char *);
 RUBY_SYMBOL_EXPORT_END
 
 #endif /* INTERNAL_TIME_H */
diff --git a/io.c b/io.c
index 2e51a46635..99ec59da29 100644
--- a/io.c
+++ b/io.c
@@ -1148,7 +1148,8 @@ io_internal_wait(VALUE thread, rb_io_t *fptr, int error, int events, struct time
 
     if (ready > 0) {
         return ready;
-    } else if (ready == 0) {
+    }
+    else if (ready == 0) {
         errno = ETIMEDOUT;
         return -1;
     }
@@ -1176,7 +1177,8 @@ internal_read_func(void *ptr)
         if (io_again_p(errno)) {
             if (io_internal_wait(iis->th, iis->fptr, errno, RB_WAITFD_IN, iis->timeout) == -1) {
                 return -1;
-            } else {
+            }
+            else {
                 goto retry;
             }
         }
@@ -1211,7 +1213,8 @@ internal_write_func(void *ptr)
         if (io_again_p(e)) {
             if (io_internal_wait(iis->th, iis->fptr, errno, RB_WAITFD_OUT, iis->timeout) == -1) {
                 return -1;
-            } else {
+            }
+            else {
                 goto retry;
             }
         }
@@ -1240,7 +1243,8 @@ internal_writev_func(void *ptr)
         if (io_again_p(errno)) {
             if (io_internal_wait(iis->th, iis->fptr, errno, RB_WAITFD_OUT, iis->timeout) == -1) {
                 return -1;
-            } else {
+            }
+            else {
                 goto retry;
             }
         }
@@ -1320,14 +1324,15 @@ rb_io_write_memory(rb_io_t *fptr, const void *buf, size_t count)
 static ssize_t
 rb_writev_internal(rb_io_t *fptr, const struct iovec *iov, int iovcnt)
 {
+    if (!iovcnt) return 0;
+
     VALUE scheduler = rb_fiber_scheduler_current();
     if (scheduler != Qnil) {
-        for (int i = 0; i < iovcnt; i += 1) {
-            VALUE result = rb_fiber_scheduler_io_write_memory(scheduler, fptr->self, iov[i].iov_base, iov[i].iov_len, 0);
+        // This path assumes at least one `iov`:
+        VALUE result = rb_fiber_scheduler_io_write_memory(scheduler, fptr->self, iov[0].iov_base, iov[0].iov_len, 0);
 
-            if (!UNDEF_P(result)) {
-                return rb_fiber_scheduler_io_result_apply(result);
-            }
+        if (!UNDEF_P(result)) {
+            return rb_fiber_scheduler_io_result_apply(result);
         }
     }
 
@@ -1788,13 +1793,11 @@ io_binwrite_string(VALUE arg)
         // Write as much as possible:
         ssize_t result = io_binwrite_string_internal(p->fptr, ptr, remaining);
 
-        // If only the internal buffer is written, result will be zero [bytes of given data written]. This means we
-        // should try again.
         if (result == 0) {
-            errno = EWOULDBLOCK;
+            // If only the internal buffer is written, result will be zero [bytes of given data written]. This means we
+            // should try again immediately.
         }
-
-        if (result > 0) {
+        else if (result > 0) {
             if ((size_t)result == remaining) break;
             ptr += result;
             remaining -= result;
@@ -2034,7 +2037,7 @@ io_binwritev_internal(VALUE arg)
     while (remaining) {
         long result = rb_writev_internal(fptr, iov, iovcnt);
 
-        if (result > 0) {
+        if (result >= 0) {
             offset += result;
             if (fptr->wbuf.ptr && fptr->wbuf.len) {
                 if (offset < (size_t)fptr->wbuf.len) {
@@ -3802,8 +3805,33 @@ rscheck(const char *rsptr, long rslen, VALUE rs)
         rb_raise(rb_eRuntimeError, "rs modified");
 }
 
+static const char *
+search_delim(const char *p, long len, int delim, rb_encoding *enc)
+{
+    if (rb_enc_mbminlen(enc) == 1) {
+        p = memchr(p, delim, len);
+        if (p) return p + 1;
+    }
+    else {
+        const char *end = p + len;
+        while (p < end) {
+            int r = rb_enc_precise_mbclen(p, end, enc);
+            if (!MBCLEN_CHARFOUND_P(r)) {
+                p += rb_enc_mbminlen(enc);
+                continue;
+            }
+            int n = MBCLEN_CHARFOUND_LEN(r);
+            if (rb_enc_mbc_to_codepoint(p, end, enc) == (unsigned int)delim) {
+                return p + n;
+            }
+            p += n;
+        }
+    }
+    return NULL;
+}
+
 static int
-appendline(rb_io_t *fptr, int delim, VALUE *strp, long *lp)
+appendline(rb_io_t *fptr, int delim, VALUE *strp, long *lp, rb_encoding *enc)
 {
     VALUE str = *strp;
     long limit = *lp;
@@ -3818,9 +3846,9 @@ appendline(rb_io_t *fptr, int delim, VALUE *strp, long *lp)
                 p = READ_CHAR_PENDING_PTR(fptr);
                 if (0 < limit && limit < searchlen)
                     searchlen = (int)limit;
-                e = memchr(p, delim, searchlen);
+                e = search_delim(p, searchlen, delim, enc);
                 if (e) {
-                    int len = (int)(e-p+1);
+                    int len = (int)(e-p);
                     if (NIL_P(str))
                         *strp = str = rb_str_new(p, len);
                     else
@@ -3860,8 +3888,8 @@ appendline(rb_io_t *fptr, int delim, VALUE *strp, long *lp)
             long last;
 
             if (limit > 0 && pending > limit) pending = limit;
-            e = memchr(p, delim, pending);
-            if (e) pending = e - p + 1;
+            e = search_delim(p, pending, delim, enc);
+            if (e) pending = e - p;
             if (!NIL_P(str)) {
                 last = RSTRING_LEN(str);
                 rb_str_resize(str, last + pending);
@@ -4121,16 +4149,26 @@ rb_io_getline_0(VALUE rs, long limit, int chomp, rb_io_t *fptr)
                     rsptr = RSTRING_PTR(rs);
                     rslen = RSTRING_LEN(rs);
                 }
+                newline = '\n';
+            }
+            else if (rb_enc_mbminlen(enc) == 1) {
+                 rsptr = RSTRING_PTR(rs);
+                 newline = (unsigned char)rsptr[rslen - 1];
             }
             else {
+                rs = rb_str_encode(rs, rb_enc_from_encoding(enc), 0, Qnil);
                 rsptr = RSTRING_PTR(rs);
+                const char *e = rsptr + rslen;
+                const char *last = rb_enc_prev_char(rsptr, e, e, enc);
+                int n;
+                newline = rb_enc_codepoint_len(last, e, &n, enc);
+                if (last + n != e) rb_raise(rb_eArgError, "broken separator");
             }
-            newline = (unsigned char)rsptr[rslen - 1];
-            chomp_cr = chomp && rslen == 1 && newline == '\n';
+            chomp_cr = chomp && newline == '\n' && rslen == rb_enc_mbminlen(enc);
         }
 
         /* MS - Optimization */
-        while ((c = appendline(fptr, newline, &str, &limit)) != EOF) {
+        while ((c = appendline(fptr, newline, &str, &limit, enc)) != EOF) {
             const char *s, *p, *pp, *e;
 
             if (c == newline) {
@@ -4152,8 +4190,8 @@ rb_io_getline_0(VALUE rs, long limit, int chomp, rb_io_t *fptr)
             if (limit == 0) {
                 s = RSTRING_PTR(str);
                 p = RSTRING_END(str);
-                pp = rb_enc_left_char_head(s, p-1, p, enc);
-                if (extra_limit &&
+                pp = rb_enc_prev_char(s, p, p, enc);
+                if (extra_limit && pp &&
                     MBCLEN_NEEDMORE_P(rb_enc_precise_mbclen(pp, p, enc))) {
                     /* relax the limit while incomplete character.
                      * extra_limit limits the relax length */
@@ -7947,7 +7985,7 @@ popen_finish(VALUE port, VALUE klass)
     if (NIL_P(port)) {
         /* child */
         if (rb_block_given_p()) {
-            rb_yield(Qnil);
+            rb_protect(rb_yield, Qnil, NULL);
             rb_io_flush(rb_ractor_stdout());
             rb_io_flush(rb_ractor_stderr());
             _exit(0);
@@ -8898,7 +8936,6 @@ io_puts_ary(VALUE ary, VALUE out, int recur)
 VALUE
 rb_io_puts(int argc, const VALUE *argv, VALUE out)
 {
-    int i, n;
     VALUE line, args[2];
 
     /* if no argument given, print newline. */
@@ -8906,22 +8943,30 @@ rb_io_puts(int argc, const VALUE *argv, VALUE out)
         rb_io_write(out, rb_default_rs);
         return Qnil;
     }
-    for (i=0; i<argc; i++) {
+    for (int i = 0; i < argc; i++) {
+        // Convert the argument to a string:
         if (RB_TYPE_P(argv[i], T_STRING)) {
             line = argv[i];
-            goto string;
         }
-        if (rb_exec_recursive(io_puts_ary, argv[i], out)) {
+        else if (rb_exec_recursive(io_puts_ary, argv[i], out)) {
             continue;
         }
-        line = rb_obj_as_string(argv[i]);
-      string:
-        n = 0;
-        args[n++] = line;
-        if (RSTRING_LEN(line) == 0 ||
-            !rb_str_end_with_asciichar(line, '\n')) {
+        else {
+            line = rb_obj_as_string(argv[i]);
+        }
+
+        // Write the line:
+        int n = 0;
+        if (RSTRING_LEN(line) == 0) {
             args[n++] = rb_default_rs;
         }
+        else {
+            args[n++] = line;
+            if (!rb_str_end_with_asciichar(line, '\n')) {
+                args[n++] = rb_default_rs;
+            }
+        }
+
         rb_io_writev(out, n, args);
     }
 
@@ -13050,6 +13095,7 @@ copy_stream_fallback_body(VALUE arg)
     while (1) {
         long numwrote;
         long l;
+        rb_str_make_independent(buf);
         if (stp->copy_length < (rb_off_t)0) {
             l = buflen;
         }
@@ -15501,13 +15547,12 @@ Init_IO(void)
     rb_gvar_ractor_local("$>");
     rb_gvar_ractor_local("$stderr");
 
-    rb_stdin  = rb_io_prep_stdin();
-    rb_stdout = rb_io_prep_stdout();
-    rb_stderr = rb_io_prep_stderr();
-
     rb_global_variable(&rb_stdin);
+    rb_stdin  = rb_io_prep_stdin();
     rb_global_variable(&rb_stdout);
+    rb_stdout = rb_io_prep_stdout();
     rb_global_variable(&rb_stderr);
+    rb_stderr = rb_io_prep_stderr();
 
     orig_stdout = rb_stdout;
     orig_stderr = rb_stderr;
diff --git a/io_buffer.c b/io_buffer.c
index 6a6bc25628..87b51c0b8c 100644
--- a/io_buffer.c
+++ b/io_buffer.c
@@ -59,7 +59,8 @@ io_buffer_map_memory(size_t size, int flags)
     int mmap_flags = MAP_ANONYMOUS;
     if (flags & RB_IO_BUFFER_SHARED) {
         mmap_flags |= MAP_SHARED;
-    } else {
+    }
+    else {
         mmap_flags |= MAP_PRIVATE;
     }
 
@@ -74,7 +75,7 @@ io_buffer_map_memory(size_t size, int flags)
 }
 
 static void
-io_buffer_map_file(struct rb_io_buffer *data, int descriptor, size_t size, rb_off_t offset, enum rb_io_buffer_flags flags)
+io_buffer_map_file(struct rb_io_buffer *buffer, int descriptor, size_t size, rb_off_t offset, enum rb_io_buffer_flags flags)
 {
 #if defined(_WIN32)
     HANDLE file = (HANDLE)_get_osfhandle(descriptor);
@@ -83,7 +84,7 @@ io_buffer_map_file(struct rb_io_buffer *data, int descriptor, size_t size, rb_of
     DWORD protect = PAGE_READONLY, access = FILE_MAP_READ;
 
     if (flags & RB_IO_BUFFER_READONLY) {
-        data->flags |= RB_IO_BUFFER_READONLY;
+        buffer->flags |= RB_IO_BUFFER_READONLY;
     }
     else {
         protect = PAGE_READWRITE;
@@ -95,12 +96,12 @@ io_buffer_map_file(struct rb_io_buffer *data, int descriptor, size_t size, rb_of
 
     if (flags & RB_IO_BUFFER_PRIVATE) {
         access |= FILE_MAP_COPY;
-        data->flags |= RB_IO_BUFFER_PRIVATE;
+        buffer->flags |= RB_IO_BUFFER_PRIVATE;
     }
     else {
-        // This buffer refers to external data.
-        data->flags |= RB_IO_BUFFER_EXTERNAL;
-        data->flags |= RB_IO_BUFFER_SHARED;
+        // This buffer refers to external buffer.
+        buffer->flags |= RB_IO_BUFFER_EXTERNAL;
+        buffer->flags |= RB_IO_BUFFER_SHARED;
     }
 
     void *base = MapViewOfFile(mapping, access, (DWORD)(offset >> 32), (DWORD)(offset & 0xFFFFFFFF), size);
@@ -110,24 +111,24 @@ io_buffer_map_file(struct rb_io_buffer *data, int descriptor, size_t size, rb_of
         rb_sys_fail("io_buffer_map_file:MapViewOfFile");
     }
 
-    data->mapping = mapping;
+    buffer->mapping = mapping;
 #else
     int protect = PROT_READ, access = 0;
 
     if (flags & RB_IO_BUFFER_READONLY) {
-        data->flags |= RB_IO_BUFFER_READONLY;
+        buffer->flags |= RB_IO_BUFFER_READONLY;
     }
     else {
         protect |= PROT_WRITE;
     }
 
     if (flags & RB_IO_BUFFER_PRIVATE) {
-        data->flags |= RB_IO_BUFFER_PRIVATE;
+        buffer->flags |= RB_IO_BUFFER_PRIVATE;
     }
     else {
-        // This buffer refers to external data.
-        data->flags |= RB_IO_BUFFER_EXTERNAL;
-        data->flags |= RB_IO_BUFFER_SHARED;
+        // This buffer refers to external buffer.
+        buffer->flags |= RB_IO_BUFFER_EXTERNAL;
+        buffer->flags |= RB_IO_BUFFER_SHARED;
         access |= MAP_SHARED;
     }
 
@@ -138,10 +139,10 @@ io_buffer_map_file(struct rb_io_buffer *data, int descriptor, size_t size, rb_of
     }
 #endif
 
-    data->base = base;
-    data->size = size;
+    buffer->base = base;
+    buffer->size = size;
 
-    data->flags |= RB_IO_BUFFER_MAPPED;
+    buffer->flags |= RB_IO_BUFFER_MAPPED;
 }
 
 static inline void
@@ -171,18 +172,18 @@ io_buffer_experimental(void)
 }
 
 static void
-io_buffer_zero(struct rb_io_buffer *data)
+io_buffer_zero(struct rb_io_buffer *buffer)
 {
-    data->base = NULL;
-    data->size = 0;
+    buffer->base = NULL;
+    buffer->size = 0;
 #if defined(_WIN32)
-    data->mapping = NULL;
+    buffer->mapping = NULL;
 #endif
-    data->source = Qnil;
+    buffer->source = Qnil;
 }
 
 static void
-io_buffer_initialize(struct rb_io_buffer *data, void *base, size_t size, enum rb_io_buffer_flags flags, VALUE source)
+io_buffer_initialize(struct rb_io_buffer *buffer, void *base, size_t size, enum rb_io_buffer_flags flags, VALUE source)
 {
     if (base) {
         // If we are provided a pointer, we use it.
@@ -205,41 +206,41 @@ io_buffer_initialize(struct rb_io_buffer *data, void *base, size_t size, enum rb
         return;
     }
 
-    data->base = base;
-    data->size = size;
-    data->flags = flags;
-    data->source = source;
+    buffer->base = base;
+    buffer->size = size;
+    buffer->flags = flags;
+    buffer->source = source;
 }
 
 static int
-io_buffer_free(struct rb_io_buffer *data)
+io_buffer_free(struct rb_io_buffer *buffer)
 {
-    if (data->base) {
-        if (data->flags & RB_IO_BUFFER_INTERNAL) {
-            free(data->base);
+    if (buffer->base) {
+        if (buffer->flags & RB_IO_BUFFER_INTERNAL) {
+            free(buffer->base);
         }
 
-        if (data->flags & RB_IO_BUFFER_MAPPED) {
-            io_buffer_unmap(data->base, data->size);
+        if (buffer->flags & RB_IO_BUFFER_MAPPED) {
+            io_buffer_unmap(buffer->base, buffer->size);
         }
 
         // Previously we had this, but we found out due to the way GC works, we
         // can't refer to any other Ruby objects here.
-        // if (RB_TYPE_P(data->source, T_STRING)) {
-        //     rb_str_unlocktmp(data->source);
+        // if (RB_TYPE_P(buffer->source, T_STRING)) {
+        //     rb_str_unlocktmp(buffer->source);
         // }
 
-        data->base = NULL;
+        buffer->base = NULL;
 
 #if defined(_WIN32)
-        if (data->mapping) {
-            CloseHandle(data->mapping);
-            data->mapping = NULL;
+        if (buffer->mapping) {
+            CloseHandle(buffer->mapping);
+            buffer->mapping = NULL;
         }
 #endif
-        data->size = 0;
-        data->flags = 0;
-        data->source = Qnil;
+        buffer->size = 0;
+        buffer->flags = 0;
+        buffer->source = Qnil;
 
         return 1;
     }
@@ -248,30 +249,30 @@ io_buffer_free(struct rb_io_buffer *data)
 }
 
 void
-rb_io_buffer_type_mark(void *_data)
+rb_io_buffer_type_mark(void *_buffer)
 {
-    struct rb_io_buffer *data = _data;
-    rb_gc_mark(data->source);
+    struct rb_io_buffer *buffer = _buffer;
+    rb_gc_mark(buffer->source);
 }
 
 void
-rb_io_buffer_type_free(void *_data)
+rb_io_buffer_type_free(void *_buffer)
 {
-    struct rb_io_buffer *data = _data;
+    struct rb_io_buffer *buffer = _buffer;
 
-    io_buffer_free(data);
+    io_buffer_free(buffer);
 
-    free(data);
+    free(buffer);
 }
 
 size_t
-rb_io_buffer_type_size(const void *_data)
+rb_io_buffer_type_size(const void *_buffer)
 {
-    const struct rb_io_buffer *data = _data;
+    const struct rb_io_buffer *buffer = _buffer;
     size_t total = sizeof(struct rb_io_buffer);
 
-    if (data->flags) {
-        total += data->size;
+    if (buffer->flags) {
+        total += buffer->size;
     }
 
     return total;
@@ -288,31 +289,138 @@ static const rb_data_type_t rb_io_buffer_type = {
     .flags = RUBY_TYPED_FREE_IMMEDIATELY,
 };
 
+// Extract an offset argument, which must be a positive integer.
+static inline size_t
+io_buffer_extract_offset(VALUE argument)
+{
+    if (rb_int_negative_p(argument)) {
+        rb_raise(rb_eArgError, "Offset can't be negative!");
+    }
+
+    return NUM2SIZET(argument);
+}
+
+// Extract a length argument, which must be a positive integer.
+// Length is generally considered a mutable property of an object and
+// semantically should be considered a subset of "size" as a concept.
+static inline size_t
+io_buffer_extract_length(VALUE argument)
+{
+    if (rb_int_negative_p(argument)) {
+        rb_raise(rb_eArgError, "Length can't be negative!");
+    }
+
+    return NUM2SIZET(argument);
+}
+
+// Extract a size argument, which must be a positive integer.
+// Size is generally considered an immutable property of an object.
+static inline size_t
+io_buffer_extract_size(VALUE argument)
+{
+    if (rb_int_negative_p(argument)) {
+        rb_raise(rb_eArgError, "Size can't be negative!");
+    }
+
+    return NUM2SIZET(argument);
+}
+
+// Compute the default length for a buffer, given an offset into that buffer.
+// The default length is the size of the buffer minus the offset. The offset
+// must be less than the size of the buffer otherwise the length will be
+// invalid; in that case, an ArgumentError exception will be raised.
+static inline size_t
+io_buffer_default_length(const struct rb_io_buffer *buffer, size_t offset)
+{
+    if (offset > buffer->size) {
+        rb_raise(rb_eArgError, "The given offset is bigger than the buffer size!");
+    }
+
+    // Note that the "length" is computed by the size the offset.
+    return buffer->size - offset;
+}
+
+// Extract the optional length and offset arguments, returning the buffer.
+// The length and offset are optional, but if they are provided, they must be
+// positive integers. If the length is not provided, the default length is
+// computed from the buffer size and offset. If the offset is not provided, it
+// defaults to zero.
+static inline struct rb_io_buffer *
+io_buffer_extract_length_offset(VALUE self, int argc, VALUE argv[], size_t *length, size_t *offset)
+{
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
+
+    if (argc >= 2) {
+        *offset = io_buffer_extract_offset(argv[1]);
+    }
+    else {
+        *offset = 0;
+    }
+
+    if (argc >= 1 && !NIL_P(argv[0])) {
+        *length = io_buffer_extract_length(argv[0]);
+    }
+    else {
+        *length = io_buffer_default_length(buffer, *offset);
+    }
+
+    return buffer;
+}
+
+// Extract the optional offset and length arguments, returning the buffer.
+// Similar to `io_buffer_extract_length_offset` but with the order of
+// arguments reversed.
+static inline struct rb_io_buffer *
+io_buffer_extract_offset_length(VALUE self, int argc, VALUE argv[], size_t *offset, size_t *length)
+{
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
+
+    if (argc >= 1) {
+        *offset = io_buffer_extract_offset(argv[0]);
+    }
+    else {
+        *offset = 0;
+    }
+
+    if (argc >= 2) {
+        *length = io_buffer_extract_length(argv[1]);
+    }
+    else {
+        *length = io_buffer_default_length(buffer, *offset);
+    }
+
+    return buffer;
+}
+
 VALUE
 rb_io_buffer_type_allocate(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    VALUE instance = TypedData_Make_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    VALUE instance = TypedData_Make_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_zero(data);
+    io_buffer_zero(buffer);
 
     return instance;
 }
 
-static VALUE
-io_buffer_for_make_instance(VALUE klass, VALUE string)
+static VALUE io_buffer_for_make_instance(VALUE klass, VALUE string, enum rb_io_buffer_flags flags)
 {
     VALUE instance = rb_io_buffer_type_allocate(klass);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    enum rb_io_buffer_flags flags = RB_IO_BUFFER_EXTERNAL;
+    flags |= RB_IO_BUFFER_EXTERNAL;
 
     if (RB_OBJ_FROZEN(string))
         flags |= RB_IO_BUFFER_READONLY;
 
-    io_buffer_initialize(data, RSTRING_PTR(string), RSTRING_LEN(string), flags, string);
+    if (!(flags & RB_IO_BUFFER_READONLY))
+        rb_str_modify(string);
+
+    io_buffer_initialize(buffer, RSTRING_PTR(string), RSTRING_LEN(string), flags, string);
 
     return instance;
 }
@@ -321,6 +429,7 @@ struct io_buffer_for_yield_instance_arguments {
     VALUE klass;
     VALUE string;
     VALUE instance;
+    enum rb_io_buffer_flags flags;
 };
 
 static VALUE
@@ -328,9 +437,9 @@ io_buffer_for_yield_instance(VALUE _arguments)
 {
     struct io_buffer_for_yield_instance_arguments *arguments = (struct io_buffer_for_yield_instance_arguments *)_arguments;
 
-    rb_str_locktmp(arguments->string);
+    arguments->instance = io_buffer_for_make_instance(arguments->klass, arguments->string, arguments->flags);
 
-    arguments->instance = io_buffer_for_make_instance(arguments->klass, arguments->string);
+    rb_str_locktmp(arguments->string);
 
     return rb_yield(arguments->instance);
 }
@@ -357,14 +466,15 @@ io_buffer_for_yield_instance_ensure(VALUE _arguments)
  *  Creates a IO::Buffer from the given string's memory. Without a block a
  *  frozen internal copy of the string is created efficiently and used as the
  *  buffer source. When a block is provided, the buffer is associated directly
- *  with the string's internal data and updating the buffer will update the
+ *  with the string's internal buffer and updating the buffer will update the
  *  string.
  *
  *  Until #free is invoked on the buffer, either explicitly or via the garbage
  *  collector, the source string will be locked and cannot be modified.
  *
  *  If the string is frozen, it will create a read-only buffer which cannot be
- *  modified.
+ *  modified. If the string is shared, it may trigger a copy-on-write when
+ *  using the block form.
  *
  *    string = 'test'
  *    buffer = IO::Buffer.for(string)
@@ -396,6 +506,7 @@ rb_io_buffer_type_for(VALUE klass, VALUE string)
             .klass = klass,
             .string = string,
             .instance = Qnil,
+            .flags = 0,
         };
 
         return rb_ensure(io_buffer_for_yield_instance, (VALUE)&arguments, io_buffer_for_yield_instance_ensure, (VALUE)&arguments);
@@ -403,7 +514,7 @@ rb_io_buffer_type_for(VALUE klass, VALUE string)
     else {
         // This internally returns the source string if it's already frozen.
         string = rb_str_tmp_frozen_acquire(string);
-        return io_buffer_for_make_instance(klass, string);
+        return io_buffer_for_make_instance(klass, string, RB_IO_BUFFER_READONLY);
     }
 }
 
@@ -412,10 +523,10 @@ rb_io_buffer_new(void *base, size_t size, enum rb_io_buffer_flags flags)
 {
     VALUE instance = rb_io_buffer_type_allocate(rb_cIOBuffer);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_initialize(data, base, size, flags, Qnil);
+    io_buffer_initialize(buffer, base, size, flags, Qnil);
 
     return instance;
 }
@@ -427,12 +538,12 @@ rb_io_buffer_map(VALUE io, size_t size, rb_off_t offset, enum rb_io_buffer_flags
 
     VALUE instance = rb_io_buffer_type_allocate(rb_cIOBuffer);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     int descriptor = rb_io_descriptor(io);
 
-    io_buffer_map_file(data, descriptor, size, offset, flags);
+    io_buffer_map_file(buffer, descriptor, size, offset, flags);
 
     return instance;
 }
@@ -486,7 +597,7 @@ io_buffer_map(int argc, VALUE *argv, VALUE klass)
 
     size_t size;
     if (argc >= 2 && !RB_NIL_P(argv[1])) {
-        size = RB_NUM2SIZE(argv[1]);
+        size = io_buffer_extract_size(argv[1]);
     }
     else {
         rb_off_t file_size = rb_file_size(io);
@@ -505,6 +616,7 @@ io_buffer_map(int argc, VALUE *argv, VALUE klass)
         }
     }
 
+    // This is the file offset, not the buffer offset:
     rb_off_t offset = 0;
     if (argc >= 3) {
         offset = NUM2OFFT(argv[2]);
@@ -562,13 +674,12 @@ rb_io_buffer_initialize(int argc, VALUE *argv, VALUE self)
 
     rb_check_arity(argc, 0, 2);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     size_t size;
-
     if (argc > 0) {
-        size = RB_NUM2SIZE(argv[0]);
+        size = io_buffer_extract_size(argv[0]);
     }
     else {
         size = RUBY_IO_BUFFER_DEFAULT_SIZE;
@@ -582,7 +693,7 @@ rb_io_buffer_initialize(int argc, VALUE *argv, VALUE self)
         flags |= io_flags_for_size(size);
     }
 
-    io_buffer_initialize(data, NULL, size, flags, Qnil);
+    io_buffer_initialize(buffer, NULL, size, flags, Qnil);
 
     return self;
 }
@@ -617,11 +728,11 @@ io_buffer_validate_slice(VALUE source, void *base, size_t size)
 }
 
 static int
-io_buffer_validate(struct rb_io_buffer *data)
+io_buffer_validate(struct rb_io_buffer *buffer)
 {
-    if (data->source != Qnil) {
+    if (buffer->source != Qnil) {
         // Only slices incur this overhead, unfortunately... better safe than sorry!
-        return io_buffer_validate_slice(data->source, data->base, data->size);
+        return io_buffer_validate_slice(buffer->source, buffer->base, buffer->size);
     }
     else {
         return 1;
@@ -640,47 +751,47 @@ io_buffer_validate(struct rb_io_buffer *data)
 VALUE
 rb_io_buffer_to_s(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     VALUE result = rb_str_new_cstr("#<");
 
     rb_str_append(result, rb_class_name(CLASS_OF(self)));
-    rb_str_catf(result, " %p+%"PRIdSIZE, data->base, data->size);
+    rb_str_catf(result, " %p+%"PRIdSIZE, buffer->base, buffer->size);
 
-    if (data->base == NULL) {
+    if (buffer->base == NULL) {
         rb_str_cat2(result, " NULL");
     }
 
-    if (data->flags & RB_IO_BUFFER_EXTERNAL) {
+    if (buffer->flags & RB_IO_BUFFER_EXTERNAL) {
         rb_str_cat2(result, " EXTERNAL");
     }
 
-    if (data->flags & RB_IO_BUFFER_INTERNAL) {
+    if (buffer->flags & RB_IO_BUFFER_INTERNAL) {
         rb_str_cat2(result, " INTERNAL");
     }
 
-    if (data->flags & RB_IO_BUFFER_MAPPED) {
+    if (buffer->flags & RB_IO_BUFFER_MAPPED) {
         rb_str_cat2(result, " MAPPED");
     }
 
-    if (data->flags & RB_IO_BUFFER_SHARED) {
+    if (buffer->flags & RB_IO_BUFFER_SHARED) {
         rb_str_cat2(result, " SHARED");
     }
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_str_cat2(result, " LOCKED");
     }
 
-    if (data->flags & RB_IO_BUFFER_READONLY) {
+    if (buffer->flags & RB_IO_BUFFER_READONLY) {
         rb_str_cat2(result, " READONLY");
     }
 
-    if (data->source != Qnil) {
+    if (buffer->source != Qnil) {
         rb_str_cat2(result, " SLICE");
     }
 
-    if (!io_buffer_validate(data)) {
+    if (!io_buffer_validate(buffer)) {
         rb_str_cat2(result, " INVALID");
     }
 
@@ -730,15 +841,15 @@ io_buffer_hexdump(VALUE string, size_t width, char *base, size_t size, int first
 static VALUE
 rb_io_buffer_hexdump(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     VALUE result = Qnil;
 
-    if (io_buffer_validate(data) && data->base) {
-        result = rb_str_buf_new(data->size*3 + (data->size/16)*12 + 1);
+    if (io_buffer_validate(buffer) && buffer->base) {
+        result = rb_str_buf_new(buffer->size*3 + (buffer->size/16)*12 + 1);
 
-        io_buffer_hexdump(result, 16, data->base, data->size, 1);
+        io_buffer_hexdump(result, 16, buffer->base, buffer->size, 1);
     }
 
     return result;
@@ -747,15 +858,15 @@ rb_io_buffer_hexdump(VALUE self)
 VALUE
 rb_io_buffer_inspect(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     VALUE result = rb_io_buffer_to_s(self);
 
-    if (io_buffer_validate(data)) {
-        // Limit the maximum size genearted by inspect.
-        if (data->size <= 256) {
-            io_buffer_hexdump(result, 16, data->base, data->size, 0);
+    if (io_buffer_validate(buffer)) {
+        // Limit the maximum size generated by inspect.
+        if (buffer->size <= 256) {
+            io_buffer_hexdump(result, 16, buffer->base, buffer->size, 0);
         }
     }
 
@@ -771,16 +882,16 @@ rb_io_buffer_inspect(VALUE self)
 VALUE
 rb_io_buffer_size(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return SIZET2NUM(data->size);
+    return SIZET2NUM(buffer->size);
 }
 
 /*
  *  call-seq: valid? -> true or false
  *
- *  Returns whether the buffer data is accessible.
+ *  Returns whether the buffer buffer is accessible.
  *
  *  A buffer becomes invalid if it is a slice of another buffer which has been
  *  freed.
@@ -788,10 +899,10 @@ rb_io_buffer_size(VALUE self)
 static VALUE
 rb_io_buffer_valid_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(io_buffer_validate(data));
+    return RBOOL(io_buffer_validate(buffer));
 }
 
 /*
@@ -803,10 +914,10 @@ rb_io_buffer_valid_p(VALUE self)
 static VALUE
 rb_io_buffer_null_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->base == NULL);
+    return RBOOL(buffer->base == NULL);
 }
 
 /*
@@ -819,10 +930,10 @@ rb_io_buffer_null_p(VALUE self)
 static VALUE
 rb_io_buffer_empty_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->size == 0);
+    return RBOOL(buffer->size == 0);
 }
 
 /*
@@ -839,10 +950,10 @@ rb_io_buffer_empty_p(VALUE self)
 static VALUE
 rb_io_buffer_external_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->flags & RB_IO_BUFFER_EXTERNAL);
+    return RBOOL(buffer->flags & RB_IO_BUFFER_EXTERNAL);
 }
 
 /*
@@ -864,10 +975,10 @@ rb_io_buffer_external_p(VALUE self)
 static VALUE
 rb_io_buffer_internal_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->flags & RB_IO_BUFFER_INTERNAL);
+    return RBOOL(buffer->flags & RB_IO_BUFFER_INTERNAL);
 }
 
 /*
@@ -886,10 +997,10 @@ rb_io_buffer_internal_p(VALUE self)
 static VALUE
 rb_io_buffer_mapped_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->flags & RB_IO_BUFFER_MAPPED);
+    return RBOOL(buffer->flags & RB_IO_BUFFER_MAPPED);
 }
 
 /*
@@ -902,10 +1013,10 @@ rb_io_buffer_mapped_p(VALUE self)
 static VALUE
 rb_io_buffer_shared_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->flags & RB_IO_BUFFER_SHARED);
+    return RBOOL(buffer->flags & RB_IO_BUFFER_SHARED);
 }
 
 /*
@@ -927,19 +1038,19 @@ rb_io_buffer_shared_p(VALUE self)
 static VALUE
 rb_io_buffer_locked_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return RBOOL(data->flags & RB_IO_BUFFER_LOCKED);
+    return RBOOL(buffer->flags & RB_IO_BUFFER_LOCKED);
 }
 
 int
 rb_io_buffer_readonly_p(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    return data->flags & RB_IO_BUFFER_READONLY;
+    return buffer->flags & RB_IO_BUFFER_READONLY;
 }
 
 /*
@@ -956,32 +1067,44 @@ io_buffer_readonly_p(VALUE self)
     return RBOOL(rb_io_buffer_readonly_p(self));
 }
 
-VALUE
-rb_io_buffer_lock(VALUE self)
+static void
+io_buffer_lock(struct rb_io_buffer *buffer)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
-
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_raise(rb_eIOBufferLockedError, "Buffer already locked!");
     }
 
-    data->flags |= RB_IO_BUFFER_LOCKED;
-
-    return self;
+    buffer->flags |= RB_IO_BUFFER_LOCKED;
 }
 
 VALUE
-rb_io_buffer_unlock(VALUE self)
+rb_io_buffer_lock(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
+
+    io_buffer_lock(buffer);
 
-    if (!(data->flags & RB_IO_BUFFER_LOCKED)) {
+    return self;
+}
+
+static void
+io_buffer_unlock(struct rb_io_buffer *buffer)
+{
+    if (!(buffer->flags & RB_IO_BUFFER_LOCKED)) {
         rb_raise(rb_eIOBufferLockedError, "Buffer not locked!");
     }
 
-    data->flags &= ~RB_IO_BUFFER_LOCKED;
+    buffer->flags &= ~RB_IO_BUFFER_LOCKED;
+}
+
+VALUE
+rb_io_buffer_unlock(VALUE self)
+{
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
+
+    io_buffer_unlock(buffer);
 
     return self;
 }
@@ -989,11 +1112,11 @@ rb_io_buffer_unlock(VALUE self)
 int
 rb_io_buffer_try_unlock(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
-        data->flags &= ~RB_IO_BUFFER_LOCKED;
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
+        buffer->flags &= ~RB_IO_BUFFER_LOCKED;
         return 1;
     }
 
@@ -1035,18 +1158,18 @@ rb_io_buffer_try_unlock(VALUE self)
 VALUE
 rb_io_buffer_locked(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_raise(rb_eIOBufferLockedError, "Buffer already locked!");
     }
 
-    data->flags |= RB_IO_BUFFER_LOCKED;
+    buffer->flags |= RB_IO_BUFFER_LOCKED;
 
     VALUE result = rb_yield(self);
 
-    data->flags &= ~RB_IO_BUFFER_LOCKED;
+    buffer->flags &= ~RB_IO_BUFFER_LOCKED;
 
     return result;
 }
@@ -1081,14 +1204,14 @@ rb_io_buffer_locked(VALUE self)
 VALUE
 rb_io_buffer_free(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_raise(rb_eIOBufferLockedError, "Buffer is locked!");
     }
 
-    io_buffer_free(data);
+    io_buffer_free(buffer);
 
     return self;
 }
@@ -1096,28 +1219,30 @@ rb_io_buffer_free(VALUE self)
 // Validate that access to the buffer is within bounds, assuming you want to
 // access length bytes from the specified offset.
 static inline void
-io_buffer_validate_range(struct rb_io_buffer *data, size_t offset, size_t length)
+io_buffer_validate_range(struct rb_io_buffer *buffer, size_t offset, size_t length)
 {
-    if (offset + length > data->size) {
-        rb_raise(rb_eArgError, "Specified offset+length exceeds data size!");
+    // We assume here that offset + length won't overflow:
+    if (offset + length > buffer->size) {
+        rb_raise(rb_eArgError, "Specified offset+length is bigger than the buffer size!");
     }
 }
 
 static VALUE
-rb_io_buffer_slice(struct rb_io_buffer *data, VALUE self, size_t offset, size_t length)
+rb_io_buffer_slice(struct rb_io_buffer *buffer, VALUE self, size_t offset, size_t length)
 {
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     VALUE instance = rb_io_buffer_type_allocate(rb_class_of(self));
     struct rb_io_buffer *slice = NULL;
     TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, slice);
 
-    slice->base = (char*)data->base + offset;
+    slice->flags |= (buffer->flags & RB_IO_BUFFER_READONLY);
+    slice->base = (char*)buffer->base + offset;
     slice->size = length;
 
     // The source should be the root buffer:
-    if (data->source != Qnil)
-        slice->source = data->source;
+    if (buffer->source != Qnil)
+        slice->source = buffer->source;
     else
         slice->source = self;
 
@@ -1125,7 +1250,7 @@ rb_io_buffer_slice(struct rb_io_buffer *data, VALUE self, size_t offset, size_t
 }
 
 /*
- *  call-seq: slice([offset = 0, [length]]) -> io_buffer
+ *  call-seq: slice([offset, [length]]) -> io_buffer
  *
  *  Produce another IO::Buffer which is a slice (or view into) the current one
  *  starting at +offset+ bytes and going for +length+ bytes.
@@ -1185,44 +1310,24 @@ io_buffer_slice(int argc, VALUE *argv, VALUE self)
 {
     rb_check_arity(argc, 0, 2);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
-
-    size_t offset = 0, length = 0;
+    size_t offset, length;
+    struct rb_io_buffer *buffer = io_buffer_extract_offset_length(self, argc, argv, &offset, &length);
 
-    if (argc > 0) {
-        if (rb_int_negative_p(argv[0])) {
-            rb_raise(rb_eArgError, "Offset can't be negative!");
-        }
-
-        offset = NUM2SIZET(argv[0]);
-    }
-
-    if (argc > 1) {
-        if (rb_int_negative_p(argv[1])) {
-            rb_raise(rb_eArgError, "Length can't be negative!");
-        }
-
-        length = NUM2SIZET(argv[1]);
-    } else {
-        length = data->size - offset;
-    }
-
-    return rb_io_buffer_slice(data, self, offset, length);
+    return rb_io_buffer_slice(buffer, self, offset, length);
 }
 
 int
 rb_io_buffer_get_bytes(VALUE self, void **base, size_t *size)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (io_buffer_validate(data)) {
-        if (data->base) {
-            *base = data->base;
-            *size = data->size;
+    if (io_buffer_validate(buffer)) {
+        if (buffer->base) {
+            *base = buffer->base;
+            *size = buffer->size;
 
-            return data->flags;
+            return buffer->flags;
         }
     }
 
@@ -1233,19 +1338,20 @@ rb_io_buffer_get_bytes(VALUE self, void **base, size_t *size)
 }
 
 static inline void
-io_buffer_get_bytes_for_writing(struct rb_io_buffer *data, void **base, size_t *size)
+io_buffer_get_bytes_for_writing(struct rb_io_buffer *buffer, void **base, size_t *size)
 {
-    if (data->flags & RB_IO_BUFFER_READONLY) {
+    if (buffer->flags & RB_IO_BUFFER_READONLY ||
+        (!NIL_P(buffer->source) && OBJ_FROZEN(buffer->source))) {
         rb_raise(rb_eIOBufferAccessError, "Buffer is not writable!");
     }
 
-    if (!io_buffer_validate(data)) {
+    if (!io_buffer_validate(buffer)) {
         rb_raise(rb_eIOBufferInvalidatedError, "Buffer is invalid!");
     }
 
-    if (data->base) {
-        *base = data->base;
-        *size = data->size;
+    if (buffer->base) {
+        *base = buffer->base;
+        *size = buffer->size;
 
         return;
     }
@@ -1256,22 +1362,22 @@ io_buffer_get_bytes_for_writing(struct rb_io_buffer *data, void **base, size_t *
 void
 rb_io_buffer_get_bytes_for_writing(VALUE self, void **base, size_t *size)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_get_bytes_for_writing(data, base, size);
+    io_buffer_get_bytes_for_writing(buffer, base, size);
 }
 
 static void
-io_buffer_get_bytes_for_reading(struct rb_io_buffer *data, const void **base, size_t *size)
+io_buffer_get_bytes_for_reading(struct rb_io_buffer *buffer, const void **base, size_t *size)
 {
-    if (!io_buffer_validate(data)) {
+    if (!io_buffer_validate(buffer)) {
         rb_raise(rb_eIOBufferInvalidatedError, "Buffer has been invalidated!");
     }
 
-    if (data->base) {
-        *base = data->base;
-        *size = data->size;
+    if (buffer->base) {
+        *base = buffer->base;
+        *size = buffer->size;
 
         return;
     }
@@ -1282,10 +1388,10 @@ io_buffer_get_bytes_for_reading(struct rb_io_buffer *data, const void **base, si
 void
 rb_io_buffer_get_bytes_for_reading(VALUE self, const void **base, size_t *size)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_get_bytes_for_reading(data, base, size);
+    io_buffer_get_bytes_for_reading(buffer, base, size);
 }
 
 /*
@@ -1310,10 +1416,10 @@ rb_io_buffer_get_bytes_for_reading(VALUE self, const void **base, size_t *size)
 VALUE
 rb_io_buffer_transfer(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_raise(rb_eIOBufferLockedError, "Cannot transfer ownership of locked buffer!");
     }
 
@@ -1321,91 +1427,96 @@ rb_io_buffer_transfer(VALUE self)
     struct rb_io_buffer *transferred;
     TypedData_Get_Struct(instance, struct rb_io_buffer, &rb_io_buffer_type, transferred);
 
-    *transferred = *data;
-    io_buffer_zero(data);
+    *transferred = *buffer;
+    io_buffer_zero(buffer);
 
     return instance;
 }
 
 static void
-io_buffer_resize_clear(struct rb_io_buffer *data, void* base, size_t size)
+io_buffer_resize_clear(struct rb_io_buffer *buffer, void* base, size_t size)
 {
-    if (size > data->size) {
-        memset((unsigned char*)base+data->size, 0, size - data->size);
+    if (size > buffer->size) {
+        memset((unsigned char*)base+buffer->size, 0, size - buffer->size);
     }
 }
 
 static void
-io_buffer_resize_copy(struct rb_io_buffer *data, size_t size)
+io_buffer_resize_copy(struct rb_io_buffer *buffer, size_t size)
 {
     // Slow path:
     struct rb_io_buffer resized;
     io_buffer_initialize(&resized, NULL, size, io_flags_for_size(size), Qnil);
 
-    if (data->base) {
-        size_t preserve = data->size;
+    if (buffer->base) {
+        size_t preserve = buffer->size;
         if (preserve > size) preserve = size;
-        memcpy(resized.base, data->base, preserve);
+        memcpy(resized.base, buffer->base, preserve);
 
-        io_buffer_resize_clear(data, resized.base, size);
+        io_buffer_resize_clear(buffer, resized.base, size);
     }
 
-    io_buffer_free(data);
-    *data = resized;
+    io_buffer_free(buffer);
+    *buffer = resized;
 }
 
 void
 rb_io_buffer_resize(VALUE self, size_t size)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    if (data->flags & RB_IO_BUFFER_LOCKED) {
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
         rb_raise(rb_eIOBufferLockedError, "Cannot resize locked buffer!");
     }
 
-    if (data->base == NULL) {
-        io_buffer_initialize(data, NULL, size, io_flags_for_size(size), Qnil);
+    if (buffer->base == NULL) {
+        io_buffer_initialize(buffer, NULL, size, io_flags_for_size(size), Qnil);
         return;
     }
 
-    if (data->flags & RB_IO_BUFFER_EXTERNAL) {
+    if (buffer->flags & RB_IO_BUFFER_EXTERNAL) {
         rb_raise(rb_eIOBufferAccessError, "Cannot resize external buffer!");
     }
 
 #if defined(HAVE_MREMAP) && defined(MREMAP_MAYMOVE)
-    if (data->flags & RB_IO_BUFFER_MAPPED) {
-        void *base = mremap(data->base, data->size, size, MREMAP_MAYMOVE);
+    if (buffer->flags & RB_IO_BUFFER_MAPPED) {
+        void *base = mremap(buffer->base, buffer->size, size, MREMAP_MAYMOVE);
 
         if (base == MAP_FAILED) {
             rb_sys_fail("rb_io_buffer_resize:mremap");
         }
 
-        io_buffer_resize_clear(data, base, size);
+        io_buffer_resize_clear(buffer, base, size);
 
-        data->base = base;
-        data->size = size;
+        buffer->base = base;
+        buffer->size = size;
 
         return;
     }
 #endif
 
-    if (data->flags & RB_IO_BUFFER_INTERNAL) {
-        void *base = realloc(data->base, size);
+    if (buffer->flags & RB_IO_BUFFER_INTERNAL) {
+        if (size == 0) {
+            io_buffer_free(buffer);
+            return;
+        }
+
+        void *base = realloc(buffer->base, size);
 
         if (!base) {
             rb_sys_fail("rb_io_buffer_resize:realloc");
         }
 
-        io_buffer_resize_clear(data, base, size);
+        io_buffer_resize_clear(buffer, base, size);
 
-        data->base = base;
-        data->size = size;
+        buffer->base = base;
+        buffer->size = size;
 
         return;
     }
 
-    io_buffer_resize_copy(data, size);
+    io_buffer_resize_copy(buffer, size);
 }
 
 /*
@@ -1429,7 +1540,7 @@ rb_io_buffer_resize(VALUE self, size_t size)
 static VALUE
 io_buffer_resize(VALUE self, VALUE size)
 {
-    rb_io_buffer_resize(self, NUM2SIZET(size));
+    rb_io_buffer_resize(self, io_buffer_extract_size(size));
 
     return self;
 }
@@ -1567,9 +1678,9 @@ IO_BUFFER_DECLARE_TYPE(F64, double, RB_IO_BUFFER_BIG_ENDIAN, DBL2NUM, NUM2DBL, r
 #undef IO_BUFFER_DECLARE_TYPE
 
 static inline size_t
-io_buffer_data_type_size(ID data_type)
+io_buffer_buffer_type_size(ID buffer_type)
 {
-#define IO_BUFFER_DATA_TYPE_SIZE(name) if (data_type == RB_IO_BUFFER_DATA_TYPE_##name) return RB_IO_BUFFER_DATA_TYPE_##name##_SIZE;
+#define IO_BUFFER_DATA_TYPE_SIZE(name) if (buffer_type == RB_IO_BUFFER_DATA_TYPE_##name) return RB_IO_BUFFER_DATA_TYPE_##name##_SIZE;
     IO_BUFFER_DATA_TYPE_SIZE(U8)
     IO_BUFFER_DATA_TYPE_SIZE(S8)
     IO_BUFFER_DATA_TYPE_SIZE(u16)
@@ -1595,10 +1706,10 @@ io_buffer_data_type_size(ID data_type)
 
 /*
  *  call-seq:
- *    size_of(data_type) -> byte size
- *    size_of(array of data_type) -> byte size
+ *    size_of(buffer_type) -> byte size
+ *    size_of(array of buffer_type) -> byte size
  *
- *  Returns the size of the given data type(s) in bytes.
+ *  Returns the size of the given buffer type(s) in bytes.
  *
  *  Example:
  *
@@ -1606,23 +1717,24 @@ io_buffer_data_type_size(ID data_type)
  *    IO::Buffer.size_of([:u32, :u32]) # => 8
  */
 static VALUE
-io_buffer_size_of(VALUE klass, VALUE data_type)
+io_buffer_size_of(VALUE klass, VALUE buffer_type)
 {
-    if (RB_TYPE_P(data_type, T_ARRAY)) {
+    if (RB_TYPE_P(buffer_type, T_ARRAY)) {
         size_t total = 0;
-        for (long i = 0; i < RARRAY_LEN(data_type); i++) {
-            total += io_buffer_data_type_size(RB_SYM2ID(RARRAY_AREF(data_type, i)));
+        for (long i = 0; i < RARRAY_LEN(buffer_type); i++) {
+            total += io_buffer_buffer_type_size(RB_SYM2ID(RARRAY_AREF(buffer_type, i)));
         }
         return SIZET2NUM(total);
-    } else {
-        return SIZET2NUM(io_buffer_data_type_size(RB_SYM2ID(data_type)));
+    }
+    else {
+        return SIZET2NUM(io_buffer_buffer_type_size(RB_SYM2ID(buffer_type)));
     }
 }
 
 static inline VALUE
-rb_io_buffer_get_value(const void* base, size_t size, ID data_type, size_t *offset)
+rb_io_buffer_get_value(const void* base, size_t size, ID buffer_type, size_t *offset)
 {
-#define IO_BUFFER_GET_VALUE(name) if (data_type == RB_IO_BUFFER_DATA_TYPE_##name) return io_buffer_read_##name(base, size, offset);
+#define IO_BUFFER_GET_VALUE(name) if (buffer_type == RB_IO_BUFFER_DATA_TYPE_##name) return io_buffer_read_##name(base, size, offset);
     IO_BUFFER_GET_VALUE(U8)
     IO_BUFFER_GET_VALUE(S8)
 
@@ -1651,9 +1763,9 @@ rb_io_buffer_get_value(const void* base, size_t size, ID data_type, size_t *offs
 }
 
 /*
- *  call-seq: get_value(data_type, offset) -> numeric
+ *  call-seq: get_value(buffer_type, offset) -> numeric
  *
- *  Read from buffer a value of +type+ at +offset+. +data_type+ should be one
+ *  Read from buffer a value of +type+ at +offset+. +buffer_type+ should be one
  *  of symbols:
  *
  *  * +:U8+: unsigned integer, 1 byte
@@ -1675,8 +1787,8 @@ rb_io_buffer_get_value(const void* base, size_t size, ID data_type, size_t *offs
  *  * +:f64+: double, 8 bytes, little-endian
  *  * +:F64+: double, 8 bytes, big-endian
  *
- *  A data type refers specifically to the type of binary data that is stored
- *  in the buffer. For example, a +:u32+ data type is a 32-bit unsigned
+ *  A buffer type refers specifically to the type of binary buffer that is stored
+ *  in the buffer. For example, a +:u32+ buffer type is a 32-bit unsigned
  *  integer in little-endian format.
  *
  *  Example:
@@ -1691,7 +1803,7 @@ io_buffer_get_value(VALUE self, VALUE type, VALUE _offset)
 {
     const void *base;
     size_t size;
-    size_t offset = NUM2SIZET(_offset);
+    size_t offset = io_buffer_extract_offset(_offset);
 
     rb_io_buffer_get_bytes_for_reading(self, &base, &size);
 
@@ -1699,9 +1811,9 @@ io_buffer_get_value(VALUE self, VALUE type, VALUE _offset)
 }
 
 /*
- *  call-seq: get_values(data_types, offset) -> array
+ *  call-seq: get_values(buffer_types, offset) -> array
  *
- *  Similar to #get_value, except that it can handle multiple data types and
+ *  Similar to #get_value, except that it can handle multiple buffer types and
  *  returns an array of values.
  *
  *  Example:
@@ -1711,22 +1823,22 @@ io_buffer_get_value(VALUE self, VALUE type, VALUE _offset)
  *    # => [1.5, 2.5]
  */
 static VALUE
-io_buffer_get_values(VALUE self, VALUE data_types, VALUE _offset)
+io_buffer_get_values(VALUE self, VALUE buffer_types, VALUE _offset)
 {
-    size_t offset = NUM2SIZET(_offset);
+    size_t offset = io_buffer_extract_offset(_offset);
 
     const void *base;
     size_t size;
     rb_io_buffer_get_bytes_for_reading(self, &base, &size);
 
-    if (!RB_TYPE_P(data_types, T_ARRAY)) {
-        rb_raise(rb_eArgError, "Argument data_types should be an array!");
+    if (!RB_TYPE_P(buffer_types, T_ARRAY)) {
+        rb_raise(rb_eArgError, "Argument buffer_types should be an array!");
     }
 
-    VALUE array = rb_ary_new_capa(RARRAY_LEN(data_types));
+    VALUE array = rb_ary_new_capa(RARRAY_LEN(buffer_types));
 
-    for (long i = 0; i < RARRAY_LEN(data_types); i++) {
-        VALUE type = rb_ary_entry(data_types, i);
+    for (long i = 0; i < RARRAY_LEN(buffer_types); i++) {
+        VALUE type = rb_ary_entry(buffer_types, i);
         VALUE value = rb_io_buffer_get_value(base, size, RB_SYM2ID(type), &offset);
         rb_ary_push(array, value);
     }
@@ -1734,12 +1846,46 @@ io_buffer_get_values(VALUE self, VALUE data_types, VALUE _offset)
     return array;
 }
 
+// Extract a count argument, which must be a positive integer.
+// Count is generally considered relative to the number of things.
+static inline size_t
+io_buffer_extract_count(VALUE argument)
+{
+    if (rb_int_negative_p(argument)) {
+        rb_raise(rb_eArgError, "Count can't be negative!");
+    }
+
+    return NUM2SIZET(argument);
+}
+
+static inline void
+io_buffer_extract_offset_count(ID buffer_type, size_t size, int argc, VALUE *argv, size_t *offset, size_t *count)
+{
+    if (argc >= 1) {
+        *offset = io_buffer_extract_offset(argv[0]);
+    }
+    else {
+        *offset = 0;
+    }
+
+    if (argc >= 2) {
+        *count = io_buffer_extract_count(argv[1]);
+    }
+    else {
+        if (*offset > size) {
+            rb_raise(rb_eArgError, "The given offset is bigger than the buffer size!");
+        }
+
+        *count = (size - *offset) / io_buffer_buffer_type_size(buffer_type);
+    }
+}
+
 /*
  *  call-seq:
- *    each(data_type, [offset, [count]]) {|offset, value| ...} -> self
- *    each(data_type, [offset, [count]]) -> enumerator
+ *    each(buffer_type, [offset, [count]]) {|offset, value| ...} -> self
+ *    each(buffer_type, [offset, [count]]) -> enumerator
  *
- *  Iterates over the buffer, yielding each +value+ of +data_type+ starting
+ *  Iterates over the buffer, yielding each +value+ of +buffer_type+ starting
  *  from +offset+.
  *
  *  If +count+ is given, only +count+ values will be yielded.
@@ -1762,30 +1908,20 @@ io_buffer_each(int argc, VALUE *argv, VALUE self)
 
     rb_io_buffer_get_bytes_for_reading(self, &base, &size);
 
-    ID data_type;
+    ID buffer_type;
     if (argc >= 1) {
-        data_type = RB_SYM2ID(argv[0]);
-    } else {
-        data_type = RB_IO_BUFFER_DATA_TYPE_U8;
+        buffer_type = RB_SYM2ID(argv[0]);
     }
-
-    size_t offset;
-    if (argc >= 2) {
-        offset = NUM2SIZET(argv[1]);
-    } else {
-        offset = 0;
+    else {
+        buffer_type = RB_IO_BUFFER_DATA_TYPE_U8;
     }
 
-    size_t count;
-    if (argc >= 3) {
-        count = NUM2SIZET(argv[2]);
-    } else {
-        count = (size - offset) / io_buffer_data_type_size(data_type);
-    }
+    size_t offset, count;
+    io_buffer_extract_offset_count(buffer_type, size, argc-1, argv+1, &offset, &count);
 
     for (size_t i = 0; i < count; i++) {
         size_t current_offset = offset;
-        VALUE value = rb_io_buffer_get_value(base, size, data_type, &offset);
+        VALUE value = rb_io_buffer_get_value(base, size, buffer_type, &offset);
         rb_yield_values(2, SIZET2NUM(current_offset), value);
     }
 
@@ -1793,9 +1929,9 @@ io_buffer_each(int argc, VALUE *argv, VALUE self)
 }
 
 /*
- *  call-seq: values(data_type, [offset, [count]]) -> array
+ *  call-seq: values(buffer_type, [offset, [count]]) -> array
  *
- *  Returns an array of values of +data_type+ starting from +offset+.
+ *  Returns an array of values of +buffer_type+ starting from +offset+.
  *
  *  If +count+ is given, only +count+ values will be returned.
  *
@@ -1812,31 +1948,21 @@ io_buffer_values(int argc, VALUE *argv, VALUE self)
 
     rb_io_buffer_get_bytes_for_reading(self, &base, &size);
 
-    ID data_type;
+    ID buffer_type;
     if (argc >= 1) {
-        data_type = RB_SYM2ID(argv[0]);
-    } else {
-        data_type = RB_IO_BUFFER_DATA_TYPE_U8;
+        buffer_type = RB_SYM2ID(argv[0]);
     }
-
-    size_t offset;
-    if (argc >= 2) {
-        offset = NUM2SIZET(argv[1]);
-    } else {
-        offset = 0;
+    else {
+        buffer_type = RB_IO_BUFFER_DATA_TYPE_U8;
     }
 
-    size_t count;
-    if (argc >= 3) {
-        count = NUM2SIZET(argv[2]);
-    } else {
-        count = (size - offset) / io_buffer_data_type_size(data_type);
-    }
+    size_t offset, count;
+    io_buffer_extract_offset_count(buffer_type, size, argc-1, argv+1, &offset, &count);
 
     VALUE array = rb_ary_new_capa(count);
 
     for (size_t i = 0; i < count; i++) {
-        VALUE value = rb_io_buffer_get_value(base, size, data_type, &offset);
+        VALUE value = rb_io_buffer_get_value(base, size, buffer_type, &offset);
         rb_ary_push(array, value);
     }
 
@@ -1870,19 +1996,8 @@ io_buffer_each_byte(int argc, VALUE *argv, VALUE self)
 
     rb_io_buffer_get_bytes_for_reading(self, &base, &size);
 
-    size_t offset;
-    if (argc >= 2) {
-        offset = NUM2SIZET(argv[1]);
-    } else {
-        offset = 0;
-    }
-
-    size_t count;
-    if (argc >= 3) {
-        count = NUM2SIZET(argv[2]);
-    } else {
-        count = (size - offset);
-    }
+    size_t offset, count;
+    io_buffer_extract_offset_count(RB_IO_BUFFER_DATA_TYPE_U8, size, argc-1, argv+1, &offset, &count);
 
     for (size_t i = 0; i < count; i++) {
         unsigned char *value = (unsigned char *)base + i + offset;
@@ -1893,9 +2008,9 @@ io_buffer_each_byte(int argc, VALUE *argv, VALUE self)
 }
 
 static inline void
-rb_io_buffer_set_value(const void* base, size_t size, ID data_type, size_t *offset, VALUE value)
+rb_io_buffer_set_value(const void* base, size_t size, ID buffer_type, size_t *offset, VALUE value)
 {
-#define IO_BUFFER_SET_VALUE(name) if (data_type == RB_IO_BUFFER_DATA_TYPE_##name) {io_buffer_write_##name(base, size, offset, value); return;}
+#define IO_BUFFER_SET_VALUE(name) if (buffer_type == RB_IO_BUFFER_DATA_TYPE_##name) {io_buffer_write_##name(base, size, offset, value); return;}
     IO_BUFFER_SET_VALUE(U8);
     IO_BUFFER_SET_VALUE(S8);
 
@@ -1958,7 +2073,7 @@ io_buffer_set_value(VALUE self, VALUE type, VALUE _offset, VALUE value)
 {
     void *base;
     size_t size;
-    size_t offset = NUM2SIZET(_offset);
+    size_t offset = io_buffer_extract_offset(_offset);
 
     rb_io_buffer_get_bytes_for_writing(self, &base, &size);
 
@@ -1968,9 +2083,9 @@ io_buffer_set_value(VALUE self, VALUE type, VALUE _offset, VALUE value)
 }
 
 /*
- *  call-seq: set_values(data_types, offset, values) -> offset
+ *  call-seq: set_values(buffer_types, offset, values) -> offset
  *
- *  Write +values+ of +data_types+ at +offset+ to the buffer. +data_types+
+ *  Write +values+ of +buffer_types+ at +offset+ to the buffer. +buffer_types+
  *  should be an array of symbols as described in #get_value. +values+ should
  *  be an array of values to write.
  *
@@ -1984,28 +2099,28 @@ io_buffer_set_value(VALUE self, VALUE type, VALUE _offset, VALUE value)
  *    # 0x00000000  01 00 02 00 00 00 00 00                         ........
  */
 static VALUE
-io_buffer_set_values(VALUE self, VALUE data_types, VALUE _offset, VALUE values)
+io_buffer_set_values(VALUE self, VALUE buffer_types, VALUE _offset, VALUE values)
 {
-    if (!RB_TYPE_P(data_types, T_ARRAY)) {
-        rb_raise(rb_eArgError, "Argument data_types should be an array!");
+    if (!RB_TYPE_P(buffer_types, T_ARRAY)) {
+        rb_raise(rb_eArgError, "Argument buffer_types should be an array!");
     }
 
     if (!RB_TYPE_P(values, T_ARRAY)) {
         rb_raise(rb_eArgError, "Argument values should be an array!");
     }
 
-    if (RARRAY_LEN(data_types) != RARRAY_LEN(values)) {
-        rb_raise(rb_eArgError, "Argument data_types and values should have the same length!");
+    if (RARRAY_LEN(buffer_types) != RARRAY_LEN(values)) {
+        rb_raise(rb_eArgError, "Argument buffer_types and values should have the same length!");
     }
 
-    size_t offset = NUM2SIZET(_offset);
+    size_t offset = io_buffer_extract_offset(_offset);
 
     void *base;
     size_t size;
     rb_io_buffer_get_bytes_for_writing(self, &base, &size);
 
-    for (long i = 0; i < RARRAY_LEN(data_types); i++) {
-        VALUE type = rb_ary_entry(data_types, i);
+    for (long i = 0; i < RARRAY_LEN(buffer_types); i++) {
+        VALUE type = rb_ary_entry(buffer_types, i);
         VALUE value = rb_ary_entry(values, i);
         rb_io_buffer_set_value(base, size, RB_SYM2ID(type), &offset, value);
     }
@@ -2014,16 +2129,16 @@ io_buffer_set_values(VALUE self, VALUE data_types, VALUE _offset, VALUE values)
 }
 
 static void
-io_buffer_memcpy(struct rb_io_buffer *data, size_t offset, const void *source_base, size_t source_offset, size_t source_size, size_t length)
+io_buffer_memcpy(struct rb_io_buffer *buffer, size_t offset, const void *source_base, size_t source_offset, size_t source_size, size_t length)
 {
     void *base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     if (source_offset + length > source_size) {
-        rb_raise(rb_eArgError, "The computed source range exceeds the size of the source!");
+        rb_raise(rb_eArgError, "The computed source range exceeds the size of the source buffer!");
     }
 
     memcpy((unsigned char*)base+offset, (unsigned char*)source_base+source_offset, length);
@@ -2031,23 +2146,20 @@ io_buffer_memcpy(struct rb_io_buffer *data, size_t offset, const void *source_ba
 
 // (offset, length, source_offset) -> length
 static VALUE
-io_buffer_copy_from(struct rb_io_buffer *data, const void *source_base, size_t source_size, int argc, VALUE *argv)
+io_buffer_copy_from(struct rb_io_buffer *buffer, const void *source_base, size_t source_size, int argc, VALUE *argv)
 {
-    size_t offset;
+    size_t offset = 0;
     size_t length;
     size_t source_offset;
 
     // The offset we copy into the buffer:
     if (argc >= 1) {
-        offset = NUM2SIZET(argv[0]);
-    }
-    else {
-        offset = 0;
+        offset = io_buffer_extract_offset(argv[0]);
     }
 
     // The offset we start from within the string:
     if (argc >= 3) {
-        source_offset = NUM2SIZET(argv[2]);
+        source_offset = io_buffer_extract_offset(argv[2]);
 
         if (source_offset > source_size) {
             rb_raise(rb_eArgError, "The given source offset is bigger than the source itself!");
@@ -2059,14 +2171,14 @@ io_buffer_copy_from(struct rb_io_buffer *data, const void *source_base, size_t s
 
     // The length we are going to copy:
     if (argc >= 2 && !RB_NIL_P(argv[1])) {
-        length = NUM2SIZET(argv[1]);
+        length = io_buffer_extract_length(argv[1]);
     }
     else {
         // Default to the source offset -> source size:
         length = source_size - source_offset;
     }
 
-    io_buffer_memcpy(data, offset, source_base, source_offset, source_size, length);
+    io_buffer_memcpy(buffer, offset, source_base, source_offset, source_size, length);
 
     return SIZET2NUM(length);
 }
@@ -2091,24 +2203,24 @@ io_buffer_copy_from(struct rb_io_buffer *data, const void *source_base, size_t s
 static VALUE
 rb_io_buffer_initialize_copy(VALUE self, VALUE source)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     const void *source_base;
     size_t source_size;
 
     rb_io_buffer_get_bytes_for_reading(source, &source_base, &source_size);
 
-    io_buffer_initialize(data, NULL, source_size, io_flags_for_size(source_size), Qnil);
+    io_buffer_initialize(buffer, NULL, source_size, io_flags_for_size(source_size), Qnil);
 
-    return io_buffer_copy_from(data, source_base, source_size, 0, NULL);
+    return io_buffer_copy_from(buffer, source_base, source_size, 0, NULL);
 }
 
 /*
  *  call-seq:
  *    copy(source, [offset, [length, [source_offset]]]) -> size
  *
- *  Efficiently copy data from a source IO::Buffer into the buffer,
+ *  Efficiently copy buffer from a source IO::Buffer into the buffer,
  *  at +offset+ using +memcpy+. For copying String instances, see #set_string.
  *
  *    buffer = IO::Buffer.new(32)
@@ -2118,22 +2230,22 @@ rb_io_buffer_initialize_copy(VALUE self, VALUE source)
  *    # 0x00000010  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................  *
  *
  *    buffer.copy(IO::Buffer.for("test"), 8)
- *    # => 4 -- size of data copied
+ *    # => 4 -- size of buffer copied
  *    buffer
  *    # =>
  *    # #<IO::Buffer 0x0000555f5cf8fe40+32 INTERNAL>
  *    # 0x00000000  00 00 00 00 00 00 00 00 74 65 73 74 00 00 00 00 ........test....
  *    # 0x00000010  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ *
  *
- *  #copy can be used to put data into strings associated with buffer:
+ *  #copy can be used to put buffer into strings associated with buffer:
  *
- *    string= "data:    "
- *    # => "data:    "
+ *    string= "buffer:    "
+ *    # => "buffer:    "
  *    buffer = IO::Buffer.for(string)
  *    buffer.copy(IO::Buffer.for("test"), 5)
  *    # => 4
  *    string
- *    # => "data:test"
+ *    # => "buffer:test"
  *
  *  Attempt to copy into a read-only buffer will fail:
  *
@@ -2151,20 +2263,20 @@ rb_io_buffer_initialize_copy(VALUE self, VALUE source)
  *    File.read('test.txt')
  *    # => "boom"
  *
- *  Attempt to copy the data which will need place outside of buffer's
+ *  Attempt to copy the buffer which will need place outside of buffer's
  *  bounds will fail:
  *
  *    buffer = IO::Buffer.new(2)
  *    buffer.copy(IO::Buffer.for('test'), 0)
- *    # in `copy': Specified offset+length exceeds source size! (ArgumentError)
+ *    # in `copy': Specified offset+length is bigger than the buffer size! (ArgumentError)
  */
 static VALUE
 io_buffer_copy(int argc, VALUE *argv, VALUE self)
 {
     rb_check_arity(argc, 1, 4);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     VALUE source = argv[0];
     const void *source_base;
@@ -2172,7 +2284,7 @@ io_buffer_copy(int argc, VALUE *argv, VALUE self)
 
     rb_io_buffer_get_bytes_for_reading(source, &source_base, &source_size);
 
-    return io_buffer_copy_from(data, source_base, source_size, argc-1, argv+1);
+    return io_buffer_copy_from(buffer, source_base, source_size, argc-1, argv+1);
 }
 
 /*
@@ -2194,33 +2306,22 @@ io_buffer_get_string(int argc, VALUE *argv, VALUE self)
 {
     rb_check_arity(argc, 0, 3);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    size_t offset, length;
+    struct rb_io_buffer *buffer = io_buffer_extract_offset_length(self, argc, argv, &offset, &length);
 
     const void *base;
     size_t size;
-    io_buffer_get_bytes_for_reading(data, &base, &size);
-
-    size_t offset = 0;
-    size_t length = size;
-    rb_encoding *encoding = rb_ascii8bit_encoding();
-
-    if (argc >= 1) {
-        offset = NUM2SIZET(argv[0]);
-    }
-
-    if (argc >= 2 && !RB_NIL_P(argv[1])) {
-        length = NUM2SIZET(argv[1]);
-    }
-    else {
-        length = size - offset;
-    }
+    io_buffer_get_bytes_for_reading(buffer, &base, &size);
 
+    rb_encoding *encoding;
     if (argc >= 3) {
         encoding = rb_find_encoding(argv[2]);
     }
+    else {
+        encoding = rb_ascii8bit_encoding();
+    }
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     return rb_enc_str_new((const char*)base + offset, length, encoding);
 }
@@ -2228,7 +2329,7 @@ io_buffer_get_string(int argc, VALUE *argv, VALUE self)
 /*
  *  call-seq: set_string(string, [offset, [length, [source_offset]]]) -> size
  *
- *  Efficiently copy data from a source String into the buffer,
+ *  Efficiently copy buffer from a source String into the buffer,
  *  at +offset+ using +memcpy+.
  *
  *    buf = IO::Buffer.new(8)
@@ -2236,7 +2337,7 @@ io_buffer_get_string(int argc, VALUE *argv, VALUE self)
  *    # #<IO::Buffer 0x0000557412714a20+8 INTERNAL>
  *    # 0x00000000  00 00 00 00 00 00 00 00                         ........
  *
- *    # set data starting from offset 1, take 2 bytes starting from string's
+ *    # set buffer starting from offset 1, take 2 bytes starting from string's
  *    # second
  *    buf.set_string('test', 1, 2, 1)
  *    # => 2
@@ -2253,28 +2354,28 @@ io_buffer_set_string(int argc, VALUE *argv, VALUE self)
 {
     rb_check_arity(argc, 1, 4);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     VALUE string = rb_str_to_str(argv[0]);
 
     const void *source_base = RSTRING_PTR(string);
     size_t source_size = RSTRING_LEN(string);
 
-    return io_buffer_copy_from(data, source_base, source_size, argc-1, argv+1);
+    return io_buffer_copy_from(buffer, source_base, source_size, argc-1, argv+1);
 }
 
 void
 rb_io_buffer_clear(VALUE self, uint8_t value, size_t offset, size_t length)
 {
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
+
     void *base;
     size_t size;
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
-    rb_io_buffer_get_bytes_for_writing(self, &base, &size);
-
-    if (offset + length > size) {
-        rb_raise(rb_eArgError, "The given offset + length out of bounds!");
-    }
+    io_buffer_validate_range(buffer, offset, length);
 
     memset((char*)base + offset, value, length);
 }
@@ -2315,26 +2416,13 @@ io_buffer_clear(int argc, VALUE *argv, VALUE self)
 {
     rb_check_arity(argc, 0, 3);
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
-
     uint8_t value = 0;
     if (argc >= 1) {
         value = NUM2UINT(argv[0]);
     }
 
-    size_t offset = 0;
-    if (argc >= 2) {
-        offset = NUM2SIZET(argv[1]);
-    }
-
-    size_t length;
-    if (argc >= 3) {
-        length = NUM2SIZET(argv[2]);
-    }
-    else {
-        length = data->size - offset;
-    }
+    size_t offset, length;
+    io_buffer_extract_offset_length(self, argc-1, argv+1, &offset, &length);
 
     rb_io_buffer_clear(self, value, offset, length);
 
@@ -2366,18 +2454,91 @@ io_buffer_default_size(size_t page_size)
     return platform_agnostic_default_size;
 }
 
+struct io_buffer_blocking_region_argument {
+    struct rb_io_buffer *buffer;
+    rb_blocking_function_t *function;
+    void *data;
+    int descriptor;
+};
+
+static VALUE
+io_buffer_blocking_region_begin(VALUE _argument)
+{
+    struct io_buffer_blocking_region_argument *argument = (void*)_argument;
+
+    return rb_thread_io_blocking_region(argument->function, argument->data, argument->descriptor);
+}
+
+static VALUE
+io_buffer_blocking_region_ensure(VALUE _argument)
+{
+    struct io_buffer_blocking_region_argument *argument = (void*)_argument;
+
+    io_buffer_unlock(argument->buffer);
+
+    return Qnil;
+}
+
+static VALUE
+io_buffer_blocking_region(struct rb_io_buffer *buffer, rb_blocking_function_t *function, void *data, int descriptor)
+{
+    struct io_buffer_blocking_region_argument argument = {
+        .buffer = buffer,
+        .function = function,
+        .data = data,
+        .descriptor = descriptor,
+    };
+
+    // If the buffer is already locked, we can skip the ensure (unlock):
+    if (buffer->flags & RB_IO_BUFFER_LOCKED) {
+        return io_buffer_blocking_region_begin((VALUE)&argument);
+    }
+    else {
+        // The buffer should be locked for the duration of the blocking region:
+        io_buffer_lock(buffer);
+
+        return rb_ensure(io_buffer_blocking_region_begin, (VALUE)&argument, io_buffer_blocking_region_ensure, (VALUE)&argument);
+    }
+}
+
 struct io_buffer_read_internal_argument {
     int descriptor;
-    void *base;
+
+    // The base pointer to read from:
+    char *base;
+    // The size of the buffer:
     size_t size;
+
+    // The minimum number of bytes to read:
+    size_t length;
 };
 
 static VALUE
 io_buffer_read_internal(void *_argument)
 {
+    size_t total = 0;
     struct io_buffer_read_internal_argument *argument = _argument;
-    ssize_t result = read(argument->descriptor, argument->base, argument->size);
-    return rb_fiber_scheduler_io_result(result, errno);
+
+    while (true) {
+        ssize_t result = read(argument->descriptor, argument->base, argument->size);
+
+        if (result < 0) {
+            return rb_fiber_scheduler_io_result(result, errno);
+        }
+        else if (result == 0) {
+            return rb_fiber_scheduler_io_result(total, 0);
+        }
+        else {
+            total += result;
+
+            if (total >= argument->length) {
+                return rb_fiber_scheduler_io_result(total, 0);
+            }
+
+            argument->base = argument->base + result;
+            argument->size = argument->size - result;
+        }
+    }
 }
 
 VALUE
@@ -2385,46 +2546,50 @@ rb_io_buffer_read(VALUE self, VALUE io, size_t length, size_t offset)
 {
     VALUE scheduler = rb_fiber_scheduler_current();
     if (scheduler != Qnil) {
-        VALUE result = rb_fiber_scheduler_io_read(scheduler, io, self, SIZET2NUM(length), SIZET2NUM(offset));
+        VALUE result = rb_fiber_scheduler_io_read(scheduler, io, self, length, offset);
 
         if (!UNDEF_P(result)) {
             return result;
         }
     }
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     int descriptor = rb_io_descriptor(io);
 
     void * base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
     base = (unsigned char*)base + offset;
+    size = size - offset;
 
     struct io_buffer_read_internal_argument argument = {
         .descriptor = descriptor,
         .base = base,
-        .size = length,
+        .size = size,
+        .length = length,
     };
 
-    return rb_thread_io_blocking_region(io_buffer_read_internal, &argument, descriptor);
+    return io_buffer_blocking_region(buffer, io_buffer_read_internal, &argument, descriptor);
 }
 
 /*
- *  call-seq: read(io, length, [offset]) -> read length or -errno
+ *  call-seq: read(io, [length, [offset]]) -> read length or -errno
  *
- *  Read at most +length+ bytes from +io+ into the buffer, starting at
+ *  Read at least +length+ bytes from the +io+, into the buffer starting at
  *  +offset+. If an error occurs, return <tt>-errno</tt>.
  *
- *  If +offset+ is not given, read from the beginning of the buffer.
+ *  If +length+ is not given or +nil+, it defaults to the size of the buffer
+ *  minus the offset, i.e. the entire buffer.
  *
- *  If +length+ is 0, read nothing.
+ *  If +length+ is zero, exactly one <tt>read</tt> operation will occur.
  *
- *  Example:
+ *  If +offset+ is not given, it defaults to zero, i.e. the beginning of the
+ *  buffer.
  *
  *    IO::Buffer.for('test') do |buffer|
  *      p buffer
@@ -2441,23 +2606,12 @@ rb_io_buffer_read(VALUE self, VALUE io, size_t length, size_t offset)
 static VALUE
 io_buffer_read(int argc, VALUE *argv, VALUE self)
 {
-    rb_check_arity(argc, 2, 3);
+    rb_check_arity(argc, 1, 3);
 
     VALUE io = argv[0];
 
-    if (rb_int_negative_p(argv[1])) {
-        rb_raise(rb_eArgError, "Length can't be negative!");
-    }
-    size_t length = NUM2SIZET(argv[1]);
-
-    size_t offset = 0;
-    if (argc >= 3) {
-        if (rb_int_negative_p(argv[2])) {
-            rb_raise(rb_eArgError, "Offset can't be negative!");
-        }
-
-        offset = NUM2SIZET(argv[2]);
-    }
+    size_t length, offset;
+    io_buffer_extract_length_offset(self, argc-1, argv+1, &length, &offset);
 
     return rb_io_buffer_read(self, io, length, offset);
 }
@@ -2499,23 +2653,23 @@ rb_io_buffer_pread(VALUE self, VALUE io, rb_off_t from, size_t length, size_t of
 {
     VALUE scheduler = rb_fiber_scheduler_current();
     if (scheduler != Qnil) {
-        VALUE result = rb_fiber_scheduler_io_pread(scheduler, io, OFFT2NUM(from), self, SIZET2NUM(length), SIZET2NUM(offset));
+        VALUE result = rb_fiber_scheduler_io_pread(scheduler, io, from, self, length, offset);
 
         if (!UNDEF_P(result)) {
             return result;
         }
     }
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     int descriptor = rb_io_descriptor(io);
 
     void * base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
     struct io_buffer_pread_internal_argument argument = {
         .descriptor = descriptor,
@@ -2523,14 +2677,14 @@ rb_io_buffer_pread(VALUE self, VALUE io, rb_off_t from, size_t length, size_t of
         // Move the base pointer to the offset:
         .base = (unsigned char*)base + offset,
 
-        // And the size to the length of data we want to read:
+        // And the size to the length of buffer we want to read:
         .size = length,
 
         // From the offset in the file we want to read from:
         .offset = from,
     };
 
-    return rb_thread_io_blocking_region(io_buffer_pread_internal, &argument, descriptor);
+    return io_buffer_blocking_region(buffer, io_buffer_pread_internal, &argument, descriptor);
 }
 
 /*
@@ -2562,41 +2716,55 @@ rb_io_buffer_pread(VALUE self, VALUE io, rb_off_t from, size_t length, size_t of
 static VALUE
 io_buffer_pread(int argc, VALUE *argv, VALUE self)
 {
-    rb_check_arity(argc, 3, 4);
+    rb_check_arity(argc, 2, 4);
 
     VALUE io = argv[0];
     rb_off_t from = NUM2OFFT(argv[1]);
 
-    size_t length;
-    if (rb_int_negative_p(argv[2])) {
-        rb_raise(rb_eArgError, "Length can't be negative!");
-    }
-    length = NUM2SIZET(argv[2]);
-
-    size_t offset = 0;
-    if (argc >= 4) {
-        if (rb_int_negative_p(argv[3])) {
-            rb_raise(rb_eArgError, "Offset can't be negative!");
-        }
-
-        offset = NUM2SIZET(argv[3]);
-    }
+    size_t length, offset;
+    io_buffer_extract_length_offset(self, argc-2, argv+2, &length, &offset);
 
     return rb_io_buffer_pread(self, io, from, length, offset);
 }
 
 struct io_buffer_write_internal_argument {
     int descriptor;
-    const void *base;
+
+    // The base pointer to write from:
+    const char *base;
+    // The size of the buffer:
     size_t size;
+
+    // The minimum length to write:
+    size_t length;
 };
 
 static VALUE
 io_buffer_write_internal(void *_argument)
 {
+    size_t total = 0;
     struct io_buffer_write_internal_argument *argument = _argument;
-    ssize_t result = write(argument->descriptor, argument->base, argument->size);
-    return rb_fiber_scheduler_io_result(result, errno);
+
+    while (true) {
+        ssize_t result = write(argument->descriptor, argument->base, argument->size);
+
+        if (result < 0) {
+            return rb_fiber_scheduler_io_result(result, errno);
+        }
+        else if (result == 0) {
+            return rb_fiber_scheduler_io_result(total, 0);
+        }
+        else {
+            total += result;
+
+            if (total >= argument->length) {
+                return rb_fiber_scheduler_io_result(total, 0);
+            }
+
+            argument->base = argument->base + result;
+            argument->size = argument->size - result;
+        }
+    }
 }
 
 VALUE
@@ -2604,43 +2772,50 @@ rb_io_buffer_write(VALUE self, VALUE io, size_t length, size_t offset)
 {
     VALUE scheduler = rb_fiber_scheduler_current();
     if (scheduler != Qnil) {
-        VALUE result = rb_fiber_scheduler_io_write(scheduler, io, self, SIZET2NUM(length), SIZET2NUM(offset));
+        VALUE result = rb_fiber_scheduler_io_write(scheduler, io, self, length, offset);
 
         if (!UNDEF_P(result)) {
             return result;
         }
     }
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     int descriptor = rb_io_descriptor(io);
 
     const void * base;
     size_t size;
-    io_buffer_get_bytes_for_reading(data, &base, &size);
+    io_buffer_get_bytes_for_reading(buffer, &base, &size);
 
-    base = (unsigned char *)base + offset;
+    base = (unsigned char*)base + offset;
+    size = size - offset;
 
     struct io_buffer_write_internal_argument argument = {
         .descriptor = descriptor,
         .base = base,
-        .size = length,
+        .size = size,
+        .length = length,
     };
 
-    return rb_thread_io_blocking_region(io_buffer_write_internal, &argument, descriptor);
+    return io_buffer_blocking_region(buffer, io_buffer_write_internal, &argument, descriptor);
 }
 
 /*
- *  call-seq: write(io, length, [offset]) -> written length or -errno
+ *  call-seq: write(io, [length, [offset]]) -> written length or -errno
  *
- *  Writes +length+ bytes from buffer into +io+, starting at
- *  +offset+ in the buffer. If an error occurs, return <tt>-errno</tt>.
+ *  Write at least +length+ bytes from the buffer starting at +offset+, into the +io+.
+ *  If an error occurs, return <tt>-errno</tt>.
  *
- *  If +offset+ is not given, the bytes are taken from the beginning
- *  of the buffer.
+ *  If +length+ is not given or +nil+, it defaults to the size of the buffer
+ *  minus the offset, i.e. the entire buffer.
+ *
+ *  If +length+ is zero, exactly one <tt>write</tt> operation will occur.
+ *
+ *  If +offset+ is not given, it defaults to zero, i.e. the beginning of the
+ *  buffer.
  *
  *    out = File.open('output.txt', 'wb')
  *    IO::Buffer.for('1234567').write(out, 3)
@@ -2650,23 +2825,12 @@ rb_io_buffer_write(VALUE self, VALUE io, size_t length, size_t offset)
 static VALUE
 io_buffer_write(int argc, VALUE *argv, VALUE self)
 {
-    rb_check_arity(argc, 2, 3);
+    rb_check_arity(argc, 1, 3);
 
     VALUE io = argv[0];
 
-    if (rb_int_negative_p(argv[1])) {
-        rb_raise(rb_eArgError, "Length can't be negative!");
-    }
-    size_t length = NUM2SIZET(argv[1]);
-
-    size_t offset = 0;
-    if (argc >= 3) {
-        if (rb_int_negative_p(argv[2])) {
-            rb_raise(rb_eArgError, "Offset can't be negative!");
-        }
-
-        offset = NUM2SIZET(argv[2]);
-    }
+    size_t length, offset;
+    io_buffer_extract_length_offset(self, argc-1, argv+1, &length, &offset);
 
     return rb_io_buffer_write(self, io, length, offset);
 }
@@ -2708,23 +2872,23 @@ rb_io_buffer_pwrite(VALUE self, VALUE io, rb_off_t from, size_t length, size_t o
 {
     VALUE scheduler = rb_fiber_scheduler_current();
     if (scheduler != Qnil) {
-        VALUE result = rb_fiber_scheduler_io_pwrite(scheduler, io, OFFT2NUM(from), self, SIZET2NUM(length), SIZET2NUM(offset));
+        VALUE result = rb_fiber_scheduler_io_pwrite(scheduler, io, from, self, length, offset);
 
         if (!UNDEF_P(result)) {
             return result;
         }
     }
 
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    io_buffer_validate_range(data, offset, length);
+    io_buffer_validate_range(buffer, offset, length);
 
     int descriptor = rb_io_descriptor(io);
 
     const void * base;
     size_t size;
-    io_buffer_get_bytes_for_reading(data, &base, &size);
+    io_buffer_get_bytes_for_reading(buffer, &base, &size);
 
     struct io_buffer_pwrite_internal_argument argument = {
         .descriptor = descriptor,
@@ -2732,14 +2896,14 @@ rb_io_buffer_pwrite(VALUE self, VALUE io, rb_off_t from, size_t length, size_t o
         // Move the base pointer to the offset:
         .base = (unsigned char *)base + offset,
 
-        // And the size to the length of data we want to read:
+        // And the size to the length of buffer we want to read:
         .size = length,
 
         // And the offset in the file we want to write from:
         .offset = from,
     };
 
-    return rb_thread_io_blocking_region(io_buffer_pwrite_internal, &argument, descriptor);
+    return io_buffer_blocking_region(buffer, io_buffer_pwrite_internal, &argument, descriptor);
 }
 
 /*
@@ -2761,25 +2925,13 @@ rb_io_buffer_pwrite(VALUE self, VALUE io, rb_off_t from, size_t length, size_t o
 static VALUE
 io_buffer_pwrite(int argc, VALUE *argv, VALUE self)
 {
-    rb_check_arity(argc, 3, 4);
+    rb_check_arity(argc, 2, 4);
 
     VALUE io = argv[0];
     rb_off_t from = NUM2OFFT(argv[1]);
 
-    size_t length;
-    if (rb_int_negative_p(argv[2])) {
-        rb_raise(rb_eArgError, "Length can't be negative!");
-    }
-    length = NUM2SIZET(argv[2]);
-
-    size_t offset = 0;
-    if (argc >= 4) {
-        if (rb_int_negative_p(argv[3])) {
-            rb_raise(rb_eArgError, "Offset can't be negative!");
-        }
-
-        offset = NUM2SIZET(argv[3]);
-    }
+    size_t length, offset;
+    io_buffer_extract_length_offset(self, argc-2, argv+2, &length, &offset);
 
     return rb_io_buffer_pwrite(self, io, from, length, offset);
 }
@@ -2814,19 +2966,19 @@ memory_and(unsigned char * restrict output, unsigned char * restrict base, size_
 static VALUE
 io_buffer_and(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
+    io_buffer_check_mask(mask_buffer);
 
-    VALUE output = rb_io_buffer_new(NULL, data->size, io_flags_for_size(data->size));
-    struct rb_io_buffer *output_data = NULL;
-    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_data);
+    VALUE output = rb_io_buffer_new(NULL, buffer->size, io_flags_for_size(buffer->size));
+    struct rb_io_buffer *output_buffer = NULL;
+    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_buffer);
 
-    memory_and(output_data->base, data->base, data->size, mask_data->base, mask_data->size);
+    memory_and(output_buffer->base, buffer->base, buffer->size, mask_buffer->base, mask_buffer->size);
 
     return output;
 }
@@ -2854,19 +3006,19 @@ memory_or(unsigned char * restrict output, unsigned char * restrict base, size_t
 static VALUE
 io_buffer_or(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
+    io_buffer_check_mask(mask_buffer);
 
-    VALUE output = rb_io_buffer_new(NULL, data->size, io_flags_for_size(data->size));
-    struct rb_io_buffer *output_data = NULL;
-    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_data);
+    VALUE output = rb_io_buffer_new(NULL, buffer->size, io_flags_for_size(buffer->size));
+    struct rb_io_buffer *output_buffer = NULL;
+    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_buffer);
 
-    memory_or(output_data->base, data->base, data->size, mask_data->base, mask_data->size);
+    memory_or(output_buffer->base, buffer->base, buffer->size, mask_buffer->base, mask_buffer->size);
 
     return output;
 }
@@ -2894,19 +3046,19 @@ memory_xor(unsigned char * restrict output, unsigned char * restrict base, size_
 static VALUE
 io_buffer_xor(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
+    io_buffer_check_mask(mask_buffer);
 
-    VALUE output = rb_io_buffer_new(NULL, data->size, io_flags_for_size(data->size));
-    struct rb_io_buffer *output_data = NULL;
-    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_data);
+    VALUE output = rb_io_buffer_new(NULL, buffer->size, io_flags_for_size(buffer->size));
+    struct rb_io_buffer *output_buffer = NULL;
+    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_buffer);
 
-    memory_xor(output_data->base, data->base, data->size, mask_data->base, mask_data->size);
+    memory_xor(output_buffer->base, buffer->base, buffer->size, mask_buffer->base, mask_buffer->size);
 
     return output;
 }
@@ -2934,14 +3086,14 @@ memory_not(unsigned char * restrict output, unsigned char * restrict base, size_
 static VALUE
 io_buffer_not(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    VALUE output = rb_io_buffer_new(NULL, data->size, io_flags_for_size(data->size));
-    struct rb_io_buffer *output_data = NULL;
-    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_data);
+    VALUE output = rb_io_buffer_new(NULL, buffer->size, io_flags_for_size(buffer->size));
+    struct rb_io_buffer *output_buffer = NULL;
+    TypedData_Get_Struct(output, struct rb_io_buffer, &rb_io_buffer_type, output_buffer);
 
-    memory_not(output_data->base, data->base, data->size);
+    memory_not(output_buffer->base, buffer->base, buffer->size);
 
     return output;
 }
@@ -2960,7 +3112,7 @@ static inline void
 io_buffer_check_overlaps(struct rb_io_buffer *a, struct rb_io_buffer *b)
 {
     if (io_buffer_overlaps(a, b))
-        rb_raise(rb_eIOBufferMaskError, "Mask overlaps source data!");
+        rb_raise(rb_eIOBufferMaskError, "Mask overlaps source buffer!");
 }
 
 static void
@@ -2991,20 +3143,20 @@ memory_and_inplace(unsigned char * restrict base, size_t size, unsigned char * r
 static VALUE
 io_buffer_and_inplace(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
-    io_buffer_check_overlaps(data, mask_data);
+    io_buffer_check_mask(mask_buffer);
+    io_buffer_check_overlaps(buffer, mask_buffer);
 
     void *base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
-    memory_and_inplace(base, size, mask_data->base, mask_data->size);
+    memory_and_inplace(base, size, mask_buffer->base, mask_buffer->size);
 
     return self;
 }
@@ -3037,20 +3189,20 @@ memory_or_inplace(unsigned char * restrict base, size_t size, unsigned char * re
 static VALUE
 io_buffer_or_inplace(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
-    io_buffer_check_overlaps(data, mask_data);
+    io_buffer_check_mask(mask_buffer);
+    io_buffer_check_overlaps(buffer, mask_buffer);
 
     void *base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
-    memory_or_inplace(base, size, mask_data->base, mask_data->size);
+    memory_or_inplace(base, size, mask_buffer->base, mask_buffer->size);
 
     return self;
 }
@@ -3083,20 +3235,20 @@ memory_xor_inplace(unsigned char * restrict base, size_t size, unsigned char * r
 static VALUE
 io_buffer_xor_inplace(VALUE self, VALUE mask)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
-    struct rb_io_buffer *mask_data = NULL;
-    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_data);
+    struct rb_io_buffer *mask_buffer = NULL;
+    TypedData_Get_Struct(mask, struct rb_io_buffer, &rb_io_buffer_type, mask_buffer);
 
-    io_buffer_check_mask(mask_data);
-    io_buffer_check_overlaps(data, mask_data);
+    io_buffer_check_mask(mask_buffer);
+    io_buffer_check_overlaps(buffer, mask_buffer);
 
     void *base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
-    memory_xor_inplace(base, size, mask_data->base, mask_data->size);
+    memory_xor_inplace(base, size, mask_buffer->base, mask_buffer->size);
 
     return self;
 }
@@ -3129,12 +3281,12 @@ memory_not_inplace(unsigned char * restrict base, size_t size)
 static VALUE
 io_buffer_not_inplace(VALUE self)
 {
-    struct rb_io_buffer *data = NULL;
-    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, data);
+    struct rb_io_buffer *buffer = NULL;
+    TypedData_Get_Struct(self, struct rb_io_buffer, &rb_io_buffer_type, buffer);
 
     void *base;
     size_t size;
-    io_buffer_get_bytes_for_writing(data, &base, &size);
+    io_buffer_get_bytes_for_writing(buffer, &base, &size);
 
     memory_not_inplace(base, size);
 
@@ -3147,8 +3299,8 @@ io_buffer_not_inplace(VALUE self)
  *  IO::Buffer is a low-level efficient buffer for input/output. There are three
  *  ways of using buffer:
  *
- *  * Create an empty buffer with ::new, fill it with data using #copy or
- *    #set_value, #set_string, get data with #get_string;
+ *  * Create an empty buffer with ::new, fill it with buffer using #copy or
+ *    #set_value, #set_string, get buffer with #get_string;
  *  * Create a buffer mapped to some string with ::for, then it could be used
  *    both for reading with #get_string or #get_value, and writing (writing will
  *    change the source string, too);
@@ -3180,7 +3332,7 @@ io_buffer_not_inplace(VALUE self)
  *
  *  \Buffer from string:
  *
- *    string = 'data'
+ *    string = 'buffer'
  *    buffer = IO::Buffer.for(string)
  *    # =>
  *    # #<IO::Buffer 0x00007f3f02be9b18+4 SLICE>
@@ -3188,7 +3340,7 @@ io_buffer_not_inplace(VALUE self)
  *    buffer
  *    # =>
  *    # #<IO::Buffer 0x00007f3f02be9b18+4 SLICE>
- *    # 0x00000000  64 61 74 61                                     data
+ *    # 0x00000000  64 61 74 61                                     buffer
  *
  *    buffer.get_string(2)  # read content starting from offset 2
  *    # => "ta"
@@ -3203,7 +3355,7 @@ io_buffer_not_inplace(VALUE self)
  *
  *  \Buffer from file:
  *
- *    File.write('test.txt', 'test data')
+ *    File.write('test.txt', 'test buffer')
  *    # => 9
  *    buffer = IO::Buffer.map(File.open('test.txt'))
  *    # =>
@@ -3220,7 +3372,7 @@ io_buffer_not_inplace(VALUE self)
  *    buffer.set_string('---', 1)
  *    # => 3 -- bytes written
  *    File.read('test.txt')
- *    # => "t--- data"
+ *    # => "t--- buffer"
  *
  *  <b>The class is experimental and the interface is subject to change.</b>
  */
@@ -3344,7 +3496,7 @@ Init_IO_Buffer(void)
     rb_define_method(rb_cIOBuffer, "get_string", io_buffer_get_string, -1);
     rb_define_method(rb_cIOBuffer, "set_string", io_buffer_set_string, -1);
 
-    // Binary data manipulations:
+    // Binary buffer manipulations:
     rb_define_method(rb_cIOBuffer, "&", io_buffer_and, 1);
     rb_define_method(rb_cIOBuffer, "|", io_buffer_or, 1);
     rb_define_method(rb_cIOBuffer, "^", io_buffer_xor, 1);
diff --git a/iseq.c b/iseq.c
index a6ba5c12bb..d17ce486c5 100644
--- a/iseq.c
+++ b/iseq.c
@@ -113,7 +113,9 @@ remove_from_constant_cache(ID id, IC ic)
         st_table *ics = (st_table *)lookup_result;
         st_delete(ics, &ic_data, NULL);
 
-        if (ics->num_entries == 0) {
+        if (ics->num_entries == 0 &&
+                // See comment in vm_track_constant_cache on why we need this check
+                id != vm->inserting_constant_cache_id) {
             rb_id_table_delete(vm->constant_cache, id);
             st_free_table(ics);
         }
@@ -187,7 +189,11 @@ rb_iseq_free(const rb_iseq_t *iseq)
             ruby_xfree((void *)body->mark_bits.list);
         }
 
+        ruby_xfree(body->variable.original_iseq);
+
         if (body->param.keyword != NULL) {
+            if (body->param.keyword->table != &body->local_table[body->param.keyword->bits_start - body->param.keyword->num])
+                ruby_xfree((void *)body->param.keyword->table);
             ruby_xfree((void *)body->param.keyword->default_values);
             ruby_xfree((void *)body->param.keyword);
         }
@@ -591,6 +597,19 @@ rb_iseq_pathobj_set(const rb_iseq_t *iseq, VALUE path, VALUE realpath)
                  rb_iseq_pathobj_new(path, realpath));
 }
 
+// Make a dummy iseq for a dummy frame that exposes a path for profilers to inspect
+rb_iseq_t *
+rb_iseq_alloc_with_dummy_path(VALUE fname)
+{
+    rb_iseq_t *dummy_iseq = iseq_alloc();
+
+    ISEQ_BODY(dummy_iseq)->type = ISEQ_TYPE_TOP;
+    RB_OBJ_WRITE(dummy_iseq, &ISEQ_BODY(dummy_iseq)->location.pathobj, fname);
+    RB_OBJ_WRITE(dummy_iseq, &ISEQ_BODY(dummy_iseq)->location.label, fname);
+
+    return dummy_iseq;
+}
+
 static rb_iseq_location_t *
 iseq_location_setup(rb_iseq_t *iseq, VALUE name, VALUE path, VALUE realpath, int first_lineno, const rb_code_location_t *code_location, const int node_id)
 {
@@ -1568,7 +1587,11 @@ rb_iseqw_to_iseq(VALUE iseqw)
 static VALUE
 iseqw_eval(VALUE self)
 {
-    return rb_iseq_eval(iseqw_check(self));
+    const rb_iseq_t *iseq = iseqw_check(self);
+    if (0 == ISEQ_BODY(iseq)->iseq_size) {
+        rb_raise(rb_eTypeError, "attempt to evaluate dummy InstructionSequence");
+    }
+    return rb_iseq_eval(iseq);
 }
 
 /*
@@ -3367,7 +3390,7 @@ rb_vm_encoded_insn_data_table_init(void)
     const void * const *table = rb_vm_get_insns_address_table();
 #define INSN_CODE(insn) ((VALUE)table[insn])
 #else
-#define INSN_CODE(insn) (insn)
+#define INSN_CODE(insn) ((VALUE)(insn))
 #endif
     st_data_t insn;
     encoded_insn_data = st_init_numtable_with_size(VM_INSTRUCTION_SIZE / 2);
diff --git a/iseq.h b/iseq.h
index e5ab4870e8..2f83e7336d 100644
--- a/iseq.h
+++ b/iseq.h
@@ -114,6 +114,7 @@ struct iseq_compile_data {
       struct iseq_compile_data_storage *storage_current;
     } insn;
     bool in_rescue;
+    bool in_masgn;
     int loopval_popped;	/* used by NODE_BREAK */
     int last_line;
     int label_no;
diff --git a/lib/bundler.rb b/lib/bundler.rb
index 88f25b523a..f83268e9cd 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -39,16 +39,6 @@ module Bundler
   environment_preserver.replace_with_backup
   SUDO_MUTEX = Thread::Mutex.new
 
-  SAFE_MARSHAL_CLASSES = [Symbol, TrueClass, String, Array, Hash, Gem::Version, Gem::Specification].freeze
-  SAFE_MARSHAL_ERROR = "Unexpected class %s present in marshaled data. Only %s are allowed."
-  SAFE_MARSHAL_PROC = proc do |object|
-    object.tap do
-      unless SAFE_MARSHAL_CLASSES.include?(object.class)
-        raise TypeError, format(SAFE_MARSHAL_ERROR, object.class, SAFE_MARSHAL_CLASSES.join(", "))
-      end
-    end
-  end
-
   autoload :Definition,             File.expand_path("bundler/definition", __dir__)
   autoload :Dependency,             File.expand_path("bundler/dependency", __dir__)
   autoload :Deprecate,              File.expand_path("bundler/deprecate", __dir__)
@@ -86,10 +76,11 @@ module Bundler
   autoload :UI,                     File.expand_path("bundler/ui", __dir__)
   autoload :URICredentialsFilter,   File.expand_path("bundler/uri_credentials_filter", __dir__)
   autoload :URINormalizer,          File.expand_path("bundler/uri_normalizer", __dir__)
+  autoload :SafeMarshal,            File.expand_path("bundler/safe_marshal", __dir__)
 
   class << self
     def configure
-      @configured ||= configure_gem_home_and_path
+      @configure ||= configure_gem_home_and_path
     end
 
     def ui
@@ -219,9 +210,10 @@ module Bundler
     end
 
     def frozen_bundle?
-      frozen = settings[:deployment]
-      frozen ||= settings[:frozen]
-      frozen
+      frozen = settings[:frozen]
+      return frozen unless frozen.nil?
+
+      settings[:deployment]
     end
 
     def locked_gems
@@ -523,7 +515,7 @@ EOF
     end
 
     def safe_load_marshal(data)
-      load_marshal(data, :marshal_proc => SAFE_MARSHAL_PROC)
+      load_marshal(data, :marshal_proc => SafeMarshal.proc)
     end
 
     def load_gemspec(file, validate = false)
@@ -532,7 +524,7 @@ EOF
       @gemspec_cache[key] ||= load_gemspec_uncached(file, validate)
       # Protect against caching side-effected gemspecs by returning a
       # new instance each time.
-      @gemspec_cache[key].dup if @gemspec_cache[key]
+      @gemspec_cache[key]&.dup
     end
 
     def load_gemspec_uncached(file, validate = false)
@@ -581,7 +573,7 @@ EOF
       @bin_path = nil
       @bundler_major_version = nil
       @bundle_path = nil
-      @configured = nil
+      @configure = nil
       @configured_bundle_path = nil
       @definition = nil
       @load = nil
diff --git a/lib/bundler/cli/binstubs.rb b/lib/bundler/cli/binstubs.rb
index 88d071571f..fc2fad47a5 100644
--- a/lib/bundler/cli/binstubs.rb
+++ b/lib/bundler/cli/binstubs.rb
@@ -11,7 +11,7 @@ module Bundler
     def run
       Bundler.definition.validate_runtime!
       path_option = options["path"]
-      path_option = nil if path_option && path_option.empty?
+      path_option = nil if path_option&.empty?
       Bundler.settings.set_command_option :bin, path_option if options["path"]
       Bundler.settings.set_command_option_if_given :shebang, options["shebang"]
       installer = Installer.new(Bundler.root, Bundler.definition)
diff --git a/lib/bundler/cli/info.rb b/lib/bundler/cli/info.rb
index 0545ce8c75..36c7a58f12 100644
--- a/lib/bundler/cli/info.rb
+++ b/lib/bundler/cli/info.rb
@@ -33,7 +33,7 @@ module Bundler
     def default_gem_spec(gem_name)
       return unless Gem::Specification.respond_to?(:find_all_by_name)
       gem_spec = Gem::Specification.find_all_by_name(gem_name).last
-      return gem_spec if gem_spec && gem_spec.respond_to?(:default_gem?) && gem_spec.default_gem?
+      return gem_spec if gem_spec&.default_gem?
     end
 
     def spec_not_found(gem_name)
diff --git a/lib/bundler/cli/install.rb b/lib/bundler/cli/install.rb
index 1765621cb3..c71bcf159f 100644
--- a/lib/bundler/cli/install.rb
+++ b/lib/bundler/cli/install.rb
@@ -154,7 +154,7 @@ module Bundler
       end
 
       bin_option = options["binstubs"]
-      bin_option = nil if bin_option && bin_option.empty?
+      bin_option = nil if bin_option&.empty?
       Bundler.settings.set_command_option :bin, bin_option if options["binstubs"]
 
       Bundler.settings.set_command_option_if_given :shebang, options["shebang"]
diff --git a/lib/bundler/cli/outdated.rb b/lib/bundler/cli/outdated.rb
index 12c3384938..68c701aefb 100644
--- a/lib/bundler/cli/outdated.rb
+++ b/lib/bundler/cli/outdated.rb
@@ -194,7 +194,7 @@ module Bundler
       end
       current_version = "#{current_spec.version}#{current_spec.git_version}"
 
-      if dependency && dependency.specific?
+      if dependency&.specific?
         dependency_version = %(, requested #{dependency.requirement})
       end
 
diff --git a/lib/bundler/cli/platform.rb b/lib/bundler/cli/platform.rb
index 73da8cf80e..32d68abbb1 100644
--- a/lib/bundler/cli/platform.rb
+++ b/lib/bundler/cli/platform.rb
@@ -8,12 +8,12 @@ module Bundler
     end
 
     def run
-      platforms, ruby_version = Bundler.ui.silence do
-        locked_ruby_version = Bundler.locked_gems && Bundler.locked_gems.ruby_version&.gsub(/p\d+\Z/, "")
-        gemfile_ruby_version = Bundler.definition.ruby_version && Bundler.definition.ruby_version.single_version_string
-        [Bundler.definition.platforms.map {|p| "* #{p}" },
-         locked_ruby_version || gemfile_ruby_version]
+      ruby_version = if Bundler.locked_gems
+        Bundler.locked_gems.ruby_version&.gsub(/p\d+\Z/, "")
+      else
+        Bundler.definition.ruby_version&.single_version_string
       end
+
       output = []
 
       if options[:ruby]
@@ -23,6 +23,8 @@ module Bundler
           output << "No ruby version specified"
         end
       else
+        platforms = Bundler.definition.platforms.map {|p| "* #{p}" }
+
         output << "Your platform is: #{Gem::Platform.local}"
         output << "Your app has gems that work on these platforms:\n#{platforms.join("\n")}"
 
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index bef86cdd60..564530a98c 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -76,8 +76,11 @@ module Bundler
 
       @lockfile               = lockfile
       @lockfile_contents      = String.new
+
       @locked_bundler_version = nil
-      @locked_ruby_version    = nil
+      @resolved_bundler_version = nil
+
+      @locked_ruby_version = nil
       @new_platform = nil
       @removed_platform = nil
 
@@ -146,7 +149,7 @@ module Bundler
       @dependency_changes = converge_dependencies
       @local_changes = converge_locals
 
-      @incomplete_lockfile = check_missing_lockfile_specs
+      @missing_lockfile_dep = check_missing_lockfile_dep
     end
 
     def gem_version_promoter
@@ -217,6 +220,7 @@ module Bundler
     rescue BundlerError => e
       @resolve = nil
       @resolver = nil
+      @resolution_packages = nil
       @specs = nil
       @gem_version_promoter = nil
 
@@ -233,6 +237,14 @@ module Bundler
     end
 
     def current_dependencies
+      filter_relevant(dependencies)
+    end
+
+    def current_locked_dependencies
+      filter_relevant(locked_dependencies)
+    end
+
+    def filter_relevant(dependencies)
       dependencies.select do |d|
         d.should_include? && !d.gem_platforms([generic_local_platform]).empty?
       end
@@ -272,7 +284,7 @@ module Bundler
       @resolve ||= if Bundler.frozen_bundle?
         Bundler.ui.debug "Frozen, using resolution from the lockfile"
         @locked_specs
-      elsif !unlocking? && nothing_changed?
+      elsif no_resolve_needed?
         if deleted_deps.any?
           Bundler.ui.debug "Some dependencies were deleted, using a subset of the resolution from the lockfile"
           SpecSet.new(filter_specs(@locked_specs, @dependencies - deleted_deps))
@@ -309,7 +321,7 @@ module Bundler
 
       if @locked_bundler_version
         locked_major = @locked_bundler_version.segments.first
-        current_major = Bundler.gem_version.segments.first
+        current_major = bundler_version_to_lock.segments.first
 
         updating_major = locked_major < current_major
       end
@@ -349,27 +361,16 @@ module Bundler
       end
     end
 
+    def bundler_version_to_lock
+      @resolved_bundler_version || Bundler.gem_version
+    end
+
     def to_lock
       require_relative "lockfile_generator"
       LockfileGenerator.generate(self)
     end
 
     def ensure_equivalent_gemfile_and_lockfile(explicit_flag = false)
-      msg = String.new
-      msg << "You are trying to install in deployment mode after changing\n" \
-             "your Gemfile. Run `bundle install` elsewhere and add the\n" \
-             "updated #{Bundler.default_lockfile.relative_path_from(SharedHelpers.pwd)} to version control."
-
-      unless explicit_flag
-        suggested_command = if Bundler.settings.locations("frozen").keys.&([:global, :local]).any?
-          "bundle config unset frozen"
-        elsif Bundler.settings.locations("deployment").keys.&([:global, :local]).any?
-          "bundle config unset deployment"
-        end
-        msg << "\n\nIf this is a development machine, remove the #{Bundler.default_gemfile} " \
-               "freeze \nby running `#{suggested_command}`." if suggested_command
-      end
-
       added =   []
       deleted = []
       changed = []
@@ -383,32 +384,36 @@ module Bundler
       deleted.concat deleted_deps.map {|d| "* #{pretty_dep(d)}" } if deleted_deps.any?
 
       both_sources = Hash.new {|h, k| h[k] = [] }
-      @dependencies.each {|d| both_sources[d.name][0] = d }
-
-      locked_dependencies.each do |d|
-        next if !Bundler.feature_flag.bundler_3_mode? && @locked_specs[d.name].empty?
-
-        both_sources[d.name][1] = d
-      end
+      current_dependencies.each {|d| both_sources[d.name][0] = d }
+      current_locked_dependencies.each {|d| both_sources[d.name][1] = d }
 
       both_sources.each do |name, (dep, lock_dep)|
         next if dep.nil? || lock_dep.nil?
 
-        gemfile_source = dep.source || sources.default_source
-        lock_source = lock_dep.source || sources.default_source
+        gemfile_source = dep.source || default_source
+        lock_source = lock_dep.source || default_source
         next if lock_source.include?(gemfile_source)
 
-        gemfile_source_name = dep.source ? gemfile_source.identifier : "no specified source"
-        lockfile_source_name = lock_dep.source ? lock_source.identifier : "no specified source"
+        gemfile_source_name = dep.source ? gemfile_source.to_gemfile : "no specified source"
+        lockfile_source_name = lock_dep.source ? lock_source.to_gemfile : "no specified source"
         changed << "* #{name} from `#{lockfile_source_name}` to `#{gemfile_source_name}`"
       end
 
       reason = change_reason
-      msg << "\n\n#{reason.split(", ").map(&:capitalize).join("\n")}" unless reason.strip.empty?
+      msg = String.new
+      msg << "#{reason.capitalize.strip}, but the lockfile can't be updated because frozen mode is set"
       msg << "\n\nYou have added to the Gemfile:\n" << added.join("\n") if added.any?
       msg << "\n\nYou have deleted from the Gemfile:\n" << deleted.join("\n") if deleted.any?
       msg << "\n\nYou have changed in the Gemfile:\n" << changed.join("\n") if changed.any?
-      msg << "\n"
+      msg << "\n\nRun `bundle install` elsewhere and add the updated #{Bundler.default_lockfile.relative_path_from(SharedHelpers.pwd)} to version control.\n"
+
+      unless explicit_flag
+        suggested_command = unless Bundler.settings.locations("frozen").keys.include?(:env)
+          "bundle config set frozen false"
+        end
+        msg << "If this is a development machine, remove the #{Bundler.default_gemfile.relative_path_from(SharedHelpers.pwd)} " \
+               "freeze by running `#{suggested_command}`." if suggested_command
+      end
 
       raise ProductionError, msg if added.any? || deleted.any? || changed.any? || !nothing_changed?
     end
@@ -473,7 +478,11 @@ module Bundler
     private :sources
 
     def nothing_changed?
-      !@source_changes && !@dependency_changes && !@new_platform && !@path_changes && !@local_changes && !@incomplete_lockfile
+      !@source_changes && !@dependency_changes && !@new_platform && !@path_changes && !@local_changes && !@missing_lockfile_dep && !@unlocking_bundler
+    end
+
+    def no_resolve_needed?
+      !unlocking? && nothing_changed?
     end
 
     def unlocking?
@@ -487,7 +496,14 @@ module Bundler
     end
 
     def expanded_dependencies
-      dependencies + metadata_dependencies
+      dependencies_with_bundler + metadata_dependencies
+    end
+
+    def dependencies_with_bundler
+      return dependencies unless @unlocking_bundler
+      return dependencies if dependencies.map(&:name).include?("bundler")
+
+      [Dependency.new("bundler", @unlocking_bundler)] + dependencies
     end
 
     def resolution_packages
@@ -553,6 +569,8 @@ module Bundler
     def start_resolution
       result = resolver.start
 
+      @resolved_bundler_version = result.find {|spec| spec.name == "bundler" }&.version
+
       SpecSet.new(SpecSet.new(result).for(dependencies, false, @platforms))
     end
 
@@ -610,7 +628,8 @@ module Bundler
         [@new_platform, "you added a new platform to your gemfile"],
         [@path_changes, "the gemspecs for path gems changed"],
         [@local_changes, "the gemspecs for git local gems changed"],
-        [@incomplete_lockfile, "your lock file is missing some gems"],
+        [@missing_lockfile_dep, "your lock file is missing \"#{@missing_lockfile_dep}\""],
+        [@unlocking_bundler, "an update to the version of Bundler itself was requested"],
       ].select(&:first).map(&:last).join(", ")
     end
 
@@ -652,8 +671,8 @@ module Bundler
 
       Bundler.settings.local_overrides.map do |k, v|
         spec   = @dependencies.find {|s| s.name == k }
-        source = spec && spec.source
-        if source && source.respond_to?(:local_override!)
+        source = spec&.source
+        if source&.respond_to?(:local_override!)
           source.unlock! if @unlock[:gems].include?(spec.name)
           locals << [source, source.local_override!(v)]
         end
@@ -665,12 +684,24 @@ module Bundler
       !sources_with_changes.each {|source| @unlock[:sources] << source.name }.empty?
     end
 
-    def check_missing_lockfile_specs
+    def check_missing_lockfile_dep
       all_locked_specs = @locked_specs.map(&:name) << "bundler"
 
-      @locked_specs.any? do |s|
+      missing = @locked_specs.select do |s|
         s.dependencies.any? {|dep| !all_locked_specs.include?(dep.name) }
       end
+
+      if missing.any?
+        @locked_specs.delete(missing)
+
+        return missing.first.name
+      end
+
+      return if @dependency_changes
+
+      current_dependencies.find do |d|
+        @locked_specs[d.name].empty? && d.name != "bundler"
+      end&.name
     end
 
     def converge_paths
@@ -774,26 +805,27 @@ module Bundler
 
     def converge_specs(specs)
       converged = []
-
-      deps = @dependencies.select do |dep|
-        specs[dep].any? {|s| s.satisfies?(dep) && (!dep.source || s.source.include?(dep.source)) }
-      end
+      deps = []
 
       @specs_that_changed_sources = []
 
       specs.each do |s|
+        name = s.name
         dep = @dependencies.find {|d| s.satisfies?(d) }
+        lockfile_source = s.source
 
-        # Replace the locked dependency's source with the equivalent source from the Gemfile
-        s.source = if dep && dep.source
-          gemfile_source = dep.source
-          lockfile_source = s.source
+        if dep
+          gemfile_source = dep.source || default_source
 
           @specs_that_changed_sources << s if gemfile_source != lockfile_source
+          deps << dep if !dep.source || lockfile_source.include?(dep.source)
+          @unlock[:gems] << name if lockfile_source.include?(dep.source) && lockfile_source != gemfile_source
 
-          gemfile_source
+          # Replace the locked dependency's source with the equivalent source from the Gemfile
+          s.source = gemfile_source
         else
-          sources.get_with_fallback(s.source)
+          # Replace the locked dependency's source with the default source, if the locked source is no longer in the Gemfile
+          s.source = default_source unless sources.get(lockfile_source)
         end
 
         next if @unlock[:sources].include?(s.source.name)
@@ -802,9 +834,9 @@ module Bundler
         if s.source.instance_of?(Source::Path) || s.source.instance_of?(Source::Gemspec)
           new_specs = begin
             s.source.specs
-          rescue PathError, GitError
+          rescue PathError
             # if we won't need the source (according to the lockfile),
-            # don't error if the path/git source isn't available
+            # don't error if the path source isn't available
             next if specs.
                     for(requested_dependencies, false).
                     none? {|locked_spec| locked_spec.source == s.source }
@@ -818,11 +850,11 @@ module Bundler
           else
             # If the spec is no longer in the path source, unlock it. This
             # commonly happens if the version changed in the gemspec
-            @unlock[:gems] << s.name
+            @unlock[:gems] << name
           end
         end
 
-        if dep.nil? && requested_dependencies.find {|d| s.name == d.name }
+        if dep.nil? && requested_dependencies.find {|d| name == d.name }
           @unlock[:gems] << s.name
         else
           converged << s
@@ -846,7 +878,7 @@ module Bundler
       source_requirements = if precompute_source_requirements_for_indirect_dependencies?
         all_requirements = source_map.all_requirements
         all_requirements = pin_locally_available_names(all_requirements) if @prefer_local
-        { :default => sources.default_source }.merge(all_requirements)
+        { :default => default_source }.merge(all_requirements)
       else
         { :default => Source::RubygemsAggregate.new(sources, source_map) }.merge(source_map.direct_requirements)
       end
@@ -854,12 +886,24 @@ module Bundler
       metadata_dependencies.each do |dep|
         source_requirements[dep.name] = sources.metadata_source
       end
-      source_requirements[:default_bundler] = source_requirements["bundler"] || sources.default_source
-      source_requirements["bundler"] = sources.metadata_source # needs to come last to override
+
+      default_bundler_source = source_requirements["bundler"] || default_source
+
+      if @unlocking_bundler
+        default_bundler_source.add_dependency_names("bundler")
+      else
+        source_requirements[:default_bundler] = default_bundler_source
+        source_requirements["bundler"] = sources.metadata_source # needs to come last to override
+      end
+
       verify_changed_sources!
       source_requirements
     end
 
+    def default_source
+      sources.default_source
+    end
+
     def verify_changed_sources!
       @specs_that_changed_sources.each do |s|
         if s.source.specs.search(s.name).empty?
@@ -878,7 +922,8 @@ module Bundler
       if preserve_unknown_sections
         sections_to_ignore = LockfileParser.sections_to_ignore(@locked_bundler_version)
         sections_to_ignore += LockfileParser.unknown_sections_in_lockfile(current)
-        sections_to_ignore += LockfileParser::ENVIRONMENT_VERSION_SECTIONS
+        sections_to_ignore << LockfileParser::RUBY
+        sections_to_ignore << LockfileParser::BUNDLED unless @unlocking_bundler
         pattern = /#{Regexp.union(sections_to_ignore)}\n(\s{2,}.*\n)+/
         whitespace_cleanup = /\n{2,}/
         current = current.gsub(pattern, "\n").gsub(whitespace_cleanup, "\n\n").strip
@@ -901,6 +946,7 @@ module Bundler
                 Bundler.local_platform == Gem::Platform::RUBY ||
                 !platforms.include?(Gem::Platform::RUBY) ||
                 (@new_platform && platforms.last == Gem::Platform::RUBY) ||
+                @path_changes ||
                 @dependency_changes ||
                 !@originally_locked_specs.incomplete_ruby_specs?(dependencies)
 
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index e74158a9f5..03c80a408c 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -41,7 +41,7 @@ module Bundler
     end
 
     def eval_gemfile(gemfile, contents = nil)
-      expanded_gemfile_path = Pathname.new(gemfile).expand_path(@gemfile && @gemfile.parent)
+      expanded_gemfile_path = Pathname.new(gemfile).expand_path(@gemfile&.parent)
       original_gemfile = @gemfile
       @gemfile = expanded_gemfile_path
       @gemfiles << expanded_gemfile_path
diff --git a/lib/bundler/env.rb b/lib/bundler/env.rb
index 8b2e292fd6..7b1152930e 100644
--- a/lib/bundler/env.rb
+++ b/lib/bundler/env.rb
@@ -122,7 +122,7 @@ module Bundler
         specs = Bundler.rubygems.find_name(name)
         out << ["  #{name}", "(#{specs.map(&:version).join(",")})"] unless specs.empty?
       end
-      if (exe = caller.last.split(":").first) && exe =~ %r{(exe|bin)/bundler?\z}
+      if (exe = caller.last.split(":").first)&.match? %r{(exe|bin)/bundler?\z}
         shebang = File.read(exe).lines.first
         shebang.sub!(/^#!\s*/, "")
         unless shebang.start_with?(Gem.ruby, "/usr/bin/env ruby")
diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index 983de3137c..ab2189f7f0 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -37,7 +37,6 @@ module Bundler
     settings_flag(:plugins) { @bundler_version >= Gem::Version.new("1.14") }
     settings_flag(:print_only_version_number) { bundler_3_mode? }
     settings_flag(:setup_makes_kernel_gem_public) { !bundler_3_mode? }
-    settings_flag(:suppress_install_using_messages) { bundler_3_mode? }
     settings_flag(:update_requires_all_flag) { bundler_4_mode? }
 
     settings_option(:default_cli_command) { bundler_3_mode? ? :cli_help : :install }
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index e12c15af8a..2119799f68 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -61,6 +61,16 @@ module Bundler
       end
     end
 
+    # This error is raised if HTTP authentication is correct, but lacks
+    # necessary permissions.
+    class AuthenticationForbiddenError < HTTPError
+      def initialize(remote_uri)
+        remote_uri = filter_uri(remote_uri)
+        super "Access token could not be authenticated for #{remote_uri}.\n" \
+          "Make sure it's valid and has the necessary scopes configured."
+      end
+    end
+
     # Exceptions classes that should bypass retry attempts. If your password didn't work the
     # first time, it's not going to the third time.
     NET_ERRORS = [:HTTPBadGateway, :HTTPBadRequest, :HTTPFailedDependency,
@@ -70,7 +80,7 @@ module Bundler
                   :HTTPRequestURITooLong, :HTTPUnauthorized, :HTTPUnprocessableEntity,
                   :HTTPUnsupportedMediaType, :HTTPVersionNotSupported].freeze
     FAIL_ERRORS = begin
-      fail_errors = [AuthenticationRequiredError, BadAuthenticationError, FallbackError]
+      fail_errors = [AuthenticationRequiredError, BadAuthenticationError, AuthenticationForbiddenError, FallbackError]
       fail_errors << Gem::Requirement::BadRequirementError
       fail_errors.concat(NET_ERRORS.map {|e| Net.const_get(e) })
     end.freeze
diff --git a/lib/bundler/fetcher/compact_index.rb b/lib/bundler/fetcher/compact_index.rb
index 77838f0361..8d30dec471 100644
--- a/lib/bundler/fetcher/compact_index.rb
+++ b/lib/bundler/fetcher/compact_index.rb
@@ -15,7 +15,7 @@ module Bundler
           method.bind(self).call(*args, &blk)
         rescue NetworkDownError, CompactIndexClient::Updater::MisMatchedChecksumError => e
           raise HTTPError, e.message
-        rescue AuthenticationRequiredError
+        rescue AuthenticationRequiredError, BadAuthenticationError
           # Fail since we got a 401 from the server.
           raise
         rescue HTTPError => e
@@ -40,7 +40,7 @@ module Bundler
           deps = begin
                    parallel_compact_index_client.dependencies(remaining_gems)
                  rescue TooManyRequestsError
-                   @bundle_worker.stop if @bundle_worker
+                   @bundle_worker&.stop
                    @bundle_worker = nil # reset it.  Not sure if necessary
                    serial_compact_index_client.dependencies(remaining_gems)
                  end
@@ -49,7 +49,7 @@ module Bundler
           complete_gems.concat(deps.map(&:first)).uniq!
           remaining_gems = next_gems - complete_gems
         end
-        @bundle_worker.stop if @bundle_worker
+        @bundle_worker&.stop
         @bundle_worker = nil # reset it.  Not sure if necessary
 
         gem_info
diff --git a/lib/bundler/fetcher/downloader.rb b/lib/bundler/fetcher/downloader.rb
index 28d33f1aed..3062899e0e 100644
--- a/lib/bundler/fetcher/downloader.rb
+++ b/lib/bundler/fetcher/downloader.rb
@@ -41,6 +41,8 @@ module Bundler
         when Net::HTTPUnauthorized
           raise BadAuthenticationError, uri.host if uri.userinfo
           raise AuthenticationRequiredError, uri.host
+        when Net::HTTPForbidden
+          raise AuthenticationForbiddenError, uri.host
         when Net::HTTPNotFound
           raise FallbackError, "Net::HTTPNotFound: #{filtered_uri}"
         else
diff --git a/lib/bundler/fetcher/index.rb b/lib/bundler/fetcher/index.rb
index 6bb9fcc193..c623647f01 100644
--- a/lib/bundler/fetcher/index.rb
+++ b/lib/bundler/fetcher/index.rb
@@ -15,8 +15,7 @@ module Bundler
           raise BadAuthenticationError, remote_uri if remote_uri.userinfo
           raise AuthenticationRequiredError, remote_uri
         when /403/
-          raise BadAuthenticationError, remote_uri if remote_uri.userinfo
-          raise AuthenticationRequiredError, remote_uri
+          raise AuthenticationForbiddenError, remote_uri
         else
           raise HTTPError, "Could not fetch specs from #{display_uri} due to underlying error <#{e.message}>"
         end
diff --git a/lib/bundler/friendly_errors.rb b/lib/bundler/friendly_errors.rb
index 71faeaf282..39afe8a071 100644
--- a/lib/bundler/friendly_errors.rb
+++ b/lib/bundler/friendly_errors.rb
@@ -95,7 +95,7 @@ module Bundler
     def serialized_exception_for(e)
       <<-EOS.gsub(/^ {8}/, "")
         #{e.class}: #{e.message}
-          #{e.backtrace && e.backtrace.join("\n          ").chomp}
+          #{e.backtrace&.join("\n          ")&.chomp}
       EOS
     end
 
diff --git a/lib/bundler/gem_helper.rb b/lib/bundler/gem_helper.rb
index 0bbd2d9b75..dcf759cded 100644
--- a/lib/bundler/gem_helper.rb
+++ b/lib/bundler/gem_helper.rb
@@ -21,7 +21,7 @@ module Bundler
 
       def gemspec(&block)
         gemspec = instance.gemspec
-        block.call(gemspec) if block
+        block&.call(gemspec)
         gemspec
       end
     end
@@ -152,8 +152,7 @@ module Bundler
 
     def gem_push_host
       env_rubygems_host = ENV["RUBYGEMS_HOST"]
-      env_rubygems_host = nil if
-        env_rubygems_host && env_rubygems_host.empty?
+      env_rubygems_host = nil if env_rubygems_host&.empty?
 
       allowed_push_host || env_rubygems_host || "rubygems.org"
     end
@@ -218,7 +217,7 @@ module Bundler
       SharedHelpers.chdir(base) do
         outbuf = IO.popen(cmd, :err => [:child, :out], &:read)
         status = $?
-        block.call(outbuf) if status.success? && block
+        block&.call(outbuf) if status.success?
         [outbuf, status]
       end
     end
diff --git a/lib/bundler/gem_version_promoter.rb b/lib/bundler/gem_version_promoter.rb
index f08fceb7e2..d281f46eeb 100644
--- a/lib/bundler/gem_version_promoter.rb
+++ b/lib/bundler/gem_version_promoter.rb
@@ -93,7 +93,7 @@ module Bundler
       locked_version = package.locked_version
 
       result = specs.sort do |a, b|
-        unless locked_version && (package.prerelease_specified? || pre?)
+        unless package.prerelease_specified? || pre?
           a_pre = a.prerelease?
           b_pre = b.prerelease?
 
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
index 680e812ac8..59b6a6ad22 100644
--- a/lib/bundler/installer.rb
+++ b/lib/bundler/installer.rb
@@ -90,7 +90,7 @@ module Bundler
 
         Gem::Specification.reset # invalidate gem specification cache so that installed gems are immediately available
 
-        lock unless Bundler.frozen_bundle?
+        lock
         Standalone.new(options[:standalone], @definition).generate if options[:standalone]
       end
     end
diff --git a/lib/bundler/installer/parallel_installer.rb b/lib/bundler/installer/parallel_installer.rb
index 58c5aafa1c..83a381f592 100644
--- a/lib/bundler/installer/parallel_installer.rb
+++ b/lib/bundler/installer/parallel_installer.rb
@@ -96,7 +96,7 @@ module Bundler
       handle_error if failed_specs.any?
       @specs
     ensure
-      worker_pool && worker_pool.stop
+      worker_pool&.stop
     end
 
     def check_for_unmet_dependencies
diff --git a/lib/bundler/lazy_specification.rb b/lib/bundler/lazy_specification.rb
index ad8191c55f..c9b161dc0e 100644
--- a/lib/bundler/lazy_specification.rb
+++ b/lib/bundler/lazy_specification.rb
@@ -122,7 +122,7 @@ module Bundler
     end
 
     def to_s
-      @__to_s ||= if platform == Gem::Platform::RUBY
+      @to_s ||= if platform == Gem::Platform::RUBY
         "#{name} (#{version})"
       else
         "#{name} (#{version}-#{platform})"
diff --git a/lib/bundler/lockfile_generator.rb b/lib/bundler/lockfile_generator.rb
index a7ee026f67..f7ba51b3e6 100644
--- a/lib/bundler/lockfile_generator.rb
+++ b/lib/bundler/lockfile_generator.rb
@@ -71,7 +71,7 @@ module Bundler
     end
 
     def add_bundled_with
-      add_section("BUNDLED WITH", Bundler::VERSION)
+      add_section("BUNDLED WITH", definition.bundler_version_to_lock.to_s)
     end
 
     def add_section(name, value)
diff --git a/lib/bundler/lockfile_parser.rb b/lib/bundler/lockfile_parser.rb
index 97cbf211ba..7360a36752 100644
--- a/lib/bundler/lockfile_parser.rb
+++ b/lib/bundler/lockfile_parser.rb
@@ -26,6 +26,7 @@ module Bundler
     KNOWN_SECTIONS = SECTIONS_BY_VERSION_INTRODUCED.values.flatten.freeze
 
     ENVIRONMENT_VERSION_SECTIONS = [BUNDLED, RUBY].freeze
+    deprecate_constant(:ENVIRONMENT_VERSION_SECTIONS)
 
     def self.sections_in_lockfile(lockfile_contents)
       lockfile_contents.scan(/^\w[\w ]*$/).uniq
diff --git a/lib/bundler/man/bundle-add.1 b/lib/bundler/man/bundle-add.1
index 0e21c75506..8549855b0d 100644
--- a/lib/bundler/man/bundle-add.1
+++ b/lib/bundler/man/bundle-add.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-ADD" "1" "February 2023" "" ""
+.TH "BUNDLE\-ADD" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-add\fR \- Add gem to the Gemfile and run bundle install
diff --git a/lib/bundler/man/bundle-binstubs.1 b/lib/bundler/man/bundle-binstubs.1
index 2774e9d28a..40c338916a 100644
--- a/lib/bundler/man/bundle-binstubs.1
+++ b/lib/bundler/man/bundle-binstubs.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-BINSTUBS" "1" "February 2023" "" ""
+.TH "BUNDLE\-BINSTUBS" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-binstubs\fR \- Install the binstubs of the listed gems
diff --git a/lib/bundler/man/bundle-cache.1 b/lib/bundler/man/bundle-cache.1
index f24b63c6fc..69b1e1e3dd 100644
--- a/lib/bundler/man/bundle-cache.1
+++ b/lib/bundler/man/bundle-cache.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-CACHE" "1" "February 2023" "" ""
+.TH "BUNDLE\-CACHE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-cache\fR \- Package your needed \fB\.gem\fR files into your application
@@ -13,7 +13,7 @@
 alias: \fBpackage\fR, \fBpack\fR
 .
 .SH "DESCRIPTION"
-Copy all of the \fB\.gem\fR files needed to run the application into the \fBvendor/cache\fR directory\. In the future, when running [bundle install(1)][bundle\-install], use the gems in the cache in preference to the ones on \fBrubygems\.org\fR\.
+Copy all of the \fB\.gem\fR files needed to run the application into the \fBvendor/cache\fR directory\. In the future, when running \fBbundle install(1)\fR \fIbundle\-install\.1\.html\fR, use the gems in the cache in preference to the ones on \fBrubygems\.org\fR\.
 .
 .SH "GIT AND PATH GEMS"
 The \fBbundle cache\fR command can also package \fB:git\fR and \fB:path\fR dependencies besides \.gem files\. This needs to be explicitly enabled via the \fB\-\-all\fR option\. Once used, the \fB\-\-all\fR option will be remembered\.
@@ -22,7 +22,7 @@ The \fBbundle cache\fR command can also package \fB:git\fR and \fB:path\fR depen
 When using gems that have different packages for different platforms, Bundler supports caching of gems for other platforms where the Gemfile has been resolved (i\.e\. present in the lockfile) in \fBvendor/cache\fR\. This needs to be enabled via the \fB\-\-all\-platforms\fR option\. This setting will be remembered in your local bundler configuration\.
 .
 .SH "REMOTE FETCHING"
-By default, if you run \fBbundle install(1)\fR](bundle\-install\.1\.html) after running bundle cache(1) \fIbundle\-cache\.1\.html\fR, bundler will still connect to \fBrubygems\.org\fR to check whether a platform\-specific gem exists for any of the gems in \fBvendor/cache\fR\.
+By default, if you run \fBbundle install(1)\fR \fIbundle\-install\.1\.html\fR after running bundle cache(1) \fIbundle\-cache\.1\.html\fR, bundler will still connect to \fBrubygems\.org\fR to check whether a platform\-specific gem exists for any of the gems in \fBvendor/cache\fR\.
 .
 .P
 For instance, consider this Gemfile(5):
diff --git a/lib/bundler/man/bundle-cache.1.ronn b/lib/bundler/man/bundle-cache.1.ronn
index 46906d2b48..8112c2c551 100644
--- a/lib/bundler/man/bundle-cache.1.ronn
+++ b/lib/bundler/man/bundle-cache.1.ronn
@@ -10,7 +10,7 @@ alias: `package`, `pack`
 ## DESCRIPTION
 
 Copy all of the `.gem` files needed to run the application into the
-`vendor/cache` directory. In the future, when running [bundle install(1)][bundle-install],
+`vendor/cache` directory. In the future, when running [`bundle install(1)`](bundle-install.1.html),
 use the gems in the cache in preference to the ones on `rubygems.org`.
 
 ## GIT AND PATH GEMS
@@ -29,7 +29,7 @@ bundler configuration.
 
 ## REMOTE FETCHING
 
-By default, if you run `bundle install(1)`](bundle-install.1.html) after running
+By default, if you run [`bundle install(1)`](bundle-install.1.html) after running
 [bundle cache(1)](bundle-cache.1.html), bundler will still connect to `rubygems.org`
 to check whether a platform-specific gem exists for any of the gems
 in `vendor/cache`.
diff --git a/lib/bundler/man/bundle-check.1 b/lib/bundler/man/bundle-check.1
index 7679945c48..748a37e7d1 100644
--- a/lib/bundler/man/bundle-check.1
+++ b/lib/bundler/man/bundle-check.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-CHECK" "1" "February 2023" "" ""
+.TH "BUNDLE\-CHECK" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-check\fR \- Verifies if dependencies are satisfied by installed gems
diff --git a/lib/bundler/man/bundle-clean.1 b/lib/bundler/man/bundle-clean.1
index 2eb745698c..af8f13cd89 100644
--- a/lib/bundler/man/bundle-clean.1
+++ b/lib/bundler/man/bundle-clean.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-CLEAN" "1" "February 2023" "" ""
+.TH "BUNDLE\-CLEAN" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-clean\fR \- Cleans up unused gems in your bundler directory
diff --git a/lib/bundler/man/bundle-config.1 b/lib/bundler/man/bundle-config.1
index 493b57e1de..4442f33105 100644
--- a/lib/bundler/man/bundle-config.1
+++ b/lib/bundler/man/bundle-config.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-CONFIG" "1" "February 2023" "" ""
+.TH "BUNDLE\-CONFIG" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-config\fR \- Set bundler configuration options
@@ -284,9 +284,6 @@ The following is a list of all configuration keys and their purpose\. You can le
 \fBssl_verify_mode\fR (\fBBUNDLE_SSL_VERIFY_MODE\fR): The SSL verification mode Bundler uses when making HTTPS requests\. Defaults to verify peer\.
 .
 .IP "\(bu" 4
-\fBsuppress_install_using_messages\fR (\fBBUNDLE_SUPPRESS_INSTALL_USING_MESSAGES\fR): Avoid printing \fBUsing \.\.\.\fR messages during installation when the version of a gem has not changed\.
-.
-.IP "\(bu" 4
 \fBsystem_bindir\fR (\fBBUNDLE_SYSTEM_BINDIR\fR): The location where RubyGems installs binstubs\. Defaults to \fBGem\.bindir\fR\.
 .
 .IP "\(bu" 4
diff --git a/lib/bundler/man/bundle-config.1.ronn b/lib/bundler/man/bundle-config.1.ronn
index bc8b27cf89..adc273ec62 100644
--- a/lib/bundler/man/bundle-config.1.ronn
+++ b/lib/bundler/man/bundle-config.1.ronn
@@ -265,9 +265,6 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
 * `ssl_verify_mode` (`BUNDLE_SSL_VERIFY_MODE`):
    The SSL verification mode Bundler uses when making HTTPS requests.
    Defaults to verify peer.
-* `suppress_install_using_messages` (`BUNDLE_SUPPRESS_INSTALL_USING_MESSAGES`):
-   Avoid printing `Using ...` messages during installation when the version of
-   a gem has not changed.
 * `system_bindir` (`BUNDLE_SYSTEM_BINDIR`):
    The location where RubyGems installs binstubs. Defaults to `Gem.bindir`.
 * `timeout` (`BUNDLE_TIMEOUT`):
diff --git a/lib/bundler/man/bundle-console.1 b/lib/bundler/man/bundle-console.1
index ff239004bf..24fff46cec 100644
--- a/lib/bundler/man/bundle-console.1
+++ b/lib/bundler/man/bundle-console.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-CONSOLE" "1" "February 2023" "" ""
+.TH "BUNDLE\-CONSOLE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-console\fR \- Deprecated way to open an IRB session with the bundle pre\-loaded
diff --git a/lib/bundler/man/bundle-doctor.1 b/lib/bundler/man/bundle-doctor.1
index e463b67477..57da8216cb 100644
--- a/lib/bundler/man/bundle-doctor.1
+++ b/lib/bundler/man/bundle-doctor.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-DOCTOR" "1" "February 2023" "" ""
+.TH "BUNDLE\-DOCTOR" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-doctor\fR \- Checks the bundle for common problems
diff --git a/lib/bundler/man/bundle-exec.1 b/lib/bundler/man/bundle-exec.1
index 9e9efe8b6d..852788db7a 100644
--- a/lib/bundler/man/bundle-exec.1
+++ b/lib/bundler/man/bundle-exec.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-EXEC" "1" "February 2023" "" ""
+.TH "BUNDLE\-EXEC" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-exec\fR \- Execute a command in the context of the bundle
diff --git a/lib/bundler/man/bundle-gem.1 b/lib/bundler/man/bundle-gem.1
index ea64871fb6..8339b727ce 100644
--- a/lib/bundler/man/bundle-gem.1
+++ b/lib/bundler/man/bundle-gem.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-GEM" "1" "February 2023" "" ""
+.TH "BUNDLE\-GEM" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-gem\fR \- Generate a project skeleton for creating a rubygem
diff --git a/lib/bundler/man/bundle-help.1 b/lib/bundler/man/bundle-help.1
index a3b059ea07..9787c2d49f 100644
--- a/lib/bundler/man/bundle-help.1
+++ b/lib/bundler/man/bundle-help.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-HELP" "1" "February 2023" "" ""
+.TH "BUNDLE\-HELP" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-help\fR \- Displays detailed help for each subcommand
diff --git a/lib/bundler/man/bundle-info.1 b/lib/bundler/man/bundle-info.1
index 5af60c6a77..2cced71520 100644
--- a/lib/bundler/man/bundle-info.1
+++ b/lib/bundler/man/bundle-info.1
@@ -1,16 +1,16 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-INFO" "1" "February 2023" "" ""
+.TH "BUNDLE\-INFO" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-info\fR \- Show information for the given gem in your bundle
 .
 .SH "SYNOPSIS"
-\fBbundle info\fR [GEM] [\-\-path]
+\fBbundle info\fR [GEM_NAME] [\-\-path]
 .
 .SH "DESCRIPTION"
-Print the basic information about the provided GEM such as homepage, version, path and summary\.
+Given a gem name present in your bundle, print the basic information about it such as homepage, version, path and summary\.
 .
 .SH "OPTIONS"
 .
diff --git a/lib/bundler/man/bundle-info.1.ronn b/lib/bundler/man/bundle-info.1.ronn
index 47e457aa3c..cecdeb564f 100644
--- a/lib/bundler/man/bundle-info.1.ronn
+++ b/lib/bundler/man/bundle-info.1.ronn
@@ -3,13 +3,13 @@ bundle-info(1) -- Show information for the given gem in your bundle
 
 ## SYNOPSIS
 
-`bundle info` [GEM]
+`bundle info` [GEM_NAME]
               [--path]
 
 ## DESCRIPTION
 
-Print the basic information about the provided GEM such as homepage, version,
-path and summary.
+Given a gem name present in your bundle, print the basic information about it
+ such as homepage, version, path and summary.
 
 ## OPTIONS
 
diff --git a/lib/bundler/man/bundle-init.1 b/lib/bundler/man/bundle-init.1
index e93b4fd5e9..c7a9a155b5 100644
--- a/lib/bundler/man/bundle-init.1
+++ b/lib/bundler/man/bundle-init.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-INIT" "1" "February 2023" "" ""
+.TH "BUNDLE\-INIT" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-init\fR \- Generates a Gemfile into the current working directory
diff --git a/lib/bundler/man/bundle-inject.1 b/lib/bundler/man/bundle-inject.1
index 657d5ef4a7..9e25c29085 100644
--- a/lib/bundler/man/bundle-inject.1
+++ b/lib/bundler/man/bundle-inject.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-INJECT" "1" "February 2023" "" ""
+.TH "BUNDLE\-INJECT" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-inject\fR \- Add named gem(s) with version requirements to Gemfile
diff --git a/lib/bundler/man/bundle-install.1 b/lib/bundler/man/bundle-install.1
index 8f144692f3..337683af06 100644
--- a/lib/bundler/man/bundle-install.1
+++ b/lib/bundler/man/bundle-install.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-INSTALL" "1" "February 2023" "" ""
+.TH "BUNDLE\-INSTALL" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-install\fR \- Install the dependencies specified in your Gemfile
diff --git a/lib/bundler/man/bundle-list.1 b/lib/bundler/man/bundle-list.1
index f24f62dd38..1680e6007a 100644
--- a/lib/bundler/man/bundle-list.1
+++ b/lib/bundler/man/bundle-list.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-LIST" "1" "February 2023" "" ""
+.TH "BUNDLE\-LIST" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-list\fR \- List all the gems in the bundle
diff --git a/lib/bundler/man/bundle-lock.1 b/lib/bundler/man/bundle-lock.1
index 55d1035d77..8722c44b3d 100644
--- a/lib/bundler/man/bundle-lock.1
+++ b/lib/bundler/man/bundle-lock.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-LOCK" "1" "February 2023" "" ""
+.TH "BUNDLE\-LOCK" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-lock\fR \- Creates / Updates a lockfile without installing
diff --git a/lib/bundler/man/bundle-open.1 b/lib/bundler/man/bundle-open.1
index ff44d1224f..3513f0d09b 100644
--- a/lib/bundler/man/bundle-open.1
+++ b/lib/bundler/man/bundle-open.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-OPEN" "1" "February 2023" "" ""
+.TH "BUNDLE\-OPEN" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-open\fR \- Opens the source directory for a gem in your bundle
diff --git a/lib/bundler/man/bundle-outdated.1 b/lib/bundler/man/bundle-outdated.1
index 8455b71b45..129ff00f58 100644
--- a/lib/bundler/man/bundle-outdated.1
+++ b/lib/bundler/man/bundle-outdated.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-OUTDATED" "1" "February 2023" "" ""
+.TH "BUNDLE\-OUTDATED" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-outdated\fR \- List installed gems with newer versions available
@@ -83,9 +83,10 @@ If the regular output shows the following:
 .
 .nf
 
-* faker (newest 1\.6\.6, installed 1\.6\.5, requested ~> 1\.4) in groups "development, test"
-* hashie (newest 3\.4\.6, installed 1\.2\.0, requested = 1\.2\.0) in groups "default"
-* headless (newest 2\.3\.1, installed 2\.2\.3) in groups "test"
+* Gem       Current  Latest  Requested  Groups
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test
+* hashie    1\.2\.0    3\.4\.6   = 1\.2\.0    default
+* headless  2\.2\.3    2\.3\.1   = 2\.2\.3    test
 .
 .fi
 .
@@ -98,7 +99,8 @@ If the regular output shows the following:
 .
 .nf
 
-* hashie (newest 3\.4\.6, installed 1\.2\.0, requested = 1\.2\.0) in groups "default"
+* Gem       Current  Latest  Requested  Groups
+* hashie    1\.2\.0    3\.4\.6   = 1\.2\.0    default
 .
 .fi
 .
@@ -111,7 +113,8 @@ If the regular output shows the following:
 .
 .nf
 
-* headless (newest 2\.3\.1, installed 2\.2\.3) in groups "test"
+* Gem       Current  Latest  Requested  Groups
+* headless  2\.2\.3    2\.3\.1   = 2\.2\.3    test
 .
 .fi
 .
@@ -124,7 +127,8 @@ If the regular output shows the following:
 .
 .nf
 
-* faker (newest 1\.6\.6, installed 1\.6\.5, requested ~> 1\.4) in groups "development, test"
+* Gem       Current  Latest  Requested  Groups
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test
 .
 .fi
 .
@@ -137,8 +141,8 @@ Filter options can be combined\. \fB\-\-filter\-minor\fR and \fB\-\-filter\-patc
 .
 .nf
 
-* faker (newest 1\.6\.6, installed 1\.6\.5, requested ~> 1\.4) in groups "development, test"
-* headless (newest 2\.3\.1, installed 2\.2\.3) in groups "test"
+* Gem       Current  Latest  Requested  Groups
+* faker     1\.6\.5    1\.6\.6   ~> 1\.4     development, test
 .
 .fi
 .
diff --git a/lib/bundler/man/bundle-outdated.1.ronn b/lib/bundler/man/bundle-outdated.1.ronn
index 04096ffbb6..27bf21ab9d 100644
--- a/lib/bundler/man/bundle-outdated.1.ronn
+++ b/lib/bundler/man/bundle-outdated.1.ronn
@@ -78,25 +78,28 @@ in the output.
 
 If the regular output shows the following:
 
-    * faker (newest 1.6.6, installed 1.6.5, requested ~> 1.4) in groups "development, test"
-    * hashie (newest 3.4.6, installed 1.2.0, requested = 1.2.0) in groups "default"
-    * headless (newest 2.3.1, installed 2.2.3) in groups "test"
+    * Gem       Current  Latest  Requested  Groups
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test
+    * hashie    1.2.0    3.4.6   = 1.2.0    default
+    * headless  2.2.3    2.3.1   = 2.2.3    test
 
 `--filter-major` would only show:
 
-    * hashie (newest 3.4.6, installed 1.2.0, requested = 1.2.0) in groups "default"
+    * Gem       Current  Latest  Requested  Groups
+    * hashie    1.2.0    3.4.6   = 1.2.0    default
 
 `--filter-minor` would only show:
 
-    * headless (newest 2.3.1, installed 2.2.3) in groups "test"
+    * Gem       Current  Latest  Requested  Groups
+    * headless  2.2.3    2.3.1   = 2.2.3    test
 
 `--filter-patch` would only show:
 
-    * faker (newest 1.6.6, installed 1.6.5, requested ~> 1.4) in groups "development, test"
+    * Gem       Current  Latest  Requested  Groups
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test
 
 Filter options can be combined. `--filter-minor` and `--filter-patch` would show:
 
-    * faker (newest 1.6.6, installed 1.6.5, requested ~> 1.4) in groups "development, test"
-    * headless (newest 2.3.1, installed 2.2.3) in groups "test"
-
+    * Gem       Current  Latest  Requested  Groups
+    * faker     1.6.5    1.6.6   ~> 1.4     development, test
 Combining all three `filter` options would be the same result as providing none of them.
diff --git a/lib/bundler/man/bundle-platform.1 b/lib/bundler/man/bundle-platform.1
index 2794878719..5021c46b4c 100644
--- a/lib/bundler/man/bundle-platform.1
+++ b/lib/bundler/man/bundle-platform.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-PLATFORM" "1" "February 2023" "" ""
+.TH "BUNDLE\-PLATFORM" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-platform\fR \- Displays platform compatibility information
diff --git a/lib/bundler/man/bundle-plugin.1 b/lib/bundler/man/bundle-plugin.1
index 39d3dfa04e..ec30e1d0fd 100644
--- a/lib/bundler/man/bundle-plugin.1
+++ b/lib/bundler/man/bundle-plugin.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-PLUGIN" "1" "February 2023" "" ""
+.TH "BUNDLE\-PLUGIN" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-plugin\fR \- Manage Bundler plugins
diff --git a/lib/bundler/man/bundle-pristine.1 b/lib/bundler/man/bundle-pristine.1
index f42c7ce156..af81c48d2b 100644
--- a/lib/bundler/man/bundle-pristine.1
+++ b/lib/bundler/man/bundle-pristine.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-PRISTINE" "1" "February 2023" "" ""
+.TH "BUNDLE\-PRISTINE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-pristine\fR \- Restores installed gems to their pristine condition
diff --git a/lib/bundler/man/bundle-remove.1 b/lib/bundler/man/bundle-remove.1
index b18d80554d..d86cf134bd 100644
--- a/lib/bundler/man/bundle-remove.1
+++ b/lib/bundler/man/bundle-remove.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-REMOVE" "1" "February 2023" "" ""
+.TH "BUNDLE\-REMOVE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-remove\fR \- Removes gems from the Gemfile
diff --git a/lib/bundler/man/bundle-show.1 b/lib/bundler/man/bundle-show.1
index efd9ccb0e0..aa91176bf2 100644
--- a/lib/bundler/man/bundle-show.1
+++ b/lib/bundler/man/bundle-show.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-SHOW" "1" "February 2023" "" ""
+.TH "BUNDLE\-SHOW" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-show\fR \- Shows all the gems in your bundle, or the path to a gem
diff --git a/lib/bundler/man/bundle-update.1 b/lib/bundler/man/bundle-update.1
index c67c44ff86..e4e10ad23b 100644
--- a/lib/bundler/man/bundle-update.1
+++ b/lib/bundler/man/bundle-update.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-UPDATE" "1" "February 2023" "" ""
+.TH "BUNDLE\-UPDATE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-update\fR \- Update your gems to the latest available versions
diff --git a/lib/bundler/man/bundle-version.1 b/lib/bundler/man/bundle-version.1
index 9a3820f3e6..5e3ed44600 100644
--- a/lib/bundler/man/bundle-version.1
+++ b/lib/bundler/man/bundle-version.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-VERSION" "1" "February 2023" "" ""
+.TH "BUNDLE\-VERSION" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-version\fR \- Prints Bundler version information
diff --git a/lib/bundler/man/bundle-viz.1 b/lib/bundler/man/bundle-viz.1
index 3a07010309..d5330ec754 100644
--- a/lib/bundler/man/bundle-viz.1
+++ b/lib/bundler/man/bundle-viz.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-VIZ" "1" "February 2023" "" ""
+.TH "BUNDLE\-VIZ" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\-viz\fR \- Generates a visual dependency graph for your Gemfile
diff --git a/lib/bundler/man/bundle.1 b/lib/bundler/man/bundle.1
index 873ba566b1..99c65a72b5 100644
--- a/lib/bundler/man/bundle.1
+++ b/lib/bundler/man/bundle.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE" "1" "February 2023" "" ""
+.TH "BUNDLE" "1" "August 2023" "" ""
 .
 .SH "NAME"
 \fBbundle\fR \- Ruby Dependency Management
diff --git a/lib/bundler/man/gemfile.5 b/lib/bundler/man/gemfile.5
index a9124d26ea..352fa0f545 100644
--- a/lib/bundler/man/gemfile.5
+++ b/lib/bundler/man/gemfile.5
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "GEMFILE" "5" "February 2023" "" ""
+.TH "GEMFILE" "5" "August 2023" "" ""
 .
 .SH "NAME"
 \fBGemfile\fR \- A format for describing gem dependencies for Ruby programs
@@ -85,6 +85,19 @@ ruby "3\.1\.2"
 .
 .IP "" 0
 .
+.P
+If you wish to derive your Ruby version from a version file (ie \.ruby\-version), you can use the \fBfile\fR option instead\.
+.
+.IP "" 4
+.
+.nf
+
+ruby file: "\.ruby\-version"
+.
+.fi
+.
+.IP "" 0
+.
 .SS "ENGINE"
 Each application \fImay\fR specify a Ruby engine\. If an engine is specified, an engine version \fImust\fR also be specified\.
 .
@@ -702,7 +715,7 @@ If you wish to use Bundler to help install dependencies for a gem while it is be
 The \fBgemspec\fR method adds any runtime dependencies as gem requirements in the default group\. It also adds development dependencies as gem requirements in the \fBdevelopment\fR group\. Finally, it adds a gem requirement on your project (\fBpath: \'\.\'\fR)\. In conjunction with \fBBundler\.setup\fR, this allows you to require project files in your test code as you would if the project were installed as a gem; you need not manipulate the load path manually or require project files via relative paths\.
 .
 .P
-The \fBgemspec\fR method supports optional \fB:path\fR, \fB:glob\fR, \fB:name\fR, and \fB:development_group\fR options, which control where bundler looks for the \fB\.gemspec\fR, the glob it uses to look for the gemspec (defaults to: "{,\fI,\fR/*}\.gemspec"), what named \fB\.gemspec\fR it uses (if more than one is present), and which group development dependencies are included in\.
+The \fBgemspec\fR method supports optional \fB:path\fR, \fB:glob\fR, \fB:name\fR, and \fB:development_group\fR options, which control where bundler looks for the \fB\.gemspec\fR, the glob it uses to look for the gemspec (defaults to: \fB{,*,*/*}\.gemspec\fR), what named \fB\.gemspec\fR it uses (if more than one is present), and which group development dependencies are included in\.
 .
 .P
 When a \fBgemspec\fR dependency encounters version conflicts during resolution, the local version under development will always be selected \-\- even if there are remote versions that better match other requirements for the \fBgemspec\fR gem\.
diff --git a/lib/bundler/man/gemfile.5.ronn b/lib/bundler/man/gemfile.5.ronn
index a3affc30cc..6749c33f59 100644
--- a/lib/bundler/man/gemfile.5.ronn
+++ b/lib/bundler/man/gemfile.5.ronn
@@ -69,6 +69,11 @@ should be the Ruby version that the engine is compatible with.
 
     ruby "3.1.2"
 
+If you wish to derive your Ruby version from a version file (ie .ruby-version),
+you can use the `file` option instead.
+
+    ruby file: ".ruby-version"
+
 ### ENGINE
 
 Each application _may_ specify a Ruby engine. If an engine is specified, an
@@ -514,7 +519,7 @@ paths.
 
 The `gemspec` method supports optional `:path`, `:glob`, `:name`, and `:development_group`
 options, which control where bundler looks for the `.gemspec`, the glob it uses to look
-for the gemspec (defaults to: "{,*,*/*}.gemspec"), what named `.gemspec` it uses
+for the gemspec (defaults to: `{,*,*/*}.gemspec`), what named `.gemspec` it uses
 (if more than one is present), and which group development dependencies are included in.
 
 When a `gemspec` dependency encounters version conflicts during resolution, the
diff --git a/lib/bundler/plugin/index.rb b/lib/bundler/plugin/index.rb
index 6fbd036f38..a2d5eaa38a 100644
--- a/lib/bundler/plugin/index.rb
+++ b/lib/bundler/plugin/index.rb
@@ -146,7 +146,7 @@ module Bundler
       # @param [Boolean] is the index file global index
       def load_index(index_file, global = false)
         SharedHelpers.filesystem_access(index_file, :read) do |index_f|
-          valid_file = index_f && index_f.exist? && !index_f.size.zero?
+          valid_file = index_f&.exist? && !index_f.size.zero?
           break unless valid_file
 
           data = index_f.read
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index c8cc88a3ee..2ad35bc931 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -160,7 +160,7 @@ module Bundler
       constraint_string = constraint.constraint_string
       requirements = constraint_string.split(" OR ").map {|req| Gem::Requirement.new(req.split(",")) }
 
-      if name == "bundler"
+      if name == "bundler" && bundler_pinned_to_current_version?
         custom_explanation = "the current Bundler version (#{Bundler::VERSION}) does not satisfy #{constraint}"
         extended_explanation = bundler_not_found_message(requirements)
       else
@@ -230,6 +230,12 @@ module Bundler
     def all_versions_for(package)
       name = package.name
       results = (@base[name] + filter_prereleases(@all_specs[name], package)).uniq {|spec| [spec.version.hash, spec.platform] }
+
+      if name == "bundler" && !bundler_pinned_to_current_version?
+        bundler_spec = Gem.loaded_specs["bundler"]
+        results << bundler_spec if bundler_spec
+      end
+
       locked_requirement = base_requirements[name]
       results = filter_matching_specs(results, locked_requirement) if locked_requirement
 
@@ -254,6 +260,14 @@ module Bundler
       @source_requirements[name] || @source_requirements[:default]
     end
 
+    def default_bundler_source
+      @source_requirements[:default_bundler]
+    end
+
+    def bundler_pinned_to_current_version?
+      !default_bundler_source.nil?
+    end
+
     def name_for_explicit_dependency_source
       Bundler.default_gemfile.basename.to_s
     rescue StandardError
@@ -398,7 +412,7 @@ module Bundler
     end
 
     def bundler_not_found_message(conflict_dependencies)
-      candidate_specs = filter_matching_specs(source_for(:default_bundler).specs.search("bundler"), conflict_dependencies)
+      candidate_specs = filter_matching_specs(default_bundler_source.specs.search("bundler"), conflict_dependencies)
 
       if candidate_specs.any?
         target_version = candidate_specs.last.version
diff --git a/lib/bundler/resolver/base.rb b/lib/bundler/resolver/base.rb
index c6afa82056..e5c3763c3f 100644
--- a/lib/bundler/resolver/base.rb
+++ b/lib/bundler/resolver/base.rb
@@ -35,9 +35,7 @@ module Bundler
       end
 
       def delete(specs)
-        specs.each do |spec|
-          @base.delete(spec)
-        end
+        @base.delete(specs)
       end
 
       def get_package(name)
diff --git a/lib/bundler/ruby_dsl.rb b/lib/bundler/ruby_dsl.rb
index 3b3a0583a5..d054969e8d 100644
--- a/lib/bundler/ruby_dsl.rb
+++ b/lib/bundler/ruby_dsl.rb
@@ -5,9 +5,15 @@ module Bundler
     def ruby(*ruby_version)
       options = ruby_version.last.is_a?(Hash) ? ruby_version.pop : {}
       ruby_version.flatten!
+
       raise GemfileError, "Please define :engine_version" if options[:engine] && options[:engine_version].nil?
       raise GemfileError, "Please define :engine" if options[:engine_version] && options[:engine].nil?
 
+      if options[:file]
+        raise GemfileError, "Cannot specify version when using the file option" if ruby_version.any?
+        ruby_version << Bundler.read_file(options[:file]).strip
+      end
+
       if options[:engine] == "ruby" && options[:engine_version] &&
          ruby_version != Array(options[:engine_version])
         raise GemfileEvalError, "ruby_version must match the :engine_version for MRI"
diff --git a/lib/bundler/ruby_version.rb b/lib/bundler/ruby_version.rb
index 9161c6afde..b5396abb6e 100644
--- a/lib/bundler/ruby_version.rb
+++ b/lib/bundler/ruby_version.rb
@@ -28,8 +28,8 @@ module Bundler
       end
 
       @gem_version        = Gem::Requirement.create(@versions.first).requirements.first.last
-      @input_engine       = engine && engine.to_s
-      @engine             = engine && engine.to_s || "ruby"
+      @input_engine       = engine&.to_s
+      @engine             = engine&.to_s || "ruby"
       @engine_versions    = (engine_version && Array(engine_version)) || @versions
       @engine_gem_version = Gem::Requirement.create(@engine_versions.first).requirements.first.last
       @patchlevel         = patchlevel || (@gem_version.prerelease? ? "-1" : nil)
@@ -107,7 +107,7 @@ module Bundler
       ruby_engine_version = RUBY_ENGINE == "ruby" ? ruby_version : RUBY_ENGINE_VERSION.dup
       patchlevel = RUBY_PATCHLEVEL.to_s
 
-      @ruby_version ||= RubyVersion.new(ruby_version, patchlevel, ruby_engine, ruby_engine_version)
+      @system ||= RubyVersion.new(ruby_version, patchlevel, ruby_engine, ruby_engine_version)
     end
 
     private
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
index 0252e1a81a..8981612706 100644
--- a/lib/bundler/rubygems_ext.rb
+++ b/lib/bundler/rubygems_ext.rb
@@ -66,7 +66,9 @@ module Gem
 
     alias_method :rg_extension_dir, :extension_dir
     def extension_dir
-      @bundler_extension_dir ||= if source.respond_to?(:extension_dir_name)
+      # following instance variable is already used in original method
+      # and that is the reason to prefix it with bundler_ and add rubocop exception
+      @bundler_extension_dir ||= if source.respond_to?(:extension_dir_name) # rubocop:disable Naming/MemoizedInstanceVariableName
         unique_extension_dir = [source.extension_dir_name, File.basename(full_gem_path)].uniq.join("-")
         File.expand_path(File.join(extensions_dir, unique_extension_dir))
       else
@@ -203,9 +205,9 @@ module Gem
         protected
 
         def _requirements_sorted?
-          return @_are_requirements_sorted if defined?(@_are_requirements_sorted)
+          return @_requirements_sorted if defined?(@_requirements_sorted)
           strings = as_list
-          @_are_requirements_sorted = strings == strings.sort
+          @_requirements_sorted = strings == strings.sort
         end
 
         def _with_sorted_requirements
diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index 72016e848b..d8b7886af7 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -247,7 +247,7 @@ module Bundler
       kernel = (class << ::Kernel; self; end)
       [kernel, ::Kernel].each do |kernel_class|
         redefine_method(kernel_class, :gem) do |dep, *reqs|
-          if executables && executables.include?(File.basename(caller.first.split(":").first))
+          if executables&.include?(File.basename(caller.first.split(":").first))
             break
           end
 
diff --git a/lib/bundler/runtime.rb b/lib/bundler/runtime.rb
index bd38353d3c..95cf78dd41 100644
--- a/lib/bundler/runtime.rb
+++ b/lib/bundler/runtime.rb
@@ -94,7 +94,7 @@ module Bundler
     definition_method :requires
 
     def lock(opts = {})
-      return if @definition.nothing_changed? && !@definition.unlocking?
+      return if @definition.no_resolve_needed?
       @definition.lock(Bundler.default_lockfile, opts[:preserve_unknown_sections])
     end
 
diff --git a/lib/bundler/safe_marshal.rb b/lib/bundler/safe_marshal.rb
new file mode 100644
index 0000000000..50aa0f60a6
--- /dev/null
+++ b/lib/bundler/safe_marshal.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Bundler
+  module SafeMarshal
+    ALLOWED_CLASSES = [
+      Array,
+      FalseClass,
+      Gem::Specification,
+      Gem::Version,
+      Hash,
+      String,
+      Symbol,
+      Time,
+      TrueClass,
+    ].freeze
+
+    ERROR = "Unexpected class %s present in marshaled data. Only %s are allowed."
+
+    PROC = proc do |object|
+      object.tap do
+        unless ALLOWED_CLASSES.include?(object.class)
+          raise TypeError, format(ERROR, object.class, ALLOWED_CLASSES.join(", "))
+        end
+      end
+    end
+
+    def self.proc
+      PROC
+    end
+  end
+end
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 1139eab503..0af2236a45 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -43,7 +43,6 @@ module Bundler
       setup_makes_kernel_gem_public
       silence_deprecations
       silence_root_warning
-      suppress_install_using_messages
       update_requires_all_flag
     ].freeze
 
@@ -219,7 +218,6 @@ module Bundler
     def path
       configs.each do |_level, settings|
         path = value_for("path", settings)
-        path = "vendor/bundle" if value_for("deployment", settings) && path.nil?
         path_system = value_for("path.system", settings)
         disabled_shared_gems = value_for("disable_shared_gems", settings)
         next if path.nil? && path_system.nil? && disabled_shared_gems.nil?
@@ -227,7 +225,9 @@ module Bundler
         return Path.new(path, system_path)
       end
 
-      Path.new(nil, false)
+      path = "vendor/bundle" if self[:deployment]
+
+      Path.new(path, false)
     end
 
     Path = Struct.new(:explicit_path, :system_path) do
diff --git a/lib/bundler/source.rb b/lib/bundler/source.rb
index 69804a2e63..f7f5ea7865 100644
--- a/lib/bundler/source.rb
+++ b/lib/bundler/source.rb
@@ -100,7 +100,7 @@ module Bundler
     end
 
     def print_using_message(message)
-      if !message.include?("(was ") && Bundler.feature_flag.suppress_install_using_messages?
+      if !message.include?("(was ")
         Bundler.ui.debug message
       else
         Bundler.ui.info message
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index 42897813b4..adbce5fce4 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -46,6 +46,14 @@ module Bundler
         out << "  specs:\n"
       end
 
+      def to_gemfile
+        specifiers = %w[ref branch tag submodules glob].map do |opt|
+          "#{opt}: #{options[opt]}" if options[opt]
+        end
+
+        uri_with_specifiers(specifiers)
+      end
+
       def hash
         [self.class, uri, ref, branch, name, version, glob, submodules].hash
       end
@@ -59,28 +67,32 @@ module Bundler
 
       alias_method :==, :eql?
 
+      def include?(other)
+        other.is_a?(Git) && uri == other.uri &&
+          name == other.name &&
+          glob == other.glob &&
+          submodules == other.submodules
+      end
+
       def to_s
         begin
-          at = if local?
-            path
-          elsif user_ref = options["ref"]
-            if /\A[a-z0-9]{4,}\z/i.match?(ref)
-              shortref_for_display(user_ref)
-            else
-              user_ref
-            end
-          elsif ref
-            ref
-          else
-            current_branch
-          end
+          at = humanized_ref || current_branch
 
           rev = "at #{at}@#{shortref_for_display(revision)}"
         rescue GitError
           ""
         end
 
-        specifiers = [rev, glob_for_display].compact
+        uri_with_specifiers([rev, glob_for_display])
+      end
+
+      def identifier
+        uri_with_specifiers([humanized_ref, cached_revision, glob_for_display])
+      end
+
+      def uri_with_specifiers(specifiers)
+        specifiers.compact!
+
         suffix =
           if specifiers.any?
             " (#{specifiers.join(", ")})"
@@ -243,6 +255,20 @@ module Bundler
 
       private
 
+      def humanized_ref
+        if local?
+          path
+        elsif user_ref = options["ref"]
+          if /\A[a-z0-9]{4,}\z/i.match?(ref)
+            shortref_for_display(user_ref)
+          else
+            user_ref
+          end
+        elsif ref
+          ref
+        end
+      end
+
       def serialize_gemspecs_in(destination)
         destination = destination.expand_path(Bundler.root) if destination.relative?
         Dir["#{destination}/#{@glob}"].each do |spec_path|
diff --git a/lib/bundler/source/git/git_proxy.rb b/lib/bundler/source/git/git_proxy.rb
index 926c9b8ead..fdb738e52e 100644
--- a/lib/bundler/source/git/git_proxy.rb
+++ b/lib/bundler/source/git/git_proxy.rb
@@ -67,8 +67,8 @@ module Bundler
         end
 
         def current_branch
-          @current_branch ||= allowed_with_path do
-            git("rev-parse", "--abbrev-ref", "HEAD", :dir => path).strip
+          @current_branch ||= with_path do
+            git_local("rev-parse", "--abbrev-ref", "HEAD", :dir => path).strip
           end
         end
 
@@ -84,7 +84,7 @@ module Bundler
         end
 
         def full_version
-          @full_version ||= git("--version").sub(/git version\s*/, "").strip
+          @full_version ||= git_local("--version").sub(/git version\s*/, "").strip
         end
 
         def checkout
@@ -162,7 +162,8 @@ module Bundler
             _, err, status = capture(command, nil)
             return extra_ref if status.success?
 
-            if err.include?("Could not find remote branch")
+            if err.include?("Could not find remote branch") || # git up to 2.49
+               err.include?("Remote branch #{branch_option} not found") # git 2.49 or higher
               raise MissingGitRevisionError.new(command_with_no_credentials, nil, explicit_ref, credential_filtered_uri)
             else
               raise GitCommandError.new(command_with_no_credentials, path, err)
@@ -231,7 +232,7 @@ module Bundler
         end
 
         def not_pinned?
-          branch || tag || ref.nil?
+          branch_option || ref.nil?
         end
 
         def pinned_to_full_sha?
@@ -253,15 +254,15 @@ module Bundler
         end
 
         def git(*command, dir: nil)
-          command_with_no_credentials = check_allowed(command)
-
-          out, err, status = capture(command, dir)
-
-          raise GitCommandError.new(command_with_no_credentials, dir || SharedHelpers.pwd, err) unless status.success?
-
-          Bundler.ui.warn err unless err.empty?
+          run_command(*command, :dir => dir) do |unredacted_command|
+            check_allowed(unredacted_command)
+          end
+        end
 
-          out
+        def git_local(*command, dir: nil)
+          run_command(*command, :dir => dir) do |unredacted_command|
+            redact_and_check_presence(unredacted_command)
+          end
         end
 
         def has_revision_cached?
@@ -330,12 +331,30 @@ module Bundler
         end
 
         def check_allowed(command)
-          require "shellwords"
-          command_with_no_credentials = URICredentialsFilter.credential_filtered_string("git #{command.shelljoin}", uri)
+          command_with_no_credentials = redact_and_check_presence(command)
           raise GitNotAllowedError.new(command_with_no_credentials) unless allow?
           command_with_no_credentials
         end
 
+        def redact_and_check_presence(command)
+          raise GitNotInstalledError.new unless Bundler.git_present?
+
+          require "shellwords"
+          URICredentialsFilter.credential_filtered_string("git #{command.shelljoin}", uri)
+        end
+
+        def run_command(*command, dir: nil)
+          command_with_no_credentials = yield(command)
+
+          out, err, status = capture(command, dir)
+
+          raise GitCommandError.new(command_with_no_credentials, dir || SharedHelpers.pwd, err) unless status.success?
+
+          Bundler.ui.warn err unless err.empty?
+
+          out
+        end
+
         def capture(cmd, dir, ignore_err: false)
           SharedHelpers.with_clean_git_env do
             require "open3"
@@ -371,7 +390,7 @@ module Bundler
           # anyways.
           return args if @revision
 
-          args += ["--branch", branch || tag] if branch || tag
+          args += ["--branch", branch_option] if branch_option
           args
         end
 
@@ -387,6 +406,10 @@ module Bundler
           extra_args
         end
 
+        def branch_option
+          branch || tag
+        end
+
         def full_clone?
           depth.nil?
         end
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 8d0c78bd61..af57acbbc2 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -7,12 +7,10 @@ module Bundler
     class Rubygems < Source
       autoload :Remote, File.expand_path("rubygems/remote", __dir__)
 
-      # Use the API when installing less than X gems
-      API_REQUEST_LIMIT = 500
       # Ask for X gems per API request
       API_REQUEST_SIZE = 50
 
-      attr_reader :remotes, :caches
+      attr_reader :remotes
 
       def initialize(options = {})
         @options = options
@@ -21,11 +19,14 @@ module Bundler
         @allow_remote = false
         @allow_cached = false
         @allow_local = options["allow_local"] || false
-        @caches = [cache_path, *Bundler.rubygems.gem_cache]
 
         Array(options["remotes"]).reverse_each {|r| add_remote(r) }
       end
 
+      def caches
+        @caches ||= [cache_path, *Bundler.rubygems.gem_cache]
+      end
+
       def local_only!
         @specs = nil
         @allow_local = true
@@ -122,6 +123,7 @@ module Bundler
         end
       end
       alias_method :name, :identifier
+      alias_method :to_gemfile, :identifier
 
       def specs
         @specs ||= begin
@@ -326,9 +328,9 @@ module Bundler
 
       def cached_path(spec)
         global_cache_path = download_cache_path(spec)
-        @caches << global_cache_path if global_cache_path
+        caches << global_cache_path if global_cache_path
 
-        possibilities = @caches.map {|p| package_path(p, spec) }
+        possibilities = caches.map {|p| package_path(p, spec) }
         possibilities.find {|p| File.exist?(p) }
       end
 
@@ -380,7 +382,6 @@ module Bundler
           idx = @allow_local ? installed_specs.dup : Index.new
 
           Dir["#{cache_path}/*.gem"].each do |gemfile|
-            next if /^bundler\-[\d\.]+?\.gem/.match?(gemfile)
             s ||= Bundler.rubygems.spec_from_gem(gemfile)
             s.source = self
             idx << s
@@ -401,12 +402,11 @@ module Bundler
           # gather lists from non-api sites
           fetch_names(index_fetchers, nil, idx, false)
 
-          # because ensuring we have all the gems we need involves downloading
-          # the gemspecs of those gems, if the non-api sites contain more than
-          # about 500 gems, we treat all sites as non-api for speed.
-          allow_api = idx.size < API_REQUEST_LIMIT && dependency_names.size < API_REQUEST_LIMIT
-          Bundler.ui.debug "Need to query more than #{API_REQUEST_LIMIT} gems." \
-            " Downloading full index instead..." unless allow_api
+          # legacy multi-remote sources need special logic to figure out
+          # dependency names and that logic can be very costly if one remote
+          # uses the dependency API but others don't. So use full indexes
+          # consistently in that particular case.
+          allow_api = !multiple_remotes?
 
           fetch_names(api_fetchers, allow_api && dependency_names, idx, false)
         end
diff --git a/lib/bundler/source_list.rb b/lib/bundler/source_list.rb
index 63798db941..4419695b7f 100644
--- a/lib/bundler/source_list.rb
+++ b/lib/bundler/source_list.rb
@@ -101,10 +101,6 @@ module Bundler
       source_list_for(source).find {|s| equivalent_source?(source, s) }
     end
 
-    def get_with_fallback(source)
-      get(source) || default_source
-    end
-
     def lock_sources
       lock_other_sources + lock_rubygems_sources
     end
diff --git a/lib/bundler/spec_set.rb b/lib/bundler/spec_set.rb
index cf63c16a70..21630e3a3e 100644
--- a/lib/bundler/spec_set.rb
+++ b/lib/bundler/spec_set.rb
@@ -63,8 +63,8 @@ module Bundler
       @sorted = nil
     end
 
-    def delete(spec)
-      @specs.delete(spec)
+    def delete(specs)
+      specs.each {|spec| @specs.delete(spec) }
       @lookup = nil
       @sorted = nil
     end
diff --git a/lib/bundler/templates/newgem/bin/console.tt b/lib/bundler/templates/newgem/bin/console.tt
index 08dfaaef69..c91ee65f93 100644
--- a/lib/bundler/templates/newgem/bin/console.tt
+++ b/lib/bundler/templates/newgem/bin/console.tt
@@ -7,9 +7,5 @@ require "<%= config[:namespaced_path] %>"
 # You can add fixtures and/or initialization code here to make experimenting
 # with your gem easier. You can also use a different console, if you like.
 
-# (If you use this, don't forget to add pry to your Gemfile!)
-# require "pry"
-# Pry.start
-
 require "irb"
 IRB.start(__FILE__)
diff --git a/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt b/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt
index 4b6e9587f7..c64385486e 100644
--- a/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt
+++ b/lib/bundler/templates/newgem/ext/newgem/Cargo.toml.tt
@@ -12,4 +12,4 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
-magnus = { version = "0.4" }
+magnus = { version = "0.6" }
diff --git a/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt b/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt
index e918063ddf..0a0c5a3d09 100644
--- a/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt
+++ b/lib/bundler/templates/newgem/ext/newgem/extconf-c.rb.tt
@@ -2,4 +2,9 @@
 
 require "mkmf"
 
+# Makes all symbols private by default to avoid unintended conflict
+# with other gems. To explicitly export symbols you can use RUBY_FUNC_EXPORTED
+# selectively, or entirely remove this flag.
+append_cflags("-fvisibility=hidden")
+
 create_makefile(<%= config[:makefile_path].inspect %>)
diff --git a/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt b/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt
index 8177c4d202..bcd5148569 100644
--- a/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt
+++ b/lib/bundler/templates/newgem/ext/newgem/newgem.c.tt
@@ -2,7 +2,7 @@
 
 VALUE rb_m<%= config[:constant_array].join %>;
 
-void
+RUBY_FUNC_EXPORTED void
 Init_<%= config[:underscored_name] %>(void)
 {
   rb_m<%= config[:constant_array].join %> = rb_define_module(<%= config[:constant_name].inspect %>);
diff --git a/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt b/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt
index b311283997..ba234529a3 100644
--- a/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt
+++ b/lib/bundler/templates/newgem/ext/newgem/src/lib.rs.tt
@@ -1,12 +1,12 @@
-use magnus::{define_module, function, prelude::*, Error};
+use magnus::{function, prelude::*, Error, Ruby};
 
 fn hello(subject: String) -> String {
-    format!("Hello from Rust, {}!", subject)
+    format!("Hello from Rust, {subject}!")
 }
 
 #[magnus::init]
-fn init() -> Result<(), Error> {
-    let module = <%= config[:constant_array].map {|c| "define_module(#{c.dump})?"}.join(".") %>;
+fn init(ruby: &Ruby) -> Result<(), Error> {
+    let module = ruby.<%= config[:constant_array].map {|c| "define_module(#{c.dump})?"}.join(".") %>;
     module.define_singleton_method("hello", function!(hello, 1))?;
     Ok(())
 }
diff --git a/lib/bundler/templates/newgem/newgem.gemspec.tt b/lib/bundler/templates/newgem/newgem.gemspec.tt
index da81f046d4..bb76680379 100644
--- a/lib/bundler/templates/newgem/newgem.gemspec.tt
+++ b/lib/bundler/templates/newgem/newgem.gemspec.tt
@@ -29,7 +29,8 @@ Gem::Specification.new do |spec|
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files = Dir.chdir(__dir__) do
     `git ls-files -z`.split("\x0").reject do |f|
-      (File.expand_path(f) == __FILE__) || f.start_with?(*%w[bin/ test/ spec/ features/ .git .circleci appveyor])
+      (File.expand_path(f) == __FILE__) ||
+        f.start_with?(*%w[bin/ test/ spec/ features/ .git .circleci appveyor Gemfile])
     end
   end
   spec.bindir = "exe"
diff --git a/lib/bundler/ui/rg_proxy.rb b/lib/bundler/ui/rg_proxy.rb
index ef6def225b..b17ca65f53 100644
--- a/lib/bundler/ui/rg_proxy.rb
+++ b/lib/bundler/ui/rg_proxy.rb
@@ -12,7 +12,7 @@ module Bundler
       end
 
       def say(message)
-        @ui && @ui.debug(message)
+        @ui&.debug(message)
       end
     end
   end
diff --git a/lib/bundler/vendor/fileutils/lib/fileutils.rb b/lib/bundler/vendor/fileutils/lib/fileutils.rb
index 04ac537a28..211311c069 100644
--- a/lib/bundler/vendor/fileutils/lib/fileutils.rb
+++ b/lib/bundler/vendor/fileutils/lib/fileutils.rb
@@ -3,7 +3,7 @@
 begin
   require 'rbconfig'
 rescue LoadError
-  # for make mjit-headers
+  # for make rjit-headers
 end
 
 # Namespace for file utility methods for copying, moving, removing, etc.
diff --git a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb
index 2cb8412cf3..4caf6b355b 100644
--- a/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb
+++ b/lib/bundler/vendor/pub_grub/lib/pub_grub/version_solver.rb
@@ -162,7 +162,7 @@ module Bundler::PubGrub
     def resolve_conflict(incompatibility)
       logger.info { "conflict: #{incompatibility}" }
 
-      new_incompatibility = false
+      new_incompatibility = nil
 
       while !incompatibility.failure?
         most_recent_term = nil
@@ -204,7 +204,7 @@ module Bundler::PubGrub
           solution.backtrack(previous_level)
 
           if new_incompatibility
-            add_incompatibility(incompatibility)
+            add_incompatibility(new_incompatibility)
           end
 
           return incompatibility
@@ -219,9 +219,14 @@ module Bundler::PubGrub
           new_terms << difference.invert
         end
 
-        incompatibility = Incompatibility.new(new_terms, cause: Incompatibility::ConflictCause.new(incompatibility, most_recent_satisfier.cause))
+        new_incompatibility = Incompatibility.new(new_terms, cause: Incompatibility::ConflictCause.new(incompatibility, most_recent_satisfier.cause))
 
-        new_incompatibility = true
+        if incompatibility.to_s == new_incompatibility.to_s
+          logger.info { "!! failed to resolve conflicts, this shouldn't have happened" }
+          break
+        end
+
+        incompatibility = new_incompatibility
 
         partially = difference ? " partially" : ""
         logger.info { "! #{most_recent_term} is#{partially} satisfied by #{most_recent_satisfier.term}" }
diff --git a/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb b/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb
index 2f8d55353b..09c22c9906 100644
--- a/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb
+++ b/lib/bundler/vendor/uri/lib/uri/rfc2396_parser.rb
@@ -497,8 +497,8 @@ module Bundler::URI
       ret = {}
 
       # for Bundler::URI::split
-      ret[:ABS_URI] = Regexp.new('\A\s*' + pattern[:X_ABS_URI] + '\s*\z', Regexp::EXTENDED)
-      ret[:REL_URI] = Regexp.new('\A\s*' + pattern[:X_REL_URI] + '\s*\z', Regexp::EXTENDED)
+      ret[:ABS_URI] = Regexp.new('\A\s*+' + pattern[:X_ABS_URI] + '\s*\z', Regexp::EXTENDED)
+      ret[:REL_URI] = Regexp.new('\A\s*+' + pattern[:X_REL_URI] + '\s*\z', Regexp::EXTENDED)
 
       # for Bundler::URI::extract
       ret[:URI_REF]     = Regexp.new(pattern[:URI_REF])
diff --git a/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb b/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb
index d527072db4..a85511c146 100644
--- a/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb
+++ b/lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb
@@ -100,7 +100,7 @@ module Bundler::URI
         QUERY: /\A(?:%\h\h|[!$&-.0-;=@-Z_a-z~\/?])*\z/,
         FRAGMENT: /\A(?:%\h\h|[!$&-.0-;=@-Z_a-z~\/?])*\z/,
         OPAQUE: /\A(?:[^\/].*)?\z/,
-        PORT: /\A[\x09\x0a\x0c\x0d ]*\d*[\x09\x0a\x0c\x0d ]*\z/,
+        PORT: /\A[\x09\x0a\x0c\x0d ]*+\d*[\x09\x0a\x0c\x0d ]*\z/,
       }
     end
 
diff --git a/lib/bundler/vendor/uri/lib/uri/version.rb b/lib/bundler/vendor/uri/lib/uri/version.rb
index 500fdb3f99..84b08eee30 100644
--- a/lib/bundler/vendor/uri/lib/uri/version.rb
+++ b/lib/bundler/vendor/uri/lib/uri/version.rb
@@ -1,6 +1,6 @@
 module Bundler::URI
   # :stopdoc:
-  VERSION_CODE = '001201'.freeze
+  VERSION_CODE = '001202'.freeze
   VERSION = VERSION_CODE.scan(/../).collect{|n| n.to_i}.join('.').freeze
   # :startdoc:
 end
diff --git a/lib/bundler/version.rb b/lib/bundler/version.rb
index bc9f8d22cd..8ef7be935b 100644
--- a/lib/bundler/version.rb
+++ b/lib/bundler/version.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 
 module Bundler
-  VERSION = "2.4.10".freeze
+  VERSION = "2.4.19".freeze
 
   def self.bundler_major_version
     @bundler_major_version ||= VERSION.split(".").first.to_i
diff --git a/lib/cgi.rb b/lib/cgi.rb
index 4cd6b3bd8e..7dc3a64941 100644
--- a/lib/cgi.rb
+++ b/lib/cgi.rb
@@ -288,7 +288,7 @@
 #
 
 class CGI
-  VERSION = "0.3.6"
+  VERSION = "0.3.7"
 end
 
 require 'cgi/core'
diff --git a/lib/cgi/cookie.rb b/lib/cgi/cookie.rb
index 9498e2f9fa..1c4ef6a600 100644
--- a/lib/cgi/cookie.rb
+++ b/lib/cgi/cookie.rb
@@ -190,9 +190,10 @@ class CGI
         values ||= ""
         values = values.split('&').collect{|v| CGI.unescape(v,@@accept_charset) }
         if cookies.has_key?(name)
-          values = cookies[name].value + values
+          cookies[name].concat(values)
+        else
+          cookies[name] = Cookie.new(name, *values)
         end
-        cookies[name] = Cookie.new(name, *values)
       end
 
       cookies
diff --git a/lib/cgi/util.rb b/lib/cgi/util.rb
index 5a5c77ac97..ce77a0ccd5 100644
--- a/lib/cgi/util.rb
+++ b/lib/cgi/util.rb
@@ -178,7 +178,7 @@ module CGI::Util
   def escapeElement(string, *elements)
     elements = elements[0] if elements[0].kind_of?(Array)
     unless elements.empty?
-      string.gsub(/<\/?(?:#{elements.join("|")})(?!\w)(?:.|\n)*?>/i) do
+      string.gsub(/<\/?(?:#{elements.join("|")})\b[^<>]*+>?/im) do
         CGI.escapeHTML($&)
       end
     else
@@ -198,7 +198,7 @@ module CGI::Util
   def unescapeElement(string, *elements)
     elements = elements[0] if elements[0].kind_of?(Array)
     unless elements.empty?
-      string.gsub(/&lt;\/?(?:#{elements.join("|")})(?!\w)(?:.|\n)*?&gt;/i) do
+      string.gsub(/&lt;\/?(?:#{elements.join("|")})\b(?>[^&]+|&(?![gl]t;)\w+;)*(?:&gt;)?/im) do
         unescapeHTML($&)
       end
     else
diff --git a/lib/net/http.rb b/lib/net/http.rb
index 47e62d6e70..387df4b8f4 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #
 # = net/http.rb
 #
@@ -34,72 +34,70 @@ module Net   #:nodoc:
 
   # \Class \Net::HTTP provides a rich library that implements the client
   # in a client-server model that uses the \HTTP request-response protocol.
-  # For information about \HTTP, see
+  # For information about \HTTP, see:
   #
   # - {Hypertext Transfer Protocol}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol].
   # - {Technical overview}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Technical_overview].
   #
-  # Note: If you are performing only a few GET requests, consider using
-  # {OpenURI}[rdoc-ref:OpenURI];
-  # otherwise, read on.
-  #
-  # == Synopsis
-  #
-  # If you are already familiar with \HTTP, this synopsis may be helpful.
-  #
-  # {Session}[rdoc-ref:Net::HTTP@Sessions] with multiple requests for
-  # {HTTP methods}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_methods]:
-  #
-  #   Net::HTTP.start(hostname) do |http|
-  #     # Session started automatically before block execution.
-  #     http.get(path_or_uri, headers = {})
-  #     http.head(path_or_uri, headers = {})
-  #     http.post(path_or_uri, data, headers = {})  # Can also have a block.
-  #     http.put(path_or_uri, data, headers = {})
-  #     http.delete(path_or_uri, headers = {Depth: 'Infinity'})
-  #     http.options(path_or_uri, headers = {})
-  #     http.trace(path_or_uri, headers = {})
-  #     http.patch(path_or_uri, data, headers = {}) # Can also have a block.
-  #     # Session finished automatically at block exit.
-  #   end
-  #
-  # {Session}[rdoc-ref:Net::HTTP@Sessions] with multiple requests for
-  # {WebDAV methods}[https://en.wikipedia.org/wiki/WebDAV#Implementation]:
-  #
-  #   Net::HTTP.start(hostname) do |http|
-  #     # Session started automatically before block execution.
-  #     http.copy(path_or_uri, headers = {})
-  #     http.lock(path_or_uri, body, headers = {})
-  #     http.mkcol(path_or_uri, body = nil, headers = {})
-  #     http.move(path_or_uri, headers = {})
-  #     http.propfind(path_or_uri, body = nil, headers = {'Depth' => '0'})
-  #     http.proppatch(path_or_uri, body, headers = {})
-  #     http.unlock(path_or_uri, body, headers = {})
-  #     # Session finished automatically at block exit.
-  #   end
-  #
-  # Each of the following methods automatically starts and finishes
-  # a {session}[rdoc-ref:Net::HTTP@Sessions] that sends a single request:
-  #
-  #   # Return string response body.
-  #   Net::HTTP.get(hostname, path, port = 80)
-  #   Net::HTTP.get(uri, headers = {}, port = 80)
-  #
-  #   # Write string response body to $stdout.
-  #   Net::HTTP.get_print(hostname, path_or_uri, port = 80)
-  #   Net::HTTP.get_print(uri, headers = {}, port = 80)
-  #
-  #   # Return response as Net::HTTPResponse object.
-  #   Net::HTTP.get_response(hostname, path_or_uri, port = 80)
-  #   Net::HTTP.get_response(uri, headers = {}, port = 80)
-  #
-  #   Net::HTTP.post(uri, data, headers = {})
-  #   Net::HTTP.post_form(uri, params)
-  #
   # == About the Examples
   #
   # :include: doc/net-http/examples.rdoc
   #
+  # == Strategies
+  #
+  # - If you will make only a few GET requests,
+  #   consider using {OpenURI}[rdoc-ref:OpenURI].
+  # - If you will make only a few requests of all kinds,
+  #   consider using the various singleton convenience methods in this class.
+  #   Each of the following methods automatically starts and finishes
+  #   a {session}[rdoc-ref:Net::HTTP@Sessions] that sends a single request:
+  #
+  #     # Return string response body.
+  #     Net::HTTP.get(hostname, path)
+  #     Net::HTTP.get(uri)
+  #
+  #     # Write string response body to $stdout.
+  #     Net::HTTP.get_print(hostname, path)
+  #     Net::HTTP.get_print(uri)
+  #
+  #     # Return response as Net::HTTPResponse object.
+  #     Net::HTTP.get_response(hostname, path)
+  #     Net::HTTP.get_response(uri)
+  #     data = '{"title": "foo", "body": "bar", "userId": 1}'
+  #     Net::HTTP.post(uri, data)
+  #     params = {title: 'foo', body: 'bar', userId: 1}
+  #     Net::HTTP.post_form(uri, params)
+  #
+  # - If performance is important, consider using sessions, which lower request overhead.
+  #   This {session}[rdoc-ref:Net::HTTP@Sessions] has multiple requests for
+  #   {HTTP methods}[https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_methods]
+  #   and {WebDAV methods}[https://en.wikipedia.org/wiki/WebDAV#Implementation]:
+  #
+  #     Net::HTTP.start(hostname) do |http|
+  #       # Session started automatically before block execution.
+  #       http.get(path)
+  #       http.head(path)
+  #       body = 'Some text'
+  #       http.post(path, body)  # Can also have a block.
+  #       http.put(path, body)
+  #       http.delete(path)
+  #       http.options(path)
+  #       http.trace(path)
+  #       http.patch(path, body) # Can also have a block.
+  #       http.copy(path)
+  #       http.lock(path, body)
+  #       http.mkcol(path, body)
+  #       http.move(path)
+  #       http.propfind(path, body)
+  #       http.proppatch(path, body)
+  #       http.unlock(path, body)
+  #       # Session finished automatically at block exit.
+  #     end
+  #
+  # The methods cited above are convenience methods that, via their few arguments,
+  # allow minimal control over the requests.
+  # For greater control, consider using {request objects}[rdoc-ref:Net::HTTPRequest].
+  #
   # == URIs
   #
   # On the internet, a URI
@@ -175,7 +173,7 @@ module Net   #:nodoc:
   # {Request Fields}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Request_fields].
   # A host may also accept other custom fields.
   #
-  # == Sessions
+  # == \HTTP Sessions
   #
   # A _session_ is a connection between a server (host) and a client that:
   #
@@ -183,7 +181,7 @@ module Net   #:nodoc:
   # - May contain any number of requests.
   # - Is ended by instance method Net::HTTP#finish.
   #
-  # See example sessions at the {Synopsis}[rdoc-ref:Net::HTTP@Synopsis].
+  # See example sessions at {Strategies}[rdoc-ref:Net::HTTP@Strategies].
   #
   # === Session Using \Net::HTTP.start
   #
@@ -264,66 +262,55 @@ module Net   #:nodoc:
   #
   # == Following Redirection
   #
-  # Each Net::HTTPResponse object belongs to a class for its response code.
+  # Each returned response is an instance of a subclass of Net::HTTPResponse.
+  # See the {response class hierarchy}[rdoc-ref:Net::HTTPResponse@Response+Subclasses].
   #
-  # For example, all 2XX responses are instances of a Net::HTTPSuccess
-  # subclass, a 3XX response is an instance of a Net::HTTPRedirection
-  # subclass and a 200 response is an instance of the Net::HTTPOK class.  For
-  # details of response classes, see the section "HTTP Response Classes"
-  # below.
+  # In particular, class Net::HTTPRedirection is the parent
+  # of all redirection classes.
+  # This allows you to craft a case statement to handle redirections properly:
   #
-  # Using a case statement you can handle various types of responses properly:
-  #
-  #   def fetch(uri_str, limit = 10)
+  #   def fetch(uri, limit = 10)
   #     # You should choose a better exception.
-  #     raise ArgumentError, 'too many HTTP redirects' if limit == 0
-  #
-  #     response = Net::HTTP.get_response(URI(uri_str))
-  #
-  #     case response
-  #     when Net::HTTPSuccess then
-  #       response
-  #     when Net::HTTPRedirection then
-  #       location = response['location']
-  #       warn "redirected to #{location}"
+  #     raise ArgumentError, 'Too many HTTP redirects' if limit == 0
+  #
+  #     res = Net::HTTP.get_response(URI(uri))
+  #     case res
+  #     when Net::HTTPSuccess     # Any success class.
+  #       res
+  #     when Net::HTTPRedirection # Any redirection class.
+  #       location = res['Location']
+  #       warn "Redirected to #{location}"
   #       fetch(location, limit - 1)
-  #     else
-  #       response.value
+  #     else                      # Any other class.
+  #       res.value
   #     end
   #   end
   #
-  #   print fetch('http://www.ruby-lang.org')
+  #   fetch(uri)
   #
   # == Basic Authentication
   #
   # Basic authentication is performed according to
-  # [RFC2617](http://www.ietf.org/rfc/rfc2617.txt).
-  #
-  #   uri = URI('http://example.com/index.html?key=value')
+  # {RFC2617}[http://www.ietf.org/rfc/rfc2617.txt]:
   #
   #   req = Net::HTTP::Get.new(uri)
-  #   req.basic_auth 'user', 'pass'
-  #
-  #   res = Net::HTTP.start(uri.hostname, uri.port) {|http|
+  #   req.basic_auth('user', 'pass')
+  #   res = Net::HTTP.start(hostname) do |http|
   #     http.request(req)
-  #   }
-  #   puts res.body
+  #   end
   #
   # == Streaming Response Bodies
   #
-  # By default Net::HTTP reads an entire response into memory.  If you are
+  # By default \Net::HTTP reads an entire response into memory.  If you are
   # handling large files or wish to implement a progress bar you can instead
   # stream the body directly to an IO.
   #
-  #   uri = URI('http://example.com/large_file')
-  #
-  #   Net::HTTP.start(uri.host, uri.port) do |http|
-  #     request = Net::HTTP::Get.new uri
-  #
-  #     http.request request do |response|
-  #       open 'large_file', 'w' do |io|
-  #         response.read_body do |chunk|
-  #           io.write chunk
+  #   Net::HTTP.start(hostname) do |http|
+  #     req = Net::HTTP::Get.new(uri)
+  #     http.request(req) do |res|
+  #       open('t.tmp', 'w') do |f|
+  #         res.read_body do |chunk|
+  #           f.write chunk
   #         end
   #       end
   #     end
@@ -331,56 +318,411 @@ module Net   #:nodoc:
   #
   # == HTTPS
   #
-  # HTTPS is enabled for an HTTP connection by Net::HTTP#use_ssl=.
-  #
-  #   uri = URI('https://secure.example.com/some_path?query=string')
+  # HTTPS is enabled for an \HTTP connection by Net::HTTP#use_ssl=:
   #
-  #   Net::HTTP.start(uri.host, uri.port, :use_ssl => true) do |http|
-  #     request = Net::HTTP::Get.new uri
-  #     response = http.request request # Net::HTTPResponse object
+  #   Net::HTTP.start(hostname, :use_ssl => true) do |http|
+  #     req = Net::HTTP::Get.new(uri)
+  #     res = http.request(req)
   #   end
   #
-  # Or if you simply want to make a GET request, you may pass in an URI
-  # object that has an HTTPS URL. Net::HTTP automatically turns on TLS
-  # verification if the URI object has a 'https' URI scheme.
+  # Or if you simply want to make a GET request, you may pass in a URI
+  # object that has an \HTTPS URL. \Net::HTTP automatically turns on TLS
+  # verification if the URI object has a 'https' URI scheme:
+  #
+  #   uri # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
+  #   Net::HTTP.get(uri)
+  #
+  # == Proxy Server
+  #
+  # An \HTTP object can have
+  # a {proxy server}[https://en.wikipedia.org/wiki/Proxy_server].
   #
-  #   uri = URI('https://example.com/')
-  #   Net::HTTP.get(uri) # => String
+  # You can create an \HTTP object with a proxy server
+  # using method Net::HTTP.new or method Net::HTTP.start.
   #
-  # In previous versions of Ruby you would need to require 'net/https' to use
-  # HTTPS. This is no longer true.
+  # The proxy may be defined either by argument +p_addr+
+  # or by environment variable <tt>'http_proxy'</tt>.
   #
-  # == Proxies
+  # === Proxy Using Argument +p_addr+ as a \String
   #
-  # Net::HTTP will automatically create a proxy from the +http_proxy+
-  # environment variable if it is present.  To disable use of +http_proxy+,
-  # pass +nil+ for the proxy address.
+  # When argument +p_addr+ is a string hostname,
+  # the returned +http+ has the given host as its proxy:
   #
-  # You may also create a custom proxy:
+  #   http = Net::HTTP.new(hostname, nil, 'proxy.example')
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => false
+  #   http.proxy_address   # => "proxy.example"
+  #   # These use default values.
+  #   http.proxy_port      # => 80
+  #   http.proxy_user      # => nil
+  #   http.proxy_pass      # => nil
   #
-  #   proxy_addr = 'your.proxy.host'
-  #   proxy_port = 8080
+  # The port, username, and password for the proxy may also be given:
   #
-  #   Net::HTTP.new('example.com', nil, proxy_addr, proxy_port).start { |http|
-  #     # always proxy via your.proxy.addr:8080
-  #   }
+  #   http = Net::HTTP.new(hostname, nil, 'proxy.example', 8000, 'pname', 'ppass')
+  #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => false
+  #   http.proxy_address   # => "proxy.example"
+  #   http.proxy_port      # => 8000
+  #   http.proxy_user      # => "pname"
+  #   http.proxy_pass      # => "ppass"
   #
-  # See Net::HTTP.new for further details and examples such as proxies that
-  # require a username and password.
+  # === Proxy Using '<tt>ENV['http_proxy']</tt>'
+  #
+  # When environment variable <tt>'http_proxy'</tt>
+  # is set to a \URI string,
+  # the returned +http+ will have the server at that URI as its proxy;
+  # note that the \URI string must have a protocol
+  # such as <tt>'http'</tt> or <tt>'https'</tt>:
+  #
+  #   ENV['http_proxy'] = 'http://example.com'
+  #   http = Net::HTTP.new(hostname)
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => true
+  #   http.proxy_address   # => "example.com"
+  #   # These use default values.
+  #   http.proxy_port      # => 80
+  #   http.proxy_user      # => nil
+  #   http.proxy_pass      # => nil
+  #
+  # The \URI string may include proxy username, password, and port number:
+  #
+  #   ENV['http_proxy'] = 'http://pname:ppass@example.com:8000'
+  #   http = Net::HTTP.new(hostname)
+  #   http.proxy?          # => true
+  #   http.proxy_from_env? # => true
+  #   http.proxy_address   # => "example.com"
+  #   http.proxy_port      # => 8000
+  #   http.proxy_user      # => "pname"
+  #   http.proxy_pass      # => "ppass"
   #
-  # == Compression
+  # === Filtering Proxies
   #
-  # Net::HTTP automatically adds Accept-Encoding for compression of response
-  # bodies and automatically decompresses gzip and deflate responses unless a
-  # Range header was sent.
+  # With method Net::HTTP.new (but not Net::HTTP.start),
+  # you can use argument +p_no_proxy+ to filter proxies:
   #
-  # Compression can be disabled through the Accept-Encoding: identity header.
+  # - Reject a certain address:
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
+  #     http.proxy_address # => nil
+  #
+  # - Reject certain domains or subdomains:
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'my.proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
+  #     http.proxy_address # => nil
+  #
+  # - Reject certain addresses and port combinations:
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:1234')
+  #     http.proxy_address # => "proxy.example"
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  # - Reject a list of the types above delimited using a comma:
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  #     http = Net::HTTP.new('example.com', nil, 'my.proxy', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
+  #     http.proxy_address # => nil
+  #
+  # == Compression and Decompression
+  #
+  # \Net::HTTP does not compress the body of a request before sending.
+  #
+  # By default, \Net::HTTP adds header <tt>'Accept-Encoding'</tt>
+  # to a new {request object}[rdoc-ref:Net::HTTPRequest]:
+  #
+  #   Net::HTTP::Get.new(uri)['Accept-Encoding']
+  #   # => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
+  #
+  # This requests the server to zip-encode the response body if there is one;
+  # the server is not required to do so.
+  #
+  # \Net::HTTP does not automatically decompress a response body
+  # if the response has header <tt>'Content-Range'</tt>.
+  #
+  # Otherwise decompression (or not) depends on the value of header
+  # {Content-Encoding}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#content-encoding-response-header]:
+  #
+  # - <tt>'deflate'</tt>, <tt>'gzip'</tt>, or <tt>'x-gzip'</tt>:
+  #   decompresses the body and deletes the header.
+  # - <tt>'none'</tt> or <tt>'identity'</tt>:
+  #   does not decompress the body, but deletes the header.
+  # - Any other value:
+  #   leaves the body and header unchanged.
+  #
+  # == What's Here
+  #
+  # This is a categorized summary of methods and attributes.
+  #
+  # === \Net::HTTP Objects
+  #
+  # - {::new}[rdoc-ref:Net::HTTP.new]:
+  #   Creates a new instance.
+  # - {#inspect}[rdoc-ref:Net::HTTP#inspect]:
+  #   Returns a string representation of +self+.
+  #
+  # === Sessions
+  #
+  # - {::start}[rdoc-ref:Net::HTTP.start]:
+  #   Begins a new session in a new \Net::HTTP object.
+  # - {#started?}[rdoc-ref:Net::HTTP#started?]
+  #   (aliased as {#active?}[rdoc-ref:Net::HTTP#active?]):
+  #   Returns whether in a session.
+  # - {#finish}[rdoc-ref:Net::HTTP#finish]:
+  #   Ends an active session.
+  # - {#start}[rdoc-ref:Net::HTTP#start]:
+  #   Begins a new session in an existing \Net::HTTP object (+self+).
+  #
+  # === Connections
+  #
+  # - {:continue_timeout}[rdoc-ref:Net::HTTP#continue_timeout]:
+  #   Returns the continue timeout.
+  # - {#continue_timeout=}[rdoc-ref:Net::HTTP#continue_timeout=]:
+  #   Sets the continue timeout seconds.
+  # - {:keep_alive_timeout}[rdoc-ref:Net::HTTP#keep_alive_timeout]:
+  #   Returns the keep-alive timeout.
+  # - {:keep_alive_timeout=}[rdoc-ref:Net::HTTP#keep_alive_timeout=]:
+  #   Sets the keep-alive timeout.
+  # - {:max_retries}[rdoc-ref:Net::HTTP#max_retries]:
+  #   Returns the maximum retries.
+  # - {#max_retries=}[rdoc-ref:Net::HTTP#max_retries=]:
+  #   Sets the maximum retries.
+  # - {:open_timeout}[rdoc-ref:Net::HTTP#open_timeout]:
+  #   Returns the open timeout.
+  # - {:open_timeout=}[rdoc-ref:Net::HTTP#open_timeout=]:
+  #   Sets the open timeout.
+  # - {:read_timeout}[rdoc-ref:Net::HTTP#read_timeout]:
+  #   Returns the open timeout.
+  # - {:read_timeout=}[rdoc-ref:Net::HTTP#read_timeout=]:
+  #   Sets the read timeout.
+  # - {:ssl_timeout}[rdoc-ref:Net::HTTP#ssl_timeout]:
+  #   Returns the ssl timeout.
+  # - {:ssl_timeout=}[rdoc-ref:Net::HTTP#ssl_timeout=]:
+  #   Sets the ssl timeout.
+  # - {:write_timeout}[rdoc-ref:Net::HTTP#write_timeout]:
+  #   Returns the write timeout.
+  # - {write_timeout=}[rdoc-ref:Net::HTTP#write_timeout=]:
+  #   Sets the write timeout.
+  #
+  # === Requests
+  #
+  # - {::get}[rdoc-ref:Net::HTTP.get]:
+  #   Sends a GET request and returns the string response body.
+  # - {::get_print}[rdoc-ref:Net::HTTP.get_print]:
+  #   Sends a GET request and write the string response body to $stdout.
+  # - {::get_response}[rdoc-ref:Net::HTTP.get_response]:
+  #   Sends a GET request and returns a response object.
+  # - {::post_form}[rdoc-ref:Net::HTTP.post_form]:
+  #   Sends a POST request with form data and returns a response object.
+  # - {::post}[rdoc-ref:Net::HTTP.post]:
+  #   Sends a POST request with data and returns a response object.
+  # - {#copy}[rdoc-ref:Net::HTTP#copy]:
+  #   Sends a COPY request and returns a response object.
+  # - {#delete}[rdoc-ref:Net::HTTP#delete]:
+  #   Sends a DELETE request and returns a response object.
+  # - {#get}[rdoc-ref:Net::HTTP#get]:
+  #   Sends a GET request and returns a response object.
+  # - {#head}[rdoc-ref:Net::HTTP#head]:
+  #   Sends a HEAD request and returns a response object.
+  # - {#lock}[rdoc-ref:Net::HTTP#lock]:
+  #   Sends a LOCK request and returns a response object.
+  # - {#mkcol}[rdoc-ref:Net::HTTP#mkcol]:
+  #   Sends a MKCOL request and returns a response object.
+  # - {#move}[rdoc-ref:Net::HTTP#move]:
+  #   Sends a MOVE request and returns a response object.
+  # - {#options}[rdoc-ref:Net::HTTP#options]:
+  #   Sends a OPTIONS request and returns a response object.
+  # - {#patch}[rdoc-ref:Net::HTTP#patch]:
+  #   Sends a PATCH request and returns a response object.
+  # - {#post}[rdoc-ref:Net::HTTP#post]:
+  #   Sends a POST request and returns a response object.
+  # - {#propfind}[rdoc-ref:Net::HTTP#propfind]:
+  #   Sends a PROPFIND request and returns a response object.
+  # - {#proppatch}[rdoc-ref:Net::HTTP#proppatch]:
+  #   Sends a PROPPATCH request and returns a response object.
+  # - {#put}[rdoc-ref:Net::HTTP#put]:
+  #   Sends a PUT request and returns a response object.
+  # - {#request}[rdoc-ref:Net::HTTP#request]:
+  #   Sends a request and returns a response object.
+  # - {#request_get}[rdoc-ref:Net::HTTP#request_get]
+  #   (aliased as {#get2}[rdoc-ref:Net::HTTP#get2]):
+  #   Sends a GET request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#request_head}[rdoc-ref:Net::HTTP#request_head]
+  #   (aliased as {#head2}[rdoc-ref:Net::HTTP#head2]):
+  #   Sends a HEAD request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#request_post}[rdoc-ref:Net::HTTP#request_post]
+  #   (aliased as {#post2}[rdoc-ref:Net::HTTP#post2]):
+  #   Sends a POST request and forms a response object;
+  #   if a block given, calls the block with the object,
+  #   otherwise returns the object.
+  # - {#send_request}[rdoc-ref:Net::HTTP#send_request]:
+  #   Sends a request and returns a response object.
+  # - {#trace}[rdoc-ref:Net::HTTP#trace]:
+  #   Sends a TRACE request and returns a response object.
+  # - {#unlock}[rdoc-ref:Net::HTTP#unlock]:
+  #   Sends an UNLOCK request and returns a response object.
+  #
+  # === Responses
+  #
+  # - {:close_on_empty_response}[rdoc-ref:Net::HTTP#close_on_empty_response]:
+  #   Returns whether to close connection on empty response.
+  # - {:close_on_empty_response=}[rdoc-ref:Net::HTTP#close_on_empty_response=]:
+  #   Sets whether to close connection on empty response.
+  # - {:ignore_eof}[rdoc-ref:Net::HTTP#ignore_eof]:
+  #   Returns whether to ignore end-of-file when reading a response body
+  #   with <tt>Content-Length</tt> headers.
+  # - {:ignore_eof=}[rdoc-ref:Net::HTTP#ignore_eof=]:
+  #   Sets whether to ignore end-of-file when reading a response body
+  #   with <tt>Content-Length</tt> headers.
+  # - {:response_body_encoding}[rdoc-ref:Net::HTTP#response_body_encoding]:
+  #   Returns the encoding to use for the response body.
+  # - {#response_body_encoding=}[rdoc-ref:Net::HTTP#response_body_encoding=]:
+  #   Sets the response body encoding.
+  #
+  # === Proxies
+  #
+  # - {:proxy_address}[rdoc-ref:Net::HTTP#proxy_address]:
+  #   Returns the proxy address.
+  # - {:proxy_address=}[rdoc-ref:Net::HTTP#proxy_address=]:
+  #   Sets the proxy address.
+  # - {::proxy_class?}[rdoc-ref:Net::HTTP.proxy_class?]:
+  #   Returns whether +self+ is a proxy class.
+  # - {#proxy?}[rdoc-ref:Net::HTTP#proxy?]:
+  #   Returns whether +self+ has a proxy.
+  # - {#proxy_address}[rdoc-ref:Net::HTTP#proxy_address]
+  #   (aliased as {#proxyaddr}[rdoc-ref:Net::HTTP#proxyaddr]):
+  #   Returns the proxy address.
+  # - {#proxy_from_env?}[rdoc-ref:Net::HTTP#proxy_from_env?]:
+  #   Returns whether the proxy is taken from an environment variable.
+  # - {:proxy_from_env=}[rdoc-ref:Net::HTTP#proxy_from_env=]:
+  #   Sets whether the proxy is to be taken from an environment variable.
+  # - {:proxy_pass}[rdoc-ref:Net::HTTP#proxy_pass]:
+  #   Returns the proxy password.
+  # - {:proxy_pass=}[rdoc-ref:Net::HTTP#proxy_pass=]:
+  #   Sets the proxy password.
+  # - {:proxy_port}[rdoc-ref:Net::HTTP#proxy_port]:
+  #   Returns the proxy port.
+  # - {:proxy_port=}[rdoc-ref:Net::HTTP#proxy_port=]:
+  #   Sets the proxy port.
+  # - {#proxy_user}[rdoc-ref:Net::HTTP#proxy_user]:
+  #   Returns the proxy user name.
+  # - {:proxy_user=}[rdoc-ref:Net::HTTP#proxy_user=]:
+  #   Sets the proxy user.
+  #
+  # === Security
+  #
+  # - {:ca_file}[rdoc-ref:Net::HTTP#ca_file]:
+  #   Returns the path to a CA certification file.
+  # - {:ca_file=}[rdoc-ref:Net::HTTP#ca_file=]:
+  #   Sets the path to a CA certification file.
+  # - {:ca_path}[rdoc-ref:Net::HTTP#ca_path]:
+  #   Returns the path of to CA directory containing certification files.
+  # - {:ca_path=}[rdoc-ref:Net::HTTP#ca_path=]:
+  #   Sets the path of to CA directory containing certification files.
+  # - {:cert}[rdoc-ref:Net::HTTP#cert]:
+  #   Returns the OpenSSL::X509::Certificate object to be used for client certification.
+  # - {:cert=}[rdoc-ref:Net::HTTP#cert=]:
+  #   Sets the OpenSSL::X509::Certificate object to be used for client certification.
+  # - {:cert_store}[rdoc-ref:Net::HTTP#cert_store]:
+  #   Returns the X509::Store to be used for verifying peer certificate.
+  # - {:cert_store=}[rdoc-ref:Net::HTTP#cert_store=]:
+  #   Sets the X509::Store to be used for verifying peer certificate.
+  # - {:ciphers}[rdoc-ref:Net::HTTP#ciphers]:
+  #   Returns the available SSL ciphers.
+  # - {:ciphers=}[rdoc-ref:Net::HTTP#ciphers=]:
+  #   Sets the available SSL ciphers.
+  # - {:extra_chain_cert}[rdoc-ref:Net::HTTP#extra_chain_cert]:
+  #   Returns the extra X509 certificates to be added to the certificate chain.
+  # - {:extra_chain_cert=}[rdoc-ref:Net::HTTP#extra_chain_cert=]:
+  #   Sets the extra X509 certificates to be added to the certificate chain.
+  # - {:key}[rdoc-ref:Net::HTTP#key]:
+  #   Returns the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
+  # - {:key=}[rdoc-ref:Net::HTTP#key=]:
+  #   Sets the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
+  # - {:max_version}[rdoc-ref:Net::HTTP#max_version]:
+  #   Returns the maximum SSL version.
+  # - {:max_version=}[rdoc-ref:Net::HTTP#max_version=]:
+  #   Sets the maximum SSL version.
+  # - {:min_version}[rdoc-ref:Net::HTTP#min_version]:
+  #   Returns the minimum SSL version.
+  # - {:min_version=}[rdoc-ref:Net::HTTP#min_version=]:
+  #   Sets the minimum SSL version.
+  # - {#peer_cert}[rdoc-ref:Net::HTTP#peer_cert]:
+  #   Returns the X509 certificate chain for the session's socket peer.
+  # - {:ssl_version}[rdoc-ref:Net::HTTP#ssl_version]:
+  #   Returns the SSL version.
+  # - {:ssl_version=}[rdoc-ref:Net::HTTP#ssl_version=]:
+  #   Sets the SSL version.
+  # - {#use_ssl=}[rdoc-ref:Net::HTTP#use_ssl=]:
+  #   Sets whether a new session is to use Transport Layer Security.
+  # - {#use_ssl?}[rdoc-ref:Net::HTTP#use_ssl?]:
+  #   Returns whether +self+ uses SSL.
+  # - {:verify_callback}[rdoc-ref:Net::HTTP#verify_callback]:
+  #   Returns the callback for the server certification verification.
+  # - {:verify_callback=}[rdoc-ref:Net::HTTP#verify_callback=]:
+  #   Sets the callback for the server certification verification.
+  # - {:verify_depth}[rdoc-ref:Net::HTTP#verify_depth]:
+  #   Returns the maximum depth for the certificate chain verification.
+  # - {:verify_depth=}[rdoc-ref:Net::HTTP#verify_depth=]:
+  #   Sets the maximum depth for the certificate chain verification.
+  # - {:verify_hostname}[rdoc-ref:Net::HTTP#verify_hostname]:
+  #   Returns the flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_hostname=}[rdoc-ref:Net::HTTP#verify_hostname=]:
+  #   Sets he flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_mode}[rdoc-ref:Net::HTTP#verify_mode]:
+  #   Returns the flags for server the certification verification at the beginning of the SSL/TLS session.
+  # - {:verify_mode=}[rdoc-ref:Net::HTTP#verify_mode=]:
+  #   Sets the flags for server the certification verification at the beginning of the SSL/TLS session.
+  #
+  # === Addresses and Ports
+  #
+  # - {:address}[rdoc-ref:Net::HTTP#address]:
+  #   Returns the string host name or host IP.
+  # - {::default_port}[rdoc-ref:Net::HTTP.default_port]:
+  #   Returns integer 80, the default port to use for HTTP requests.
+  # - {::http_default_port}[rdoc-ref:Net::HTTP.http_default_port]:
+  #   Returns integer 80, the default port to use for HTTP requests.
+  # - {::https_default_port}[rdoc-ref:Net::HTTP.https_default_port]:
+  #   Returns integer 443, the default port to use for HTTPS requests.
+  # - {#ipaddr}[rdoc-ref:Net::HTTP#ipaddr]:
+  #   Returns the IP address for the connection.
+  # - {#ipaddr=}[rdoc-ref:Net::HTTP#ipaddr=]:
+  #   Sets the IP address for the connection.
+  # - {:local_host}[rdoc-ref:Net::HTTP#local_host]:
+  #   Returns the string local host used to establish the connection.
+  # - {:local_host=}[rdoc-ref:Net::HTTP#local_host=]:
+  #   Sets the string local host used to establish the connection.
+  # - {:local_port}[rdoc-ref:Net::HTTP#local_port]:
+  #   Returns the integer local port used to establish the connection.
+  # - {:local_port=}[rdoc-ref:Net::HTTP#local_port=]:
+  #   Sets the integer local port used to establish the connection.
+  # - {:port}[rdoc-ref:Net::HTTP#port]:
+  #   Returns the integer port number.
+  #
+  # === \HTTP Version
+  #
+  # - {::version_1_2?}[rdoc-ref:Net::HTTP.version_1_2?]
+  #   (aliased as {::is_version_1_2?}[rdoc-ref:Net::HTTP.is_version_1_2?]
+  #   and {::version_1_2}[rdoc-ref:Net::HTTP.version_1_2]):
+  #   Returns true; retained for compatibility.
+  #
+  # === Debugging
+  #
+  # - {#set_debug_output}[rdoc-ref:Net::HTTP#set_debug_output]:
+  #   Sets the output stream for debugging.
   #
   class HTTP < Protocol
 
     # :stopdoc:
-    VERSION = "0.3.2"
-    Revision = %q$Revision$.split[1]
+    VERSION = "0.4.1"
     HTTPVersion = '1.1'
     begin
       require 'zlib'
@@ -548,10 +890,10 @@ module Net   #:nodoc:
     end
 
     #
-    # HTTP session management
+    # \HTTP session management
     #
 
-    # Returns intger +80+, the default port to use for HTTP requests:
+    # Returns integer +80+, the default port to use for \HTTP requests:
     #
     #   Net::HTTP.default_port # => 80
     #
@@ -559,7 +901,7 @@ module Net   #:nodoc:
       http_default_port()
     end
 
-    # Returns integer +80+, the default port to use for HTTP requests:
+    # Returns integer +80+, the default port to use for \HTTP requests:
     #
     #   Net::HTTP.http_default_port # => 80
     #
@@ -585,14 +927,11 @@ module Net   #:nodoc:
     #
     # Creates a new \Net::HTTP object, +http+, via \Net::HTTP.new:
     #
-    #   Net::HTTP.new(address, port, p_addr, p_port, p_user, p_pass)
-    #
-    # - For arguments +hostname+ through +p_pass+, see Net::HTTP.new.
+    # - For arguments +address+ and +port+, see Net::HTTP.new.
+    # - For proxy-defining arguments +p_addr+ through +p_pass+,
+    #   see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     # - For argument +opts+, see below.
     #
-    # Note: If +port+ is +nil+ and <tt>opts[:use_ssl]</tt> is a truthy value,
-    # the value passed to +new+ is Net::HTTP.https_default_port, not +port+.
-    #
     # With no block given:
     #
     # - Calls <tt>http.start</tt> with no block (see #start),
@@ -665,6 +1004,9 @@ module Net   #:nodoc:
     # - #verify_mode
     # - #write_timeout
     #
+    # Note: If +port+ is +nil+ and <tt>opts[:use_ssl]</tt> is a truthy value,
+    # the value passed to +new+ is Net::HTTP.https_default_port, not +port+.
+    #
     def HTTP.start(address, *arg, &block) # :yield: +http+
       arg.pop if opt = Hash.try_convert(arg[-1])
       port, p_addr, p_port, p_user, p_pass = *arg
@@ -691,12 +1033,10 @@ module Net   #:nodoc:
       alias newobj new # :nodoc:
     end
 
-    # Returns a new Net::HTTP object +http+
-    # (but does not open a TCP connection or HTTP session).
-    #
-    # <b>No Proxy</b>
+    # Returns a new \Net::HTTP object +http+
+    # (but does not open a TCP connection or \HTTP session).
     #
-    # With only string argument +hostname+ given
+    # With only string argument +address+ given
     # (and <tt>ENV['http_proxy']</tt> undefined or +nil+),
     # the returned +http+:
     #
@@ -719,85 +1059,8 @@ module Net   #:nodoc:
     #   # => #<Net::HTTP jsonplaceholder.typicode.com:8000 open=false>
     #   http.port # => 8000
     #
-    # <b>Proxy Using Argument +p_addr+ as a \String</b>
-    #
-    # When argument +p_addr+ is a string hostname,
-    # the returned +http+ has a proxy:
-    #
-    #   http = Net::HTTP.new(hostname, nil, 'proxy.example')
-    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
-    #   http.proxy?        # => true
-    #   http.proxy_address # => "proxy.example"
-    #   # These use default values.
-    #   http.proxy_port    # => 80
-    #   http.proxy_user    # => nil
-    #   http.proxy_pass    # => nil
-    #
-    # The port, username, and password for the proxy may also be given:
-    #
-    #   http = Net::HTTP.new(hostname, nil, 'proxy.example', 8000, 'pname', 'ppass')
-    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
-    #   http.proxy?        # => true
-    #   http.proxy_address # => "proxy.example"
-    #   http.proxy_port    # => 8000
-    #   http.proxy_user    # => "pname"
-    #   http.proxy_pass    # => "ppass"
-    #
-    # <b>Proxy Using <tt>ENV['http_proxy']</tt></b>
-    #
-    # When environment variable <tt>'http_proxy'</tt>
-    # is set to a \URI string,
-    # the returned +http+ will have that URI as its proxy;
-    # note that the \URI string must have a protocol
-    # such as <tt>'http'</tt> or <tt>'https'</tt>:
-    #
-    #   ENV['http_proxy'] = 'http://example.com'
-    #   # => "http://example.com"
-    #   http = Net::HTTP.new(hostname)
-    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
-    #   http.proxy?        # => true
-    #   http.address       # => "jsonplaceholder.typicode.com"
-    #   http.proxy_address # => "example.com"
-    #
-    # The \URI string may include proxy username, password, and port number:
-    #
-    #   ENV['http_proxy'] = 'http://pname:ppass@example.com:8000'
-    #   # => "http://pname:ppass@example.com:8000"
-    #   http = Net::HTTP.new(hostname)
-    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
-    #   http.proxy_port # => 8000
-    #   http.proxy_user # => "pname"
-    #   http.proxy_pass # => "ppass"
-    #
-    # <b>Argument +p_no_proxy+</b>
-    #
-    # You can use argument +p_no_proxy+ to reject certain proxies:
-    #
-    # - Reject a certain address:
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
-    #     http.proxy_address # => nil
-    #
-    # - Reject certain domains or subdomains:
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'my.proxy.example', 8000, 'pname', 'ppass', 'proxy.example')
-    #     http.proxy_address # => nil
-    #
-    # - Reject certain addresses and port combinations:
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:1234')
-    #     http.proxy_address # => "proxy.example"
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'proxy.example:8000')
-    #     http.proxy_address # => nil
-    #
-    # - Reject a list of the types above delimited using a comma:
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'proxy.example', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
-    #     http.proxy_address # => nil
-    #
-    #     http = Net::HTTP.new('example.com', nil, 'my.proxy', 8000, 'pname', 'ppass', 'my.proxy,proxy.example:8000')
-    #     http.proxy_address # => nil
+    # For proxy-defining arguments +p_addr+ through +p_no_proxy+,
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     #
     def HTTP.new(address, port = nil, p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil, p_no_proxy = nil)
       http = super address, port
@@ -811,7 +1074,7 @@ module Net   #:nodoc:
       elsif p_addr == :ENV then
         http.proxy_from_env = true
       else
-        if p_addr && p_no_proxy && !URI::Generic.use_proxy?(p_addr, p_addr, p_port, p_no_proxy)
+        if p_addr && p_no_proxy && !URI::Generic.use_proxy?(address, address, port, p_no_proxy)
           p_addr = nil
           p_port = nil
         end
@@ -824,10 +1087,10 @@ module Net   #:nodoc:
       http
     end
 
-    # Creates a new Net::HTTP object for the specified server address,
-    # without opening the TCP connection or initializing the HTTP session.
+    # Creates a new \Net::HTTP object for the specified server address,
+    # without opening the TCP connection or initializing the \HTTP session.
     # The +address+ should be a DNS hostname or IP address.
-    def initialize(address, port = nil)
+    def initialize(address, port = nil) # :nodoc:
       @address = address
       @port    = (port || HTTP.default_port)
       @ipaddr = nil
@@ -927,21 +1190,22 @@ module Net   #:nodoc:
       @debug_output = output
     end
 
-    # The DNS host name or IP address to connect to.
+    # Returns the string host name or host IP given as argument +address+ in ::new.
     attr_reader :address
 
-    # The port number to connect to.
+    # Returns the integer port number given as argument +port+ in ::new.
     attr_reader :port
 
-    # The local host used to establish the connection.
+    # Sets or returns the string local host used to establish the connection;
+    # initially +nil+.
     attr_accessor :local_host
 
-    # The local port used to establish the connection.
+    # Sets or returns the integer local port used to establish the connection;
+    # initially +nil+.
     attr_accessor :local_port
 
-    # The encoding to use for the response body.  If Encoding, uses the
-    # specified encoding.  If other true value, tries to detect the response
-    # body encoding.
+    # Returns the encoding to use for the response body;
+    # see #response_body_encoding=.
     attr_reader :response_body_encoding
 
     # Sets the encoding to be used for the response body;
@@ -967,10 +1231,25 @@ module Net   #:nodoc:
       @response_body_encoding = value
     end
 
+    # Sets whether to determine the proxy from environment variable
+    # '<tt>ENV['http_proxy']</tt>';
+    # see {Proxy Using ENV['http_proxy']}[rdoc-ref:Net::HTTP@Proxy+Using+-27ENV-5B-27http_proxy-27-5D-27].
     attr_writer :proxy_from_env
+
+    # Sets the proxy address;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     attr_writer :proxy_address
+
+    # Sets the proxy port;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     attr_writer :proxy_port
+
+    # Sets the proxy user;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     attr_writer :proxy_user
+
+    # Sets the proxy password;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     attr_writer :proxy_pass
 
     # Returns the IP address for the connection.
@@ -1009,27 +1288,25 @@ module Net   #:nodoc:
       @ipaddr = addr
     end
 
-    # Number of seconds to wait for the connection to open. Any number
-    # may be used, including Floats for fractional seconds. If the HTTP
-    # object cannot open a connection in this many seconds, it raises a
-    # Net::OpenTimeout exception. The default value is 60 seconds.
+    # Sets or returns the numeric (\Integer or \Float) number of seconds
+    # to wait for a connection to open;
+    # initially 60.
+    # If the connection is not made in the given interval,
+    # an exception is raised.
     attr_accessor :open_timeout
 
-    # Number of seconds to wait for one block to be read (via one read(2)
-    # call). Any number may be used, including Floats for fractional
-    # seconds. If the HTTP object cannot read data in this many seconds,
-    # it raises a Net::ReadTimeout exception. The default value is 60 seconds.
+    # Returns the numeric (\Integer or \Float) number of seconds
+    # to wait for one block to be read (via one read(2) call);
+    # see #read_timeout=.
     attr_reader :read_timeout
 
-    # Number of seconds to wait for one block to be written (via one write(2)
-    # call). Any number may be used, including Floats for fractional
-    # seconds. If the HTTP object cannot write data in this many seconds,
-    # it raises a Net::WriteTimeout exception. The default value is 60 seconds.
-    # Net::WriteTimeout is not raised on Windows.
+    # Returns the numeric (\Integer or \Float) number of seconds
+    # to wait for one block to be written (via one write(2) call);
+    # see #write_timeout=.
     attr_reader :write_timeout
 
     # Sets the maximum number of times to retry an idempotent request in case of
-    # Net::ReadTimeout, IOError, EOFError, Errno::ECONNRESET,
+    # \Net::ReadTimeout, IOError, EOFError, Errno::ECONNRESET,
     # Errno::ECONNABORTED, Errno::EPIPE, OpenSSL::SSL::SSLError,
     # Timeout::Error.
     # The initial value is 1.
@@ -1048,6 +1325,8 @@ module Net   #:nodoc:
       @max_retries = retries
     end
 
+    # Returns the maximum number of times to retry an idempotent request;
+    # see #max_retries=.
     attr_reader :max_retries
 
     # Sets the read timeout, in seconds, for +self+ to integer +sec+;
@@ -1069,52 +1348,90 @@ module Net   #:nodoc:
     # Sets the write timeout, in seconds, for +self+ to integer +sec+;
     # the initial value is 60.
     #
-    # Argument +sec+ must be a non-negative numeric value.
+    # Argument +sec+ must be a non-negative numeric value:
+    #
+    #   _uri = uri.dup
+    #   _uri.path = '/posts'
+    #   body = 'bar' * 200000
+    #   data = <<EOF
+    #   {"title": "foo", "body": "#{body}", "userId": "1"}
+    #   EOF
+    #   headers = {'content-type': 'application/json'}
+    #   http = Net::HTTP.new(hostname)
+    #   http.write_timeout # => 60
+    #   http.post(_uri.path, data, headers)
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
+    #   http.write_timeout = 0
+    #   http.post(_uri.path, data, headers) # Raises Net::WriteTimeout.
     #
     def write_timeout=(sec)
       @socket.write_timeout = sec if @socket
       @write_timeout = sec
     end
 
-    # Seconds to wait for 100 Continue response. If the HTTP object does not
-    # receive a response in this many seconds it sends the request body. The
-    # default value is +nil+.
+    # Returns the continue timeout value;
+    # see continue_timeout=.
     attr_reader :continue_timeout
 
-    # Setter for the continue_timeout attribute.
+    # Sets the continue timeout value,
+    # which is the number of seconds to wait for an expected 100 Continue response.
+    # If the \HTTP object does not receive a response in this many seconds
+    # it sends the request body.
     def continue_timeout=(sec)
       @socket.continue_timeout = sec if @socket
       @continue_timeout = sec
     end
 
-    # Seconds to reuse the connection of the previous request.
-    # If the idle time is less than this Keep-Alive Timeout,
-    # Net::HTTP reuses the TCP/IP socket used by the previous communication.
-    # The default value is 2 seconds.
+    # Sets or returns the numeric (\Integer or \Float) number of seconds
+    # to keep the connection open after a request is sent;
+    # initially 2.
+    # If a new request is made during the given interval,
+    # the still-open connection is used;
+    # otherwise the connection will have been closed
+    # and a new connection is opened.
     attr_accessor :keep_alive_timeout
 
-    # Whether to ignore EOF when reading response bodies with defined
-    # Content-Length headers. For backwards compatibility, the default is true.
+    # Sets or returns whether to ignore end-of-file when reading a response body
+    # with <tt>Content-Length</tt> headers;
+    # initially +true+.
     attr_accessor :ignore_eof
 
-    # Returns true if the HTTP session has been started.
+    # Returns +true+ if the \HTTP session has been started:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.started? # => false
+    #   http.start
+    #   http.started? # => true
+    #   http.finish # => nil
+    #   http.started? # => false
+    #
+    #   Net::HTTP.start(hostname) do |http|
+    #     http.started?
+    #   end # => true
+    #   http.started? # => false
+    #
     def started?
       @started
     end
 
     alias active? started?   #:nodoc: obsolete
 
+    # Sets or returns whether to close the connection when the response is empty;
+    # initially +false+.
     attr_accessor :close_on_empty_response
 
-    # Returns true if SSL/TLS is being used with HTTP.
+    # Returns +true+ if +self+ uses SSL, +false+ otherwise.
+    # See Net::HTTP#use_ssl=.
     def use_ssl?
       @use_ssl
     end
 
-    # Turn on/off SSL.
-    # This flag must be set before starting session.
-    # If you change use_ssl value after session started,
-    # a Net::HTTP object raises IOError.
+    # Sets whether a new session is to use
+    # {Transport Layer Security}[https://en.wikipedia.org/wiki/Transport_Layer_Security]:
+    #
+    # Raises IOError if attempting to change during a session.
+    #
+    # Raises OpenSSL::SSL::SSLError if the port is not an HTTPS port.
     def use_ssl=(flag)
       flag = flag ? true : false
       if started? and @use_ssl != flag
@@ -1139,7 +1456,7 @@ module Net   #:nodoc:
       :@verify_depth,
       :@verify_mode,
       :@verify_hostname,
-    ]
+    ] # :nodoc:
     SSL_ATTRIBUTES = [
       :ca_file,
       :ca_path,
@@ -1156,64 +1473,67 @@ module Net   #:nodoc:
       :verify_depth,
       :verify_mode,
       :verify_hostname,
-    ]
+    ] # :nodoc:
 
-    # Sets path of a CA certification file in PEM format.
-    #
-    # The file can contain several CA certificates.
+    # Sets or returns the path to a CA certification file in PEM format.
     attr_accessor :ca_file
 
-    # Sets path of a CA certification directory containing certifications in
-    # PEM format.
+    # Sets or returns the path of to CA directory
+    # containing certification files in PEM format.
     attr_accessor :ca_path
 
-    # Sets an OpenSSL::X509::Certificate object as client certificate.
-    # (This method is appeared in Michal Rokos's OpenSSL extension).
+    # Sets or returns the OpenSSL::X509::Certificate object
+    # to be used for client certification.
     attr_accessor :cert
 
-    # Sets the X509::Store to verify peer certificate.
+    # Sets or returns the X509::Store to be used for verifying peer certificate.
     attr_accessor :cert_store
 
-    # Sets the available ciphers.  See OpenSSL::SSL::SSLContext#ciphers=
+    # Sets or returns the available SSL ciphers.
+    # See {OpenSSL::SSL::SSLContext#ciphers=}[rdoc-ref:OpenSSL::SSL::SSLContext#ciphers-3D].
     attr_accessor :ciphers
 
-    # Sets the extra X509 certificates to be added to the certificate chain.
-    # See OpenSSL::SSL::SSLContext#extra_chain_cert=
+    # Sets or returns the extra X509 certificates to be added to the certificate chain.
+    # See {OpenSSL::SSL::SSLContext#add_certificate}[rdoc-ref:OpenSSL::SSL::SSLContext#add_certificate].
     attr_accessor :extra_chain_cert
 
-    # Sets an OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
-    # (This method is appeared in Michal Rokos's OpenSSL extension.)
+    # Sets or returns the OpenSSL::PKey::RSA or OpenSSL::PKey::DSA object.
     attr_accessor :key
 
-    # Sets the SSL timeout seconds.
+    # Sets or returns the SSL timeout seconds.
     attr_accessor :ssl_timeout
 
-    # Sets the SSL version.  See OpenSSL::SSL::SSLContext#ssl_version=
+    # Sets or returns the SSL version.
+    # See {OpenSSL::SSL::SSLContext#ssl_version=}[rdoc-ref:OpenSSL::SSL::SSLContext#ssl_version-3D].
     attr_accessor :ssl_version
 
-    # Sets the minimum SSL version.  See OpenSSL::SSL::SSLContext#min_version=
+    # Sets or returns the minimum SSL version.
+    # See {OpenSSL::SSL::SSLContext#min_version=}[rdoc-ref:OpenSSL::SSL::SSLContext#min_version-3D].
     attr_accessor :min_version
 
-    # Sets the maximum SSL version.  See OpenSSL::SSL::SSLContext#max_version=
+    # Sets or returns the maximum SSL version.
+    # See {OpenSSL::SSL::SSLContext#max_version=}[rdoc-ref:OpenSSL::SSL::SSLContext#max_version-3D].
     attr_accessor :max_version
 
-    # Sets the verify callback for the server certification verification.
+    # Sets or returns the callback for the server certification verification.
     attr_accessor :verify_callback
 
-    # Sets the maximum depth for the certificate chain verification.
+    # Sets or returns the maximum depth for the certificate chain verification.
     attr_accessor :verify_depth
 
-    # Sets the flags for server the certification verification at beginning of
-    # SSL/TLS session.
-    #
+    # Sets or returns the flags for server the certification verification
+    # at the beginning of the SSL/TLS session.
     # OpenSSL::SSL::VERIFY_NONE or OpenSSL::SSL::VERIFY_PEER are acceptable.
     attr_accessor :verify_mode
 
-    # Sets to check the server certificate is valid for the hostname.
-    # See OpenSSL::SSL::SSLContext#verify_hostname=
+    # Sets or returns whether to verify that the server certificate is valid
+    # for the hostname.
+    # See {OpenSSL::SSL::SSLContext#verify_hostname=}[rdoc-ref:OpenSSL::SSL::SSLContext#attribute-i-verify_mode].
     attr_accessor :verify_hostname
 
-    # Returns the X.509 certificates the server presented.
+    # Returns the X509 certificate chain (an array of strings)
+    # for the session's socket peer,
+    # or +nil+ if none.
     def peer_cert
       if not use_ssl? or not @socket
         return nil
@@ -1221,14 +1541,26 @@ module Net   #:nodoc:
       @socket.io.peer_cert
     end
 
-    # Opens a TCP connection and HTTP session.
+    # Starts an \HTTP session.
+    #
+    # Without a block, returns +self+:
     #
-    # When this method is called with a block, it passes the Net::HTTP
-    # object to the block, and closes the TCP connection and HTTP session
-    # after the block has been executed.
+    #   http = Net::HTTP.new(hostname)
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+    #   http.start
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=true>
+    #   http.started? # => true
+    #   http.finish
+    #
+    # With a block, calls the block with +self+,
+    # finishes the session when the block exits,
+    # and returns the block's value:
     #
-    # When called with a block, it returns the return value of the
-    # block; otherwise, it returns self.
+    #   http.start do |http|
+    #     http
+    #   end
+    #   # => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
+    #   http.started? # => false
     #
     def start  # :yield: http
       raise IOError, 'HTTP session already opened' if @started
@@ -1282,8 +1614,8 @@ module Net   #:nodoc:
                                       write_timeout: @write_timeout,
                                       continue_timeout: @continue_timeout,
                                       debug_output: @debug_output)
-          buf = "CONNECT #{conn_address}:#{@port} HTTP/#{HTTPVersion}\r\n"
-          buf << "Host: #{@address}:#{@port}\r\n"
+          buf = +"CONNECT #{conn_address}:#{@port} HTTP/#{HTTPVersion}\r\n" \
+            "Host: #{@address}:#{@port}\r\n"
           if proxy_user
             credential = ["#{proxy_user}:#{proxy_pass}"].pack('m0')
             buf << "Proxy-Authorization: Basic #{credential}\r\n"
@@ -1364,8 +1696,15 @@ module Net   #:nodoc:
     end
     private :on_connect
 
-    # Finishes the HTTP session and closes the TCP connection.
-    # Raises IOError if the session has not been started.
+    # Finishes the \HTTP session:
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.start
+    #   http.started? # => true
+    #   http.finish   # => nil
+    #   http.started? # => false
+    #
+    # Raises IOError if not in a session.
     def finish
       raise IOError, 'HTTP session not yet started' unless started?
       do_finish
@@ -1392,11 +1731,11 @@ module Net   #:nodoc:
     @proxy_user = nil
     @proxy_pass = nil
 
-    # Creates an HTTP proxy class which behaves like Net::HTTP, but
+    # Creates an \HTTP proxy class which behaves like \Net::HTTP, but
     # performs all access via the specified proxy.
     #
     # This class is obsolete.  You may pass these same parameters directly to
-    # Net::HTTP.new.  See Net::HTTP.new for details of the arguments.
+    # \Net::HTTP.new.  See Net::HTTP.new for details of the arguments.
     def HTTP.Proxy(p_addr = :ENV, p_port = nil, p_user = nil, p_pass = nil) #:nodoc:
       return self unless p_addr
 
@@ -1419,31 +1758,37 @@ module Net   #:nodoc:
     end
 
     class << HTTP
-      # returns true if self is a class which was created by HTTP::Proxy.
+      # Returns true if self is a class which was created by HTTP::Proxy.
       def proxy_class?
         defined?(@is_proxy_class) ? @is_proxy_class : false
       end
 
-      # Address of proxy host. If Net::HTTP does not use a proxy, nil.
+      # Returns the address of the proxy host, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_address
 
-      # Port number of proxy host. If Net::HTTP does not use a proxy, nil.
+      # Returns the port number of the proxy host, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_port
 
-      # User name for accessing proxy. If Net::HTTP does not use a proxy, nil.
+      # Returns the user name for accessing the proxy, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_user
 
-      # User password for accessing proxy. If Net::HTTP does not use a proxy,
-      # nil.
+      # Returns the password for accessing the proxy, or +nil+ if none;
+      # see Net::HTTP@Proxy+Server.
       attr_reader :proxy_pass
     end
 
-    # True if requests for this connection will be proxied
+    # Returns +true+ if a proxy server is defined, +false+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy?
       !!(@proxy_from_env ? proxy_uri : @proxy_address)
     end
 
-    # True if the proxy for this connection is determined from the environment
+    # Returns +true+ if the proxy server is defined in the environment,
+    # +false+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_from_env?
       @proxy_from_env
     end
@@ -1452,12 +1797,13 @@ module Net   #:nodoc:
     def proxy_uri # :nodoc:
       return if @proxy_uri == false
       @proxy_uri ||= URI::HTTP.new(
-        "http".freeze, nil, address, port, nil, nil, nil, nil, nil
+        "http", nil, address, port, nil, nil, nil, nil, nil
       ).find_proxy || false
       @proxy_uri || nil
     end
 
-    # The address of the proxy server, if one is configured.
+    # Returns the address of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_address
       if @proxy_from_env then
         proxy_uri&.hostname
@@ -1466,7 +1812,8 @@ module Net   #:nodoc:
       end
     end
 
-    # The port of the proxy server, if one is configured.
+    # Returns the port number of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_port
       if @proxy_from_env then
         proxy_uri&.port
@@ -1475,7 +1822,8 @@ module Net   #:nodoc:
       end
     end
 
-    # The username of the proxy server, if one is configured.
+    # Returns the user name of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_user
       if @proxy_from_env
         user = proxy_uri&.user
@@ -1485,7 +1833,8 @@ module Net   #:nodoc:
       end
     end
 
-    # The password of the proxy server, if one is configured.
+    # Returns the password of the proxy server, if defined, +nil+ otherwise;
+    # see {Proxy Server}[rdoc-ref:Net::HTTP@Proxy+Server].
     def proxy_pass
       if @proxy_from_env
         pass = proxy_uri&.password
@@ -1533,45 +1882,38 @@ module Net   #:nodoc:
 
     public
 
-    # Retrieves data from +path+ on the connected-to host which may be an
-    # absolute path String or a URI to extract the path from.
+    # :call-seq:
+    #    get(path, initheader = nil) {|res| ... }
     #
-    # +initheader+ must be a Hash like { 'Accept' => '*/*', ... },
-    # and it defaults to an empty hash.
-    # If +initheader+ doesn't have the key 'accept-encoding', then
-    # a value of "gzip;q=1.0,deflate;q=0.6,identity;q=0.3" is used,
-    # so that gzip compression is used in preference to deflate
-    # compression, which is used in preference to no compression.
-    # Ruby doesn't have libraries to support the compress (Lempel-Ziv)
-    # compression, so that is not supported.  The intent of this is
-    # to reduce bandwidth by default.   If this routine sets up
-    # compression, then it does the decompression also, removing
-    # the header as well to prevent confusion.  Otherwise
-    # it leaves the body as it found it.
+    # Sends a GET request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTP::Get object
+    # created from string +path+ and initial headers hash +initheader+.
     #
-    # If called with a block, yields each fragment of the
-    # entity body in turn as a string as it is read from
-    # the socket.  Note that in this case, the returned response
-    # object will *not* contain a (meaningful) body.
+    # With a block given, calls the block with the response body:
     #
-    # +dest+ argument is obsolete.
-    # It still works but you must not use it.
+    #   http = Net::HTTP.new(hostname)
+    #   http.get('/todos/1') do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    # This method never raises an exception.
+    # Output:
+    #
+    #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false\n}"
+    #
+    # With no block given, simply returns the response object:
     #
-    #     response = http.get('/index.html')
+    #   http.get('/') # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    #     # using block
-    #     File.open('result.txt', 'w') {|f|
-    #       http.get('/~foo/') do |str|
-    #         f.write str
-    #       end
-    #     }
+    # Related:
+    #
+    # - Net::HTTP::Get: request class for \HTTP method GET.
+    # - Net::HTTP.get: sends GET request, returns response body.
     #
     def get(path, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       res = nil
+
       request(Get.new(path, initheader)) {|r|
         r.read_body dest, &block
         res = r
@@ -1579,198 +1921,312 @@ module Net   #:nodoc:
       res
     end
 
-    # Gets only the header from +path+ on the connected-to host.
-    # +header+ is a Hash like { 'Accept' => '*/*', ... }.
+    # Sends a HEAD request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTP::Head object
+    # created from string +path+ and initial headers hash +initheader+:
     #
-    # This method never raises an exception.
-    #
-    #     response = nil
-    #     Net::HTTP.start('some.www.server', 80) {|http|
-    #       response = http.head('/index.html')
-    #     }
-    #     p response['content-type']
+    #   res = http.head('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
+    #   res.body                    # => nil
+    #   res.to_hash.take(3)
+    #   # =>
+    #   [["date", ["Wed, 15 Feb 2023 15:25:42 GMT"]],
+    #    ["content-type", ["application/json; charset=utf-8"]],
+    #    ["connection", ["close"]]]
     #
     def head(path, initheader = nil)
       request(Head.new(path, initheader))
     end
 
-    # Posts +data+ (must be a String) to +path+. +header+ must be a Hash
-    # like { 'Accept' => '*/*', ... }.
+    # :call-seq:
+    #    post(path, data, initheader = nil) {|res| ... }
+    #
+    # Sends a POST request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTP::Post object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    # With a block given, calls the block with the response body:
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.post('/todos', data) do |res|
+    #     p res
+    #   end # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # If called with a block, yields each fragment of the
-    # entity body in turn as a string as it is read from
-    # the socket.  Note that in this case, the returned response
-    # object will *not* contain a (meaningful) body.
+    # Output:
     #
-    # +dest+ argument is obsolete.
-    # It still works but you must not use it.
+    #   "{\n  \"{\\\"userId\\\": 1, \\\"id\\\": 1, \\\"title\\\": \\\"delectus aut autem\\\", \\\"completed\\\": false}\": \"\",\n  \"id\": 201\n}"
     #
-    # This method never raises exception.
+    # With no block given, simply returns the response object:
     #
-    #     response = http.post('/cgi-bin/search.rb', 'query=foo')
+    #   http.post('/todos', data) # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    #     # using block
-    #     File.open('result.txt', 'w') {|f|
-    #       http.post('/cgi-bin/search.rb', 'query=foo') do |str|
-    #         f.write str
-    #       end
-    #     }
+    # Related:
     #
-    # You should set Content-Type: header field for POST.
-    # If no Content-Type: field given, this method uses
-    # "application/x-www-form-urlencoded" by default.
+    # - Net::HTTP::Post: request class for \HTTP method POST.
+    # - Net::HTTP.post: sends POST request, returns response body.
     #
     def post(path, data, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       send_entity(path, data, initheader, dest, Post, &block)
     end
 
-    # Sends a PATCH request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # :call-seq:
+    #    patch(path, data, initheader = nil) {|res| ... }
+    #
+    # Sends a PATCH request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Patch object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    # With a block given, calls the block with the response body:
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.patch('/todos/1', data) do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
+    #
+    #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false,\n  \"{\\\"userId\\\": 1, \\\"id\\\": 1, \\\"title\\\": \\\"delectus aut autem\\\", \\\"completed\\\": false}\": \"\"\n}"
+    #
+    # With no block given, simply returns the response object:
+    #
+    #   http.patch('/todos/1', data) # => #<Net::HTTPCreated 201 Created readbody=true>
+    #
     def patch(path, data, initheader = nil, dest = nil, &block) # :yield: +body_segment+
       send_entity(path, data, initheader, dest, Patch, &block)
     end
 
-    def put(path, data, initheader = nil)   #:nodoc:
+    # Sends a PUT request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Put object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.put('/todos/1', data) # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    def put(path, data, initheader = nil)
       request(Put.new(path, initheader), data)
     end
 
-    # Sends a PROPPATCH request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a PROPPATCH request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Proppatch object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.proppatch('/todos/1', data)
+    #
     def proppatch(path, body, initheader = nil)
       request(Proppatch.new(path, initheader), body)
     end
 
-    # Sends a LOCK request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a LOCK request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Lock object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.lock('/todos/1', data)
+    #
     def lock(path, body, initheader = nil)
       request(Lock.new(path, initheader), body)
     end
 
-    # Sends a UNLOCK request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends an UNLOCK request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Unlock object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.unlock('/todos/1', data)
+    #
     def unlock(path, body, initheader = nil)
       request(Unlock.new(path, initheader), body)
     end
 
-    # Sends a OPTIONS request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends an Options request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Options object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.options('/')
+    #
     def options(path, initheader = nil)
       request(Options.new(path, initheader))
     end
 
-    # Sends a PROPFIND request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a PROPFIND request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Propfind object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http = Net::HTTP.new(hostname)
+    #   http.propfind('/todos/1', data)
+    #
     def propfind(path, body = nil, initheader = {'Depth' => '0'})
       request(Propfind.new(path, initheader), body)
     end
 
-    # Sends a DELETE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a DELETE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Delete object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.delete('/todos/1')
+    #
     def delete(path, initheader = {'Depth' => 'Infinity'})
       request(Delete.new(path, initheader))
     end
 
-    # Sends a MOVE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a MOVE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Move object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.move('/todos/1')
+    #
     def move(path, initheader = nil)
       request(Move.new(path, initheader))
     end
 
-    # Sends a COPY request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a COPY request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Copy object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.copy('/todos/1')
+    #
     def copy(path, initheader = nil)
       request(Copy.new(path, initheader))
     end
 
-    # Sends a MKCOL request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a MKCOL request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Mkcol object
+    # created from string +path+, string +body+, and initial headers hash +initheader+.
+    #
+    #   data = '{"userId": 1, "id": 1, "title": "delectus aut autem", "completed": false}'
+    #   http.mkcol('/todos/1', data)
+    #   http = Net::HTTP.new(hostname)
+    #
     def mkcol(path, body = nil, initheader = nil)
       request(Mkcol.new(path, initheader), body)
     end
 
-    # Sends a TRACE request to the +path+ and gets a response,
-    # as an HTTPResponse object.
+    # Sends a TRACE request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Trace object
+    # created from string +path+ and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.trace('/todos/1')
+    #
     def trace(path, initheader = nil)
       request(Trace.new(path, initheader))
     end
 
-    # Sends a GET request to the +path+.
-    # Returns the response as a Net::HTTPResponse object.
+    # Sends a GET request to the server;
+    # forms the response into a Net::HTTPResponse object.
     #
-    # When called with a block, passes an HTTPResponse object to the block.
-    # The body of the response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body,
-    # if desired.
+    # The request is based on the Net::HTTP::Get object
+    # created from string +path+ and initial headers hash +initheader+.
     #
-    # Returns the response.
+    # With no block given, returns the response object:
     #
-    # This method never raises Net::* exceptions.
+    #   http = Net::HTTP.new(hostname)
+    #   http.request_get('/todos') # => #<Net::HTTPOK 200 OK readbody=true>
     #
-    #     response = http.request_get('/index.html')
-    #     # The entity body is already read in this case.
-    #     p response['content-type']
-    #     puts response.body
+    # With a block given, calls the block with the response object
+    # and returns the response object:
     #
-    #     # Using a block
-    #     http.request_get('/index.html') {|response|
-    #       p response['content-type']
-    #       response.read_body do |str|   # read body now
-    #         print str
-    #       end
-    #     }
+    #   http.request_get('/todos') do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
+    #
+    #   #<Net::HTTPOK 200 OK readbody=false>
     #
     def request_get(path, initheader = nil, &block) # :yield: +response+
       request(Get.new(path, initheader), &block)
     end
 
-    # Sends a HEAD request to the +path+ and returns the response
-    # as a Net::HTTPResponse object.
-    #
-    # Returns the response.
+    # Sends a HEAD request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # This method never raises Net::* exceptions.
+    # The request is based on the Net::HTTP::Head object
+    # created from string +path+ and initial headers hash +initheader+.
     #
-    #     response = http.request_head('/index.html')
-    #     p response['content-type']
+    #   http = Net::HTTP.new(hostname)
+    #   http.head('/todos/1') # => #<Net::HTTPOK 200 OK readbody=true>
     #
     def request_head(path, initheader = nil, &block)
       request(Head.new(path, initheader), &block)
     end
 
-    # Sends a POST request to the +path+.
+    # Sends a POST request to the server;
+    # forms the response into a Net::HTTPResponse object.
+    #
+    # The request is based on the Net::HTTP::Post object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
     #
-    # Returns the response as a Net::HTTPResponse object.
+    # With no block given, returns the response object:
     #
-    # When called with a block, the block is passed an HTTPResponse
-    # object.  The body of that response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body, if desired.
+    #   http = Net::HTTP.new(hostname)
+    #   http.post('/todos', 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # Returns the response.
+    # With a block given, calls the block with the response body
+    # and returns the response object:
     #
-    # This method never raises Net::* exceptions.
+    #   http.post('/todos', 'xyzzy') do |res|
+    #     p res
+    #   end # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    #     # example
-    #     response = http.request_post('/cgi-bin/nice.rb', 'datadatadata...')
-    #     p response.status
-    #     puts response.body          # body is already read in this case
+    # Output:
     #
-    #     # using block
-    #     http.request_post('/cgi-bin/nice.rb', 'datadatadata...') {|response|
-    #       p response.status
-    #       p response['content-type']
-    #       response.read_body do |str|   # read body now
-    #         print str
-    #       end
-    #     }
+    #   "{\n  \"xyzzy\": \"\",\n  \"id\": 201\n}"
     #
     def request_post(path, data, initheader = nil, &block) # :yield: +response+
       request Post.new(path, initheader), data, &block
     end
 
+    # Sends a PUT request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
+    #
+    # The request is based on the Net::HTTP::Put object
+    # created from string +path+, string +data+, and initial headers hash +initheader+.
+    #
+    #   http = Net::HTTP.new(hostname)
+    #   http.put('/todos/1', 'xyzzy')
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
+    #
     def request_put(path, data, initheader = nil, &block)   #:nodoc:
       request Put.new(path, initheader), data, &block
     end
@@ -1780,16 +2236,25 @@ module Net   #:nodoc:
     alias post2  request_post   #:nodoc: obsolete
     alias put2   request_put    #:nodoc: obsolete
 
-
-    # Sends an HTTP request to the HTTP server.
-    # Also sends a DATA string if +data+ is given.
+    # Sends an \HTTP request to the server;
+    # returns an instance of a subclass of Net::HTTPResponse.
     #
-    # Returns a Net::HTTPResponse object.
+    # The request is based on the Net::HTTPRequest object
+    # created from string +path+, string +data+, and initial headers hash +header+.
+    # That object is an instance of the
+    # {subclass of Net::HTTPRequest}[rdoc-ref:Net::HTTPRequest@Request+Subclasses],
+    # that corresponds to the given uppercase string +name+,
+    # which must be
+    # an {HTTP request method}[https://en.wikipedia.org/wiki/HTTP#Request_methods]
+    # or a {WebDAV request method}[https://en.wikipedia.org/wiki/WebDAV#Implementation].
     #
-    # This method never raises Net::* exceptions.
+    # Examples:
     #
-    #    response = http.send_request('GET', '/index.html')
-    #    puts response.body
+    #   http = Net::HTTP.new(hostname)
+    #   http.send_request('GET', '/todos/1')
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
+    #   http.send_request('POST', '/todos', 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
     def send_request(name, path, data = nil, header = nil)
       has_response_body = name != 'HEAD'
@@ -1797,20 +2262,35 @@ module Net   #:nodoc:
       request r, data
     end
 
-    # Sends an HTTPRequest object +req+ to the HTTP server.
+    # Sends the given request +req+ to the server;
+    # forms the response into a Net::HTTPResponse object.
+    #
+    # The given +req+ must be an instance of a
+    # {subclass of Net::HTTPRequest}[rdoc-ref:Net::HTTPRequest@Request+Subclasses].
+    # Argument +body+ should be given only if needed for the request.
     #
-    # If +req+ is a Net::HTTP::Post or Net::HTTP::Put request containing
-    # data, the data is also sent. Providing data for a Net::HTTP::Head or
-    # Net::HTTP::Get request results in an ArgumentError.
+    # With no block given, returns the response object:
     #
-    # Returns an HTTPResponse object.
+    #   http = Net::HTTP.new(hostname)
+    #
+    #   req = Net::HTTP::Get.new('/todos/1')
+    #   http.request(req)
+    #   # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    #   req = Net::HTTP::Post.new('/todos')
+    #   http.request(req, 'xyzzy')
+    #   # => #<Net::HTTPCreated 201 Created readbody=true>
     #
-    # When called with a block, passes an HTTPResponse object to the block.
-    # The body of the response will not have been read yet;
-    # the block can process it using HTTPResponse#read_body,
-    # if desired.
+    # With a block given, calls the block with the response and returns the response:
+    #
+    #   req = Net::HTTP::Get.new('/todos/1')
+    #   http.request(req) do |res|
+    #     p res
+    #   end # => #<Net::HTTPOK 200 OK readbody=true>
+    #
+    # Output:
     #
-    # This method never raises Net::* exceptions.
+    #   #<Net::HTTPOK 200 OK readbody=false>
     #
     def request(req, body = nil, &block)  # :yield: +response+
       unless started?
diff --git a/lib/net/http/backward.rb b/lib/net/http/backward.rb
index 691e41e4f1..b44577edbd 100644
--- a/lib/net/http/backward.rb
+++ b/lib/net/http/backward.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # for backward compatibility
 
 # :enddoc:
diff --git a/lib/net/http/exceptions.rb b/lib/net/http/exceptions.rb
index 9c425cae16..ceec8f7b0a 100644
--- a/lib/net/http/exceptions.rb
+++ b/lib/net/http/exceptions.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Net
   # Net::HTTP exception class.
   # You cannot use Net::HTTPExceptions directly; instead, you must use
diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
index d56835c76f..44e329a0c8 100644
--- a/lib/net/http/generic_request.rb
+++ b/lib/net/http/generic_request.rb
@@ -1,14 +1,18 @@
-# frozen_string_literal: false
-# HTTPGenericRequest is the parent of the Net::HTTPRequest class.
-# Do not use this directly; use a subclass of Net::HTTPRequest.
+# frozen_string_literal: true
 #
-# Mixes in the Net::HTTPHeader module to provide easier access to HTTP headers.
+# \HTTPGenericRequest is the parent of the Net::HTTPRequest class.
+#
+# Do not use this directly; instead, use a subclass of Net::HTTPRequest.
+#
+# == About the Examples
+#
+# :include: doc/net-http/examples.rdoc
 #
 class Net::HTTPGenericRequest
 
   include Net::HTTPHeader
 
-  def initialize(m, reqbody, resbody, uri_or_path, initheader = nil)
+  def initialize(m, reqbody, resbody, uri_or_path, initheader = nil) # :nodoc:
     @method = m
     @request_has_body = reqbody
     @response_has_body = resbody
@@ -19,7 +23,7 @@ class Net::HTTPGenericRequest
       raise ArgumentError, "no host component for URI" unless (hostname && hostname.length > 0)
       @uri = uri_or_path.dup
       host = @uri.hostname.dup
-      host << ":".freeze << @uri.port.to_s if @uri.port != @uri.default_port
+      host << ":" << @uri.port.to_s if @uri.port != @uri.default_port
       @path = uri_or_path.request_uri
       raise ArgumentError, "no HTTP request path given" unless @path
     else
@@ -53,15 +57,47 @@ class Net::HTTPGenericRequest
     @body_data = nil
   end
 
+  # Returns the string method name for the request:
+  #
+  #   Net::HTTP::Get.new(uri).method  # => "GET"
+  #   Net::HTTP::Post.new(uri).method # => "POST"
+  #
   attr_reader :method
+
+  # Returns the string path for the request:
+  #
+  #   Net::HTTP::Get.new(uri).path # => "/"
+  #   Net::HTTP::Post.new('example.com').path # => "example.com"
+  #
   attr_reader :path
+
+  # Returns the URI object for the request, or +nil+ if none:
+  #
+  #   Net::HTTP::Get.new(uri).uri
+  #   # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
+  #   Net::HTTP::Get.new('example.com').uri # => nil
+  #
   attr_reader :uri
 
-  # Automatically set to false if the user sets the Accept-Encoding header.
-  # This indicates they wish to handle Content-encoding in responses
-  # themselves.
+  # Returns +false+ if the request's header <tt>'Accept-Encoding'</tt>
+  # has been set manually or deleted
+  # (indicating that the user intends to handle encoding in the response),
+  # +true+ otherwise:
+  #
+  #   req = Net::HTTP::Get.new(uri) # => #<Net::HTTP::Get GET>
+  #   req['Accept-Encoding']        # => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
+  #   req.decode_content            # => true
+  #   req['Accept-Encoding'] = 'foo'
+  #   req.decode_content            # => false
+  #   req.delete('Accept-Encoding')
+  #   req.decode_content            # => false
+  #
   attr_reader :decode_content
 
+  # Returns a string representation of the request:
+  #
+  #   Net::HTTP::Post.new(uri).inspect # => "#<Net::HTTP::Post POST>"
+  #
   def inspect
     "\#<#{self.class} #{@method}>"
   end
@@ -76,21 +112,45 @@ class Net::HTTPGenericRequest
     super key, val
   end
 
+  # Returns whether the request may have a body:
+  #
+  #   Net::HTTP::Post.new(uri).request_body_permitted? # => true
+  #   Net::HTTP::Get.new(uri).request_body_permitted?  # => false
+  #
   def request_body_permitted?
     @request_has_body
   end
 
+  # Returns whether the response may have a body:
+  #
+  #   Net::HTTP::Post.new(uri).response_body_permitted? # => true
+  #   Net::HTTP::Head.new(uri).response_body_permitted? # => false
+  #
   def response_body_permitted?
     @response_has_body
   end
 
-  def body_exist?
+  def body_exist? # :nodoc:
     warn "Net::HTTPRequest#body_exist? is obsolete; use response_body_permitted?", uplevel: 1 if $VERBOSE
     response_body_permitted?
   end
 
+  # Returns the string body for the request, or +nil+ if there is none:
+  #
+  #   req = Net::HTTP::Post.new(uri)
+  #   req.body # => nil
+  #   req.body = '{"title": "foo","body": "bar","userId": 1}'
+  #   req.body # => "{\"title\": \"foo\",\"body\": \"bar\",\"userId\": 1}"
+  #
   attr_reader :body
 
+  # Sets the body for the request:
+  #
+  #   req = Net::HTTP::Post.new(uri)
+  #   req.body # => nil
+  #   req.body = '{"title": "foo","body": "bar","userId": 1}'
+  #   req.body # => "{\"title\": \"foo\",\"body\": \"bar\",\"userId\": 1}"
+  #
   def body=(str)
     @body = str
     @body_stream = nil
@@ -98,8 +158,24 @@ class Net::HTTPGenericRequest
     str
   end
 
+  # Returns the body stream object for the request, or +nil+ if there is none:
+  #
+  #   req = Net::HTTP::Post.new(uri)          # => #<Net::HTTP::Post POST>
+  #   req.body_stream                         # => nil
+  #   require 'stringio'
+  #   req.body_stream = StringIO.new('xyzzy') # => #<StringIO:0x0000027d1e5affa8>
+  #   req.body_stream                         # => #<StringIO:0x0000027d1e5affa8>
+  #
   attr_reader :body_stream
 
+  # Sets the body stream for the request:
+  #
+  #   req = Net::HTTP::Post.new(uri)          # => #<Net::HTTP::Post POST>
+  #   req.body_stream                         # => nil
+  #   require 'stringio'
+  #   req.body_stream = StringIO.new('xyzzy') # => #<StringIO:0x0000027d1e5affa8>
+  #   req.body_stream                         # => #<StringIO:0x0000027d1e5affa8>
+  #
   def body_stream=(input)
     @body = nil
     @body_stream = input
@@ -136,15 +212,15 @@ class Net::HTTPGenericRequest
     return unless @uri
 
     if ssl
-      scheme = 'https'.freeze
+      scheme = 'https'
       klass = URI::HTTPS
     else
-      scheme = 'http'.freeze
+      scheme = 'http'
       klass = URI::HTTP
     end
 
     if host = self['host']
-      host.sub!(/:.*/m, ''.freeze)
+      host.sub!(/:.*/m, '')
     elsif host = @uri.host
     else
      host = addr
@@ -240,7 +316,7 @@ class Net::HTTPGenericRequest
     boundary ||= SecureRandom.urlsafe_base64(40)
     chunked_p = chunked?
 
-    buf = ''
+    buf = +''
     params.each do |key, value, h={}|
       key = quote_string(key, charset)
       filename =
@@ -325,7 +401,7 @@ class Net::HTTPGenericRequest
     if /[\r\n]/ =~ reqline
       raise ArgumentError, "A Request-Line must not contain CR or LF"
     end
-    buf = ""
+    buf = +''
     buf << reqline << "\r\n"
     each_capitalized do |k,v|
       buf << "#{k}: #{v}\r\n"
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
index 40c119a353..6660c8075a 100644
--- a/lib/net/http/header.rb
+++ b/lib/net/http/header.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #
 # The \HTTPHeader module provides access to \HTTP headers.
 #
@@ -179,6 +179,8 @@
 # - #each_value: Passes each string field value to the block.
 #
 module Net::HTTPHeader
+  MAX_KEY_LENGTH = 1024
+  MAX_FIELD_LENGTH = 65536
 
   def initialize_http_header(initheader) #:nodoc:
     @header = {}
@@ -189,6 +191,12 @@ module Net::HTTPHeader
         warn "net/http: nil HTTP header: #{key}", uplevel: 3 if $VERBOSE
       else
         value = value.strip # raise error for invalid byte sequences
+        if key.to_s.bytesize > MAX_KEY_LENGTH
+          raise ArgumentError, "too long (#{key.bytesize} bytes) header: #{key[0, 30].inspect}..."
+        end
+        if value.to_s.bytesize > MAX_FIELD_LENGTH
+          raise ArgumentError, "header #{key} has too long field value: #{value.bytesize}"
+        end
         if value.count("\r\n") > 0
           raise ArgumentError, "header #{key} has field value #{value.inspect}, this cannot include CR/LF"
         end
@@ -691,10 +699,14 @@ module Net::HTTPHeader
   #   res.content_type    # => "application/json"
   #
   def content_type
-    return nil unless main_type()
-    if sub_type()
-    then "#{main_type()}/#{sub_type()}"
-    else main_type()
+    main = main_type()
+    return nil unless main
+
+    sub = sub_type()
+    if sub
+      "#{main}/#{sub}"
+    else
+      main
     end
   end
 
@@ -763,19 +775,38 @@ module Net::HTTPHeader
 
   alias content_type= set_content_type
 
-  # Set header fields and a body from HTML form data.
-  # +params+ should be an Array of Arrays or
-  # a Hash containing HTML form data.
-  # Optional argument +sep+ means data record separator.
+  # Sets the request body to a URL-encoded string derived from argument +params+,
+  # and sets request header field <tt>'Content-Type'</tt>
+  # to <tt>'application/x-www-form-urlencoded'</tt>.
+  #
+  # The resulting request is suitable for HTTP request +POST+ or +PUT+.
+  #
+  # Argument +params+ must be suitable for use as argument +enum+ to
+  # {URI.encode_www_form}[rdoc-ref:URI.encode_www_form].
+  #
+  # With only argument +params+ given,
+  # sets the body to a URL-encoded string with the default separator <tt>'&'</tt>:
   #
-  # Values are URL encoded as necessary and the content-type is set to
-  # application/x-www-form-urlencoded
+  #   req = Net::HTTP::Post.new('example.com')
   #
-  # Example:
+  #   req.set_form_data(q: 'ruby', lang: 'en')
+  #   req.body            # => "q=ruby&lang=en"
+  #   req['Content-Type'] # => "application/x-www-form-urlencoded"
   #
-  #    http.form_data = {"q" => "ruby", "lang" => "en"}
-  #    http.form_data = {"q" => ["ruby", "perl"], "lang" => "en"}
-  #    http.set_form_data({"q" => "ruby", "lang" => "en"}, ';')
+  #   req.set_form_data([['q', 'ruby'], ['lang', 'en']])
+  #   req.body            # => "q=ruby&lang=en"
+  #
+  #   req.set_form_data(q: ['ruby', 'perl'], lang: 'en')
+  #   req.body            # => "q=ruby&q=perl&lang=en"
+  #
+  #   req.set_form_data([['q', 'ruby'], ['q', 'perl'], ['lang', 'en']])
+  #   req.body            # => "q=ruby&q=perl&lang=en"
+  #
+  # With string argument +sep+ also given,
+  # uses that string as the separator:
+  #
+  #   req.set_form_data({q: 'ruby', lang: 'en'}, '|')
+  #   req.body # => "q=ruby|lang=en"
   #
   # Net::HTTPHeader#form_data= is an alias for Net::HTTPHeader#set_form_data.
   def set_form_data(params, sep = '&')
@@ -787,56 +818,108 @@ module Net::HTTPHeader
 
   alias form_data= set_form_data
 
-  # Set an HTML form data set.
-  # +params+ :: The form data to set, which should be an enumerable.
-  #             See below for more details.
-  # +enctype+ :: The content type to use to encode the form submission,
-  #              which should be application/x-www-form-urlencoded or
-  #              multipart/form-data.
-  # +formopt+ :: An options hash, supporting the following options:
-  #              :boundary :: The boundary of the multipart message. If
-  #                           not given, a random boundary will be used.
-  #              :charset :: The charset of the form submission. All
-  #                          field names and values of non-file fields
-  #                          should be encoded with this charset.
-  #
-  # Each item of params should respond to +each+ and yield 2-3 arguments,
-  # or an array of 2-3 elements. The arguments yielded should be:
-  #
-  # - The name of the field.
-  # - The value of the field, it should be a String or a File or IO-like.
-  # - An options hash, supporting the following options
-  #   (used only for file uploads); entries:
-  #
-  #   - +:filename+: The name of the file to use.
-  #   - +:content_type+: The content type of the uploaded file.
-  #
-  # Each item is a file field or a normal field.
-  # If +value+ is a File object or the +opt+ hash has a :filename key,
-  # the item is treated as a file field.
-  #
-  # If Transfer-Encoding is set as chunked, this sends the request using
-  # chunked encoding. Because chunked encoding is HTTP/1.1 feature,
-  # you should confirm that the server supports HTTP/1.1 before using
-  # chunked encoding.
-  #
-  # Example:
-  #
-  #    req.set_form([["q", "ruby"], ["lang", "en"]])
-  #
-  #    req.set_form({"f"=>File.open('/path/to/filename')},
-  #                 "multipart/form-data",
-  #                 charset: "UTF-8",
-  #    )
-  #
-  #    req.set_form([["f",
-  #                   File.open('/path/to/filename.bar'),
-  #                   {filename: "other-filename.foo"}
-  #                 ]],
-  #                 "multipart/form-data",
-  #    )
-  #
-  # See also RFC 2388, RFC 2616, HTML 4.01, and HTML5
+  # Stores form data to be used in a +POST+ or +PUT+ request.
+  #
+  # The form data given in +params+ consists of zero or more fields;
+  # each field is:
+  #
+  # - A scalar value.
+  # - A name/value pair.
+  # - An IO stream opened for reading.
+  #
+  # Argument +params+ should be an
+  # {Enumerable}[rdoc-ref:Enumerable@Enumerable+in+Ruby+Classes]
+  # (method <tt>params.map</tt> will be called),
+  # and is often an array or hash.
+  #
+  # First, we set up a request:
+  #
+  #   _uri = uri.dup
+  #   _uri.path ='/posts'
+  #   req = Net::HTTP::Post.new(_uri)
+  #
+  # <b>Argument +params+ As an Array</b>
+  #
+  # When +params+ is an array,
+  # each of its elements is a subarray that defines a field;
+  # the subarray may contain:
+  #
+  # - One string:
+  #
+  #     req.set_form([['foo'], ['bar'], ['baz']])
+  #
+  # - Two strings:
+  #
+  #     req.set_form([%w[foo 0], %w[bar 1], %w[baz 2]])
+  #
+  # - When argument +enctype+ (see below) is given as
+  #   <tt>'multipart/form-data'</tt>:
+  #
+  #   - A string name and an IO stream opened for reading:
+  #
+  #       require 'stringio'
+  #       req.set_form([['file', StringIO.new('Ruby is cool.')]])
+  #
+  #   - A string name, an IO stream opened for reading,
+  #     and an options hash, which may contain these entries:
+  #
+  #     - +:filename+: The name of the file to use.
+  #     - +:content_type+: The content type of the uploaded file.
+  #
+  #     Example:
+  #
+  #       req.set_form([['file', file, {filename: "other-filename.foo"}]]
+  #
+  # The various forms may be mixed:
+  #
+  #   req.set_form(['foo', %w[bar 1], ['file', file]])
+  #
+  # <b>Argument +params+ As a Hash</b>
+  #
+  # When +params+ is a hash,
+  # each of its entries is a name/value pair that defines a field:
+  #
+  # - The name is a string.
+  # - The value may be:
+  #
+  #   - +nil+.
+  #   - Another string.
+  #   - An IO stream opened for reading
+  #     (only when argument +enctype+ -- see below -- is given as
+  #     <tt>'multipart/form-data'</tt>).
+  #
+  # Examples:
+  #
+  #   # Nil-valued fields.
+  #   req.set_form({'foo' => nil, 'bar' => nil, 'baz' => nil})
+  #
+  #   # String-valued fields.
+  #   req.set_form({'foo' => 0, 'bar' => 1, 'baz' => 2})
+  #
+  #   # IO-valued field.
+  #   require 'stringio'
+  #   req.set_form({'file' => StringIO.new('Ruby is cool.')})
+  #
+  #   # Mixture of fields.
+  #   req.set_form({'foo' => nil, 'bar' => 1, 'file' => file})
+  #
+  # Optional argument +enctype+ specifies the value to be given
+  # to field <tt>'Content-Type'</tt>, and must be one of:
+  #
+  # - <tt>'application/x-www-form-urlencoded'</tt> (the default).
+  # - <tt>'multipart/form-data'</tt>;
+  #   see {RFC 7578}[https://www.rfc-editor.org/rfc/rfc7578].
+  #
+  # Optional argument +formopt+ is a hash of options
+  # (applicable only when argument +enctype+
+  # is <tt>'multipart/form-data'</tt>)
+  # that may include the following entries:
+  #
+  # - +:boundary+: The value is the boundary string for the multipart message.
+  #   If not given, the boundary is a random string.
+  #   See {Boundary}[https://www.rfc-editor.org/rfc/rfc7578#section-4.1].
+  # - +:charset+: Value is the character set for the form submission.
+  #   Field names and values of non-file fields should be encoded with this charset.
   #
   def set_form(params, enctype='application/x-www-form-urlencoded', formopt={})
     @body_data = params
@@ -852,12 +935,24 @@ module Net::HTTPHeader
     end
   end
 
-  # Set the Authorization: header for "Basic" authorization.
+  # Sets header <tt>'Authorization'</tt> using the given
+  # +account+ and +password+ strings:
+  #
+  #   req.basic_auth('my_account', 'my_password')
+  #   req['Authorization']
+  #   # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="
+  #
   def basic_auth(account, password)
     @header['authorization'] = [basic_encode(account, password)]
   end
 
-  # Set Proxy-Authorization: header for "Basic" authorization.
+  # Sets header <tt>'Proxy-Authorization'</tt> using the given
+  # +account+ and +password+ strings:
+  #
+  #   req.proxy_basic_auth('my_account', 'my_password')
+  #   req['Proxy-Authorization']
+  #   # => "Basic bXlfYWNjb3VudDpteV9wYXNzd29yZA=="
+  #
   def proxy_basic_auth(account, password)
     @header['proxy-authorization'] = [basic_encode(account, password)]
   end
@@ -867,6 +962,7 @@ module Net::HTTPHeader
   end
   private :basic_encode
 
+# Returns whether the HTTP session is to be closed.
   def connection_close?
     token = /(?:\A|,)\s*close\s*(?:\z|,)/i
     @header['connection']&.grep(token) {return true}
@@ -874,6 +970,7 @@ module Net::HTTPHeader
     false
   end
 
+# Returns whether the HTTP session is to be kept alive.
   def connection_keep_alive?
     token = /(?:\A|,)\s*keep-alive\s*(?:\z|,)/i
     @header['connection']&.grep(token) {return true}
diff --git a/lib/net/http/net-http.gemspec b/lib/net/http/net-http.gemspec
index a7f122fc0e..0021136793 100644
--- a/lib/net/http/net-http.gemspec
+++ b/lib/net/http/net-http.gemspec
@@ -2,9 +2,14 @@
 
 name = File.basename(__FILE__, ".gemspec")
 version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
-  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
-    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
-  end rescue nil
+  file = File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")
+  begin
+    break File.foreach(file, mode: "rb") do |line|
+      /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+    end
+  rescue SystemCallError
+    next
+  end
 end
 
 Gem::Specification.new do |spec|
@@ -25,7 +30,7 @@ Gem::Specification.new do |spec|
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
-    `git ls-files -z 2>/dev/null`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+    `git ls-files -z 2>#{IO::NULL}`.split("\x0").reject { |f| f.match(%r{\A(?:(?:test|spec|features)/|\.git)}) }
   end
   spec.bindir        = "exe"
   spec.require_paths = ["lib"]
diff --git a/lib/net/http/proxy_delta.rb b/lib/net/http/proxy_delta.rb
index a2f770ebdb..e7d30def64 100644
--- a/lib/net/http/proxy_delta.rb
+++ b/lib/net/http/proxy_delta.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Net::HTTP::ProxyDelta   #:nodoc: internal use only
   private
 
diff --git a/lib/net/http/request.rb b/lib/net/http/request.rb
index f3d32edb62..4a138572e9 100644
--- a/lib/net/http/request.rb
+++ b/lib/net/http/request.rb
@@ -1,10 +1,55 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
-# This class is the base class for \Net::HTTP request classes;
-# it wraps together the request path and the request headers.
-#
+# This class is the base class for \Net::HTTP request classes.
 # The class should not be used directly;
-# instead you should use its subclasses.
+# instead you should use its subclasses, listed below.
+#
+# == Creating a Request
+#
+# An request object may be created with either a URI or a string hostname:
+#
+#   require 'net/http'
+#   uri = URI('https://jsonplaceholder.typicode.com/')
+#   req = Net::HTTP::Get.new(uri)          # => #<Net::HTTP::Get GET>
+#   req = Net::HTTP::Get.new(uri.hostname) # => #<Net::HTTP::Get GET>
+#
+# And with any of the subclasses:
+#
+#   req = Net::HTTP::Head.new(uri) # => #<Net::HTTP::Head HEAD>
+#   req = Net::HTTP::Post.new(uri) # => #<Net::HTTP::Post POST>
+#   req = Net::HTTP::Put.new(uri)  # => #<Net::HTTP::Put PUT>
+#   # ...
+#
+# The new instance is suitable for use as the argument to Net::HTTP#request.
+#
+# == Request Headers
+#
+# A new request object has these header fields by default:
+#
+#   req.to_hash
+#   # =>
+#   {"accept-encoding"=>["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"],
+#   "accept"=>["*/*"],
+#   "user-agent"=>["Ruby"],
+#   "host"=>["jsonplaceholder.typicode.com"]}
+#
+# See:
+#
+# - {Request header Accept-Encoding}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Accept-Encoding]
+#   and {Compression and Decompression}[rdoc-ref:Net::HTTP@Compression+and+Decompression].
+# - {Request header Accept}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#accept-request-header].
+# - {Request header User-Agent}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#user-agent-request-header].
+# - {Request header Host}[https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#host-request-header].
+#
+# You can add headers or override default headers:
+#
+#   #   res = Net::HTTP::Get.new(uri, {'foo' => '0', 'bar' => '1'})
+#
+# This class (and therefore its subclasses) also includes (indirectly)
+# module Net::HTTPHeader, which gives access to its
+# {methods for setting headers}[rdoc-ref:Net::HTTPHeader@Setters].
+#
+# == Request Subclasses
 #
 # Subclasses for HTTP requests:
 #
diff --git a/lib/net/http/requests.rb b/lib/net/http/requests.rb
index 294b8e8841..5724164205 100644
--- a/lib/net/http/requests.rb
+++ b/lib/net/http/requests.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
 # HTTP/1.1 methods --- RFC2616
 
@@ -13,6 +13,8 @@
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: optional.
@@ -43,6 +45,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: optional.
@@ -75,6 +79,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: yes.
@@ -108,6 +114,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: yes.
@@ -134,6 +142,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: optional.
@@ -163,6 +173,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: optional.
@@ -192,6 +204,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: no.
@@ -224,6 +238,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Properties:
 #
 # - Request body: yes.
@@ -257,6 +273,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#propfind: sends +PROPFIND+ request, returns response object.
@@ -278,6 +296,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#proppatch: sends +PROPPATCH+ request, returns response object.
@@ -299,6 +319,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#mkcol: sends +MKCOL+ request, returns response object.
@@ -320,6 +342,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#copy: sends +COPY+ request, returns response object.
@@ -341,6 +365,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#move: sends +MOVE+ request, returns response object.
@@ -362,6 +388,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#lock: sends +LOCK+ request, returns response object.
@@ -383,6 +411,8 @@ end
 #     http.request(req)
 #   end
 #
+# See {Request Headers}[rdoc-ref:Net::HTTPRequest@Request+Headers].
+#
 # Related:
 #
 # - Net::HTTP#unlock: sends +UNLOCK+ request, returns response object.
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
index 83853ffd19..40de963868 100644
--- a/lib/net/http/response.rb
+++ b/lib/net/http/response.rb
@@ -1,6 +1,6 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
-# This class is the base class for \Net::HTTP request classes.
+# This class is the base class for \Net::HTTP response classes.
 #
 # == About the Examples
 #
@@ -224,13 +224,32 @@ class Net::HTTPResponse
   # Accept-Encoding header from the user.
   attr_accessor :decode_content
 
-  # The encoding to use for the response body. If Encoding, use that encoding.
-  # If other true value, attempt to detect the appropriate encoding, and use
-  # that.
+  # Returns the value set by body_encoding=, or +false+ if none;
+  # see #body_encoding=.
   attr_reader :body_encoding
 
-  # Set the encoding to use for the response body.  If given a String, find
-  # the related Encoding.
+  # Sets the encoding that should be used when reading the body:
+  #
+  # - If the given value is an Encoding object, that encoding will be used.
+  # - Otherwise if the value is a string, the value of
+  #   {Encoding#find(value)}[rdoc-ref:Encoding.find]
+  #   will be used.
+  # - Otherwise an encoding will be deduced from the body itself.
+  #
+  # Examples:
+  #
+  #   http = Net::HTTP.new(hostname)
+  #   req = Net::HTTP::Get.new('/')
+  #
+  #   http.request(req) do |res|
+  #     p res.body.encoding # => #<Encoding:ASCII-8BIT>
+  #   end
+  #
+  #   http.request(req) do |res|
+  #     res.body_encoding = "UTF-8"
+  #     p res.body.encoding # => #<Encoding:UTF-8>
+  #   end
+  #
   def body_encoding=(value)
     value = Encoding.find(value) if value.is_a?(String)
     @body_encoding = value
@@ -254,7 +273,7 @@ class Net::HTTPResponse
 
   def error!   #:nodoc:
     message = @code
-    message += ' ' + @message.dump if @message
+    message = "#{message} #{@message.dump}" if @message
     raise error_type().new(message, self)
   end
 
@@ -347,6 +366,7 @@ class Net::HTTPResponse
       @body = nil
     end
     @read = true
+    return if @body.nil?
 
     case enc = @body_encoding
     when Encoding, false, nil
@@ -362,26 +382,26 @@ class Net::HTTPResponse
     @body
   end
 
-  # Returns the full entity body.
+  # Returns the string response body;
+  # note that repeated calls for the unmodified body return a cached string:
   #
-  # Calling this method a second or subsequent time will return the
-  # string already read.
+  #   path = '/todos/1'
+  #   Net::HTTP.start(hostname) do |http|
+  #     res = http.get(path)
+  #     p res.body
+  #     p http.head(path).body # No body.
+  #   end
   #
-  #   http.request_get('/index.html') {|res|
-  #     puts res.body
-  #   }
+  # Output:
   #
-  #   http.request_get('/index.html') {|res|
-  #     p res.body.object_id   # 538149362
-  #     p res.body.object_id   # 538149362
-  #   }
+  #   "{\n  \"userId\": 1,\n  \"id\": 1,\n  \"title\": \"delectus aut autem\",\n  \"completed\": false\n}"
+  #   nil
   #
   def body
     read_body()
   end
 
-  # Because it may be necessary to modify the body, Eg, decompression
-  # this method facilitates that.
+  # Sets the body of the response to the given value.
   def body=(value)
     @body = value
   end
@@ -620,7 +640,7 @@ class Net::HTTPResponse
   end
 
   def stream_check
-    raise IOError, 'attempt to read body out of block' if @socket.closed?
+    raise IOError, 'attempt to read body out of block' if @socket.nil? || @socket.closed?
   end
 
   def procdest(dest, block)
@@ -629,7 +649,7 @@ class Net::HTTPResponse
     if block
       Net::ReadAdapter.new(block)
     else
-      dest || ''
+      dest || +''
     end
   end
 
diff --git a/lib/net/http/responses.rb b/lib/net/http/responses.rb
index b2dad10537..6f6fb8d055 100644
--- a/lib/net/http/responses.rb
+++ b/lib/net/http/responses.rb
@@ -85,6 +85,8 @@ module Net
   #
   # A +Continue+ response indicates that the server has received the request headers.
   #
+  # :include: doc/net-http/included_getters.rdoc
+  #
   # References:
   #
   # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/100].
@@ -100,6 +102,8 @@ module Net
   # The <tt>Switching Protocol<tt> response indicates that the server has received
   # a request to switch protocols, and has agreed to do so.
   #
+  # :include: doc/net-http/included_getters.rdoc
+  #
   # References:
   #
   # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101].
@@ -115,8 +119,11 @@ module Net
   # The +Processing+ response indicates that the server has received
   # and is processing the request, but no response is available yet.
   #
+  # :include: doc/net-http/included_getters.rdoc
+  #
   # References:
   #
+  # - {RFC 2518}[https://www.rfc-editor.org/rfc/rfc2518#section-10.1].
   # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#102].
   #
   class HTTPProcessing < HTTPInformation
@@ -129,9 +136,12 @@ module Net
   # and is processing the request, and contains certain headers;
   # the final response is not available yet.
   #
+  # :include: doc/net-http/included_getters.rdoc
+  #
   # References:
   #
   # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/103].
+  # - {RFC 8297}[https://www.rfc-editor.org/rfc/rfc8297.html#section-2].
   # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#103].
   #
   class HTTPEarlyHints < HTTPInformation
@@ -142,7 +152,15 @@ module Net
   #
   # The +OK+ response indicates that the server has received
   # a request and has responded successfully.
-  # See {200 OK}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#200].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/200].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-200-ok].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#200].
+  #
   class HTTPOK < HTTPSuccess
     HAS_BODY = true
   end
@@ -151,7 +169,15 @@ module Net
   #
   # The +Created+ response indicates that the server has received
   # and has fulfilled a request to create a new resource.
-  # See {201 Created}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#201].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/201].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-201-created].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#201].
+  #
   class HTTPCreated < HTTPSuccess
     HAS_BODY = true
   end
@@ -160,7 +186,15 @@ module Net
   #
   # The +Accepted+ response indicates that the server has received
   # and is processing a request, but the processing has not yet been completed.
-  # See {202 Accepted}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#202].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/202].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-202-accepted].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#202].
+  #
   class HTTPAccepted < HTTPSuccess
     HAS_BODY = true
   end
@@ -171,7 +205,15 @@ module Net
   # is a transforming proxy (such as a Web accelerator)
   # that received a 200 OK response from its origin,
   # and is returning a modified version of the origin's response.
-  # See {203 Non-Authoritative Information}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#203].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/203].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-203-non-authoritative-infor].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#203].
+  #
   class HTTPNonAuthoritativeInformation < HTTPSuccess
     HAS_BODY = true
   end
@@ -180,7 +222,15 @@ module Net
   #
   # The <tt>No Content</tt> response indicates that the server
   # successfully processed the request, and is not returning any content.
-  # See {204 No Content}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#204].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/204].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-204-no-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#204].
+  #
   class HTTPNoContent < HTTPSuccess
     HAS_BODY = false
   end
@@ -190,7 +240,15 @@ module Net
   # The <tt>Reset Content</tt> response indicates that the server
   # successfully processed the request,
   # asks that the client reset its document view, and is not returning any content.
-  # See {205 Reset Content}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#205].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/205].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-205-reset-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#205].
+  #
   class HTTPResetContent < HTTPSuccess
     HAS_BODY = false
   end
@@ -200,7 +258,15 @@ module Net
   # The <tt>Partial Content</tt> response indicates that the server is delivering
   # only part of the resource (byte serving)
   # due to a Range header in the request.
-  # See {206 Partial Content}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#206].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/206].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-206-partial-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#206].
+  #
   class HTTPPartialContent < HTTPSuccess
     HAS_BODY = true
   end
@@ -210,7 +276,14 @@ module Net
   # The <tt>Multi-Status (WebDAV)</tt> response indicates that the server
   # has received the request,
   # and that the message body can contain a number of separate response codes.
-  # See {207 Multi-Status (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#207].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4818}[https://www.rfc-editor.org/rfc/rfc4918#section-11.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#207].
+  #
   class HTTPMultiStatus < HTTPSuccess
     HAS_BODY = true
   end
@@ -222,7 +295,14 @@ module Net
   # and that the members of a DAV binding have already been enumerated
   # in a preceding part of the (multi-status) response,
   # and are not being included again.
-  # See {208 Already Reported (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#208].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 5842}[https://www.rfc-editor.org/rfc/rfc5842.html#section-7.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#208].
+  #
   class HTTPAlreadyReported < HTTPSuccess
     HAS_BODY = true
   end
@@ -232,7 +312,14 @@ module Net
   # The <tt>IM Used</tt> response indicates that the server has fulfilled a request
   # for the resource, and the response is a representation of the result
   # of one or more instance-manipulations applied to the current instance.
-  # See {226 IM Used}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#226].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 3229}[https://www.rfc-editor.org/rfc/rfc3229.html#section-10.4.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#226].
+  #
   class HTTPIMUsed < HTTPSuccess
     HAS_BODY = true
   end
@@ -241,7 +328,15 @@ module Net
   #
   # The <tt>Multiple Choices</tt> response indicates that the server
   # offers multiple options for the resource from which the client may choose.
-  # See {300 Multiple Choices}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#300].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/300].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-300-multiple-choices].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#300].
+  #
   class HTTPMultipleChoices < HTTPRedirection
     HAS_BODY = true
   end
@@ -251,7 +346,15 @@ module Net
   #
   # The <tt>Moved Permanently</tt> response indicates that links or records
   # returning this response should be updated to use the given URL.
-  # See {301 Moved Permanently}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#301].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/301].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-301-moved-permanently].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#301].
+  #
   class HTTPMovedPermanently < HTTPRedirection
     HAS_BODY = true
   end
@@ -260,7 +363,15 @@ module Net
   #
   # The <tt>Found</tt> response indicates that the client
   # should look at (browse to) another URL.
-  # See {302 Found}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#302].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/302].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-302-found].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#302].
+  #
   class HTTPFound < HTTPRedirection
     HAS_BODY = true
   end
@@ -269,7 +380,15 @@ module Net
   # Response class for <tt>See Other</tt> responses (status code 303).
   #
   # The response to the request can be found under another URI using the GET method.
-  # See {303 See Other}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#303].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/303].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-303-see-other].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#303].
+  #
   class HTTPSeeOther < HTTPRedirection
     HAS_BODY = true
   end
@@ -278,7 +397,15 @@ module Net
   #
   # Indicates that the resource has not been modified since the version
   # specified by the request headers.
-  # See {304 Not Modified}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#304].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/304].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-304-not-modified].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#304].
+  #
   class HTTPNotModified < HTTPRedirection
     HAS_BODY = false
   end
@@ -287,7 +414,14 @@ module Net
   #
   # The requested resource is available only through a proxy,
   # whose address is provided in the response.
-  # See {305 Use Proxy}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#305].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-305-use-proxy].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#305].
+  #
   class HTTPUseProxy < HTTPRedirection
     HAS_BODY = false
   end
@@ -296,7 +430,15 @@ module Net
   #
   # The request should be repeated with another URI;
   # however, future requests should still use the original URI.
-  # See {307 Temporary Redirect}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#307].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/307].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-307-temporary-redirect].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#307].
+  #
   class HTTPTemporaryRedirect < HTTPRedirection
     HAS_BODY = true
   end
@@ -304,7 +446,15 @@ module Net
   # Response class for <tt>Permanent Redirect</tt> responses (status code 308).
   #
   # This and all future requests should be directed to the given URI.
-  # See {308 Permanent Redirect}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#308].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-308-permanent-redirect].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#308].
+  #
   class HTTPPermanentRedirect < HTTPRedirection
     HAS_BODY = true
   end
@@ -312,7 +462,15 @@ module Net
   # Response class for <tt>Bad Request</tt> responses (status code 400).
   #
   # The server cannot or will not process the request due to an apparent client error.
-  # See {400 Bad Request}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#400].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-400-bad-request].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#400].
+  #
   class HTTPBadRequest < HTTPClientError
     HAS_BODY = true
   end
@@ -320,7 +478,15 @@ module Net
   # Response class for <tt>Unauthorized</tt> responses (status code 401).
   #
   # Authentication is required, but either was not provided or failed.
-  # See {401 Unauthorized}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#401].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/401].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-401-unauthorized].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#401].
+  #
   class HTTPUnauthorized < HTTPClientError
     HAS_BODY = true
   end
@@ -328,7 +494,15 @@ module Net
   # Response class for <tt>Payment Required</tt> responses (status code 402).
   #
   # Reserved for future use.
-  # See {402 Payment Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#402].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/402].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-402-payment-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#402].
+  #
   class HTTPPaymentRequired < HTTPClientError
     HAS_BODY = true
   end
@@ -337,7 +511,15 @@ module Net
   #
   # The request contained valid data and was understood by the server,
   # but the server is refusing action.
-  # See {403 Forbidden}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#403].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/403].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-403-forbidden].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#403].
+  #
   class HTTPForbidden < HTTPClientError
     HAS_BODY = true
   end
@@ -345,7 +527,15 @@ module Net
   # Response class for <tt>Not Found</tt> responses (status code 404).
   #
   # The requested resource could not be found but may be available in the future.
-  # See {404 Not Found}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#404].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/404].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-404-not-found].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#404].
+  #
   class HTTPNotFound < HTTPClientError
     HAS_BODY = true
   end
@@ -353,7 +543,15 @@ module Net
   # Response class for <tt>Method Not Allowed</tt> responses (status code 405).
   #
   # The request method is not supported for the requested resource.
-  # See {405 Method Not Allowed}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#405].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/405].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-405-method-not-allowed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#405].
+  #
   class HTTPMethodNotAllowed < HTTPClientError
     HAS_BODY = true
   end
@@ -362,7 +560,15 @@ module Net
   #
   # The requested resource is capable of generating only content
   # that not acceptable according to the Accept headers sent in the request.
-  # See {406 Not Acceptable}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#406].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/406].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-406-not-acceptable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#406].
+  #
   class HTTPNotAcceptable < HTTPClientError
     HAS_BODY = true
   end
@@ -370,7 +576,15 @@ module Net
   # Response class for <tt>Proxy Authentication Required</tt> responses (status code 407).
   #
   # The client must first authenticate itself with the proxy.
-  # See {407 Proxy Authentication Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#407].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/407].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-407-proxy-authentication-re].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#407].
+  #
   class HTTPProxyAuthenticationRequired < HTTPClientError
     HAS_BODY = true
   end
@@ -378,7 +592,15 @@ module Net
   # Response class for <tt>Request Timeout</tt> responses (status code 408).
   #
   # The server timed out waiting for the request.
-  # See {408 Request Timeout}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#408].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/408].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-408-request-timeout].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#408].
+  #
   class HTTPRequestTimeout < HTTPClientError
     HAS_BODY = true
   end
@@ -387,7 +609,15 @@ module Net
   # Response class for <tt>Conflict</tt> responses (status code 409).
   #
   # The request could not be processed because of conflict in the current state of the resource.
-  # See {409 Conflict}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#409].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/409].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-409-conflict].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#409].
+  #
   class HTTPConflict < HTTPClientError
     HAS_BODY = true
   end
@@ -396,7 +626,15 @@ module Net
   #
   # The resource requested was previously in use but is no longer available
   # and will not be available again.
-  # See {410 Gone}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#410].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/410].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-410-gone].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#410].
+  #
   class HTTPGone < HTTPClientError
     HAS_BODY = true
   end
@@ -405,7 +643,15 @@ module Net
   #
   # The request did not specify the length of its content,
   # which is required by the requested resource.
-  # See {411 Length Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#411].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/411].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-411-length-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#411].
+  #
   class HTTPLengthRequired < HTTPClientError
     HAS_BODY = true
   end
@@ -414,7 +660,15 @@ module Net
   #
   # The server does not meet one of the preconditions
   # specified in the request headers.
-  # See {412 Precondition Failed}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#412].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/412].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-412-precondition-failed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#412].
+  #
   class HTTPPreconditionFailed < HTTPClientError
     HAS_BODY = true
   end
@@ -422,7 +676,15 @@ module Net
   # Response class for <tt>Payload Too Large</tt> responses (status code 413).
   #
   # The request is larger than the server is willing or able to process.
-  # See {413 Payload Too Large}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#413].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/413].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-413-content-too-large].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#413].
+  #
   class HTTPPayloadTooLarge < HTTPClientError
     HAS_BODY = true
   end
@@ -431,7 +693,15 @@ module Net
   # Response class for <tt>URI Too Long</tt> responses (status code 414).
   #
   # The URI provided was too long for the server to process.
-  # See {414 URI Too Long}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#414].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/414].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-414-uri-too-long].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#414].
+  #
   class HTTPURITooLong < HTTPClientError
     HAS_BODY = true
   end
@@ -441,7 +711,15 @@ module Net
   # Response class for <tt>Unsupported Media Type</tt> responses (status code 415).
   #
   # The request entity has a media type which the server or resource does not support.
-  # See {415 Unsupported Media Type}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#415].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/415].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-415-unsupported-media-type].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#415].
+  #
   class HTTPUnsupportedMediaType < HTTPClientError
     HAS_BODY = true
   end
@@ -449,7 +727,15 @@ module Net
   # Response class for <tt>Range Not Satisfiable</tt> responses (status code 416).
   #
   # The request entity has a media type which the server or resource does not support.
-  # See {416 Range Not Satisfiable}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#416].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/416].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-416-range-not-satisfiable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#416].
+  #
   class HTTPRangeNotSatisfiable < HTTPClientError
     HAS_BODY = true
   end
@@ -458,7 +744,15 @@ module Net
   # Response class for <tt>Expectation Failed</tt> responses (status code 417).
   #
   # The server cannot meet the requirements of the Expect request-header field.
-  # See {417 Expectation Failed}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#417].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/417].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-417-expectation-failed].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#417].
+  #
   class HTTPExpectationFailed < HTTPClientError
     HAS_BODY = true
   end
@@ -471,7 +765,14 @@ module Net
   # Response class for <tt>Misdirected Request</tt> responses (status code 421).
   #
   # The request was directed at a server that is not able to produce a response.
-  # See {421 Misdirected Request}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#421].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-421-misdirected-request].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#421].
+  #
   class HTTPMisdirectedRequest < HTTPClientError
     HAS_BODY = true
   end
@@ -479,7 +780,15 @@ module Net
   # Response class for <tt>Unprocessable Entity</tt> responses (status code 422).
   #
   # The request was well-formed but had semantic errors.
-  # See {422 Unprocessable Entity}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#422].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/422].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-422-unprocessable-content].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#422].
+  #
   class HTTPUnprocessableEntity < HTTPClientError
     HAS_BODY = true
   end
@@ -487,7 +796,14 @@ module Net
   # Response class for <tt>Locked (WebDAV)</tt> responses (status code 423).
   #
   # The requested resource is locked.
-  # See {423 Locked (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#423].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#423].
+  #
   class HTTPLocked < HTTPClientError
     HAS_BODY = true
   end
@@ -496,6 +812,14 @@ module Net
   #
   # The request failed because it depended on another request and that request failed.
   # See {424 Failed Dependency (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#424].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.4].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#424].
+  #
   class HTTPFailedDependency < HTTPClientError
     HAS_BODY = true
   end
@@ -506,7 +830,15 @@ module Net
   # Response class for <tt>Upgrade Required</tt> responses (status code 426).
   #
   # The client should switch to the protocol given in the Upgrade header field.
-  # See {426 Upgrade Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#426].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/426].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-426-upgrade-required].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#426].
+  #
   class HTTPUpgradeRequired < HTTPClientError
     HAS_BODY = true
   end
@@ -514,7 +846,15 @@ module Net
   # Response class for <tt>Precondition Required</tt> responses (status code 428).
   #
   # The origin server requires the request to be conditional.
-  # See {428 Precondition Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#428].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/428].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#428].
+  #
   class HTTPPreconditionRequired < HTTPClientError
     HAS_BODY = true
   end
@@ -522,7 +862,15 @@ module Net
   # Response class for <tt>Too Many Requests</tt> responses (status code 429).
   #
   # The user has sent too many requests in a given amount of time.
-  # See {429 Too Many Requests}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#429].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/429].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-4].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#429].
+  #
   class HTTPTooManyRequests < HTTPClientError
     HAS_BODY = true
   end
@@ -531,7 +879,15 @@ module Net
   #
   # An individual header field is too large,
   # or all the header fields collectively, are too large.
-  # See {431 Request Header Fields Too Large}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#431].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/431].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-5].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#431].
+  #
   class HTTPRequestHeaderFieldsTooLarge < HTTPClientError
     HAS_BODY = true
   end
@@ -540,7 +896,15 @@ module Net
   #
   # A server operator has received a legal demand to deny access to a resource or to a set of resources
   # that includes the requested resource.
-  # See {451 Unavailable For Legal Reasons}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#451].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/451].
+  # - {RFC 7725}[https://www.rfc-editor.org/rfc/rfc7725.html#section-3].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#451].
+  #
   class HTTPUnavailableForLegalReasons < HTTPClientError
     HAS_BODY = true
   end
@@ -552,7 +916,15 @@ module Net
   # Response class for <tt>Internal Server Error</tt> responses (status code 500).
   #
   # An unexpected condition was encountered and no more specific message is suitable.
-  # See {500 Internal Server Error}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#500].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/500].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-500-internal-server-error].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#500].
+  #
   class HTTPInternalServerError < HTTPServerError
     HAS_BODY = true
   end
@@ -561,7 +933,15 @@ module Net
   #
   # The server either does not recognize the request method,
   # or it lacks the ability to fulfil the request.
-  # See {501 Not Implemented}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#501].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/501].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-501-not-implemented].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#501].
+  #
   class HTTPNotImplemented < HTTPServerError
     HAS_BODY = true
   end
@@ -570,7 +950,15 @@ module Net
   #
   # The server was acting as a gateway or proxy
   # and received an invalid response from the upstream server.
-  # See {502 Bad Gateway}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#502].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/502].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-502-bad-gateway].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#502].
+  #
   class HTTPBadGateway < HTTPServerError
     HAS_BODY = true
   end
@@ -579,7 +967,15 @@ module Net
   #
   # The server cannot handle the request
   # (because it is overloaded or down for maintenance).
-  # See {503 Service Unavailable}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#503].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/503].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-503-service-unavailable].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#503].
+  #
   class HTTPServiceUnavailable < HTTPServerError
     HAS_BODY = true
   end
@@ -588,7 +984,15 @@ module Net
   #
   # The server was acting as a gateway or proxy
   # and did not receive a timely response from the upstream server.
-  # See {504 Gateway Timeout}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#504].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/504].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-504-gateway-timeout].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#504].
+  #
   class HTTPGatewayTimeout < HTTPServerError
     HAS_BODY = true
   end
@@ -597,7 +1001,15 @@ module Net
   # Response class for <tt>HTTP Version Not Supported</tt> responses (status code 505).
   #
   # The server does not support the HTTP version used in the request.
-  # See {505 HTTP Version Not Supported}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#505].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/505].
+  # - {RFC 9110}[https://www.rfc-editor.org/rfc/rfc9110.html#name-505-http-version-not-suppor].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#505].
+  #
   class HTTPVersionNotSupported < HTTPServerError
     HAS_BODY = true
   end
@@ -605,7 +1017,15 @@ module Net
   # Response class for <tt>Variant Also Negotiates</tt> responses (status code 506).
   #
   # Transparent content negotiation for the request results in a circular reference.
-  # See {506 Variant Also Negotiates}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#506].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/506].
+  # - {RFC 2295}[https://www.rfc-editor.org/rfc/rfc2295#section-8.1].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#506].
+  #
   class HTTPVariantAlsoNegotiates < HTTPServerError
     HAS_BODY = true
   end
@@ -613,7 +1033,15 @@ module Net
   # Response class for <tt>Insufficient Storage (WebDAV)</tt> responses (status code 507).
   #
   # The server is unable to store the representation needed to complete the request.
-  # See {507 Insufficient Storage (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#507].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/507].
+  # - {RFC 4918}[https://www.rfc-editor.org/rfc/rfc4918#section-11.5].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#507].
+  #
   class HTTPInsufficientStorage < HTTPServerError
     HAS_BODY = true
   end
@@ -621,7 +1049,15 @@ module Net
   # Response class for <tt>Loop Detected (WebDAV)</tt> responses (status code 508).
   #
   # The server detected an infinite loop while processing the request.
-  # See {508 Loop Detected (WebDAV)}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#508].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/508].
+  # - {RFC 5942}[https://www.rfc-editor.org/rfc/rfc5842.html#section-7.2].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#508].
+  #
   class HTTPLoopDetected < HTTPServerError
     HAS_BODY = true
   end
@@ -630,7 +1066,15 @@ module Net
   # Response class for <tt>Not Extended</tt> responses (status code 510).
   #
   # Further extensions to the request are required for the server to fulfill it.
-  # See {510 Not Extended}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#510].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/510].
+  # - {RFC 2774}[https://www.rfc-editor.org/rfc/rfc2774.html#section-7].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#510].
+  #
   class HTTPNotExtended < HTTPServerError
     HAS_BODY = true
   end
@@ -638,7 +1082,15 @@ module Net
   # Response class for <tt>Network Authentication Required</tt> responses (status code 511).
   #
   # The client needs to authenticate to gain network access.
-  # See {511 Network Authentication Required}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#511].
+  #
+  # :include: doc/net-http/included_getters.rdoc
+  #
+  # References:
+  #
+  # - {Mozilla}[https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/511].
+  # - {RFC 6585}[https://www.rfc-editor.org/rfc/rfc6585#section-6].
+  # - {Wikipedia}[https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#511].
+  #
   class HTTPNetworkAuthenticationRequired < HTTPServerError
     HAS_BODY = true
   end
diff --git a/lib/net/http/status.rb b/lib/net/http/status.rb
index 8db3f7d9e3..e70b47d9fb 100644
--- a/lib/net/http/status.rb
+++ b/lib/net/http/status.rb
@@ -4,7 +4,7 @@ require_relative '../http'
 
 if $0 == __FILE__
   require 'open-uri'
-  IO.foreach(__FILE__) do |line|
+  File.foreach(__FILE__) do |line|
     puts line
     break if line.start_with?('end')
   end
@@ -16,7 +16,7 @@ if $0 == __FILE__
     next if ['(Unused)', 'Unassigned', 'Description'].include?(mes)
     puts "  #{code} => '#{mes}',"
   end
-  puts "}"
+  puts "} # :nodoc:"
 end
 
 Net::HTTP::STATUS_CODES = {
@@ -55,15 +55,16 @@ Net::HTTP::STATUS_CODES = {
   410 => 'Gone',
   411 => 'Length Required',
   412 => 'Precondition Failed',
-  413 => 'Payload Too Large',
+  413 => 'Content Too Large',
   414 => 'URI Too Long',
   415 => 'Unsupported Media Type',
   416 => 'Range Not Satisfiable',
   417 => 'Expectation Failed',
   421 => 'Misdirected Request',
-  422 => 'Unprocessable Entity',
+  422 => 'Unprocessable Content',
   423 => 'Locked',
   424 => 'Failed Dependency',
+  425 => 'Too Early',
   426 => 'Upgrade Required',
   428 => 'Precondition Required',
   429 => 'Too Many Requests',
@@ -78,6 +79,6 @@ Net::HTTP::STATUS_CODES = {
   506 => 'Variant Also Negotiates',
   507 => 'Insufficient Storage',
   508 => 'Loop Detected',
-  510 => 'Not Extended',
+  510 => 'Not Extended (OBSOLETED)',
   511 => 'Network Authentication Required',
-}
+} # :nodoc:
diff --git a/lib/net/https.rb b/lib/net/https.rb
index d46721c82a..0f23e1fb13 100644
--- a/lib/net/https.rb
+++ b/lib/net/https.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 =begin
 
 = net/https -- SSL/TLS enhancement for Net::HTTP.
diff --git a/lib/rdoc/store.rb b/lib/rdoc/store.rb
index 9fc540d317..c793e49ed8 100644
--- a/lib/rdoc/store.rb
+++ b/lib/rdoc/store.rb
@@ -556,9 +556,7 @@ class RDoc::Store
   def load_cache
     #orig_enc = @encoding
 
-    File.open cache_path, 'rb' do |io|
-      @cache = Marshal.load io
-    end
+    @cache = marshal_load(cache_path)
 
     load_enc = @cache[:encoding]
 
@@ -615,9 +613,7 @@ class RDoc::Store
   def load_class_data klass_name
     file = class_file klass_name
 
-    File.open file, 'rb' do |io|
-      Marshal.load io
-    end
+    marshal_load(file)
   rescue Errno::ENOENT => e
     error = MissingFileError.new(self, file, klass_name)
     error.set_backtrace e.backtrace
@@ -630,14 +626,10 @@ class RDoc::Store
   def load_method klass_name, method_name
     file = method_file klass_name, method_name
 
-    File.open file, 'rb' do |io|
-      obj = Marshal.load io
-      obj.store = self
-      obj.parent =
-        find_class_or_module(klass_name) || load_class(klass_name) unless
-          obj.parent
-      obj
-    end
+    obj = marshal_load(file)
+    obj.store = self
+    obj.parent ||= find_class_or_module(klass_name) || load_class(klass_name)
+    obj
   rescue Errno::ENOENT => e
     error = MissingFileError.new(self, file, klass_name + method_name)
     error.set_backtrace e.backtrace
@@ -650,11 +642,9 @@ class RDoc::Store
   def load_page page_name
     file = page_file page_name
 
-    File.open file, 'rb' do |io|
-      obj = Marshal.load io
-      obj.store = self
-      obj
-    end
+    obj = marshal_load(file)
+    obj.store = self
+    obj
   rescue Errno::ENOENT => e
     error = MissingFileError.new(self, file, page_name)
     error.set_backtrace e.backtrace
@@ -976,4 +966,21 @@ class RDoc::Store
     @unique_modules
   end
 
+  private
+  def marshal_load(file)
+    File.open(file, 'rb') {|io| Marshal.load(io, MarshalFilter)}
+  end
+
+  MarshalFilter = proc do |obj|
+    case obj
+    when true, false, nil, Array, Class, Encoding, Hash, Integer, String, Symbol, RDoc::Text
+    else
+      unless obj.class.name.start_with?("RDoc::")
+        raise TypeError, "not permitted class: #{obj.class.name}"
+      end
+    end
+    obj
+  end
+  private_constant :MarshalFilter
+
 end
diff --git a/lib/rdoc/version.rb b/lib/rdoc/version.rb
index 04322a1970..31c1aa0276 100644
--- a/lib/rdoc/version.rb
+++ b/lib/rdoc/version.rb
@@ -5,6 +5,6 @@ module RDoc
   ##
   # RDoc version you are using
 
-  VERSION = '6.5.0'
+  VERSION = '6.5.1.1'
 
 end
diff --git a/lib/resolv.gemspec b/lib/resolv.gemspec
index db256dc1b0..f221010ab6 100644
--- a/lib/resolv.gemspec
+++ b/lib/resolv.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = "resolv"
-  spec.version       = "0.2.2"
+  spec.version       = "0.2.3"
   spec.authors       = ["Tanaka Akira"]
   spec.email         = ["akr@fsij.org"]
 
diff --git a/lib/resolv.rb b/lib/resolv.rb
index 61c9c7d5cf..eaea69bfd5 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -1624,6 +1624,7 @@ class Resolv
           prev_index = @index
           save_index = nil
           d = []
+          size = -1
           while true
             raise DecodeError.new("limit exceeded") if @limit <= @index
             case @data.getbyte(@index)
@@ -1644,7 +1645,10 @@ class Resolv
               end
               @index = idx
             else
-              d << self.get_label
+              l = self.get_label
+              d << l
+              size += 1 + l.string.bytesize
+              raise DecodeError.new("name label data exceed 255 octets") if size > 255
             end
           end
         end
diff --git a/lib/ruby_vm/mjit/compiler.rb b/lib/ruby_vm/mjit/compiler.rb
index a9f2aeda8d..81022cd0a8 100644
--- a/lib/ruby_vm/mjit/compiler.rb
+++ b/lib/ruby_vm/mjit/compiler.rb
@@ -75,6 +75,13 @@ class RubyVM::MJIT::Compiler # :nodoc: all
     src << "#undef GET_SELF\n"
     src << "#define GET_SELF() cfp_self\n"
 
+    # Generate merged ivar guards first if needed
+    if !status.compile_info.disable_ivar_cache && using_ivar?(iseq.body)
+      src << "    if (UNLIKELY(!RB_TYPE_P(GET_SELF(), T_OBJECT))) {"
+      src << "        goto ivar_cancel;\n"
+      src << "    }\n"
+    end
+
     # Simulate `opt_pc` in setup_parameters_complex. Other PCs which may be passed by catch tables
     # are not considered since vm_exec doesn't call jit_exec for catch tables.
     if iseq.body.param.flags.has_opt
@@ -88,13 +95,6 @@ class RubyVM::MJIT::Compiler # :nodoc: all
       src << "    }\n"
     end
 
-    # Generate merged ivar guards first if needed
-    if !status.compile_info.disable_ivar_cache && using_ivar?(iseq.body)
-      src << "    if (UNLIKELY(!RB_TYPE_P(GET_SELF(), T_OBJECT))) {"
-      src << "        goto ivar_cancel;\n"
-      src << "    }\n"
-    end
-
     compile_insns(0, 0, status, iseq.body, src)
     compile_cancel_handler(src, iseq.body, status)
     src << "#undef GET_SELF\n"
diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index ef5f079a80..af86646a82 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -8,7 +9,7 @@
 require "rbconfig"
 
 module Gem
-  VERSION = "3.4.10"
+  VERSION = "3.4.19"
 end
 
 # Must be first since it unloads the prelude from 1.9.2
@@ -855,8 +856,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   # Returns the version of the latest release-version of gem +name+
 
   def self.latest_version_for(name)
-    spec = latest_spec_for name
-    spec && spec.version
+    latest_spec_for(name)&.version
   end
 
   ##
diff --git a/lib/rubygems/available_set.rb b/lib/rubygems/available_set.rb
index 58b601f6b0..2ab3e137da 100644
--- a/lib/rubygems/available_set.rb
+++ b/lib/rubygems/available_set.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 class Gem::AvailableSet
   include Enumerable
 
diff --git a/lib/rubygems/basic_specification.rb b/lib/rubygems/basic_specification.rb
index dcc64e6409..5d198114e0 100644
--- a/lib/rubygems/basic_specification.rb
+++ b/lib/rubygems/basic_specification.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # BasicSpecification is an abstract class which implements some common code
 # used by both Specification and StubSpecification.
diff --git a/lib/rubygems/bundler_version_finder.rb b/lib/rubygems/bundler_version_finder.rb
index 2cbc4ff624..5b34227d3a 100644
--- a/lib/rubygems/bundler_version_finder.rb
+++ b/lib/rubygems/bundler_version_finder.rb
@@ -47,7 +47,7 @@ module Gem::BundlerVersionFinder
 
   def self.lockfile_contents
     gemfile = ENV["BUNDLE_GEMFILE"]
-    gemfile = nil if gemfile && gemfile.empty?
+    gemfile = nil if gemfile&.empty?
 
     unless gemfile
       begin
diff --git a/lib/rubygems/command.rb b/lib/rubygems/command.rb
index 1e15f612de..07cf4e0e81 100644
--- a/lib/rubygems/command.rb
+++ b/lib/rubygems/command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/command_manager.rb b/lib/rubygems/command_manager.rb
index 0a4b53abe5..b3913d465a 100644
--- a/lib/rubygems/command_manager.rb
+++ b/lib/rubygems/command_manager.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -83,7 +84,7 @@ class Gem::CommandManager
   # Return the authoritative instance of the command manager.
 
   def self.instance
-    @command_manager ||= new
+    @instance ||= new
   end
 
   ##
@@ -98,7 +99,7 @@ class Gem::CommandManager
   # Reset the authoritative instance of the command manager.
 
   def self.reset
-    @command_manager = nil
+    @instance = nil
   end
 
   ##
diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index 5d6152d3b9..68e020d94a 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../package"
 require_relative "../version_option"
diff --git a/lib/rubygems/commands/cert_command.rb b/lib/rubygems/commands/cert_command.rb
index 17b1d11b19..344f31fba9 100644
--- a/lib/rubygems/commands/cert_command.rb
+++ b/lib/rubygems/commands/cert_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../security"
 
diff --git a/lib/rubygems/commands/check_command.rb b/lib/rubygems/commands/check_command.rb
index 4d1f8782b1..b300b4f87a 100644
--- a/lib/rubygems/commands/check_command.rb
+++ b/lib/rubygems/commands/check_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 require_relative "../validator"
diff --git a/lib/rubygems/commands/cleanup_command.rb b/lib/rubygems/commands/cleanup_command.rb
index 1ae84924c1..ee5e1252b6 100644
--- a/lib/rubygems/commands/cleanup_command.rb
+++ b/lib/rubygems/commands/cleanup_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../dependency_list"
 require_relative "../uninstaller"
diff --git a/lib/rubygems/commands/contents_command.rb b/lib/rubygems/commands/contents_command.rb
index c5fdfca31e..f378441ca4 100644
--- a/lib/rubygems/commands/contents_command.rb
+++ b/lib/rubygems/commands/contents_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 
diff --git a/lib/rubygems/commands/dependency_command.rb b/lib/rubygems/commands/dependency_command.rb
index 3f69a95e83..cef98e30d3 100644
--- a/lib/rubygems/commands/dependency_command.rb
+++ b/lib/rubygems/commands/dependency_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../version_option"
diff --git a/lib/rubygems/commands/environment_command.rb b/lib/rubygems/commands/environment_command.rb
index d95e1d0dbb..28dbf93c50 100644
--- a/lib/rubygems/commands/environment_command.rb
+++ b/lib/rubygems/commands/environment_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::EnvironmentCommand < Gem::Command
diff --git a/lib/rubygems/commands/exec_command.rb b/lib/rubygems/commands/exec_command.rb
index 1d7e836ed0..383c8c5b37 100644
--- a/lib/rubygems/commands/exec_command.rb
+++ b/lib/rubygems/commands/exec_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../dependency_installer"
 require_relative "../gem_runner"
diff --git a/lib/rubygems/commands/fetch_command.rb b/lib/rubygems/commands/fetch_command.rb
index 5eb45d259c..950d4fe30e 100644
--- a/lib/rubygems/commands/fetch_command.rb
+++ b/lib/rubygems/commands/fetch_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../version_option"
diff --git a/lib/rubygems/commands/generate_index_command.rb b/lib/rubygems/commands/generate_index_command.rb
index bc71e60ff0..ce580cfaf9 100644
--- a/lib/rubygems/commands/generate_index_command.rb
+++ b/lib/rubygems/commands/generate_index_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../indexer"
 
diff --git a/lib/rubygems/commands/help_command.rb b/lib/rubygems/commands/help_command.rb
index bf4ffefbb7..20b99fa366 100644
--- a/lib/rubygems/commands/help_command.rb
+++ b/lib/rubygems/commands/help_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::HelpCommand < Gem::Command
diff --git a/lib/rubygems/commands/install_command.rb b/lib/rubygems/commands/install_command.rb
index c04c01f258..b0bc2908b4 100644
--- a/lib/rubygems/commands/install_command.rb
+++ b/lib/rubygems/commands/install_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../install_update_options"
 require_relative "../dependency_installer"
diff --git a/lib/rubygems/commands/list_command.rb b/lib/rubygems/commands/list_command.rb
index 011873b99c..522c771f90 100644
--- a/lib/rubygems/commands/list_command.rb
+++ b/lib/rubygems/commands/list_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../query_utils"
 
diff --git a/lib/rubygems/commands/lock_command.rb b/lib/rubygems/commands/lock_command.rb
index da636492c9..3a9512fe3f 100644
--- a/lib/rubygems/commands/lock_command.rb
+++ b/lib/rubygems/commands/lock_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::LockCommand < Gem::Command
diff --git a/lib/rubygems/commands/mirror_command.rb b/lib/rubygems/commands/mirror_command.rb
index b633cd3d81..b91a8db12d 100644
--- a/lib/rubygems/commands/mirror_command.rb
+++ b/lib/rubygems/commands/mirror_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 unless defined? Gem::Commands::MirrorCommand
diff --git a/lib/rubygems/commands/open_command.rb b/lib/rubygems/commands/open_command.rb
index d5283f72dd..5a13074a1d 100644
--- a/lib/rubygems/commands/open_command.rb
+++ b/lib/rubygems/commands/open_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 
diff --git a/lib/rubygems/commands/outdated_command.rb b/lib/rubygems/commands/outdated_command.rb
index 1785194389..08a9221a26 100644
--- a/lib/rubygems/commands/outdated_command.rb
+++ b/lib/rubygems/commands/outdated_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../spec_fetcher"
diff --git a/lib/rubygems/commands/owner_command.rb b/lib/rubygems/commands/owner_command.rb
index 959a6186dc..b51c9cf888 100644
--- a/lib/rubygems/commands/owner_command.rb
+++ b/lib/rubygems/commands/owner_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../gemcutter_utilities"
@@ -98,8 +99,10 @@ permission to.
         action = method == :delete ? "Removing" : "Adding"
 
         with_response response, "#{action} #{owner}"
-      rescue
-        # ignore
+      rescue Gem::WebauthnVerificationError => e
+        raise e
+      rescue StandardError
+        # ignore early exits to allow for completing the iteration of all owners
       end
     end
   end
diff --git a/lib/rubygems/commands/pristine_command.rb b/lib/rubygems/commands/pristine_command.rb
index d7c78ba13d..64608a033f 100644
--- a/lib/rubygems/commands/pristine_command.rb
+++ b/lib/rubygems/commands/pristine_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../package"
 require_relative "../installer"
diff --git a/lib/rubygems/commands/push_command.rb b/lib/rubygems/commands/push_command.rb
index 46b65f4e15..79ca3d59b0 100644
--- a/lib/rubygems/commands/push_command.rb
+++ b/lib/rubygems/commands/push_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../gemcutter_utilities"
diff --git a/lib/rubygems/commands/query_command.rb b/lib/rubygems/commands/query_command.rb
index c6315acf8c..4fa201272e 100644
--- a/lib/rubygems/commands/query_command.rb
+++ b/lib/rubygems/commands/query_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../query_utils"
 require_relative "../deprecate"
diff --git a/lib/rubygems/commands/rdoc_command.rb b/lib/rubygems/commands/rdoc_command.rb
index a998a9704c..e318a52914 100644
--- a/lib/rubygems/commands/rdoc_command.rb
+++ b/lib/rubygems/commands/rdoc_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 require_relative "../rdoc"
diff --git a/lib/rubygems/commands/search_command.rb b/lib/rubygems/commands/search_command.rb
index 3f8f7e13f2..c7469e1fa8 100644
--- a/lib/rubygems/commands/search_command.rb
+++ b/lib/rubygems/commands/search_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../query_utils"
 
diff --git a/lib/rubygems/commands/server_command.rb b/lib/rubygems/commands/server_command.rb
index 56be07c79d..f1dde4aa02 100644
--- a/lib/rubygems/commands/server_command.rb
+++ b/lib/rubygems/commands/server_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 unless defined? Gem::Commands::ServerCommand
diff --git a/lib/rubygems/commands/setup_command.rb b/lib/rubygems/commands/setup_command.rb
index c779b7c244..df1732b49e 100644
--- a/lib/rubygems/commands/setup_command.rb
+++ b/lib/rubygems/commands/setup_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 ##
@@ -244,7 +245,7 @@ By default, this RubyGems will install gem as:
   def install_executables(bin_dir)
     prog_mode = options[:prog_mode] || 0755
 
-    executables = { "gem" => "bin" }
+    executables = { "gem" => "exe" }
     executables.each do |tool, path|
       say "Installing #{tool} executable" if @verbose
 
diff --git a/lib/rubygems/commands/signin_command.rb b/lib/rubygems/commands/signin_command.rb
index 2660eee4f3..0f77908c5b 100644
--- a/lib/rubygems/commands/signin_command.rb
+++ b/lib/rubygems/commands/signin_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../gemcutter_utilities"
 
diff --git a/lib/rubygems/commands/signout_command.rb b/lib/rubygems/commands/signout_command.rb
index fa688ea3f8..bdd01e4393 100644
--- a/lib/rubygems/commands/signout_command.rb
+++ b/lib/rubygems/commands/signout_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::SignoutCommand < Gem::Command
diff --git a/lib/rubygems/commands/sources_command.rb b/lib/rubygems/commands/sources_command.rb
index 5a8f5af9c3..85cc68ac09 100644
--- a/lib/rubygems/commands/sources_command.rb
+++ b/lib/rubygems/commands/sources_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../remote_fetcher"
 require_relative "../spec_fetcher"
diff --git a/lib/rubygems/commands/specification_command.rb b/lib/rubygems/commands/specification_command.rb
index 12004a6d56..ed158506e0 100644
--- a/lib/rubygems/commands/specification_command.rb
+++ b/lib/rubygems/commands/specification_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../version_option"
diff --git a/lib/rubygems/commands/stale_command.rb b/lib/rubygems/commands/stale_command.rb
index 0246f42e3e..a94d77c193 100644
--- a/lib/rubygems/commands/stale_command.rb
+++ b/lib/rubygems/commands/stale_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::StaleCommand < Gem::Command
diff --git a/lib/rubygems/commands/uninstall_command.rb b/lib/rubygems/commands/uninstall_command.rb
index 29f6013c59..feba1c5b7c 100644
--- a/lib/rubygems/commands/uninstall_command.rb
+++ b/lib/rubygems/commands/uninstall_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 require_relative "../uninstaller"
diff --git a/lib/rubygems/commands/unpack_command.rb b/lib/rubygems/commands/unpack_command.rb
index b1f939b0bc..1bff53429b 100644
--- a/lib/rubygems/commands/unpack_command.rb
+++ b/lib/rubygems/commands/unpack_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../version_option"
 require_relative "../security_option"
diff --git a/lib/rubygems/commands/update_command.rb b/lib/rubygems/commands/update_command.rb
index 5c90981645..6f084d1c38 100644
--- a/lib/rubygems/commands/update_command.rb
+++ b/lib/rubygems/commands/update_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../command_manager"
 require_relative "../dependency_installer"
diff --git a/lib/rubygems/commands/which_command.rb b/lib/rubygems/commands/which_command.rb
index 5b9a79b734..ec464d9672 100644
--- a/lib/rubygems/commands/which_command.rb
+++ b/lib/rubygems/commands/which_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 
 class Gem::Commands::WhichCommand < Gem::Command
diff --git a/lib/rubygems/commands/yank_command.rb b/lib/rubygems/commands/yank_command.rb
index 1499f72f5d..d344a020c3 100644
--- a/lib/rubygems/commands/yank_command.rb
+++ b/lib/rubygems/commands/yank_command.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../command"
 require_relative "../local_remote_options"
 require_relative "../version_option"
diff --git a/lib/rubygems/config_file.rb b/lib/rubygems/config_file.rb
index 4aa8b4d33a..68c653269e 100644
--- a/lib/rubygems/config_file.rb
+++ b/lib/rubygems/config_file.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 568ac347b4..0869c8746f 100644
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/core_ext/tcpsocket_init.rb b/lib/rubygems/core_ext/tcpsocket_init.rb
index c9e0a92953..451ffa50b2 100644
--- a/lib/rubygems/core_ext/tcpsocket_init.rb
+++ b/lib/rubygems/core_ext/tcpsocket_init.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "socket"
 
 module CoreExtensions
diff --git a/lib/rubygems/defaults.rb b/lib/rubygems/defaults.rb
index b186375f69..2b1baa333d 100644
--- a/lib/rubygems/defaults.rb
+++ b/lib/rubygems/defaults.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 module Gem
   DEFAULT_HOST = "https://rubygems.org"
 
diff --git a/lib/rubygems/dependency.rb b/lib/rubygems/dependency.rb
index cd03e7e299..d9e0c07b0f 100644
--- a/lib/rubygems/dependency.rb
+++ b/lib/rubygems/dependency.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # The Dependency class holds a Gem name and a Gem::Requirement.
 
diff --git a/lib/rubygems/dependency_installer.rb b/lib/rubygems/dependency_installer.rb
index 1009376b90..a8d73e521b 100644
--- a/lib/rubygems/dependency_installer.rb
+++ b/lib/rubygems/dependency_installer.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "dependency_list"
 require_relative "package"
diff --git a/lib/rubygems/dependency_list.rb b/lib/rubygems/dependency_list.rb
index eaf6702177..5820298bb9 100644
--- a/lib/rubygems/dependency_list.rb
+++ b/lib/rubygems/dependency_list.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/deprecate.rb b/lib/rubygems/deprecate.rb
index 56505512c3..9fff306949 100644
--- a/lib/rubygems/deprecate.rb
+++ b/lib/rubygems/deprecate.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Provides 3 methods for declaring when something is going away.
 #
diff --git a/lib/rubygems/doctor.rb b/lib/rubygems/doctor.rb
index 96829227fc..1d3889af77 100644
--- a/lib/rubygems/doctor.rb
+++ b/lib/rubygems/doctor.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "user_interaction"
 
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
index ac82a551a5..b36fabffc2 100644
--- a/lib/rubygems/errors.rb
+++ b/lib/rubygems/errors.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # This file contains all the various exceptions and other errors that are used
 # inside of RubyGems.
diff --git a/lib/rubygems/exceptions.rb b/lib/rubygems/exceptions.rb
index ca4fbb20de..b92396f0ef 100644
--- a/lib/rubygems/exceptions.rb
+++ b/lib/rubygems/exceptions.rb
@@ -214,6 +214,16 @@ class Gem::RubyVersionMismatch < Gem::Exception; end
 class Gem::VerificationError < Gem::Exception; end
 
 ##
+# Raised by Gem::WebauthnListener when an error occurs during security
+# device verification.
+
+class Gem::WebauthnVerificationError < Gem::Exception
+  def initialize(message)
+    super "Security device verification failed: #{message}"
+  end
+end
+
+##
 # Raised to indicate that a system exit should occur with the specified
 # exit_code
 
diff --git a/lib/rubygems/ext.rb b/lib/rubygems/ext.rb
index d714985c21..b5ca126a08 100644
--- a/lib/rubygems/ext.rb
+++ b/lib/rubygems/ext.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/build_error.rb b/lib/rubygems/ext/build_error.rb
index 727bc065c2..0329c1eec3 100644
--- a/lib/rubygems/ext/build_error.rb
+++ b/lib/rubygems/ext/build_error.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Raised when there is an error while building extensions.
 
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index 43ea207b23..4960ddd7b1 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -6,6 +7,7 @@
 #++
 
 require_relative "../user_interaction"
+require_relative "../shellwords"
 
 class Gem::Ext::Builder
   include Gem::UserInteraction
@@ -56,9 +58,8 @@ class Gem::Ext::Builder
   end
 
   def self.ruby
-    require "shellwords"
     # Gem.ruby is quoted if it contains whitespace
-    cmd = Gem.ruby.shellsplit
+    cmd = Shellwords.split(Gem.ruby)
 
     # This load_path is only needed when running rubygems test without a proper installation.
     # Prepending it in a normal installation will cause problem with order of $LOAD_PATH.
@@ -82,8 +83,7 @@ class Gem::Ext::Builder
         p(command)
       end
       results << "current directory: #{dir}"
-      require "shellwords"
-      results << command.shelljoin
+      results << Shellwords.join(command)
 
       require "open3"
       # Set $SOURCE_DATE_EPOCH for the subprocess.
diff --git a/lib/rubygems/ext/cargo_builder.rb b/lib/rubygems/ext/cargo_builder.rb
index 022aabf481..ce3b296f79 100644
--- a/lib/rubygems/ext/cargo_builder.rb
+++ b/lib/rubygems/ext/cargo_builder.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative "../shellwords"
+
 # This class is used by rubygems to build Rust extensions. It is a thin-wrapper
 # over the `cargo rustc` command which takes care of building Rust code in a way
 # that Ruby can use.
@@ -73,8 +75,6 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
   end
 
   def cargo_command(cargo_toml, dest_path, args = [], crate_name = nil)
-    require "shellwords"
-
     cmd = []
     cmd += [cargo, "rustc"]
     cmd += ["--crate-type", "cdylib"]
diff --git a/lib/rubygems/ext/configure_builder.rb b/lib/rubygems/ext/configure_builder.rb
index 51106c6370..6b8590ba2e 100644
--- a/lib/rubygems/ext/configure_builder.rb
+++ b/lib/rubygems/ext/configure_builder.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/ext_conf_builder.rb b/lib/rubygems/ext/ext_conf_builder.rb
index 2f4193d697..9c22329fe3 100644
--- a/lib/rubygems/ext/ext_conf_builder.rb
+++ b/lib/rubygems/ext/ext_conf_builder.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/rake_builder.rb b/lib/rubygems/ext/rake_builder.rb
index e74ec8750f..8f39a63e11 100644
--- a/lib/rubygems/ext/rake_builder.rb
+++ b/lib/rubygems/ext/rake_builder.rb
@@ -1,4 +1,7 @@
 # frozen_string_literal: true
+
+require_relative "../shellwords"
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -14,8 +17,7 @@ class Gem::Ext::RakeBuilder < Gem::Ext::Builder
     rake = ENV["rake"]
 
     if rake
-      require "shellwords"
-      rake = rake.shellsplit
+      rake = Shellwords.split(rake)
     else
       begin
         rake = ruby << "-rrubygems" << Gem.bin_path("rake", "rake")
diff --git a/lib/rubygems/gem_runner.rb b/lib/rubygems/gem_runner.rb
index 31890a60d7..d238a5863b 100644
--- a/lib/rubygems/gem_runner.rb
+++ b/lib/rubygems/gem_runner.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/gemcutter_utilities.rb b/lib/rubygems/gemcutter_utilities.rb
index 3477422b79..92739617f6 100644
--- a/lib/rubygems/gemcutter_utilities.rb
+++ b/lib/rubygems/gemcutter_utilities.rb
@@ -1,6 +1,9 @@
 # frozen_string_literal: true
+
 require_relative "remote_fetcher"
 require_relative "text"
+require_relative "gemcutter_utilities/webauthn_listener"
+require_relative "gemcutter_utilities/webauthn_poller"
 
 ##
 # Utility methods for using the RubyGems API.
@@ -70,8 +73,7 @@ module Gem::GemcutterUtilities
     @host ||=
       begin
         env_rubygems_host = ENV["RUBYGEMS_HOST"]
-        env_rubygems_host = nil if
-          env_rubygems_host && env_rubygems_host.empty?
+        env_rubygems_host = nil if env_rubygems_host&.empty?
 
         env_rubygems_host || configured_host
       end
@@ -82,7 +84,7 @@ module Gem::GemcutterUtilities
   #
   # If +allowed_push_host+ metadata is present, then it will only allow that host.
 
-  def rubygems_api_request(method, path, host = nil, allowed_push_host = nil, scope: nil, &block)
+  def rubygems_api_request(method, path, host = nil, allowed_push_host = nil, scope: nil, credentials: {}, &block)
     require "net/http"
 
     self.host = host if host
@@ -105,7 +107,7 @@ module Gem::GemcutterUtilities
     response = request_with_otp(method, uri, &block)
 
     if mfa_unauthorized?(response)
-      ask_otp
+      fetch_otp(credentials)
       response = request_with_otp(method, uri, &block)
     end
 
@@ -167,11 +169,12 @@ module Gem::GemcutterUtilities
     mfa_params   = get_mfa_params(profile)
     all_params   = scope_params.merge(mfa_params)
     warning      = profile["warning"]
+    credentials  = { email: email, password: password }
 
     say "#{warning}\n" if warning
 
     response = rubygems_api_request(:post, "api/v1/api_key",
-                                    sign_in_host, scope: scope) do |request|
+                                    sign_in_host, credentials: credentials, scope: scope) do |request|
       request.basic_auth email, password
       request["OTP"] = otp if otp
       request.body = URI.encode_www_form({ name: key_name }.merge(all_params))
@@ -250,9 +253,52 @@ module Gem::GemcutterUtilities
     end
   end
 
-  def ask_otp
-    say "You have enabled multi-factor authentication. Please enter OTP code."
-    options[:otp] = ask "Code: "
+  def fetch_otp(credentials)
+    options[:otp] = if webauthn_url = webauthn_verification_url(credentials)
+      server = TCPServer.new 0
+      port = server.addr[1].to_s
+
+      url_with_port = "#{webauthn_url}?port=#{port}"
+      say "You have enabled multi-factor authentication. Please visit #{url_with_port} to authenticate via security device. If you can't verify using WebAuthn but have OTP enabled, you can re-run the gem signin command with the `--otp [your_code]` option."
+
+      threads = [WebauthnListener.listener_thread(host, server), WebauthnPoller.poll_thread(options, host, webauthn_url, credentials)]
+      otp_thread = wait_for_otp_thread(*threads)
+
+      threads.each(&:join)
+
+      if error = otp_thread[:error]
+        alert_error error.message
+        terminate_interaction(1)
+      end
+
+      say "You are verified with a security device. You may close the browser window."
+      otp_thread[:otp]
+    else
+      say "You have enabled multi-factor authentication. Please enter OTP code."
+      ask "Code: "
+    end
+  end
+
+  def wait_for_otp_thread(*threads)
+    loop do
+      threads.each do |otp_thread|
+        return otp_thread unless otp_thread.alive?
+      end
+      sleep 0.1
+    end
+  ensure
+    threads.each(&:exit)
+  end
+
+  def webauthn_verification_url(credentials)
+    response = rubygems_api_request(:post, "api/v1/webauthn_verification") do |request|
+      if credentials.empty?
+        request.add_field "Authorization", api_key
+      else
+        request.basic_auth credentials[:email], credentials[:password]
+      end
+    end
+    response.is_a?(Net::HTTPSuccess) ? response.body : nil
   end
 
   def pretty_host(host)
diff --git a/lib/rubygems/gemcutter_utilities/webauthn_listener.rb b/lib/rubygems/gemcutter_utilities/webauthn_listener.rb
new file mode 100644
index 0000000000..bea9d9e397
--- /dev/null
+++ b/lib/rubygems/gemcutter_utilities/webauthn_listener.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+require_relative "webauthn_listener/response"
+
+##
+# The WebauthnListener class retrieves an OTP after a user successfully WebAuthns with the Gem host.
+# An instance opens a socket using the TCPServer instance given and listens for a request from the Gem host.
+# The request should be a GET request to the root path and contains the OTP code in the form
+# of a query parameter `code`. The listener will return the code which will be used as the OTP for
+# API requests.
+#
+# Types of responses sent by the listener after receiving a request:
+#   - 200 OK: OTP code was successfully retrieved
+#   - 204 No Content: If the request was an OPTIONS request
+#   - 400 Bad Request: If the request did not contain a query parameter `code`
+#   - 404 Not Found: The request was not to the root path
+#   - 405 Method Not Allowed: OTP code was not retrieved because the request was not a GET/OPTIONS request
+#
+# Example usage:
+#
+#   thread = Gem::WebauthnListener.listener_thread("https://rubygems.example", server)
+#   thread.join
+#   otp = thread[:otp]
+#   error = thread[:error]
+#
+
+module Gem::GemcutterUtilities
+  class WebauthnListener
+    attr_reader :host
+
+    def initialize(host)
+      @host = host
+    end
+
+    def self.listener_thread(host, server)
+      Thread.new do
+        thread = Thread.current
+        thread.abort_on_exception = true
+        thread.report_on_exception = false
+        thread[:otp] = new(host).wait_for_otp_code(server)
+      rescue Gem::WebauthnVerificationError => e
+        thread[:error] = e
+      ensure
+        server.close
+      end
+    end
+
+    def wait_for_otp_code(server)
+      loop do
+        socket = server.accept
+        request_line = socket.gets
+
+        method, req_uri, _protocol = request_line.split(" ")
+        req_uri = URI.parse(req_uri)
+
+        responder = SocketResponder.new(socket)
+
+        unless root_path?(req_uri)
+          responder.send(NotFoundResponse.for(host))
+          raise Gem::WebauthnVerificationError, "Page at #{req_uri.path} not found."
+        end
+
+        case method.upcase
+        when "OPTIONS"
+          responder.send(NoContentResponse.for(host))
+          next # will be GET
+        when "GET"
+          if otp = parse_otp_from_uri(req_uri)
+            responder.send(OkResponse.for(host))
+            return otp
+          end
+          responder.send(BadRequestResponse.for(host))
+          raise Gem::WebauthnVerificationError, "Did not receive OTP from #{host}."
+        else
+          responder.send(MethodNotAllowedResponse.for(host))
+          raise Gem::WebauthnVerificationError, "Invalid HTTP method #{method.upcase} received."
+        end
+      end
+    end
+
+    private
+
+    def root_path?(uri)
+      uri.path == "/"
+    end
+
+    def parse_otp_from_uri(uri)
+      require "cgi"
+
+      return if uri.query.nil?
+      CGI.parse(uri.query).dig("code", 0)
+    end
+
+    class SocketResponder
+      def initialize(socket)
+        @socket = socket
+      end
+
+      def send(response)
+        @socket.print response.to_s
+        @socket.close
+      end
+    end
+  end
+end
diff --git a/lib/rubygems/gemcutter_utilities/webauthn_listener/response.rb b/lib/rubygems/gemcutter_utilities/webauthn_listener/response.rb
new file mode 100644
index 0000000000..7709a8fef3
--- /dev/null
+++ b/lib/rubygems/gemcutter_utilities/webauthn_listener/response.rb
@@ -0,0 +1,163 @@
+# frozen_string_literal: true
+
+##
+# The WebauthnListener Response class is used by the WebauthnListener to create
+# responses to be sent to the Gem host. It creates a Net::HTTPResponse instance
+# when initialized and can be converted to the appropriate format to be sent by a socket using `to_s`.
+# Net::HTTPResponse instances cannot be directly sent over a socket.
+#
+# Types of response classes:
+#   - OkResponse
+#   - NoContentResponse
+#   - BadRequestResponse
+#   - NotFoundResponse
+#   - MethodNotAllowedResponse
+#
+# Example usage:
+#
+#   server = TCPServer.new(0)
+#   socket = server.accept
+#
+#   response = OkResponse.for("https://rubygems.example")
+#   socket.print response.to_s
+#   socket.close
+#
+
+module Gem::GemcutterUtilities
+  class WebauthnListener
+    class Response
+      attr_reader :http_response
+
+      def self.for(host)
+        new(host)
+      end
+
+      def initialize(host)
+        @host = host
+
+        build_http_response
+      end
+
+      def to_s
+        status_line = "HTTP/#{@http_response.http_version} #{@http_response.code} #{@http_response.message}\r\n"
+        headers = @http_response.to_hash.map {|header, value| "#{header}: #{value.join(", ")}\r\n" }.join + "\r\n"
+        body = @http_response.body ? "#{@http_response.body}\n" : ""
+
+        status_line + headers + body
+      end
+
+      private
+
+      # Must be implemented in subclasses
+      def code
+        raise NotImplementedError
+      end
+
+      def reason_phrase
+        raise NotImplementedError
+      end
+
+      def body; end
+
+      def build_http_response
+        response_class = Net::HTTPResponse::CODE_TO_OBJ[code.to_s]
+        @http_response = response_class.new("1.1", code, reason_phrase)
+        @http_response.instance_variable_set(:@read, true)
+
+        add_connection_header
+        add_access_control_headers
+        add_body
+      end
+
+      def add_connection_header
+        @http_response["connection"] = "close"
+      end
+
+      def add_access_control_headers
+        @http_response["access-control-allow-origin"] = @host
+        @http_response["access-control-allow-methods"] = "POST"
+        @http_response["access-control-allow-headers"] = %w[Content-Type Authorization x-csrf-token]
+      end
+
+      def add_body
+        return unless body
+        @http_response["content-type"] = "text/plain; charset=utf-8"
+        @http_response["content-length"] = body.bytesize
+        @http_response.instance_variable_set(:@body, body)
+      end
+    end
+
+    class OkResponse < Response
+      private
+
+      def code
+        200
+      end
+
+      def reason_phrase
+        "OK"
+      end
+
+      def body
+        "success"
+      end
+    end
+
+    class NoContentResponse < Response
+      private
+
+      def code
+        204
+      end
+
+      def reason_phrase
+        "No Content"
+      end
+    end
+
+    class BadRequestResponse < Response
+      private
+
+      def code
+        400
+      end
+
+      def reason_phrase
+        "Bad Request"
+      end
+
+      def body
+        "missing code parameter"
+      end
+    end
+
+    class NotFoundResponse < Response
+      private
+
+      def code
+        404
+      end
+
+      def reason_phrase
+        "Not Found"
+      end
+    end
+
+    class MethodNotAllowedResponse < Response
+      private
+
+      def code
+        405
+      end
+
+      def reason_phrase
+        "Method Not Allowed"
+      end
+
+      def add_access_control_headers
+        super
+        @http_response["allow"] = %w[GET OPTIONS]
+      end
+    end
+  end
+end
diff --git a/lib/rubygems/gemcutter_utilities/webauthn_poller.rb b/lib/rubygems/gemcutter_utilities/webauthn_poller.rb
new file mode 100644
index 0000000000..e7068605a4
--- /dev/null
+++ b/lib/rubygems/gemcutter_utilities/webauthn_poller.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+##
+# The WebauthnPoller class retrieves an OTP after a user successfully WebAuthns. An instance
+# polls the Gem host for the OTP code. The polling request (api/v1/webauthn_verification/<webauthn_token>/status.json)
+# is sent to the Gem host every 5 seconds and will timeout after 5 minutes. If the status field in the json response
+# is "success", the code field will contain the OTP code.
+#
+# Example usage:
+#
+#   thread = Gem::WebauthnPoller.poll_thread(
+#     {},
+#     "RubyGems.org",
+#     "https://rubygems.org/api/v1/webauthn_verification/odow34b93t6aPCdY",
+#     { email: "email@example.com", password: "password" }
+#   )
+#   thread.join
+#   otp = thread[:otp]
+#   error = thread[:error]
+#
+
+module Gem::GemcutterUtilities
+  class WebauthnPoller
+    include Gem::GemcutterUtilities
+    TIMEOUT_IN_SECONDS = 300
+
+    attr_reader :options, :host
+
+    def initialize(options, host)
+      @options = options
+      @host = host
+    end
+
+    def self.poll_thread(options, host, webauthn_url, credentials)
+      Thread.new do
+        thread = Thread.current
+        thread.abort_on_exception = true
+        thread.report_on_exception = false
+        thread[:otp] = new(options, host).poll_for_otp(webauthn_url, credentials)
+      rescue Gem::WebauthnVerificationError, Timeout::Error => e
+        thread[:error] = e
+      end
+    end
+
+    def poll_for_otp(webauthn_url, credentials)
+      Timeout.timeout(TIMEOUT_IN_SECONDS) do
+        loop do
+          response = webauthn_verification_poll_response(webauthn_url, credentials)
+          raise Gem::WebauthnVerificationError, response.message unless response.is_a?(Net::HTTPSuccess)
+
+          require "json"
+          parsed_response = JSON.parse(response.body)
+          case parsed_response["status"]
+          when "pending"
+            sleep 5
+          when "success"
+            return parsed_response["code"]
+          else
+            raise Gem::WebauthnVerificationError, parsed_response.fetch("message", "Invalid response from server")
+          end
+        end
+      end
+    end
+
+    private
+
+    def webauthn_verification_poll_response(webauthn_url, credentials)
+      webauthn_token = %r{(?<=\/)[^\/]+(?=$)}.match(webauthn_url)[0]
+      rubygems_api_request(:get, "api/v1/webauthn_verification/#{webauthn_token}/status.json") do |request|
+        if credentials.empty?
+          request.add_field "Authorization", api_key
+        else
+          request.basic_auth credentials[:email], credentials[:password]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/rubygems/indexer.rb b/lib/rubygems/indexer.rb
index d0061ff82e..0935fe8486 100644
--- a/lib/rubygems/indexer.rb
+++ b/lib/rubygems/indexer.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "package"
 require "tmpdir"
diff --git a/lib/rubygems/install_default_message.rb b/lib/rubygems/install_default_message.rb
index 0d112a15df..0640eaaf08 100644
--- a/lib/rubygems/install_default_message.rb
+++ b/lib/rubygems/install_default_message.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "user_interaction"
 
diff --git a/lib/rubygems/install_message.rb b/lib/rubygems/install_message.rb
index 2565f36261..a24e26b918 100644
--- a/lib/rubygems/install_message.rb
+++ b/lib/rubygems/install_message.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "user_interaction"
 
diff --git a/lib/rubygems/install_update_options.rb b/lib/rubygems/install_update_options.rb
index 79effcf21f..e125b3b9b3 100644
--- a/lib/rubygems/install_update_options.rb
+++ b/lib/rubygems/install_update_options.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/installer.rb b/lib/rubygems/installer.rb
index 9fbb2824c7..1b152aaf1f 100644
--- a/lib/rubygems/installer.rb
+++ b/lib/rubygems/installer.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
@@ -342,6 +343,8 @@ class Gem::Installer
 
     Gem::Specification.add_spec(spec)
 
+    load_plugin
+
     run_post_install_hooks
 
     spec
@@ -388,7 +391,7 @@ class Gem::Installer
   # we'll be installing into.
 
   def installed_specs
-    @specs ||= begin
+    @installed_specs ||= begin
       specs = []
 
       Gem::Util.glob_files_in_dir("*.gemspec", File.join(gem_home, "specifications")).each do |path|
@@ -1002,4 +1005,17 @@ TEXT
       ""
     end
   end
+
+  def load_plugin
+    specs = Gem::Specification.find_all_by_name(spec.name)
+    # If old version already exists, this plugin isn't loaded
+    # immediately. It's for avoiding a case that multiple versions
+    # are loaded at the same time.
+    return unless specs.size == 1
+
+    plugin_files = spec.plugins.map do |plugin|
+      File.join(@plugins_dir, "#{spec.name}_plugin#{File.extname(plugin)}")
+    end
+    Gem.load_plugin_files(plugin_files)
+  end
 end
diff --git a/lib/rubygems/local_remote_options.rb b/lib/rubygems/local_remote_options.rb
index b2c2dea905..3d970ef225 100644
--- a/lib/rubygems/local_remote_options.rb
+++ b/lib/rubygems/local_remote_options.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/mock_gem_ui.rb b/lib/rubygems/mock_gem_ui.rb
index 5cc67ad099..2dfdc6d523 100644
--- a/lib/rubygems/mock_gem_ui.rb
+++ b/lib/rubygems/mock_gem_ui.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "user_interaction"
 
 ##
diff --git a/lib/rubygems/name_tuple.rb b/lib/rubygems/name_tuple.rb
index 767dc1fb45..c26d0765e6 100644
--- a/lib/rubygems/name_tuple.rb
+++ b/lib/rubygems/name_tuple.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 #
 # Represents a gem of name +name+ at +version+ of +platform+. These
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index 4672866985..f28d521bdf 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
@@ -616,8 +617,7 @@ EOM
 
     verify_checksums @digests, @checksums
 
-    @security_policy.verify_signatures @spec, @digests, @signatures if
-      @security_policy
+    @security_policy&.verify_signatures @spec, @digests, @signatures
 
     true
   rescue Gem::Security::Exception
diff --git a/lib/rubygems/package/digest_io.rb b/lib/rubygems/package/digest_io.rb
index 4736f76d93..1572cb9f2c 100644
--- a/lib/rubygems/package/digest_io.rb
+++ b/lib/rubygems/package/digest_io.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # IO wrapper that creates digests of contents written to the IO it wraps.
 
diff --git a/lib/rubygems/package/file_source.rb b/lib/rubygems/package/file_source.rb
index 14c7a9f6d2..d9717e0f2a 100644
--- a/lib/rubygems/package/file_source.rb
+++ b/lib/rubygems/package/file_source.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # The primary source of gems is a file on disk, including all usages
 # internal to rubygems.
diff --git a/lib/rubygems/package/io_source.rb b/lib/rubygems/package/io_source.rb
index 03d7714524..227835dfce 100644
--- a/lib/rubygems/package/io_source.rb
+++ b/lib/rubygems/package/io_source.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Supports reading and writing gems from/to a generic IO object.  This is
 # useful for other applications built on top of rubygems, such as
diff --git a/lib/rubygems/package/old.rb b/lib/rubygems/package/old.rb
index 09a02d3ecd..bf0ed61b0a 100644
--- a/lib/rubygems/package/old.rb
+++ b/lib/rubygems/package/old.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/package/source.rb b/lib/rubygems/package/source.rb
index 69701e55e9..8c44f8c305 100644
--- a/lib/rubygems/package/source.rb
+++ b/lib/rubygems/package/source.rb
@@ -1,3 +1,4 @@
 # frozen_string_literal: true
+
 class Gem::Package::Source # :nodoc:
 end
diff --git a/lib/rubygems/package/tar_header.rb b/lib/rubygems/package/tar_header.rb
index 31566e5865..99bd755f90 100644
--- a/lib/rubygems/package/tar_header.rb
+++ b/lib/rubygems/package/tar_header.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_reader.rb b/lib/rubygems/package/tar_reader.rb
index 9f1d49035b..a8dd39c572 100644
--- a/lib/rubygems/package/tar_reader.rb
+++ b/lib/rubygems/package/tar_reader.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_reader/entry.rb b/lib/rubygems/package/tar_reader/entry.rb
index 9e7b327431..e770079f41 100644
--- a/lib/rubygems/package/tar_reader/entry.rb
+++ b/lib/rubygems/package/tar_reader/entry.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #++
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_writer.rb b/lib/rubygems/package/tar_writer.rb
index db5242c5e4..32a13e9162 100644
--- a/lib/rubygems/package/tar_writer.rb
+++ b/lib/rubygems/package/tar_writer.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package_task.rb b/lib/rubygems/package_task.rb
index 8432bc5806..a67d8cb916 100644
--- a/lib/rubygems/package_task.rb
+++ b/lib/rubygems/package_task.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 # Copyright (c) 2003, 2004 Jim Weirich, 2009 Eric Hodel
 #
 # Permission is hereby granted, free of charge, to any person obtaining
diff --git a/lib/rubygems/path_support.rb b/lib/rubygems/path_support.rb
index d601e653c9..d9df543ad9 100644
--- a/lib/rubygems/path_support.rb
+++ b/lib/rubygems/path_support.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 #
 # Gem::PathSupport facilitates the GEM_HOME and GEM_PATH environment settings
diff --git a/lib/rubygems/platform.rb b/lib/rubygems/platform.rb
index f4983c1153..b721629b78 100644
--- a/lib/rubygems/platform.rb
+++ b/lib/rubygems/platform.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "deprecate"
 
 ##
diff --git a/lib/rubygems/psych_tree.rb b/lib/rubygems/psych_tree.rb
index b90f9f7d1d..2d478c94d9 100644
--- a/lib/rubygems/psych_tree.rb
+++ b/lib/rubygems/psych_tree.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 module Gem
   if defined? ::Psych::Visitors
     class NoAliasYAMLTree < Psych::Visitors::YAMLTree
diff --git a/lib/rubygems/rdoc.rb b/lib/rubygems/rdoc.rb
index 769ec61d1e..907dcd9431 100644
--- a/lib/rubygems/rdoc.rb
+++ b/lib/rubygems/rdoc.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 
 begin
diff --git a/lib/rubygems/remote_fetcher.rb b/lib/rubygems/remote_fetcher.rb
index 0ac6eaa130..1c8a441d0c 100644
--- a/lib/rubygems/remote_fetcher.rb
+++ b/lib/rubygems/remote_fetcher.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "../rubygems"
 require_relative "request"
 require_relative "request/connection_pools"
diff --git a/lib/rubygems/request.rb b/lib/rubygems/request.rb
index c3ea46e0eb..8ea39d9358 100644
--- a/lib/rubygems/request.rb
+++ b/lib/rubygems/request.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require "net/http"
 require_relative "user_interaction"
 
diff --git a/lib/rubygems/request/http_pool.rb b/lib/rubygems/request/http_pool.rb
index 7b309eedd3..52543de41f 100644
--- a/lib/rubygems/request/http_pool.rb
+++ b/lib/rubygems/request/http_pool.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # A connection "pool" that only manages one connection for now.  Provides
 # thread safe `checkout` and `checkin` methods.  The pool consists of one
diff --git a/lib/rubygems/request/https_pool.rb b/lib/rubygems/request/https_pool.rb
index 50f42d9e0d..cb1d4b59b6 100644
--- a/lib/rubygems/request/https_pool.rb
+++ b/lib/rubygems/request/https_pool.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 class Gem::Request::HTTPSPool < Gem::Request::HTTPPool # :nodoc:
   private
 
diff --git a/lib/rubygems/request_set.rb b/lib/rubygems/request_set.rb
index 64701a8214..b6e0995726 100644
--- a/lib/rubygems/request_set.rb
+++ b/lib/rubygems/request_set.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "tsort"
 
 ##
@@ -107,7 +108,7 @@ class Gem::RequestSet
     @requests            = []
     @sets                = []
     @soft_missing        = false
-    @sorted              = nil
+    @sorted_requests     = nil
     @specs               = nil
     @vendor_set          = nil
     @source_set          = nil
@@ -424,7 +425,7 @@ class Gem::RequestSet
   end
 
   def sorted_requests
-    @sorted ||= strongly_connected_components.flatten
+    @sorted_requests ||= strongly_connected_components.flatten
   end
 
   def specs
diff --git a/lib/rubygems/request_set/gem_dependency_api.rb b/lib/rubygems/request_set/gem_dependency_api.rb
index 0681f8802a..2fd0da340a 100644
--- a/lib/rubygems/request_set/gem_dependency_api.rb
+++ b/lib/rubygems/request_set/gem_dependency_api.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # A semi-compatible DSL for the Bundler Gemfile and Isolate gem dependencies
 # files.
diff --git a/lib/rubygems/request_set/lockfile.rb b/lib/rubygems/request_set/lockfile.rb
index 3ba202f661..9523fa7786 100644
--- a/lib/rubygems/request_set/lockfile.rb
+++ b/lib/rubygems/request_set/lockfile.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Parses a gem.deps.rb.lock file and constructs a LockSet containing the
 # dependencies found inside.  If the lock file is missing no LockSet is
diff --git a/lib/rubygems/request_set/lockfile/parser.rb b/lib/rubygems/request_set/lockfile/parser.rb
index 8446f9df8e..1daec1fabd 100644
--- a/lib/rubygems/request_set/lockfile/parser.rb
+++ b/lib/rubygems/request_set/lockfile/parser.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 class Gem::RequestSet::Lockfile::Parser
   ###
   # Parses lockfiles
@@ -331,7 +332,7 @@ class Gem::RequestSet::Lockfile::Parser
       set.find_all(requirement)
     end.compact.first
 
-    specification && specification.version
+    specification&.version
   end
 
   ##
diff --git a/lib/rubygems/request_set/lockfile/tokenizer.rb b/lib/rubygems/request_set/lockfile/tokenizer.rb
index 4476a041c4..e91a11ca93 100644
--- a/lib/rubygems/request_set/lockfile/tokenizer.rb
+++ b/lib/rubygems/request_set/lockfile/tokenizer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 #) frozen_string_literal: true
 require_relative "parser"
 
diff --git a/lib/rubygems/requirement.rb b/lib/rubygems/requirement.rb
index bc2fd9af55..eed12c4914 100644
--- a/lib/rubygems/requirement.rb
+++ b/lib/rubygems/requirement.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "version"
 
 ##
diff --git a/lib/rubygems/resolver.rb b/lib/rubygems/resolver.rb
index 76d1e9d0cc..a912729b37 100644
--- a/lib/rubygems/resolver.rb
+++ b/lib/rubygems/resolver.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative "dependency"
 require_relative "exceptions"
 require_relative "util/list"
diff --git a/lib/rubygems/resolver/activation_request.rb b/lib/rubygems/resolver/activation_request.rb
index 27877e0f4b..d59859c102 100644
--- a/lib/rubygems/resolver/activation_request.rb
+++ b/lib/rubygems/resolver/activation_request.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Specifies a Specification object that should be activated.  Also contains a
 # dependency that was used to introduce this activation.
diff --git a/lib/rubygems/resolver/api_set.rb b/lib/rubygems/resolver/api_set.rb
index f2bef54a9c..9b57b03192 100644
--- a/lib/rubygems/resolver/api_set.rb
+++ b/lib/rubygems/resolver/api_set.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # The global rubygems pool, available via the rubygems.org API.
 # Returns instances of APISpecification.
diff --git a/lib/rubygems/resolver/api_specification.rb b/lib/rubygems/resolver/api_specification.rb
index 1e65d5e5a9..f26f82757e 100644
--- a/lib/rubygems/resolver/api_specification.rb
+++ b/lib/rubygems/resolver/api_specification.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # Represents a specification retrieved via the rubygems.org API.
 #
diff --git a/lib/rubygems/resolver/best_set.rb b/lib/rubygems/resolver/best_set.rb
index 075ee1ef5c..d75fa7c00a 100644
--- a/lib/rubygems/resolver/best_set.rb
+++ b/lib/rubygems/resolver/best_set.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # The BestSet chooses the best available method to query a remote index.
 #
diff --git a/lib/rubygems/resolver/composed_set.rb b/lib/rubygems/resolver/composed_set.rb
index 226da1e1e0..0991f0713e 100644
--- a/lib/rubygems/resolver/composed_set.rb
+++ b/lib/rubygems/resolver/composed_set.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 ##
 # A ComposedSet allows multiple sets to be queried like a single set.
 #
diff --git a/lib/rubygems/resolver/conflict.rb b/lib/rubygems/resolver/conflict.rb
index aba6d73ea7..dca41da51f 100644
--- a/
author	卜部昌平 <shyouhei@ruby-lang.org>	2020-05-29 16:04:53 +0900
committer	卜部昌平 <shyouhei@ruby-lang.org>	2020-06-09 09:52:46 +0900
commit	8f3d4090f037ae35fc9ba6380ee284aec837201f (patch)
tree	fcdc79400e8c8f05d99e018bde2f3002b3fa2c08 /benchmark/vm_poly_method.yml
parent	77293cef91a9aa424c086ae05f03211d9a8a87d3 (diff)