path: root/doc/NEWS/NEWS-3.2.0.md

# NEWS for Ruby 3.2.0

This document is a list of user-visible feature changes
since the **3.1.0** release, except for bug fixes.

Note that each entry is kept to a minimum, see links for details.

## Language changes

* Anonymous rest and keyword rest arguments can now be passed as
  arguments, instead of just used in method parameters.
  [[Feature #18351]]

    ```ruby
    def foo(*)
      bar(*)
    end
    def baz(**)
      quux(**)
    end
    ```

* A proc that accepts a single positional argument and keywords will
  no longer autosplat. [[Bug #18633]]

    ```ruby
    proc{|a, **k| a}.call([1, 2])
    # Ruby 3.1 and before
    # => 1
    # Ruby 3.2 and after
    # => [1, 2]
    ```

* Constant assignment evaluation order for constants set on explicit
  objects has been made consistent with single attribute assignment
  evaluation order. With this code:

    ```ruby
    foo::BAR = baz
    ```

    `foo` is now called before `baz`. Similarly, for multiple assignments
    to constants,  left-to-right evaluation order is used. With this
    code:

    ```ruby
    foo1::BAR1, foo2::BAR2 = baz1, baz2
    ```

    The following evaluation order is now used:

    1. `foo1`
    2. `foo2`
    3. `baz1`
    4. `baz2`

    [[Bug #15928]]

* "Find pattern" is no longer experimental.
  [[Feature #18585]]

* Methods taking a rest parameter (like `*args`) and wishing to delegate keyword
  arguments through `foo(*args)` must now be marked with `ruby2_keywords`
  (if not already the case). In other words, all methods wishing to delegate
  keyword arguments through `*args` must now be marked with `ruby2_keywords`,
  with no exception. This will make it easier to transition to other ways of
  delegation once a library can require Ruby 3+. Previously, the `ruby2_keywords`
  flag was kept if the receiving method took `*args`, but this was a bug and an
  inconsistency. A good technique to find the potentially-missing `ruby2_keywords`
  is to run the test suite, for where it fails find the last method which must
  receive keyword arguments, use `puts nil, caller, nil` there, and check each
  method/block on the call chain which must delegate keywords is correctly marked
  as `ruby2_keywords`. [[Bug #18625]] [[Bug #16466]]

    ```ruby
    def target(**kw)
    end

    # Accidentally worked without ruby2_keywords in Ruby 2.7-3.1, ruby2_keywords
    # needed in 3.2+. Just like (*args, **kwargs) or (...) would be needed on
    # both #foo and #bar when migrating away from ruby2_keywords.
    ruby2_keywords def bar(*args)
      target(*args)
    end

    ruby2_keywords def foo(*args)
      bar(*args)
    end

    foo(k: 1)
    ```

## Core classes updates

Note: We're only listing outstanding class updates.

* Fiber

    * Introduce Fiber.[] and Fiber.[]= for inheritable fiber storage.
      Introduce Fiber#storage and Fiber#storage= (experimental) for
      getting and resetting the current storage.  Introduce
      `Fiber.new(storage:)` for setting the storage when creating a
      fiber. [[Feature #19078]]

        Existing Thread and Fiber local variables can be tricky to use.
        Thread-local variables are shared between all fibers, making it
        hard to isolate, while Fiber-local variables can be hard to
        share.  It is often desirable to define unit of execution
        ("execution context") such that some state is shared between all
        fibers and threads created in that context.  This is what Fiber
        storage provides.

        ```ruby
        def log(message)
          puts "#{Fiber[:request_id]}: #{message}"
        end

        def handle_requests
          while request = read_request
            Fiber.schedule do
              Fiber[:request_id] = SecureRandom.uuid

              request.messages.each do |message|
                Fiber.schedule do
                  log("Handling #{message}") # Log includes inherited request_id.
                end
              end
            end
          end
        end
        ```

        You should generally consider Fiber storage for any state which
        you want to be shared implicitly between all fibers and threads
        created in a given context, e.g. a connection pool, a request
        id, a logger level, environment variables, configuration, etc.

* Fiber::Scheduler

    * Introduce `Fiber::Scheduler#io_select` for non-blocking IO.select.
      [[Feature #19060]]

* IO

    * Introduce IO#timeout= and IO#timeout which can cause
      IO::TimeoutError to be raised if a blocking operation exceeds the
      specified timeout. [[Feature #18630]]

        ```ruby
        STDIN.timeout = 1
        STDIN.read # => Blocking operation timed out! (IO::TimeoutError)
        ```

    * Introduce `IO.new(..., path:)` and promote `File#path` to `IO#path`.
      [[Feature #19036]]

* Class

    * Class#attached_object, which returns the object for which
      the receiver is the singleton class. Raises TypeError if the
      receiver is not a singleton class.
      [[Feature #12084]]

        ```ruby
        class Foo; end

        Foo.singleton_class.attached_object        #=> Foo
        Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
        Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
        nil.singleton_class.attached_object        #=> TypeError: `NilClass' is not a singleton class
        ```

* Data

    * New core class to represent simple immutable value object. The class is
      similar to Struct and partially shares an implementation, but has more
      lean and strict API. [[Feature #16122]]

        ```ruby
        Measure = Data.define(:amount, :unit)
        distance = Measure.new(100, 'km')            #=> #<data Measure amount=100, unit="km">
        weight = Measure.new(amount: 50, unit: 'kg') #=> #<data Measure amount=50, unit="kg">
        weight.with(amount: 40)                      #=> #<data Measure amount=40, unit="kg">
        weight.amount                                #=> 50
        weight.amount = 40                           #=> NoMethodError: undefined method `amount='
        ```

* Encoding

    * Encoding#replicate has been deprecated and will be removed in 3.3. [[Feature #18949]]
    * The dummy `Encoding::UTF_16` and `Encoding::UTF_32` encodings no longer
      try to dynamically guess the endian based on a byte order mark.
      Use `Encoding::UTF_16BE`/`UTF_16LE` and `Encoding::UTF_32BE`/`UTF_32LE` instead.
      This change speeds up getting the encoding of a String. [[Feature #18949]]
    * Limit maximum encoding set size by 256.
      If exceeding maximum size, `EncodingError` will be raised. [[Feature #18949]]

* Enumerator

    * Enumerator.product has been added.  Enumerator::Product is the implementation. [[Feature #18685]]

* Exception

    * Exception#detailed_message has been added.
      The default error printer calls this method on the Exception object
      instead of #message. [[Feature #18564]]

* Hash

    * Hash#shift now always returns nil if the hash is
      empty, instead of returning the default value or
      calling the default proc. [[Bug #16908]]

* Integer

    * Integer#ceildiv has been added. [[Feature #18809]]

* Kernel

    * Kernel#binding raises RuntimeError if called from a non-Ruby frame
      (such as a method defined in C). [[Bug #18487]]

* MatchData

    * MatchData#byteoffset has been added. [[Feature #13110]]
    * MatchData#deconstruct has been added. [[Feature #18821]]
    * MatchData#deconstruct_keys has been added. [[Feature #18821]]

* Module

    * Module.used_refinements has been added. [[Feature #14332]]
    * Module#refinements has been added. [[Feature #12737]]
    * Module#const_added has been added. [[Feature #17881]]
    * Module#undefined_instance_methods has been added. [[Feature #12655]]

* Proc

    * Proc#dup returns an instance of subclass. [[Bug #17545]]
    * Proc#parameters now accepts lambda keyword. [[Feature #15357]]

* Process
    * Added `RLIMIT_NPTS` constant to FreeBSD platform

* Regexp

    * The cache-based optimization is introduced.
      Many (but not all) Regexp matching is now in linear time, which
      will prevent regular expression denial of service (ReDoS)
      vulnerability. [[Feature #19104]]

    * Regexp.linear_time? is introduced. [[Feature #19194]]

    * Regexp.new now supports passing the regexp flags not only as an Integer,
      but also as a String.  Unknown flags raise ArgumentError.
      Otherwise, anything other than `true`, `false`, `nil` or Integer will be warned.
      [[Feature #18788]]

    * Regexp.timeout= has been added. Also, Regexp.new new supports timeout keyword.
      See [[Feature #17837]]

* Refinement

    * Refinement#refined_class has been added. [[Feature #12737]]

* RubyVM::AbstractSyntaxTree

    * Add `error_tolerant` option for `parse`, `parse_file` and `of`. [[Feature #19013]]
      With this option

        1. SyntaxError is suppressed
        2. AST is returned for invalid input
        3. `end` is complemented when a parser reaches to the end of input but `end` is insufficient
        4. `end` is treated as keyword based on indent

        ```ruby
        # Without error_tolerant option
        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY)
        def m
          a = 10
          if
        end
        RUBY
        # => <internal:ast>:33:in `parse': syntax error, unexpected `end' (SyntaxError)

        # With error_tolerant option
        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
        def m
          a = 10
          if
        end
        RUBY
        p root # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-4:3>

        # `end` is treated as keyword based on indent
        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
        module Z
          class Foo
            foo.
          end

          def bar
          end
        end
        RUBY
        p root.children[-1].children[-1].children[-1].children[-2..-1]
        # => [#<RubyVM::AbstractSyntaxTree::Node:CLASS@2:2-4:5>, #<RubyVM::AbstractSyntaxTree::Node:DEFN@6:2-7:5>]
        ```

    * Add `keep_tokens` option for `parse`, `parse_file` and `of`. Add `#tokens` and `#all_tokens`
      for RubyVM::AbstractSyntaxTree::Node [[Feature #19070]]

        ```ruby
        root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2", keep_tokens: true)
        root.tokens # => [[0, :tIDENTIFIER, "x", [1, 0, 1, 1]], [1, :tSP, " ", [1, 1, 1, 2]], ...]
        root.tokens.map{_1[2]}.join # => "x = 1 + 2"
        ```

* Set

    * Set is now available as a built-in class without the need for `require "set"`. [[Feature #16989]]
      It is currently autoloaded via the Set constant or a call to Enumerable#to_set.

* String

    * String#byteindex and String#byterindex have been added. [[Feature #13110]]
    * Update Unicode to Version 15.0.0 and Emoji Version 15.0. [[Feature #18639]]
      (also applies to Regexp)
    * String#bytesplice has been added.  [[Feature #18598]]
    * String#dedup has been added as an alias to String#-@.  [[Feature #18595]]

* Struct

    * A Struct class can also be initialized with keyword arguments
      without `keyword_init: true` on Struct.new [[Feature #16806]]

        ```ruby
        Post = Struct.new(:id, :name)
        Post.new(1, "hello") #=> #<struct Post id=1, name="hello">
        # From Ruby 3.2, the following code also works without keyword_init: true.
        Post.new(id: 1, name: "hello") #=> #<struct Post id=1, name="hello">
        ```

* Thread

    * Thread.each_caller_location is added. [[Feature #16663]]

* Thread::Queue

    * Thread::Queue#pop(timeout: sec) is added. [[Feature #18774]]

* Thread::SizedQueue

    * Thread::SizedQueue#pop(timeout: sec) is added. [[Feature #18774]]
    * Thread::SizedQueue#push(timeout: sec) is added. [[Feature #18944]]

* Time

    * Time#deconstruct_keys is added, allowing to use Time instances
      in pattern-matching expressions [[Feature #19071]]

    * Time.new now can parse a string like generated by Time#inspect
      and return a Time instance based on the given argument.
      [[Feature #18033]]

* SyntaxError
    * SyntaxError#path has been added.  [[Feature #19138]]

* TracePoint

    * TracePoint#binding now returns `nil` for `c_call`/`c_return` TracePoints.
      [[Bug #18487]]
    * TracePoint#enable `target_thread` keyword argument now defaults to the
      current thread if a block is given and `target` and `target_line` keyword
      arguments are not passed. [[Bug #16889]]

* UnboundMethod

    * `UnboundMethod#==` returns `true` if the actual method is same. For example,
      `String.instance_method(:object_id) == Array.instance_method(:object_id)`
      returns `true`. [[Feature #18798]]

    * `UnboundMethod#inspect` does not show the receiver of `instance_method`.
      For example `String.instance_method(:object_id).inspect` returns
      `"#<UnboundMethod: Kernel#object_id()>"`
      (was `"#<UnboundMethod: String(Kernel)#object_id()>"`).

* GC

    * Expose `need_major_gc` via `GC.latest_gc_info`. [GH-6791]

* ObjectSpace

    * `ObjectSpace.dump_all` dump shapes as well. [GH-6868]

## Stdlib updates

* Bundler

    * Bundler now uses [PubGrub] resolver instead of [Molinillo] for performance improvement.
    * Add --ext=rust support to bundle gem for creating simple gems with Rust extensions.
      [[GH-rubygems-6149]]
    * Make cloning git repos faster [[GH-rubygems-4475]]

* RubyGems

    * Add mswin support for cargo builder. [[GH-rubygems-6167]]

* CGI

    * `CGI.escapeURIComponent` and `CGI.unescapeURIComponent` are added.
      [[Feature #18822]]

* Coverage

    * `Coverage.setup` now accepts `eval: true`. By this, `eval` and related methods are
      able to generate code coverage. [[Feature #19008]]

    * `Coverage.supported?(mode)` enables detection of what coverage modes are
      supported. [[Feature #19026]]

* Date

    * Added `Date#deconstruct_keys` and `DateTime#deconstruct_keys` same as [[Feature #19071]]

* ERB

    * `ERB::Util.html_escape` is made faster than `CGI.escapeHTML`.
        * It no longer allocates a String object when no character needs to be escaped.
        * It skips calling `#to_s` method when an argument is already a String.
        * `ERB::Escape.html_escape` is added as an alias to `ERB::Util.html_escape`,
          which has not been monkey-patched by Rails.
    * `ERB::Util.url_encode` is made faster using `CGI.escapeURIComponent`.
    * `-S` option is removed from `erb` command.

* FileUtils

    * Add FileUtils.ln_sr method and `relative:` option to FileUtils.ln_s.
      [[Feature #18925]]

* IRB

    * debug.gem integration commands have been added: `debug`, `break`, `catch`,
      `next`, `delete`, `step`, `continue`, `finish`, `backtrace`, `info`
        * They work even if you don't have `gem "debug"` in your Gemfile.
        * See also: [What's new in Ruby 3.2's IRB?](https://st0012.dev/whats-new-in-ruby-3-2-irb)
    * More Pry-like commands and features have been added.
        * `edit` and `show_cmds` (like Pry's `help`) are added.
        * `ls` takes `-g` or `-G` option to filter out outputs.
        * `show_source` is aliased from `$` and accepts unquoted inputs.
        * `whereami` is aliased from `@`.

* Net::Protocol

    * Improve `Net::BufferedIO` performance. [[GH-net-protocol-14]]

* Pathname

    * Added `Pathname#lutime`. [[GH-pathname-20]]

* Socket

    * Added the following constants for supported platforms.
        * `SO_INCOMING_CPU`
        * `SO_INCOMING_NAPI_ID`
        * `SO_RTABLE`
        * `SO_SETFIB`
        * `SO_USER_COOKIE`
        * `TCP_KEEPALIVE`
        * `TCP_CONNECTION_INFO`

* SyntaxSuggest

    * The feature of `syntax_suggest` formerly `dead_end` is integrated in Ruby.
      [[Feature #18159]]

* UNIXSocket

    * Add support for UNIXSocket on Windows. Emulate anonymous sockets. Add
      support for File.socket? and File::Stat#socket? where possible.
      [[Feature #19135]]

*   The following default gems are updated.

    * RubyGems 3.4.1
    * abbrev 0.1.1
    * benchmark 0.2.1
    * bigdecimal 3.1.3
    * bundler 2.4.1
    * cgi 0.3.6
    * csv 3.2.6
    * date 3.3.3
    * delegate 0.3.0
    * did_you_mean 1.6.3
    * digest 3.1.1
    * drb 2.1.1
    * english 0.7.2
    * erb 4.0.2
    * error_highlight 0.5.1
    * etc 1.4.2
    * fcntl 1.0.2
    * fiddle 1.1.1
    * fileutils 1.7.0
    * forwardable 1.3.3
    * getoptlong 0.2.0
    * io-console 0.6.0
    * io-nonblock 0.2.0
    * io-wait 0.3.0
    * ipaddr 1.2.5
    * irb 1.6.2
    * json 2.6.3
    * logger 1.5.3
    * mutex_m 0.1.2
    * net-http 0.3.2
    * net-protocol 0.2.1
    * nkf 0.1.2
    * open-uri 0.3.0
    * open3 0.1.2
    * openssl 3.1.0
    * optparse 0.3.1
    * ostruct 0.5.5
    * pathname 0.2.1
    * pp 0.4.0
    * pstore 0.1.2
    * psych 5.0.1
    * racc 1.6.2
    * rdoc 6.5.0
    * readline-ext 0.1.5
    * reline 0.3.2
    * resolv 0.2.2
    * resolv-replace 0.1.1
    * securerandom 0.2.2
    * set 1.0.3
    * stringio 3.0.4
    * strscan 3.0.5
    * syntax_suggest 1.0.2
    * syslog 0.1.1
    * tempfile 0.1.3
    * time 0.2.1
    * timeout 0.3.1
    * tmpdir 0.1.3
    * tsort 0.1.1
    * un 0.2.1
    * uri 0.12.0
    * weakref 0.1.2
    * win32ole 1.8.9
    * yaml 0.2.1
    * zlib 3.0.0

*   The following bundled gems are updated.

    * minitest 5.16.3
    * power_assert 2.0.3
    * test-unit 3.5.7
    * net-ftp 0.2.0
    * net-imap 0.3.4
    * net-pop 0.1.2
    * net-smtp 0.3.3
    * rbs 2.8.2
    * typeprof 0.21.3
    * debug 1.7.1

See GitHub releases like [GitHub Releases of Logger](https://github.com/ruby/logger/releases) or changelog for details of the default gems or bundled gems.

## Supported platforms

* WebAssembly/WASI is added. See [wasm/README.md] and [ruby.wasm] for more details. [[Feature #18462]]

## Compatibility issues

* `String#to_c` currently treat a sequence of underscores as an end of Complex
  string. [[Bug #19087]]

* Now `ENV.clone` raises `TypeError` as well as `ENV.dup` [[Bug #17767]]

### Removed constants

The following deprecated constants are removed.

* `Fixnum` and `Bignum` [[Feature #12005]]
* `Random::DEFAULT` [[Feature #17351]]
* `Struct::Group`
* `Struct::Passwd`

### Removed methods

The following deprecated methods are removed.

* `Dir.exists?` [[Feature #17391]]
* `File.exists?` [[Feature #17391]]
* `Kernel#=~` [[Feature #15231]]
* `Kernel#taint`, `Kernel#untaint`, `Kernel#tainted?`
  [[Feature #16131]]
* `Kernel#trust`, `Kernel#untrust`, `Kernel#untrusted?`
  [[Feature #16131]]
* `Method#public?`, `Method#private?`, `Method#protected?`,
  `UnboundMethod#public?`, `UnboundMethod#private?`, `UnboundMethod#protected?`
  [[Bug #18729]] [[Bug #18751]] [[Bug #18435]]

### Source code incompatibility of extension libraries

* Extension libraries provide PRNG, subclasses of Random, need updates.
  See [PRNG update] below for more information. [[Bug #19100]]

### Error printer

* Ruby no longer escapes control characters and backslashes in an
  error message. [[Feature #18367]]

### Constant lookup when defining a class/module

* When defining a class/module directly under the Object class by class/module
  statement, if there is already a class/module defined by `Module#include`
  with the same name, the statement was handled as "open class" in Ruby 3.1 or before.
  Since Ruby 3.2, a new class is defined instead. [[Feature #18832]]

## Stdlib compatibility issues

* Psych no longer bundles libyaml sources.
  And also Fiddle no longer bundles libffi sources.
  Users need to install the libyaml/libffi library themselves via the package
  manager like apt, yum, brew, etc.

    Psych and fiddle supported the static build with specific version of libyaml
    and libffi sources. You can build psych with libyaml-0.2.5 like this.

    ```bash
    $ ./configure --with-libyaml-source-dir=/path/to/libyaml-0.2.5
    ```

    And you can build fiddle with libffi-3.4.4 like this.

    ```bash
    $ ./configure --with-libffi-source-dir=/path/to/libffi-3.4.4
    ```

    [[Feature #18571]]

* Check cookie name/path/domain characters in `CGI::Cookie`. [[CVE-2021-33621]]

* `URI.parse` return empty string in host instead of nil. [[sec-156615]]

## C API updates

### Updated C APIs

The following APIs are updated.

* PRNG update

    `rb_random_interface_t` in ruby/random.h updated and versioned.
    Extension libraries which use this interface and built for older
    versions need to rebuild with adding `init_int32` function.

### Added C APIs

* `VALUE rb_hash_new_capa(long capa)` was added to created hashes with the desired capacity.
* `rb_internal_thread_add_event_hook` and `rb_internal_thread_add_event_hook` were added to instrument threads scheduling.
  The following events are available:
    * `RUBY_INTERNAL_THREAD_EVENT_STARTED`
    * `RUBY_INTERNAL_THREAD_EVENT_READY`
    * `RUBY_INTERNAL_THREAD_EVENT_RESUMED`
    * `RUBY_INTERNAL_THREAD_EVENT_SUSPENDED`
    * `RUBY_INTERNAL_THREAD_EVENT_EXITED`
* `rb_debug_inspector_current_depth` and `rb_debug_inspector_frame_depth` are added for debuggers.

### Removed C APIs

The following deprecated APIs are removed.

* `rb_cData` variable.
* "taintedness" and "trustedness" functions. [[Feature #16131]]

## Implementation improvements

* Fixed several race conditions in Kernel#autoload. [[Bug #18782]]
* Cache invalidation for expressions referencing constants is now
  more fine-grained. `RubyVM.stat(:global_constant_state)` was
  removed because it was closely tied to the previous caching scheme
  where setting any constant invalidates all caches in the system.
  New keys, `:constant_cache_invalidations` and `:constant_cache_misses`,
  were introduced to help with use cases for `:global_constant_state`.
  [[Feature #18589]]
* The cache-based optimization for Regexp matching is introduced.
  [[Feature #19104]]
* [Variable Width Allocation](https://shopify.engineering/ruby-variable-width-allocation)
  is now enabled by default. [[Feature #18239]]
* Added a new instance variable caching mechanism, called object shapes, which
  improves inline cache hits for most objects and allows us to generate very
  efficient JIT code. Objects whose instance variables are defined in a
  consistent order will see the most performance benefits.
  [[Feature #18776]]
* Speed up marking instruction sequences by using a bitmap to find "markable"
  objects.  This change results in faster major collections.
  [[Feature #18875]]

## JIT

### YJIT

* YJIT is no longer experimental
    * Has been tested on production workloads for over a year and proven to be quite stable.
* YJIT now supports both x86-64 and arm64/aarch64 CPUs on Linux, MacOS, BSD and other UNIX platforms.
    * This release brings support for Mac M1/M2, AWS Graviton and Raspberry Pi 4.
* Building YJIT now requires Rust 1.58.0+. [[Feature #18481]]
    * In order to ensure that CRuby is built with YJIT, please install `rustc` >= 1.58.0
      before running `./configure`
    * Please reach out to the YJIT team should you run into any issues.
* Physical memory for JIT code is lazily allocated. Unlike Ruby 3.1,
  the RSS of a Ruby process is minimized because virtual memory pages
  allocated by `--yjit-exec-mem-size` will not be mapped to physical
  memory pages until actually utilized by JIT code.
* Introduce Code GC that frees all code pages when the memory consumption
  by JIT code reaches `--yjit-exec-mem-size`.
    * `RubyVM::YJIT.runtime_stats` returns Code GC metrics in addition to
      existing `inline_code_size` and `outlined_code_size` keys:
      `code_gc_count`, `live_page_count`, `freed_page_count`, and `freed_code_size`.
* Most of the statistics produced by `RubyVM::YJIT.runtime_stats` are now available in release builds.
    * Simply run ruby with `--yjit-stats` to compute and dump stats (incurs some run-time overhead).
* YJIT is now optimized to take advantage of object shapes. [[Feature #18776]]
* Take advantage of finer-grained constant invalidation to invalidate less code when defining new constants. [[Feature #18589]]
* The default `--yjit-exec-mem-size` is changed to 64 (MiB).
* The default `--yjit-call-threshold` is changed to 30.

### MJIT

* The MJIT compiler is re-implemented in Ruby as `ruby_vm/mjit/compiler`.
* MJIT compiler is executed under a forked Ruby process instead of
  doing it in a native thread called MJIT worker. [[Feature #18968]]
    * As a result, Microsoft Visual Studio (MSWIN) is no longer supported.
* MinGW is no longer supported. [[Feature #18824]]
* Rename `--mjit-min-calls` to `--mjit-call-threshold`.
* Change default `--mjit-max-cache` back from 10000 to 100.

[Feature #12005]:     https://bugs.ruby-lang.org/issues/12005
[Feature #12084]:     https://bugs.ruby-lang.org/issues/12084
[Feature #12655]:     https://bugs.ruby-lang.org/issues/12655
[Feature #12737]:     https://bugs.ruby-lang.org/issues/12737
[Feature #13110]:     https://bugs.ruby-lang.org/issues/13110
[Feature #14332]:     https://bugs.ruby-lang.org/issues/14332
[Feature #15231]:     https://bugs.ruby-lang.org/issues/15231
[Feature #15357]:     https://bugs.ruby-lang.org/issues/15357
[Bug #15928]:         https://bugs.ruby-lang.org/issues/15928
[Feature #16122]:     https://bugs.ruby-lang.org/issues/16122
[Feature #16131]:     https://bugs.ruby-lang.org/issues/16131
[Bug #16466]:         https://bugs.ruby-lang.org/issues/16466
[Feature #16663]:     https://bugs.ruby-lang.org/issues/16663
[Feature #16806]:     https://bugs.ruby-lang.org/issues/16806
[Bug #16889]:         https://bugs.ruby-lang.org/issues/16889
[Bug #16908]:         https://bugs.ruby-lang.org/issues/16908
[Feature #16989]:     https://bugs.ruby-lang.org/issues/16989
[Feature #17351]:     https://bugs.ruby-lang.org/issues/17351
[Feature #17391]:     https://bugs.ruby-lang.org/issues/17391
[Bug #17545]:         https://bugs.ruby-lang.org/issues/17545
[Bug #17767]:         https://bugs.ruby-lang.org/issues/17767
[Feature #17837]:     https://bugs.ruby-lang.org/issues/17837
[Feature #17881]:     https://bugs.ruby-lang.org/issues/17881
[Feature #18033]:     https://bugs.ruby-lang.org/issues/18033
[Feature #18159]:     https://bugs.ruby-lang.org/issues/18159
[Feature #18239]:     https://bugs.ruby-lang.org/issues/18239#note-17
[Feature #18351]:     https://bugs.ruby-lang.org/issues/18351
[Feature #18367]:     https://bugs.ruby-lang.org/issues/18367
[Bug #18435]:         https://bugs.ruby-lang.org/issues/18435
[Feature #18462]:     https://bugs.ruby-lang.org/issues/18462
[Feature #18481]:     https://bugs.ruby-lang.org/issues/18481
[Bug #18487]:         https://bugs.ruby-lang.org/issues/18487
[Feature #18564]:     https://bugs.ruby-lang.org/issues/18564
[Feature #18571]:     https://bugs.ruby-lang.org/issues/18571
[Feature #18585]:     https://bugs.ruby-lang.org/issues/18585
[Feature #18589]:     https://bugs.ruby-lang.org/issues/18589
[Feature #18595]:     https://bugs.ruby-lang.org/issues/18595
[Feature #18598]:     https://bugs.ruby-lang.org/issues/18598
[Bug #18625]:         https://bugs.ruby-lang.org/issues/18625
[Feature #18630]:     https://bugs.ruby-lang.org/issues/18630
[Bug #18633]:         https://bugs.ruby-lang.org/issues/18633
[Feature #18639]:     https://bugs.ruby-lang.org/issues/18639
[Feature #18685]:     https://bugs.ruby-lang.org/issues/18685
[Bug #18729]:         https://bugs.ruby-lang.org/issues/18729
[Bug #18751]:         https://bugs.ruby-lang.org/issues/18751
[Feature #18774]:     https://bugs.ruby-lang.org/issues/18774
[Feature #18776]:     https://bugs.ruby-lang.org/issues/18776
[Bug #18782]:         https://bugs.ruby-lang.org/issues/18782
[Feature #18788]:     https://bugs.ruby-lang.org/issues/18788
[Feature #18798]:     https://bugs.ruby-lang.org/issues/18798
[Feature #18809]:     https://bugs.ruby-lang.org/issues/18809
[Feature #18821]:     https://bugs.ruby-lang.org/issues/18821
[Feature #18822]:     https://bugs.ruby-lang.org/issues/18822
[Feature #18824]:     https://bugs.ruby-lang.org/issues/18824
[Feature #18832]:     https://bugs.ruby-lang.org/issues/18832
[Feature #18875]:     https://bugs.ruby-lang.org/issues/18875
[Feature #18925]:     https://bugs.ruby-lang.org/issues/18925
[Feature #18944]:     https://bugs.ruby-lang.org/issues/18944
[Feature #18949]:     https://bugs.ruby-lang.org/issues/18949
[Feature #18968]:     https://bugs.ruby-lang.org/issues/18968
[Feature #19008]:     https://bugs.ruby-lang.org/issues/19008
[Feature #19013]:     https://bugs.ruby-lang.org/issues/19013
[Feature #19026]:     https://bugs.ruby-lang.org/issues/19026
[Feature #19036]:     https://bugs.ruby-lang.org/issues/19036
[Feature #19060]:     https://bugs.ruby-lang.org/issues/19060
[Feature #19070]:     https://bugs.ruby-lang.org/issues/19070
[Feature #19071]:     https://bugs.ruby-lang.org/issues/19071
[Feature #19078]:     https://bugs.ruby-lang.org/issues/19078
[Bug #19087]:         https://bugs.ruby-lang.org/issues/19087
[Bug #19100]:         https://bugs.ruby-lang.org/issues/19100
[Feature #19104]:     https://bugs.ruby-lang.org/issues/19104
[Feature #19135]:     https://bugs.ruby-lang.org/issues/19135
[Feature #19138]:     https://bugs.ruby-lang.org/issues/19138
[Feature #19194]:     https://bugs.ruby-lang.org/issues/19194
[Molinillo]:          https://github.com/CocoaPods/Molinillo
[PubGrub]:            https://github.com/jhawthorn/pub_grub
[GH-net-protocol-14]: https://github.com/ruby/net-protocol/pull/14
[GH-pathname-20]:     https://github.com/ruby/pathname/pull/20
[GH-6791]:            https://github.com/ruby/ruby/pull/6791
[GH-6868]:            https://github.com/ruby/ruby/pull/6868
[GH-rubygems-4475]:   https://github.com/rubygems/rubygems/pull/4475
[GH-rubygems-6149]:   https://github.com/rubygems/rubygems/pull/6149
[GH-rubygems-6167]:   https://github.com/rubygems/rubygems/pull/6167
[sec-156615]:         https://hackerone.com/reports/156615
[CVE-2021-33621]:     https://www.ruby-lang.org/en/news/2022/11/22/http-response-splitting-in-cgi-cve-2021-33621/
[wasm/README.md]:     https://github.com/ruby/ruby/blob/master/wasm/README.md
[ruby.wasm]:          https://github.com/ruby/ruby.wasm