Sync latest development version of bundler & rubygems

79 files changed, 649 insertions, 438 deletions

diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 249f5b2027..421f42cb52 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -586,6 +586,7 @@ module Bundler
     method_option :git, :type => :boolean, :default => true, :desc => "Initialize a git repo inside your library."
     method_option :mit, :type => :boolean, :desc => "Generate an MIT license file. Set a default with `bundle config set --global gem.mit true`."
     method_option :rubocop, :type => :boolean, :desc => "Add rubocop to the generated Rakefile and gemspec. Set a default with `bundle config set --global gem.rubocop true`."
+    method_option :changelog, :type => :boolean, :desc => "Generate changelog file. Set a default with `bundle config set --global gem.changelog true`."
     method_option :test, :type => :string, :lazy_default => Bundler.settings["gem.test"] || "", :aliases => "-t", :banner => "Use the specified test framework for your library",
                          :desc => "Generate a test directory for your library, either rspec, minitest or test-unit. Set a default with `bundle config set --global gem.test (rspec|minitest|test-unit)`."
     method_option :ci, :type => :string, :lazy_default => Bundler.settings["gem.ci"] || "",
diff --git a/lib/bundler/cli/cache.rb b/lib/bundler/cli/cache.rb
index c14c8877f0..9cd6133879 100644
--- a/lib/bundler/cli/cache.rb
+++ b/lib/bundler/cli/cache.rb
@@ -30,6 +30,7 @@ module Bundler
       require_relative "install"
       options = self.options.dup
       options["local"] = false if Bundler.settings[:cache_all_platforms]
+      options["no-cache"] = true
       Bundler::CLI::Install.new(options).run
     end
 
diff --git a/lib/bundler/cli/gem.rb b/lib/bundler/cli/gem.rb
index 6ef1473b1e..5b3d9c332e 100644
--- a/lib/bundler/cli/gem.rb
+++ b/lib/bundler/cli/gem.rb
@@ -39,11 +39,11 @@ module Bundler
       constant_name = name.gsub(/-[_-]*(?![_-]|$)/) { "::" }.gsub(/([_-]+|(::)|^)(.|$)/) { $2.to_s + $3.upcase }
       constant_array = constant_name.split("::")
 
-      git_installed = Bundler.git_present?
+      use_git = Bundler.git_present? && options[:git]
 
-      git_author_name = git_installed ? `git config user.name`.chomp : ""
-      github_username = git_installed ? `git config github.user`.chomp : ""
-      git_user_email = git_installed ? `git config user.email`.chomp : ""
+      git_author_name = use_git ? `git config user.name`.chomp : ""
+      github_username = use_git ? `git config github.user`.chomp : ""
+      git_user_email = use_git ? `git config user.email`.chomp : ""
 
       config = {
         :name             => name,
@@ -58,7 +58,9 @@ module Bundler
         :ext              => options[:ext],
         :exe              => options[:exe],
         :bundler_version  => bundler_dependency_version,
+        :git              => use_git,
         :github_username  => github_username.empty? ? "[USERNAME]" : github_username,
+        :required_ruby_version => Gem.ruby_version < Gem::Version.new("2.4.a") ? "2.3.0" : "2.4.0",
       }
       ensure_safe_gem_name(name, constant_array)
 
@@ -78,7 +80,7 @@ module Bundler
         bin/setup
       ]
 
-      templates.merge!("gitignore.tt" => ".gitignore") if Bundler.git_present?
+      templates.merge!("gitignore.tt" => ".gitignore") if use_git
 
       if test_framework = ask_and_set_test_framework
         config[:test] = test_framework
@@ -141,12 +143,25 @@ module Bundler
         templates.merge!("CODE_OF_CONDUCT.md.tt" => "CODE_OF_CONDUCT.md")
       end
 
+      if ask_and_set(:changelog, "Do you want to include a changelog?",
+        "A changelog is a file which contains a curated, chronologically ordered list of notable " \
+        "changes for each version of a project. To make it easier for users and contributors to" \
+        " see precisely what notable changes have been made between each release (or version) of" \
+        " the project. Whether consumers or developers, the end users of software are" \
+        " human beings who care about what's in the software. When the software changes, people " \
+        "want to know why and how. see https://keepachangelog.com")
+        config[:changelog] = true
+        Bundler.ui.info "Changelog enabled in config"
+        templates.merge!("CHANGELOG.md.tt" => "CHANGELOG.md")
+      end
+
       if ask_and_set(:rubocop, "Do you want to add rubocop as a dependency for gems you generate?",
         "RuboCop is a static code analyzer that has out-of-the-box rules for many " \
         "of the guidelines in the community style guide. " \
         "For more information, see the RuboCop docs (https://docs.rubocop.org/en/stable/) " \
         "and the Ruby Style Guides (https://github.com/rubocop-hq/ruby-style-guide).")
         config[:rubocop] = true
+        config[:rubocop_version] = Gem.ruby_version < Gem::Version.new("2.4.a") ? "0.81.0" : "1.7"
         Bundler.ui.info "RuboCop enabled in config"
         templates.merge!("rubocop.yml.tt" => ".rubocop.yml")
       end
@@ -161,24 +176,31 @@ module Bundler
         )
       end
 
+      if File.exist?(target) && !File.directory?(target)
+        Bundler.ui.error "Couldn't create a new gem named `#{gem_name}` because there's an existing file named `#{gem_name}`."
+        exit Bundler::BundlerError.all_errors[Bundler::GenericSystemCallError]
+      end
+
+      if use_git
+        Bundler.ui.info "Initializing git repo in #{target}"
+        `git init #{target}`
+
+        config[:git_default_branch] = File.read("#{target}/.git/HEAD").split("/").last.chomp
+      end
+
       templates.each do |src, dst|
         destination = target.join(dst)
-        SharedHelpers.filesystem_access(destination) do
-          thor.template("newgem/#{src}", destination, config)
-        end
+        thor.template("newgem/#{src}", destination, config)
       end
 
       executables.each do |file|
-        SharedHelpers.filesystem_access(target.join(file)) do |path|
-          executable = (path.stat.mode | 0o111)
-          path.chmod(executable)
-        end
+        path = target.join(file)
+        executable = (path.stat.mode | 0o111)
+        path.chmod(executable)
       end
 
-      if Bundler.git_present? && options[:git]
-        Bundler.ui.info "Initializing git repo in #{target}"
+      if use_git
         Dir.chdir(target) do
-          `git init`
           `git add .`
         end
       end
@@ -188,8 +210,6 @@ module Bundler
 
       Bundler.ui.info "Gem '#{name}' was successfully created. " \
         "For more information on making a RubyGem visit https://bundler.io/guides/creating_gem.html"
-    rescue Errno::EEXIST => e
-      raise GenericSystemCallError.new(e, "There was a conflict while creating the new gem.")
     end
 
     private
diff --git a/lib/bundler/compact_index_client/updater.rb b/lib/bundler/compact_index_client/updater.rb
index 66d1735583..9e0180fac7 100644
--- a/lib/bundler/compact_index_client/updater.rb
+++ b/lib/bundler/compact_index_client/updater.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 require_relative "../vendored_fileutils"
-require "stringio"
-require "zlib"
 
 module Bundler
   class CompactIndexClient
@@ -45,24 +43,18 @@ module Bundler
               else
                 "bytes=#{local_temp_path.size}-"
               end
-          else
-            # Fastly ignores Range when Accept-Encoding: gzip is set
-            headers["Accept-Encoding"] = "gzip"
           end
 
           response = @fetcher.call(remote_path, headers)
           return nil if response.is_a?(Net::HTTPNotModified)
 
           content = response.body
-          if response["Content-Encoding"] == "gzip"
-            content = Zlib::GzipReader.new(StringIO.new(content)).read
-          end
 
           SharedHelpers.filesystem_access(local_temp_path) do
             if response.is_a?(Net::HTTPPartialContent) && local_temp_path.size.nonzero?
               local_temp_path.open("a") {|f| f << slice_body(content, 1..-1) }
             else
-              local_temp_path.open("w") {|f| f << content }
+              local_temp_path.open("wb") {|f| f << content }
             end
           end
 
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index 349fa632a0..5f02b15e5f 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require_relative "lockfile_parser"
-require "set"
 
 module Bundler
   class Definition
@@ -88,11 +87,7 @@ module Bundler
         @lockfile_contents = Bundler.read_file(lockfile)
         @locked_gems = LockfileParser.new(@lockfile_contents)
         @locked_platforms = @locked_gems.platforms
-        if Bundler.settings[:force_ruby_platform]
-          @platforms = [Gem::Platform::RUBY]
-        else
-          @platforms = @locked_platforms.dup
-        end
+        @platforms = @locked_platforms.dup
         @locked_bundler_version = @locked_gems.bundler_version
         @locked_ruby_version = @locked_gems.ruby_version
 
@@ -264,23 +259,18 @@ module Bundler
     def resolve
       @resolve ||= begin
         last_resolve = converge_locked_specs
-        resolve =
-          if Bundler.frozen_bundle?
-            Bundler.ui.debug "Frozen, using resolution from the lockfile"
-            last_resolve
-          elsif !unlocking? && nothing_changed?
-            Bundler.ui.debug("Found no changes, using resolution from the lockfile")
-            last_resolve
-          else
-            # Run a resolve against the locally available gems
-            Bundler.ui.debug("Found changes from the lockfile, re-resolving dependencies because #{change_reason}")
-            expanded_dependencies = expand_dependencies(dependencies + metadata_dependencies, @remote)
-            last_resolve.merge Resolver.resolve(expanded_dependencies, index, source_requirements, last_resolve, gem_version_promoter, additional_base_requirements_for_resolve, platforms)
-          end
-
-        # filter out gems that _can_ be installed on multiple platforms, but don't need
-        # to be
-        resolve.for(expand_dependencies(dependencies, true), [], false, false, false)
+        if Bundler.frozen_bundle?
+          Bundler.ui.debug "Frozen, using resolution from the lockfile"
+          last_resolve
+        elsif !unlocking? && nothing_changed?
+          Bundler.ui.debug("Found no changes, using resolution from the lockfile")
+          last_resolve
+        else
+          # Run a resolve against the locally available gems
+          Bundler.ui.debug("Found changes from the lockfile, re-resolving dependencies because #{change_reason}")
+          expanded_dependencies = expand_dependencies(dependencies + metadata_dependencies, @remote)
+          Resolver.resolve(expanded_dependencies, source_requirements, last_resolve, gem_version_promoter, additional_base_requirements_for_resolve, platforms)
+        end
       end
     end
 
@@ -611,7 +601,7 @@ module Bundler
       deps_for_source = @dependencies.select {|s| s.source == source }
       locked_deps_for_source = @locked_deps.values.select {|dep| dep.source == locked_source }
 
-      Set.new(deps_for_source) != Set.new(locked_deps_for_source)
+      deps_for_source.uniq.sort != locked_deps_for_source.sort
     end
 
     def specs_for_source_changed?(source)
@@ -673,19 +663,20 @@ module Bundler
     def converge_rubygems_sources
       return false if Bundler.feature_flag.disable_multisource?
 
-      changes = false
-
       # Get the RubyGems sources from the Gemfile.lock
       locked_gem_sources = @locked_sources.select {|s| s.is_a?(Source::Rubygems) }
+      return false if locked_gem_sources.empty?
+
       # Get the RubyGems remotes from the Gemfile
       actual_remotes = sources.rubygems_remotes
+      return false if actual_remotes.empty?
+
+      changes = false
 
       # If there is a RubyGems source in both
-      if !locked_gem_sources.empty? && !actual_remotes.empty?
-        locked_gem_sources.each do |locked_gem|
-          # Merge the remotes from the Gemfile into the Gemfile.lock
-          changes |= locked_gem.replace_remotes(actual_remotes, Bundler.settings[:allow_deployment_source_credential_changes])
-        end
+      locked_gem_sources.each do |locked_gem|
+        # Merge the remotes from the Gemfile into the Gemfile.lock
+        changes |= locked_gem.replace_remotes(actual_remotes, Bundler.settings[:allow_deployment_source_credential_changes])
       end
 
       changes
@@ -825,11 +816,6 @@ module Bundler
           # commonly happens if the version changed in the gemspec
           next unless new_spec
 
-          new_runtime_deps = new_spec.dependencies.select {|d| d.type != :development }
-          old_runtime_deps = s.dependencies.select {|d| d.type != :development }
-          # If the dependencies of the path source have changed and locked spec can't satisfy new dependencies, unlock it
-          next unless new_runtime_deps.sort == old_runtime_deps.sort || new_runtime_deps.all? {|d| satisfies_locked_spec?(d) }
-
           s.dependencies.replace(new_spec.dependencies)
         end
 
@@ -896,7 +882,7 @@ module Bundler
       dependencies.each do |dep|
         dep = Dependency.new(dep, ">= 0") unless dep.respond_to?(:name)
         next unless remote || dep.current_platform?
-        target_platforms = dep.gem_platforms(remote ? Resolver.sort_platforms(@platforms) : [generic_local_platform])
+        target_platforms = dep.gem_platforms(remote ? @platforms : [generic_local_platform])
         deps += expand_dependency_with_platforms(dep, target_platforms)
       end
       deps
@@ -904,7 +890,7 @@ module Bundler
 
     def expand_dependency_with_platforms(dep, platforms)
       platforms.map do |p|
-        DepProxy.new(dep, p)
+        DepProxy.get_proxy(dep, p)
       end
     end
 
@@ -915,29 +901,18 @@ module Bundler
       # Record the specs available in each gem's source, so that those
       # specs will be available later when the resolver knows where to
       # look for that gemspec (or its dependencies)
-      default = sources.default_source
-      source_requirements = { :default => default }
-      default = nil unless Bundler.feature_flag.disable_multisource?
-      dependencies.each do |dep|
-        next unless source = dep.source || default
-        source_requirements[dep.name] = source
-      end
+      source_requirements = { :default => sources.default_source }.merge(dependency_source_requirements)
       metadata_dependencies.each do |dep|
         source_requirements[dep.name] = sources.metadata_source
       end
+      source_requirements[:global] = index unless Bundler.feature_flag.disable_multisource?
+      source_requirements[:default_bundler] = source_requirements["bundler"] || source_requirements[:default]
       source_requirements["bundler"] = sources.metadata_source # needs to come last to override
       source_requirements
     end
 
     def pinned_spec_names(skip = nil)
-      pinned_names = []
-      default = Bundler.feature_flag.disable_multisource? && sources.default_source
-      @dependencies.each do |dep|
-        next unless dep_source = dep.source || default
-        next if dep_source == skip
-        pinned_names << dep.name
-      end
-      pinned_names
+      dependency_source_requirements.reject {|_, source| source == skip }.keys
     end
 
     def requested_groups
@@ -984,7 +959,7 @@ module Bundler
         next requirements if @locked_gems.dependencies[name] != dependency
         next requirements if dependency.source.is_a?(Source::Path)
         dep = Gem::Dependency.new(name, ">= #{locked_spec.version}")
-        requirements[name] = DepProxy.new(dep, locked_spec.platform)
+        requirements[name] = DepProxy.get_proxy(dep, locked_spec.platform)
         requirements
       end.values
     end
@@ -994,5 +969,17 @@ module Bundler
 
       Bundler.settings[:allow_deployment_source_credential_changes] && source.equivalent_remotes?(sources.rubygems_remotes)
     end
+
+    def dependency_source_requirements
+      @dependency_source_requirements ||= begin
+        source_requirements = {}
+        default = sources.default_source
+        dependencies.each do |dep|
+          dep_source = dep.source || default
+          source_requirements[dep.name] = dep_source
+        end
+        source_requirements
+      end
+    end
   end
 end
diff --git a/lib/bundler/dep_proxy.rb b/lib/bundler/dep_proxy.rb
index bb09fe9ea6..a32dc37b49 100644
--- a/lib/bundler/dep_proxy.rb
+++ b/lib/bundler/dep_proxy.rb
@@ -4,19 +4,18 @@ module Bundler
   class DepProxy
     attr_reader :__platform, :dep
 
+    @proxies = {}
+
+    def self.get_proxy(dep, platform)
+      @proxies[[dep, platform]] ||= new(dep, platform).freeze
+    end
+
     def initialize(dep, platform)
       @dep = dep
       @__platform = platform
     end
 
-    def hash
-      @hash ||= [dep, __platform].hash
-    end
-
-    def ==(other)
-      return false if other.class != self.class
-      dep == other.dep && __platform == other.__platform
-    end
+    private_class_method :new
 
     alias_method :eql?, :==
 
@@ -39,6 +38,14 @@ module Bundler
       s
     end
 
+    def dup
+      raise NoMethodError.new("DepProxy cannot be duplicated")
+    end
+
+    def clone
+      raise NoMethodError.new("DepProxy cannot be cloned")
+    end
+
     private
 
     def method_missing(*args, &blk)
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index 1cc7908b8a..23fba99ffa 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -24,6 +24,9 @@ module Bundler
     def initialize
       @source               = nil
       @sources              = SourceList.new
+
+      @global_rubygems_sources = []
+
       @git_sources          = {}
       @dependencies         = []
       @groups               = []
@@ -45,6 +48,7 @@ module Bundler
       @gemfiles << expanded_gemfile_path
       contents ||= Bundler.read_file(@gemfile.to_s)
       instance_eval(contents.dup.tap{|x| x.untaint if RUBY_VERSION < "2.7" }, gemfile.to_s, 1)
+      check_primary_source_safety
     rescue Exception => e # rubocop:disable Lint/RescueException
       message = "There was an error " \
         "#{e.is_a?(GemfileEvalError) ? "evaluating" : "parsing"} " \
@@ -164,8 +168,7 @@ module Bundler
       elsif block_given?
         with_source(@sources.add_rubygems_source("remotes" => source), &blk)
       else
-        check_primary_source_safety(@sources)
-        @sources.global_rubygems_source = source
+        @global_rubygems_sources << source
       end
     end
 
@@ -183,24 +186,14 @@ module Bundler
     end
 
     def path(path, options = {}, &blk)
-      unless block_given?
-        msg = "You can no longer specify a path source by itself. Instead, \n" \
-              "either use the :path option on a gem, or specify the gems that \n" \
-              "bundler should find in the path source by passing a block to \n" \
-              "the path method, like: \n\n" \
-              "    path 'dir/containing/rails' do\n" \
-              "      gem 'rails'\n" \
-              "    end\n\n"
-
-        raise DeprecatedError, msg if Bundler.feature_flag.disable_multisource?
-        SharedHelpers.major_deprecation(2, msg.strip)
-      end
-
       source_options = normalize_hash(options).merge(
         "path" => Pathname.new(path),
         "root_path" => gemfile_root,
         "gemspec" => gemspecs.find {|g| g.name == options["name"] }
       )
+
+      source_options["global"] = true unless block_given?
+
       source = @sources.add_path_source(source_options)
       with_source(source, &blk)
     end
@@ -279,6 +272,11 @@ module Bundler
       raise GemfileError, "Undefined local variable or method `#{name}' for Gemfile"
     end
 
+    def check_primary_source_safety
+      check_path_source_safety
+      check_rubygems_source_safety
+    end
+
     private
 
     def add_git_sources
@@ -440,17 +438,33 @@ repo_name ||= user_name
       end
     end
 
-    def check_primary_source_safety(source_list)
-      return if source_list.rubygems_primary_remotes.empty? && source_list.global_rubygems_source.nil?
+    def check_path_source_safety
+      return if @sources.global_path_source.nil?
+
+      msg = "You can no longer specify a path source by itself. Instead, \n" \
+              "either use the :path option on a gem, or specify the gems that \n" \
+              "bundler should find in the path source by passing a block to \n" \
+              "the path method, like: \n\n" \
+              "    path 'dir/containing/rails' do\n" \
+              "      gem 'rails'\n" \
+              "    end\n\n"
+
+      SharedHelpers.major_deprecation(2, msg.strip)
+    end
+
+    def check_rubygems_source_safety
+      @sources.global_rubygems_source = @global_rubygems_sources.shift
+      return if @global_rubygems_sources.empty?
+
+      @global_rubygems_sources.each do |source|
+        @sources.add_rubygems_remote(source)
+      end
 
       if Bundler.feature_flag.disable_multisource?
         msg = "This Gemfile contains multiple primary sources. " \
           "Each source after the first must include a block to indicate which gems " \
-          "should come from that source"
-        unless Bundler.feature_flag.bundler_2_mode?
-          msg += ". To downgrade this error to a warning, run " \
-            "`bundle config unset disable_multisource`"
-        end
+          "should come from that source. To downgrade this error to a warning, run " \
+          "`bundle config unset disable_multisource`"
         raise GemfileEvalError, msg
       else
         Bundler::SharedHelpers.major_deprecation 2, "Your Gemfile contains multiple primary sources. " \
diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index a92ec8756d..a1b443b042 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -27,7 +27,6 @@ module Bundler
 
     (1..10).each {|v| define_method("bundler_#{v}_mode?") { major_version >= v } }
 
-    settings_flag(:allow_bundler_dependency_conflicts) { bundler_3_mode? }
     settings_flag(:allow_offline_install) { bundler_3_mode? }
     settings_flag(:auto_clean_without_path) { bundler_3_mode? }
     settings_flag(:cache_all) { bundler_3_mode? }
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index 2d9b4c2945..f9c54f7ad2 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -137,7 +137,6 @@ module Bundler
       end
 
       specs.each do |name, version, platform, dependencies, metadata|
-        next if name == "bundler"
         spec = if dependencies
           EndpointSpecification.new(name, version, platform, dependencies, metadata)
         else
diff --git a/lib/bundler/gem_helper.rb b/lib/bundler/gem_helper.rb
index 0acaa69f25..d3e30124f9 100644
--- a/lib/bundler/gem_helper.rb
+++ b/lib/bundler/gem_helper.rb
@@ -116,19 +116,21 @@ module Bundler
 
     def git_push(remote = nil)
       remote ||= default_remote
-      perform_git_push remote
+      perform_git_push "#{remote} refs/heads/#{current_branch}"
       perform_git_push "#{remote} refs/tags/#{version_tag}"
       Bundler.ui.confirm "Pushed git commits and release tag."
     end
 
     def default_remote
-      # We can replace this with `git branch --show-current` once we drop support for git < 2.22.0
-      current_branch = sh(%w[git rev-parse --abbrev-ref HEAD]).gsub(%r{\Aheads/}, "").strip
+      remote_for_branch, status = sh_with_status(%W[git config --get branch.#{current_branch}.remote])
+      return "origin" unless status.success?
 
-      remote_for_branch = sh(%W[git config --get branch.#{current_branch}.remote]).strip
-      return "origin" if remote_for_branch.empty?
+      remote_for_branch.strip
+    end
 
-      remote_for_branch
+    def current_branch
+      # We can replace this with `git branch --show-current` once we drop support for git < 2.22.0
+      sh(%w[git rev-parse --abbrev-ref HEAD]).gsub(%r{\Aheads/}, "").strip
     end
 
     def allowed_push_host
diff --git a/lib/bundler/gem_version_promoter.rb b/lib/bundler/gem_version_promoter.rb
index 2e87b7d443..3cce3f2139 100644
--- a/lib/bundler/gem_version_promoter.rb
+++ b/lib/bundler/gem_version_promoter.rb
@@ -81,8 +81,8 @@ module Bundler
           sort_dep_specs(spec_groups, locked_spec)
         end.tap do |specs|
           if DEBUG
-            warn before_result
-            warn " after sort_versions: #{debug_format_result(dep, specs).inspect}"
+            puts before_result
+            puts " after sort_versions: #{debug_format_result(dep, specs).inspect}"
           end
         end
       end
diff --git a/lib/bundler/index.rb b/lib/bundler/index.rb
index f26f542fde..f945176037 100644
--- a/lib/bundler/index.rb
+++ b/lib/bundler/index.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "set"
-
 module Bundler
   class Index
     include Enumerable
@@ -65,11 +63,14 @@ module Bundler
     def unsorted_search(query, base)
       results = local_search(query, base)
 
-      seen = results.map(&:full_name).to_set unless @sources.empty?
+      seen = results.map(&:full_name).uniq unless @sources.empty?
 
       @sources.each do |source|
         source.unsorted_search(query, base).each do |spec|
-          results << spec if seen.add?(spec.full_name)
+          next if seen.include?(spec.full_name)
+
+          seen << spec.full_name
+          results << spec
         end
       end
 
@@ -170,7 +171,7 @@ module Bundler
     def dependencies_eql?(spec, other_spec)
       deps       = spec.dependencies.select {|d| d.type != :development }
       other_deps = other_spec.dependencies.select {|d| d.type != :development }
-      Set.new(deps) == Set.new(other_deps)
+      deps.sort == other_deps.sort
     end
 
     def add_source(index)
diff --git a/lib/bundler/inline.rb b/lib/bundler/inline.rb
index 59211193d4..02da06cee9 100644
--- a/lib/bundler/inline.rb
+++ b/lib/bundler/inline.rb
@@ -50,6 +50,7 @@ def gemfile(install = false, options = {}, &gemfile)
     Bundler::Plugin.gemfile_install(&gemfile) if Bundler.feature_flag.plugins?
     builder = Bundler::Dsl.new
     builder.instance_eval(&gemfile)
+    builder.check_primary_source_safety
 
     Bundler.settings.temporary(:frozen => false) do
       definition = builder.to_definition(nil, true)
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
index 048b0786a7..09c8b1c157 100644
--- a/lib/bundler/installer.rb
+++ b/lib/bundler/installer.rb
@@ -82,7 +82,6 @@ module Bundler
 
         if resolve_if_needed(options)
           ensure_specs_are_compatible!
-          warn_on_incompatible_bundler_deps
           load_plugins
           options.delete(:jobs)
         else
@@ -90,6 +89,8 @@ module Bundler
         end
         install(options)
 
+        Gem::Specification.reset # invalidate gem specification cache so that installed gems are immediately available
+
         lock unless Bundler.frozen_bundle?
         Standalone.new(options[:standalone], @definition).generate if options[:standalone]
       end
@@ -265,22 +266,6 @@ module Bundler
       end
     end
 
-    def warn_on_incompatible_bundler_deps
-      bundler_version = Gem::Version.create(Bundler::VERSION)
-      @definition.specs.each do |spec|
-        spec.dependencies.each do |dep|
-          next if dep.type == :development
-          next unless dep.name == "bundler".freeze
-          next if dep.requirement.satisfied_by?(bundler_version)
-
-          Bundler.ui.warn "#{spec.name} (#{spec.version}) has dependency" \
-            " #{SharedHelpers.pretty_dependency(dep)}" \
-            ", which is unsatisfied by the current bundler version #{VERSION}" \
-            ", so the dependency is being ignored"
-        end
-      end
-    end
-
     def install_in_parallel(size, standalone, force = false)
       spec_installations = ParallelInstaller.call(self, @definition.specs, size, standalone, force)
       spec_installations.each do |installation|
diff --git a/lib/bundler/installer/standalone.rb b/lib/bundler/installer/standalone.rb
index 0720d6d38a..2a3f5cfe35 100644
--- a/lib/bundler/installer/standalone.rb
+++ b/lib/bundler/installer/standalone.rb
@@ -15,6 +15,7 @@ module Bundler
         file.puts "ruby_engine = RUBY_ENGINE"
         file.puts "ruby_version = RbConfig::CONFIG[\"ruby_version\"]"
         file.puts "path = File.expand_path('..', __FILE__)"
+        file.puts reverse_rubygems_kernel_mixin
         paths.each do |path|
           file.puts %($:.unshift File.expand_path("\#{path}/#{path}"))
         end
@@ -48,5 +49,19 @@ module Bundler
       error_message = "#{spec.name} #{spec.version} has an invalid gemspec"
       raise Gem::InvalidSpecificationException.new(error_message)
     end
+
+    def reverse_rubygems_kernel_mixin
+      <<~END
+      kernel = (class << ::Kernel; self; end)
+      [kernel, ::Kernel].each do |k|
+        if k.private_method_defined?(:gem_original_require)
+          private_require = k.private_method_defined?(:require)
+          k.send(:remove_method, :require)
+          k.send(:define_method, :require, k.instance_method(:gem_original_require))
+          k.send(:private, :require) if private_require
+        end
+      end
+      END
+    end
   end
 end
diff --git a/lib/bundler/lazy_specification.rb b/lib/bundler/lazy_specification.rb
index 1081910816..04ba2a2364 100644
--- a/lib/bundler/lazy_specification.rb
+++ b/lib/bundler/lazy_specification.rb
@@ -4,22 +4,6 @@ require_relative "match_platform"
 
 module Bundler
   class LazySpecification
-    Identifier = Struct.new(:name, :version, :platform)
-    class Identifier
-      include Comparable
-      def <=>(other)
-        return unless other.is_a?(Identifier)
-        [name, version, platform_string] <=> [other.name, other.version, other.platform_string]
-      end
-
-      protected
-
-      def platform_string
-        platform_string = platform.to_s
-        platform_string == Index::RUBY ? Index::NULL : platform_string
-      end
-    end
-
     include MatchPlatform
 
     attr_reader :name, :version, :dependencies, :platform
@@ -108,7 +92,7 @@ module Bundler
     end
 
     def identifier
-      @__identifier ||= Identifier.new(name, version, platform)
+      @__identifier ||= [name, version, platform_string]
     end
 
     def git_version
@@ -116,6 +100,13 @@ module Bundler
       " #{source.revision[0..6]}"
     end
 
+    protected
+
+    def platform_string
+      platform_string = platform.to_s
+      platform_string == Index::RUBY ? Index::NULL : platform_string
+    end
+
     private
 
     def to_ary
@@ -140,7 +131,7 @@ module Bundler
     # explicitly add a more specific platform.
     #
     def ruby_platform_materializes_to_ruby_platform?
-      !Bundler.most_specific_locked_platform?(Gem::Platform::RUBY)
+      !Bundler.most_specific_locked_platform?(Gem::Platform::RUBY) || Bundler.settings[:force_ruby_platform]
     end
   end
 end
diff --git a/lib/bundler/lockfile_parser.rb b/lib/bundler/lockfile_parser.rb
index f836737621..058d353bbe 100644
--- a/lib/bundler/lockfile_parser.rb
+++ b/lib/bundler/lockfile_parser.rb
@@ -64,8 +64,6 @@ module Bundler
       @state        = nil
       @specs        = {}
 
-      @rubygems_aggregate = Source::Rubygems.new
-
       if lockfile.match(/<<<<<<<|=======|>>>>>>>|\|\|\|\|\|\|\|/)
         raise LockfileError, "Your #{Bundler.default_lockfile.relative_path_from(SharedHelpers.pwd)} contains merge conflicts.\n" \
           "Run `git checkout HEAD -- #{Bundler.default_lockfile.relative_path_from(SharedHelpers.pwd)}` first to get a clean lock."
@@ -89,7 +87,6 @@ module Bundler
           send("parse_#{@state}", line)
         end
       end
-      @sources << @rubygems_aggregate unless Bundler.feature_flag.disable_multisource?
       @specs = @specs.values.sort_by(&:identifier)
       warn_for_outdated_bundler_version
     rescue ArgumentError => e
@@ -134,16 +131,19 @@ module Bundler
             @sources << @current_source
           end
         when GEM
-          if Bundler.feature_flag.disable_multisource?
+          source_remotes = Array(@opts["remote"])
+
+          if source_remotes.size == 1
             @opts["remotes"] = @opts.delete("remote")
             @current_source = TYPES[@type].from_lock(@opts)
-            @sources << @current_source
           else
-            Array(@opts["remote"]).each do |url|
-              @rubygems_aggregate.add_remote(url)
+            source_remotes.each do |url|
+              rubygems_aggregate.add_remote(url)
             end
-            @current_source = @rubygems_aggregate
+            @current_source = rubygems_aggregate
           end
+
+          @sources << @current_source
         when PLUGIN
           @current_source = Plugin.source_from_lock(@opts)
           @sources << @current_source
@@ -245,5 +245,9 @@ module Bundler
     def parse_ruby(line)
       @ruby_version = line.strip
     end
+
+    def rubygems_aggregate
+      @rubygems_aggregate ||= Source::Rubygems.new
+    end
   end
 end
diff --git a/lib/bundler/man/bundle-add.1 b/lib/bundler/man/bundle-add.1
index 29b2cadf33..b44295b2d3 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" "December 2020" "" ""
+.TH "BUNDLE\-ADD" "1" "January 2021" "" ""
 .
 .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 6ba4ed914d..99876d023e 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" "December 2020" "" ""
+.TH "BUNDLE\-BINSTUBS" "1" "January 2021" "" ""
 .
 .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 8aa45ca213..3b3c6f9734 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" "December 2020" "" ""
+.TH "BUNDLE\-CACHE" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-cache\fR \- Package your needed \fB\.gem\fR files into your application
diff --git a/lib/bundler/man/bundle-check.1 b/lib/bundler/man/bundle-check.1
index 5013cd8cda..4436c3e971 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" "December 2020" "" ""
+.TH "BUNDLE\-CHECK" "1" "January 2021" "" ""
 .
 .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 231ce273a8..b7e882ecbf 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" "December 2020" "" ""
+.TH "BUNDLE\-CLEAN" "1" "January 2021" "" ""
 .
 .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 f690b0a8f0..ad36c6bde0 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" "December 2020" "" ""
+.TH "BUNDLE\-CONFIG" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-config\fR \- Set bundler configuration options
@@ -136,9 +136,6 @@ Any periods in the configuration keys must be replaced with two underscores when
 The following is a list of all configuration keys and their purpose\. You can learn more about their operation in bundle install(1) \fIbundle\-install\.1\.html\fR\.
 .
 .IP "\(bu" 4
-\fBallow_bundler_dependency_conflicts\fR (\fBBUNDLE_ALLOW_BUNDLER_DEPENDENCY_CONFLICTS\fR): Allow resolving to specifications that have dependencies on \fBbundler\fR that are incompatible with the running Bundler version\.
-.
-.IP "\(bu" 4
 \fBallow_deployment_source_credential_changes\fR (\fBBUNDLE_ALLOW_DEPLOYMENT_SOURCE_CREDENTIAL_CHANGES\fR): When in deployment mode, allow changing the credentials to a gem\'s source\. Ex: \fBhttps://some\.host\.com/gems/path/\fR \-> \fBhttps://user_name:password@some\.host\.com/gems/path\fR
 .
 .IP "\(bu" 4
@@ -184,6 +181,9 @@ The following is a list of all configuration keys and their purpose\. You can le
 \fBdisable_local_branch_check\fR (\fBBUNDLE_DISABLE_LOCAL_BRANCH_CHECK\fR): Allow Bundler to use a local git override without a branch specified in the Gemfile\.
 .
 .IP "\(bu" 4
+\fBdisable_local_revision_check\fR (\fBBUNDLE_DISABLE_LOCAL_REVISION_CHECK\fR): Allow Bundler to use a local git override without checking if the revision present in the lockfile is present in the repository\.
+.
+.IP "\(bu" 4
 \fBdisable_multisource\fR (\fBBUNDLE_DISABLE_MULTISOURCE\fR): When set, Gemfiles containing multiple sources will produce errors instead of warnings\. Use \fBbundle config unset disable_multisource\fR to unset\.
 .
 .IP "\(bu" 4
diff --git a/lib/bundler/man/bundle-config.1.ronn b/lib/bundler/man/bundle-config.1.ronn
index 7ca5dbed72..90ec5ab59e 100644
--- a/lib/bundler/man/bundle-config.1.ronn
+++ b/lib/bundler/man/bundle-config.1.ronn
@@ -133,9 +133,6 @@ the environment variable `BUNDLE_LOCAL__RACK`.
 The following is a list of all configuration keys and their purpose. You can
 learn more about their operation in [bundle install(1)](bundle-install.1.html).
 
-* `allow_bundler_dependency_conflicts` (`BUNDLE_ALLOW_BUNDLER_DEPENDENCY_CONFLICTS`):
-   Allow resolving to specifications that have dependencies on `bundler` that
-   are incompatible with the running Bundler version.
 * `allow_deployment_source_credential_changes` (`BUNDLE_ALLOW_DEPLOYMENT_SOURCE_CREDENTIAL_CHANGES`):
    When in deployment mode, allow changing the credentials to a gem's source.
    Ex: `https://some.host.com/gems/path/` -> `https://user_name:password@some.host.com/gems/path`
@@ -178,6 +175,9 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
 * `disable_local_branch_check` (`BUNDLE_DISABLE_LOCAL_BRANCH_CHECK`):
    Allow Bundler to use a local git override without a branch specified in the
    Gemfile.
+* `disable_local_revision_check` (`BUNDLE_DISABLE_LOCAL_REVISION_CHECK`):
+   Allow Bundler to use a local git override without checking if the revision
+   present in the lockfile is present in the repository.
 * `disable_multisource` (`BUNDLE_DISABLE_MULTISOURCE`):
    When set, Gemfiles containing multiple sources will produce errors
    instead of warnings.
diff --git a/lib/bundler/man/bundle-doctor.1 b/lib/bundler/man/bundle-doctor.1
index dd3471cfa9..2923517608 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" "December 2020" "" ""
+.TH "BUNDLE\-DOCTOR" "1" "January 2021" "" ""
 .
 .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 374d2b11ed..aa0c509278 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" "December 2020" "" ""
+.TH "BUNDLE\-EXEC" "1" "January 2021" "" ""
 .
 .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 2ec18ecc65..c1abf90f5c 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" "December 2020" "" ""
+.TH "BUNDLE\-GEM" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-gem\fR \- Generate a project skeleton for creating a rubygem
diff --git a/lib/bundler/man/bundle-info.1 b/lib/bundler/man/bundle-info.1
index e7386e3699..c715af4063 100644
--- a/lib/bundler/man/bundle-info.1
+++ b/lib/bundler/man/bundle-info.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BUNDLE\-INFO" "1" "December 2020" "" ""
+.TH "BUNDLE\-INFO" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-info\fR \- Show information for the given gem in your bundle
diff --git a/lib/bundler/man/bundle-init.1 b/lib/bundler/man/bundle-init.1
index 756dc2c67c..6c8f441bdd 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" "December 2020" "" ""
+.TH "BUNDLE\-INIT" "1" "January 2021" "" ""
 .
 .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 4c66eaf78f..2342b44716 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" "December 2020" "" ""
+.TH "BUNDLE\-INJECT" "1" "January 2021" "" ""
 .
 .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 34dca1f0bc..c223185b6f 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" "December 2020" "" ""
+.TH "BUNDLE\-INSTALL" "1" "January 2021" "" ""
 .
 .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 ec507a566b..929b0f79f8 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" "December 2020" "" ""
+.TH "BUNDLE\-LIST" "1" "January 2021" "" ""
 .
 .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 6f468db581..bcf588a3cf 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" "December 2020" "" ""
+.TH "BUNDLE\-LOCK" "1" "January 2021" "" ""
 .
 .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 7131bfad9f..27308ff624 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" "December 2020" "" ""
+.TH "BUNDLE\-OPEN" "1" "January 2021" "" ""
 .
 .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 8c6ce260c8..40b23568d5 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" "December 2020" "" ""
+.TH "BUNDLE\-OUTDATED" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-outdated\fR \- List installed gems with newer versions available
diff --git a/lib/bundler/man/bundle-platform.1 b/lib/bundler/man/bundle-platform.1
index cd8eeb29c0..d0ec5c643c 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" "December 2020" "" ""
+.TH "BUNDLE\-PLATFORM" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-platform\fR \- Displays platform compatibility information
diff --git a/lib/bundler/man/bundle-pristine.1 b/lib/bundler/man/bundle-pristine.1
index 4fc59626bd..9fd42d04a4 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" "December 2020" "" ""
+.TH "BUNDLE\-PRISTINE" "1" "January 2021" "" ""
 .
 .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 764b33527a..366e5f4be2 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" "December 2020" "" ""
+.TH "BUNDLE\-REMOVE" "1" "January 2021" "" ""
 .
 .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 25cbddf5fb..e2de241438 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" "December 2020" "" ""
+.TH "BUNDLE\-SHOW" "1" "January 2021" "" ""
 .
 .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 a97692911c..a78633bbf8 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" "December 2020" "" ""
+.TH "BUNDLE\-UPDATE" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-update\fR \- Update your gems to the latest available versions
diff --git a/lib/bundler/man/bundle-viz.1 b/lib/bundler/man/bundle-viz.1
index c84a0bd8b1..fead09e6ad 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" "December 2020" "" ""
+.TH "BUNDLE\-VIZ" "1" "January 2021" "" ""
 .
 .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 58043ff91d..50aa6e17c7 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" "December 2020" "" ""
+.TH "BUNDLE" "1" "January 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\fR \- Ruby Dependency Management
diff --git a/lib/bundler/man/gemfile.5 b/lib/bundler/man/gemfile.5
index d6c26d91ef..460295da4d 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" "December 2020" "" ""
+.TH "GEMFILE" "5" "January 2021" "" ""
 .
 .SH "NAME"
 \fBGemfile\fR \- A format for describing gem dependencies for Ruby programs
diff --git a/lib/bundler/plugin.rb b/lib/bundler/plugin.rb
index da3f468da5..dddb468582 100644
--- a/lib/bundler/plugin.rb
+++ b/lib/bundler/plugin.rb
@@ -105,6 +105,7 @@ module Bundler
         else
           builder.eval_gemfile(gemfile)
         end
+        builder.check_primary_source_safety
         definition = builder.to_definition(nil, true)
 
         return if definition.dependencies.empty?
diff --git a/lib/bundler/plugin/installer.rb b/lib/bundler/plugin/installer.rb
index 26cec4f18c..980b0e29b8 100644
--- a/lib/bundler/plugin/installer.rb
+++ b/lib/bundler/plugin/installer.rb
@@ -16,15 +16,13 @@ module Bundler
 
         version = options[:version] || [">= 0"]
 
-        Bundler.settings.temporary(:disable_multisource => false) do
-          if options[:git]
-            install_git(names, version, options)
-          elsif options[:local_git]
-            install_local_git(names, version, options)
-          else
-            sources = options[:source] || Bundler.rubygems.sources
-            install_rubygems(names, version, sources)
-          end
+        if options[:git]
+          install_git(names, version, options)
+        elsif options[:local_git]
+          install_local_git(names, version, options)
+        else
+          sources = options[:source] || Bundler.rubygems.sources
+          install_rubygems(names, version, sources)
         end
       end
 
@@ -79,7 +77,7 @@ module Bundler
         source_list = SourceList.new
 
         source_list.add_git_source(git_source_options) if git_source_options
-        source_list.add_rubygems_source("remotes" => rubygems_source) if rubygems_source
+        source_list.global_rubygems_source = rubygems_source if rubygems_source
 
         deps = names.map {|name| Dependency.new name, version }
 
diff --git a/lib/bundler/plugin/source_list.rb b/lib/bundler/plugin/source_list.rb
index b90a331d28..547661cf2f 100644
--- a/lib/bundler/plugin/source_list.rb
+++ b/lib/bundler/plugin/source_list.rb
@@ -17,6 +17,10 @@ module Bundler
         path_sources + git_sources + rubygems_sources + [metadata_source]
       end
 
+      def default_source
+        git_sources.first || global_rubygems_source
+      end
+
       private
 
       def rubygems_aggregate_class
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index 636dc8af46..69899dc6c3 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -5,6 +5,8 @@ module Bundler
     require_relative "vendored_molinillo"
     require_relative "resolver/spec_group"
 
+    include GemHelpers
+
     # Figures out the best possible configuration of gems that satisfies
     # the list of passed dependencies and any child dependencies without
     # causing any gem activation errors.
@@ -15,31 +17,38 @@ module Bundler
     # ==== Returns
     # <GemBundle>,nil:: If the list of dependencies can be resolved, a
     #   collection of gemspecs is returned. Otherwise, nil is returned.
-    def self.resolve(requirements, index, source_requirements = {}, base = [], gem_version_promoter = GemVersionPromoter.new, additional_base_requirements = [], platforms = nil)
-      platforms = Set.new(platforms) if platforms
+    def self.resolve(requirements, source_requirements = {}, base = [], gem_version_promoter = GemVersionPromoter.new, additional_base_requirements = [], platforms = nil)
       base = SpecSet.new(base) unless base.is_a?(SpecSet)
-      resolver = new(index, source_requirements, base, gem_version_promoter, additional_base_requirements, platforms)
+      resolver = new(source_requirements, base, gem_version_promoter, additional_base_requirements, platforms)
       result = resolver.start(requirements)
       SpecSet.new(result)
     end
 
-    def initialize(index, source_requirements, base, gem_version_promoter, additional_base_requirements, platforms)
-      @index = index
+    def initialize(source_requirements, base, gem_version_promoter, additional_base_requirements, platforms)
       @source_requirements = source_requirements
+
+      @index_requirements = source_requirements.each_with_object({}) do |source_requirement, index_requirements|
+        name, source = source_requirement
+        index_requirements[name] = name == :global ? source : source.specs
+      end
+
       @base = base
       @resolver = Molinillo::Resolver.new(self, self)
       @search_for = {}
       @base_dg = Molinillo::DependencyGraph.new
       @base.each do |ls|
         dep = Dependency.new(ls.name, ls.version)
-        @base_dg.add_vertex(ls.name, DepProxy.new(dep, ls.platform), true)
+        @base_dg.add_vertex(ls.name, DepProxy.get_proxy(dep, ls.platform), true)
       end
       additional_base_requirements.each {|d| @base_dg.add_vertex(d.name, d) }
-      @platforms = platforms
+      @platforms = platforms.reject {|p| p != Gem::Platform::RUBY && (platforms - [p]).any? {|pl| generic(pl) == p } }
+      @resolving_only_for_ruby = platforms == [Gem::Platform::RUBY]
       @gem_version_promoter = gem_version_promoter
-      @allow_bundler_dependency_conflicts = Bundler.feature_flag.allow_bundler_dependency_conflicts?
       @use_gvp = Bundler.feature_flag.use_gem_version_promoter_for_major_updates? || !@gem_version_promoter.major?
-      @lockfile_uses_separate_rubygems_sources = Bundler.feature_flag.disable_multisource?
+      @no_aggregate_global_source = @source_requirements[:global].nil?
+
+      @variant_specific_names = []
+      @generic_names = ["Ruby\0", "RubyGems\0"]
     end
 
     def start(requirements)
@@ -75,7 +84,7 @@ module Bundler
       return unless debug?
       debug_info = yield
       debug_info = debug_info.inspect unless debug_info.is_a?(String)
-      puts debug_info.split("\n").map {|s| "BUNDLER: " + "  " * depth + s }
+      puts debug_info.split("\n").map {|s| depth == 0 ? "BUNDLER: #{s}" : "BUNDLER(#{depth}): #{s}" }
     end
 
     def debug?
@@ -103,16 +112,25 @@ module Bundler
     include Molinillo::SpecificationProvider
 
     def dependencies_for(specification)
-      specification.dependencies_for_activated_platforms
+      all_dependencies = specification.dependencies_for_activated_platforms
+
+      if @variant_specific_names.include?(specification.name)
+        @variant_specific_names |= all_dependencies.map(&:name) - @generic_names
+      else
+        generic_names, variant_specific_names = specification.partitioned_dependency_names_for_activated_platforms
+        @variant_specific_names |= variant_specific_names - @generic_names
+        @generic_names |= generic_names
+      end
+
+      all_dependencies
     end
 
     def search_for(dependency_proxy)
       platform = dependency_proxy.__platform
       dependency = dependency_proxy.dep
-      @search_for[dependency_proxy] ||= begin
-        name = dependency.name
-        index = index_for(dependency)
-        results = index.search(dependency, @base[name])
+      name = dependency.name
+      search_result = @search_for[dependency_proxy] ||= begin
+        results = results_for(dependency, @base[name])
 
         if vertex = @base_dg.vertex_named(name)
           locked_requirement = vertex.payload.requirement
@@ -137,55 +155,67 @@ module Bundler
           end
           nested.reduce([]) do |groups, (version, specs)|
             next groups if locked_requirement && !locked_requirement.satisfied_by?(version)
-            spec_group = SpecGroup.new(specs)
-            spec_group.ignores_bundler_dependencies = @allow_bundler_dependency_conflicts
-            groups << spec_group
+
+            specs_by_platform = Hash.new do |current_specs, current_platform|
+              current_specs[current_platform] = select_best_platform_match(specs, current_platform)
+            end
+
+            spec_group_ruby = SpecGroup.create_for(specs_by_platform, [Gem::Platform::RUBY], Gem::Platform::RUBY)
+            groups << spec_group_ruby if spec_group_ruby
+
+            next groups if @resolving_only_for_ruby
+
+            spec_group = SpecGroup.create_for(specs_by_platform, @platforms, platform)
+            groups << spec_group if spec_group
+
+            groups
           end
         else
           []
         end
         # GVP handles major itself, but it's still a bit risky to trust it with it
         # until we get it settled with new behavior. For 2.x it can take over all cases.
-        search = if !@use_gvp
+        if !@use_gvp
           spec_groups
         else
           @gem_version_promoter.sort_versions(dependency, spec_groups)
         end
-        selected_sgs = []
-        search.each do |sg|
-          next unless sg.for?(platform)
-          sg_all_platforms = sg.copy_for(self.class.sort_platforms(@platforms).reverse)
-          next unless sg_all_platforms
-
-          selected_sgs << sg_all_platforms
-
-          next if sg_all_platforms.activated_platforms == [Gem::Platform::RUBY]
-          # Add a spec group for "non platform specific spec" as the fallback
-          # spec group.
-          sg_ruby = sg.copy_for([Gem::Platform::RUBY])
-          selected_sgs.insert(-2, sg_ruby) if sg_ruby
+      end
+
+      unless search_result.empty?
+        specific_dependency = @variant_specific_names.include?(name)
+        return search_result unless specific_dependency
+
+        search_result.each do |sg|
+          if @generic_names.include?(name)
+            @variant_specific_names -= [name]
+            sg.activate_all_platforms!
+          else
+            sg.activate_platform!(platform)
+          end
         end
-        selected_sgs
       end
+
+      search_result
     end
 
     def index_for(dependency)
-      source = @source_requirements[dependency.name]
+      source = @index_requirements[dependency.name]
       if source
-        source.specs
-      elsif @lockfile_uses_separate_rubygems_sources
+        source
+      elsif @no_aggregate_global_source
         Index.build do |idx|
-          if dependency.all_sources
-            dependency.all_sources.each {|s| idx.add_source(s.specs) if s }
-          else
-            idx.add_source @source_requirements[:default].specs
-          end
+          dependency.all_sources.each {|s| idx.add_source(s.specs) }
         end
       else
-        @index
+        @index_requirements[:global]
       end
     end
 
+    def results_for(dependency, base)
+      index_for(dependency).search(dependency, base)
+    end
+
     def name_for(dependency)
       dependency.name
     end
@@ -206,21 +236,27 @@ module Bundler
       requirement.matches_spec?(spec) || spec.source.is_a?(Source::Gemspec)
     end
 
+    def dependencies_equal?(dependencies, other_dependencies)
+      dependencies.map(&:dep) == other_dependencies.map(&:dep)
+    end
+
     def relevant_sources_for_vertex(vertex)
       if vertex.root?
         [@source_requirements[vertex.name]]
-      elsif @lockfile_uses_separate_rubygems_sources
+      elsif @no_aggregate_global_source
         vertex.recursive_predecessors.map do |v|
           @source_requirements[v.name]
-        end << @source_requirements[:default]
+        end.compact << @source_requirements[:default]
+      else
+        []
       end
     end
 
     def sort_dependencies(dependencies, activated, conflicts)
       dependencies.sort_by do |dependency|
-        dependency.all_sources = relevant_sources_for_vertex(activated.vertex_named(dependency.name))
         name = name_for(dependency)
         vertex = activated.vertex_named(name)
+        dependency.all_sources = relevant_sources_for_vertex(vertex)
         [
           @base_dg.vertex_named(name) ? 0 : 1,
           vertex.payload ? 0 : 1,
@@ -233,13 +269,6 @@ module Bundler
       end
     end
 
-    # Sort platforms from most general to most specific
-    def self.sort_platforms(platforms)
-      platforms.sort_by do |platform|
-        platform_sort_key(platform)
-      end
-    end
-
     def self.platform_sort_key(platform)
       # Prefer specific platform to not specific platform
       return ["99-LAST", "", "", ""] if Gem::Platform::RUBY == platform
@@ -294,7 +323,7 @@ module Bundler
             "If you are updating multiple gems in your Gemfile at once,\n" \
             "try passing them all to `bundle update`"
         elsif source = @source_requirements[name]
-          specs = source.specs[name]
+          specs = source.specs.search(name)
           versions_with_platforms = specs.map {|s| [s.version, s.platform] }
           message = String.new("Could not find gem '#{SharedHelpers.pretty_dependency(requirement)}' in #{source}#{cache_message}.\n")
           message << if versions_with_platforms.any?
@@ -303,7 +332,7 @@ module Bundler
             "The source does not contain any versions of '#{name}'"
           end
         else
-          message = "Could not find gem '#{requirement}' in any of the gem sources " \
+          message = "Could not find gem '#{SharedHelpers.pretty_dependency(requirement)}' in any of the gem sources " \
             "listed in your Gemfile#{cache_message}."
         end
         raise GemNotFound, message
@@ -324,10 +353,16 @@ module Bundler
     def version_conflict_message(e)
       # only show essential conflicts, if possible
       conflicts = e.conflicts.dup
-      conflicts.delete_if do |_name, conflict|
-        deps = conflict.requirement_trees.map(&:last).flatten(1)
-        !Bundler::VersionRanges.empty?(*Bundler::VersionRanges.for_many(deps.map(&:requirement)))
+
+      if conflicts["bundler"]
+        conflicts.replace("bundler" => conflicts["bundler"])
+      else
+        conflicts.delete_if do |_name, conflict|
+          deps = conflict.requirement_trees.map(&:last).flatten(1)
+          !Bundler::VersionRanges.empty?(*Bundler::VersionRanges.for_many(deps.map(&:requirement)))
+        end
       end
+
       e = Molinillo::VersionConflict.new(conflicts, e.specification_provider) unless conflicts.empty?
 
       solver_name = "Bundler"
@@ -355,15 +390,25 @@ module Bundler
         :additional_message_for_conflict => lambda do |o, name, conflict|
           if name == "bundler"
             o << %(\n  Current Bundler version:\n    bundler (#{Bundler::VERSION}))
-            other_bundler_required = !conflict.requirement.requirement.satisfied_by?(Gem::Version.new(Bundler::VERSION))
-          end
 
-          if name == "bundler" && other_bundler_required
-            o << "\n"
-            o << "This Gemfile requires a different version of Bundler.\n"
-            o << "Perhaps you need to update Bundler by running `gem install bundler`?\n"
-          end
-          if conflict.locked_requirement
+            conflict_dependency = conflict.requirement
+            conflict_requirement = conflict_dependency.requirement
+            other_bundler_required = !conflict_requirement.satisfied_by?(Gem::Version.new(Bundler::VERSION))
+
+            if other_bundler_required
+              o << "\n\n"
+
+              candidate_specs = @index_requirements[:default_bundler].search(conflict_dependency)
+              if candidate_specs.any?
+                target_version = candidate_specs.last.version
+                new_command = [File.basename($PROGRAM_NAME), "_#{target_version}_", *ARGV].join(" ")
+                o << "Your bundle requires a different version of Bundler than the one you're running.\n"
+                o << "Install the necessary version with `gem install bundler:#{target_version}` and rerun bundler using `#{new_command}`\n"
+              else
+                o << "Your bundle requires a different version of Bundler than the one you're running, and that version could not be found.\n"
+              end
+            end
+          elsif conflict.locked_requirement
             o << "\n"
             o << %(Running `bundle update` will rebuild your snapshot from scratch, using only\n)
             o << %(the gems in your Gemfile, which may resolve the conflict.\n)
@@ -372,14 +417,8 @@ module Bundler
 
             relevant_sources = if conflict.requirement.source
               [conflict.requirement.source]
-            elsif conflict.requirement.all_sources
-              conflict.requirement.all_sources
-            elsif @lockfile_uses_separate_rubygems_sources
-              # every conflict should have an explicit group of sources when we
-              # enforce strict pinning
-              raise "no source set for #{conflict}"
             else
-              []
+              conflict.requirement.all_sources
             end.compact.map(&:to_s).uniq.sort
 
             metadata_requirement = name.end_with?("\0")
@@ -416,23 +455,21 @@ module Bundler
     def validate_resolved_specs!(resolved_specs)
       resolved_specs.each do |v|
         name = v.name
-        next unless sources = relevant_sources_for_vertex(v)
-        sources.compact!
+        sources = relevant_sources_for_vertex(v)
+        next unless sources.any?
         if default_index = sources.index(@source_requirements[:default])
           sources.delete_at(default_index)
         end
-        sources.reject! {|s| s.specs[name].empty? }
+        sources.reject! {|s| s.specs.search(name).empty? }
         sources.uniq!
         next if sources.size <= 1
 
-        multisource_disabled = Bundler.feature_flag.disable_multisource?
-
         msg = ["The gem '#{name}' was found in multiple relevant sources."]
         msg.concat sources.map {|s| "  * #{s}" }.sort
-        msg << "You #{multisource_disabled ? :must : :should} add this gem to the source block for the source you wish it to be installed from."
+        msg << "You #{@no_aggregate_global_source ? :must : :should} add this gem to the source block for the source you wish it to be installed from."
         msg = msg.join("\n")
 
-        raise SecurityError, msg if multisource_disabled
+        raise SecurityError, msg if @no_aggregate_global_source
         Bundler.ui.warn "Warning: #{msg}"
       end
     end
diff --git a/lib/bundler/resolver/spec_group.rb b/lib/bundler/resolver/spec_group.rb
index 34780f9528..73ffec5838 100644
--- a/lib/bundler/resolver/spec_group.rb
+++ b/lib/bundler/resolver/spec_group.rb
@@ -3,28 +3,37 @@
 module Bundler
   class Resolver
     class SpecGroup
-      include GemHelpers
-
       attr_accessor :name, :version, :source
-      attr_accessor :ignores_bundler_dependencies, :activated_platforms
+      attr_accessor :activated_platforms
+
+      def self.create_for(specs, all_platforms, specific_platform)
+        specific_platform_specs = specs[specific_platform]
+        return unless specific_platform_specs.any?
+
+        platforms = all_platforms.select {|p| specs[p].any? }
+
+        new(specific_platform_specs.first, specs, platforms)
+      end
 
-      def initialize(all_specs)
-        @all_specs = all_specs
-        raise ArgumentError, "cannot initialize with an empty value" unless exemplary_spec = all_specs.first
+      def initialize(exemplary_spec, specs, relevant_platforms)
+        @exemplary_spec = exemplary_spec
         @name = exemplary_spec.name
         @version = exemplary_spec.version
         @source = exemplary_spec.source
 
-        @activated_platforms = []
-        @dependencies = nil
-        @specs        = Hash.new do |specs, platform|
-          specs[platform] = select_best_platform_match(all_specs, platform)
+        @all_platforms = relevant_platforms
+        @activated_platforms = relevant_platforms
+        @dependencies = Hash.new do |dependencies, platforms|
+          dependencies[platforms] = dependencies_for(platforms)
         end
-        @ignores_bundler_dependencies = true
+        @partitioned_dependency_names = Hash.new do |partitioned_dependency_names, platforms|
+          partitioned_dependency_names[platforms] = partitioned_dependency_names_for(platforms)
+        end
+        @specs = specs
       end
 
       def to_specs
-        @activated_platforms.map do |p|
+        activated_platforms.map do |p|
           specs = @specs[p]
           next unless specs.any?
 
@@ -36,18 +45,12 @@ module Bundler
         end.flatten.compact.uniq
       end
 
-      def copy_for(platforms)
-        platforms.select! {|p| for?(p) }
-        return unless platforms.any?
-
-        copied_sg = self.class.new(@all_specs)
-        copied_sg.ignores_bundler_dependencies = @ignores_bundler_dependencies
-        copied_sg.activated_platforms = platforms
-        copied_sg
+      def activate_platform!(platform)
+        self.activated_platforms = [platform]
       end
 
-      def for?(platform)
-        @specs[platform].any?
+      def activate_all_platforms!
+        self.activated_platforms = @all_platforms
       end
 
       def to_s
@@ -56,11 +59,11 @@ module Bundler
       end
 
       def dependencies_for_activated_platforms
-        dependencies = @activated_platforms.map {|p| __dependencies[p] }
-        metadata_dependencies = @activated_platforms.map do |platform|
-          metadata_dependencies(@specs[platform].first, platform)
-        end
-        dependencies.concat(metadata_dependencies).flatten
+        @dependencies[activated_platforms]
+      end
+
+      def partitioned_dependency_names_for_activated_platforms
+        @partitioned_dependency_names[activated_platforms]
       end
 
       def ==(other)
@@ -86,34 +89,43 @@ module Bundler
       protected
 
       def sorted_activated_platforms
-        @activated_platforms.sort_by(&:to_s)
+        activated_platforms.sort_by(&:to_s)
       end
 
       private
 
-      def __dependencies
-        @dependencies = Hash.new do |dependencies, platform|
-          dependencies[platform] = []
-          specs = @specs[platform]
-          if spec = specs.first
-            spec.dependencies.each do |dep|
-              next if dep.type == :development
-              next if @ignores_bundler_dependencies && dep.name == "bundler".freeze
-              dependencies[platform] << DepProxy.new(dep, platform)
-            end
-          end
-          dependencies[platform]
+      def dependencies_for(platforms)
+        platforms.map do |platform|
+          __dependencies(platform) + metadata_dependencies(platform)
+        end.flatten
+      end
+
+      def partitioned_dependency_names_for(platforms)
+        return @dependencies[platforms].map(&:name), [] if platforms.size == 1
+
+        @dependencies[platforms].partition do |dep_proxy|
+          @dependencies[platforms].count {|dp| dp.dep == dep_proxy.dep } == platforms.size
+        end.map {|deps| deps.map(&:name) }
+      end
+
+      def __dependencies(platform)
+        dependencies = []
+        @specs[platform].first.dependencies.each do |dep|
+          next if dep.type == :development
+          dependencies << DepProxy.get_proxy(dep, platform)
         end
+        dependencies
       end
 
-      def metadata_dependencies(spec, platform)
-        return [] unless spec && spec.is_a?(Gem::Specification)
+      def metadata_dependencies(platform)
+        spec = @specs[platform].first
+        return [] unless spec.is_a?(Gem::Specification)
         dependencies = []
         if !spec.required_ruby_version.nil? && !spec.required_ruby_version.none?
-          dependencies << DepProxy.new(Gem::Dependency.new("Ruby\0", spec.required_ruby_version), platform)
+          dependencies << DepProxy.get_proxy(Gem::Dependency.new("Ruby\0", spec.required_ruby_version), platform)
         end
         if !spec.required_rubygems_version.nil? && !spec.required_rubygems_version.none?
-          dependencies << DepProxy.new(Gem::Dependency.new("RubyGems\0", spec.required_rubygems_version), platform)
+          dependencies << DepProxy.get_proxy(Gem::Dependency.new("RubyGems\0", spec.required_rubygems_version), platform)
         end
         dependencies
       end
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
index 0322b06d07..2bd2dcb451 100644
--- a/lib/bundler/rubygems_ext.rb
+++ b/lib/bundler/rubygems_ext.rb
@@ -158,6 +158,22 @@ module Gem
     end
   end
 
+  if Gem::Requirement.new("~> 2.0").hash == Gem::Requirement.new("~> 2.0.0").hash
+    class Requirement
+      module CorrectHashForLambdaOperator
+        def hash
+          if requirements.any? {|r| r.first == "~>" }
+            requirements.map {|r| r.first == "~>" ? [r[0], r[1].to_s] : r }.sort.hash
+          else
+            super
+          end
+        end
+      end
+
+      prepend CorrectHashForLambdaOperator
+    end
+  end
+
   class Platform
     JAVA  = Gem::Platform.new("java") unless defined?(JAVA)
     MSWIN = Gem::Platform.new("mswin32") unless defined?(MSWIN)
diff --git a/lib/bundler/rubygems_gem_installer.rb b/lib/bundler/rubygems_gem_installer.rb
index cd5eb152f9..f5f3c53309 100644
--- a/lib/bundler/rubygems_gem_installer.rb
+++ b/lib/bundler/rubygems_gem_installer.rb
@@ -8,6 +8,53 @@ module Bundler
       # Bundler needs to install gems regardless of binstub overwriting
     end
 
+    def install
+      pre_install_checks
+
+      run_pre_install_hooks
+
+      spec.loaded_from = spec_file
+
+      # Completely remove any previous gem files
+      FileUtils.rm_rf gem_dir
+      FileUtils.rm_rf spec.extension_dir
+
+      FileUtils.mkdir_p gem_dir, :mode => 0o755
+
+      extract_files
+
+      build_extensions
+      write_build_info_file
+      run_post_build_hooks
+
+      generate_bin
+      generate_plugins
+
+      write_spec
+      write_cache_file
+
+      say spec.post_install_message unless spec.post_install_message.nil?
+
+      run_post_install_hooks
+
+      spec
+    end
+
+    def generate_plugins
+      return unless Gem::Installer.instance_methods(false).include?(:generate_plugins)
+
+      latest = Gem::Specification.stubs_for(spec.name).first
+      return if latest && latest.version > spec.version
+
+      ensure_writable_dir @plugins_dir
+
+      if spec.plugins.empty?
+        remove_plugins_for(spec, @plugins_dir)
+      else
+        regenerate_plugins_for(spec, @plugins_dir)
+      end
+    end
+
     def pre_install_checks
       super && validate_bundler_checksum(options[:bundler_expected_checksum])
     end
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 1c669491f6..749e4eb60e 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -7,7 +7,6 @@ module Bundler
     autoload :Validator, File.expand_path("settings/validator", __dir__)
 
     BOOL_KEYS = %w[
-      allow_bundler_dependency_conflicts
       allow_deployment_source_credential_changes
       allow_offline_install
       auto_clean_without_path
@@ -20,6 +19,7 @@ module Bundler
       disable_checksum_validation
       disable_exec_load
       disable_local_branch_check
+      disable_local_revision_check
       disable_multisource
       disable_shared_gems
       disable_version_check
diff --git a/lib/bundler/shared_helpers.rb b/lib/bundler/shared_helpers.rb
index a56a3bff4b..f43e3301ef 100644
--- a/lib/bundler/shared_helpers.rb
+++ b/lib/bundler/shared_helpers.rb
@@ -187,11 +187,11 @@ module Bundler
       return @md5_available if defined?(@md5_available)
       @md5_available = begin
         require "openssl"
-        OpenSSL::Digest.digest("MD5", "")
+        ::OpenSSL::Digest.digest("MD5", "")
         true
       rescue LoadError
         true
-      rescue OpenSSL::Digest::DigestError
+      rescue ::OpenSSL::Digest::DigestError
         false
       end
     end
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index 0157995cb0..fb13ca0578 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -22,7 +22,7 @@ module Bundler
         @uri        = options["uri"] || ""
         @safe_uri   = URICredentialsFilter.credential_filtered_uri(@uri)
         @branch     = options["branch"]
-        @ref        = options["ref"] || options["branch"] || options["tag"] || "master"
+        @ref        = options["ref"] || options["branch"] || options["tag"]
         @submodules = options["submodules"]
         @name       = options["name"]
         @version    = options["version"].to_s.strip.gsub("-", ".pre.")
@@ -60,25 +60,27 @@ module Bundler
       alias_method :==, :eql?
 
       def to_s
-        at = if local?
-          path
-        elsif user_ref = options["ref"]
-          if ref =~ /\A[a-z0-9]{4,}\z/i
-            shortref_for_display(user_ref)
+        begin
+          at = if local?
+            path
+          elsif user_ref = options["ref"]
+            if ref =~ /\A[a-z0-9]{4,}\z/i
+              shortref_for_display(user_ref)
+            else
+              user_ref
+            end
+          elsif ref
+            ref
           else
-            user_ref
+            git_proxy.branch
           end
-        else
-          ref
-        end
 
-        rev = begin
-                "@#{shortref_for_display(revision)}"
-              rescue GitError
-                nil
-              end
+          rev = " (at #{at}@#{shortref_for_display(revision)})"
+        rescue GitError
+          ""
+        end
 
-        "#{@safe_uri} (at #{at}#{rev})"
+        "#{@safe_uri}#{rev}"
       end
 
       def name
@@ -146,7 +148,7 @@ module Bundler
 
         changed = cached_revision && cached_revision != git_proxy.revision
 
-        if changed && !@unlocked && !git_proxy.contains?(cached_revision)
+        if !Bundler.settings[:disable_local_revision_check] && changed && !@unlocked && !git_proxy.contains?(cached_revision)
           raise GitError, "The Gemfile lock is pointing to revision #{shortref_for_display(cached_revision)} " \
             "but the current branch in your local override for #{name} does not contain such commit. " \
             "Please make sure your branch is up to date."
diff --git a/lib/bundler/source/git/git_proxy.rb b/lib/bundler/source/git/git_proxy.rb
index dd65c674d8..ae21770306 100644
--- a/lib/bundler/source/git/git_proxy.rb
+++ b/lib/bundler/source/git/git_proxy.rb
@@ -17,7 +17,7 @@ module Bundler
       class GitNotAllowedError < GitError
         def initialize(command)
           msg = String.new
-          msg << "Bundler is trying to run a `git #{command}` at runtime. You probably need to run `bundle install`. However, "
+          msg << "Bundler is trying to run `#{command}` at runtime. You probably need to run `bundle install`. However, "
           msg << "this error message could probably be more useful. Please submit a ticket at https://github.com/rubygems/rubygems/issues/new?labels=Bundler&template=bundler-related-issue.md "
           msg << "with steps to reproduce as well as the following\n\nCALLER: #{caller.join("\n")}"
           super msg
@@ -27,11 +27,11 @@ module Bundler
       class GitCommandError < GitError
         attr_reader :command
 
-        def initialize(command, path, destination_path, extra_info = nil)
+        def initialize(command, path, extra_info = nil)
           @command = command
 
           msg = String.new
-          msg << "Git error: command `git #{command}` in directory #{destination_path} has failed."
+          msg << "Git error: command `#{command}` in directory #{path} has failed."
           msg << "\n#{extra_info}" if extra_info
           msg << "\nIf this error persists you could try removing the cache directory '#{path}'" if path.exist?
           super msg
@@ -39,9 +39,9 @@ module Bundler
       end
 
       class MissingGitRevisionError < GitCommandError
-        def initialize(command, path, destination_path, ref, repo)
+        def initialize(command, destination_path, ref, repo)
           msg = "Revision #{ref} does not exist in the repository #{repo}. Maybe you misspelled it?"
-          super command, path, destination_path, msg
+          super command, destination_path, msg
         end
       end
 
@@ -132,7 +132,7 @@ module Bundler
           begin
             git "reset", "--hard", @revision, :dir => destination
           rescue GitCommandError => e
-            raise MissingGitRevisionError.new(e.command, path, destination, @revision, URICredentialsFilter.credential_filtered_uri(uri))
+            raise MissingGitRevisionError.new(e.command, destination, @revision, URICredentialsFilter.credential_filtered_uri(uri))
           end
 
           if submodules
@@ -145,32 +145,36 @@ module Bundler
 
         private
 
-        def git_null(*command, dir: SharedHelpers.pwd)
+        def git_null(*command, dir: nil)
           check_allowed(command)
 
           out, status = SharedHelpers.with_clean_git_env do
-            capture_and_ignore_stderr("git", "-C", dir.to_s, *command)
+            capture_and_ignore_stderr(*capture3_args_for(command, dir))
           end
 
           [URICredentialsFilter.credential_filtered_string(out, uri), status]
         end
 
-        def git_retry(*command, dir: SharedHelpers.pwd)
-          Bundler::Retry.new("`git -C #{dir} #{URICredentialsFilter.credential_filtered_string(command.shelljoin, uri)}`", GitNotAllowedError).attempts do
+        def git_retry(*command, dir: nil)
+          command_with_no_credentials = check_allowed(command)
+
+          Bundler::Retry.new("`#{command_with_no_credentials}` at #{dir || SharedHelpers.pwd}").attempts do
             git(*command, :dir => dir)
           end
         end
 
-        def git(*command, dir: SharedHelpers.pwd)
+        def git(*command, dir: nil)
           command_with_no_credentials = check_allowed(command)
 
           out, status = SharedHelpers.with_clean_git_env do
-            capture_and_filter_stderr("git", "-C", dir.to_s, *command)
+            capture_and_filter_stderr(*capture3_args_for(command, dir))
           end
 
-          raise GitCommandError.new(command_with_no_credentials, path, dir) unless status.success?
+          filtered_out = URICredentialsFilter.credential_filtered_string(out, uri)
+
+          raise GitCommandError.new(command_with_no_credentials, dir || SharedHelpers.pwd, filtered_out) unless status.success?
 
-          URICredentialsFilter.credential_filtered_string(out, uri)
+          filtered_out
         end
 
         def has_revision_cached?
@@ -187,10 +191,10 @@ module Bundler
 
         def find_local_revision
           allowed_with_path do
-            git("rev-parse", "--verify", ref, :dir => path).strip
+            git("rev-parse", "--verify", ref || "HEAD", :dir => path).strip
           end
         rescue GitCommandError => e
-          raise MissingGitRevisionError.new(e.command, path, path, ref, URICredentialsFilter.credential_filtered_uri(uri))
+          raise MissingGitRevisionError.new(e.command, path, ref, URICredentialsFilter.credential_filtered_uri(uri))
         end
 
         # Adds credentials to the URI as Fetcher#configured_uri_for does
@@ -220,7 +224,7 @@ module Bundler
         end
 
         def check_allowed(command)
-          command_with_no_credentials = URICredentialsFilter.credential_filtered_string(command.shelljoin, uri)
+          command_with_no_credentials = URICredentialsFilter.credential_filtered_string("git #{command.shelljoin}", uri)
           raise GitNotAllowedError.new(command_with_no_credentials) unless allow?
           command_with_no_credentials
         end
@@ -237,6 +241,20 @@ module Bundler
           return_value, _, status = Open3.capture3(*cmd)
           [return_value, status]
         end
+
+        def capture3_args_for(cmd, dir)
+          return ["git", *cmd] unless dir
+
+          if Bundler.feature_flag.bundler_3_mode? || supports_minus_c?
+            ["git", "-C", dir.to_s, *cmd]
+          else
+            ["git", *cmd, { :chdir => dir.to_s }]
+          end
+        end
+
+        def supports_minus_c?
+          @supports_minus_c ||= Gem::Version.new(version) >= Gem::Version.new("1.8.5")
+        end
       end
     end
   end
diff --git a/lib/bundler/source/path/installer.rb b/lib/bundler/source/path/installer.rb
index 6be58e2087..72bfbb4836 100644
--- a/lib/bundler/source/path/installer.rb
+++ b/lib/bundler/source/path/installer.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative "../../rubygems_gem_installer"
+
 module Bundler
   class Source
     class Path
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 79ad278da3..5b89b1645d 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -145,6 +145,8 @@ module Bundler
 
           Bundler.mkdir_p bin_path, :no_sudo => true unless spec.executables.empty? || Bundler.rubygems.provides?(">= 2.7.5")
 
+          require_relative "../rubygems_gem_installer"
+
           installed_spec = Bundler::RubyGemsGemInstaller.at(
             path,
             :install_dir         => install_path.to_s,
@@ -351,7 +353,6 @@ module Bundler
       def installed_specs
         @installed_specs ||= Index.build do |idx|
           Bundler.rubygems.all_specs.reverse_each do |spec|
-            next if spec.name == "bundler"
             spec.source = self
             if Bundler.rubygems.spec_missing_extensions?(spec, false)
               Bundler.ui.debug "Source #{self} is ignoring #{spec} because it is missing extensions"
diff --git a/lib/bundler/source_list.rb b/lib/bundler/source_list.rb
index 731a791531..44b167ca3e 100644
--- a/lib/bundler/source_list.rb
+++ b/lib/bundler/source_list.rb
@@ -1,21 +1,23 @@
 # frozen_string_literal: true
 
-require "set"
-
 module Bundler
   class SourceList
     attr_reader :path_sources,
       :git_sources,
       :plugin_sources,
-      :global_rubygems_source,
+      :global_path_source,
       :metadata_source
 
+    def global_rubygems_source
+      @global_rubygems_source ||= rubygems_aggregate_class.new
+    end
+
     def initialize
       @path_sources           = []
       @git_sources            = []
       @plugin_sources         = []
       @global_rubygems_source = nil
-      @rubygems_aggregate     = rubygems_aggregate_class.new
+      @global_path_source     = nil
       @rubygems_sources       = []
       @metadata_source        = Source::Metadata.new
     end
@@ -24,7 +26,9 @@ module Bundler
       if options["gemspec"]
         add_source_to_list Source::Gemspec.new(options), path_sources
       else
-        add_source_to_list Source::Path.new(options), path_sources
+        path_source = add_source_to_list Source::Path.new(options), path_sources
+        @global_path_source ||= path_source if options["global"]
+        path_source
       end
     end
 
@@ -43,24 +47,20 @@ module Bundler
     end
 
     def global_rubygems_source=(uri)
-      if Bundler.feature_flag.disable_multisource?
-        @global_rubygems_source ||= rubygems_aggregate_class.new("remotes" => uri)
-      end
-      add_rubygems_remote(uri)
+      @global_rubygems_source ||= rubygems_aggregate_class.new("remotes" => uri)
     end
 
     def add_rubygems_remote(uri)
-      return if Bundler.feature_flag.disable_multisource?
-      @rubygems_aggregate.add_remote(uri)
-      @rubygems_aggregate
+      global_rubygems_source.add_remote(uri)
+      global_rubygems_source
     end
 
     def default_source
-      global_rubygems_source || @rubygems_aggregate
+      global_path_source || global_rubygems_source
     end
 
     def rubygems_sources
-      @rubygems_sources + [default_source]
+      @rubygems_sources + [global_rubygems_source]
     end
 
     def rubygems_remotes
@@ -96,10 +96,9 @@ module Bundler
 
       replacement_rubygems = !Bundler.feature_flag.disable_multisource? &&
         replacement_sources.detect {|s| s.is_a?(Source::Rubygems) }
-      @rubygems_aggregate = replacement_rubygems if replacement_rubygems
+      @global_rubygems_source = replacement_rubygems if replacement_rubygems
 
       return true if !equal_sources?(lock_sources, replacement_sources) && !equivalent_sources?(lock_sources, replacement_sources)
-      return true if replacement_rubygems && rubygems_remotes.to_set != replacement_rubygems.remotes.to_set
 
       false
     end
@@ -112,10 +111,6 @@ module Bundler
       all_sources.each(&:remote!)
     end
 
-    def rubygems_primary_remotes
-      @rubygems_aggregate.remotes
-    end
-
     private
 
     def rubygems_aggregate_class
@@ -153,7 +148,7 @@ module Bundler
     end
 
     def equal_sources?(lock_sources, replacement_sources)
-      lock_sources.to_set == replacement_sources.to_set
+      lock_sources.sort_by(&:to_s) == replacement_sources.sort_by(&:to_s)
     end
 
     def equal_source?(source, other_source)
diff --git a/lib/bundler/spec_set.rb b/lib/bundler/spec_set.rb
index a0b9552c18..399c91fea5 100644
--- a/lib/bundler/spec_set.rb
+++ b/lib/bundler/spec_set.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "tsort"
-require "set"
 
 module Bundler
   class SpecSet
@@ -13,14 +12,16 @@ module Bundler
     end
 
     def for(dependencies, skip = [], check = false, match_current_platform = false, raise_on_missing = true)
-      handled = Set.new
+      handled = []
       deps = dependencies.dup
       specs = []
       skip += ["bundler"]
 
       loop do
         break unless dep = deps.shift
-        next if !handled.add?(dep) || skip.include?(dep.name)
+        next if handled.include?(dep) || skip.include?(dep.name)
+
+        handled << dep
 
         specs_for_dep = spec_for_dependency(dep, match_current_platform)
         if specs_for_dep.any?
@@ -28,7 +29,7 @@ module Bundler
 
           specs_for_dep.first.dependencies.each do |d|
             next if d.type == :development
-            d = DepProxy.new(d, dep.__platform) unless match_current_platform
+            d = DepProxy.get_proxy(d, dep.__platform) unless match_current_platform
             deps << d
           end
         elsif check
diff --git a/lib/bundler/stub_specification.rb b/lib/bundler/stub_specification.rb
index 2456d268da..fa071901e5 100644
--- a/lib/bundler/stub_specification.rb
+++ b/lib/bundler/stub_specification.rb
@@ -26,11 +26,19 @@ module Bundler
 
     # @!group Stub Delegates
 
+    def manually_installed?
+      # This is for manually installed gems which are gems that were fixed in place after a
+      # failed installation. Once the issue was resolved, the user then manually created
+      # the gem specification using the instructions provided by `gem help install`
+      installed_by_version == Gem::Version.new(0)
+    end
+
     # This is defined directly to avoid having to loading the full spec
     def missing_extensions?
       return false if default_gem?
       return false if extensions.empty?
       return false if File.exist? gem_build_complete_path
+      return false if manually_installed?
 
       true
     end
diff --git a/lib/bundler/templates/newgem/CHANGELOG.md.tt b/lib/bundler/templates/newgem/CHANGELOG.md.tt
new file mode 100644
index 0000000000..c9ea96d453
--- /dev/null
+++ b/lib/bundler/templates/newgem/CHANGELOG.md.tt
@@ -0,0 +1,5 @@
+## [Unreleased]
+
+## [0.1.0] - <%= Time.now.strftime('%F') %>
+
+- Initial release
diff --git a/lib/bundler/templates/newgem/Gemfile.tt b/lib/bundler/templates/newgem/Gemfile.tt
index 1d55fd7a90..b09ccfff15 100644
--- a/lib/bundler/templates/newgem/Gemfile.tt
+++ b/lib/bundler/templates/newgem/Gemfile.tt
@@ -16,5 +16,5 @@ gem "<%= config[:test] %>", "~> <%= config[:test_framework_version] %>"
 <%- end -%>
 <%- if config[:rubocop] -%>
 
-gem "rubocop", "~> 0.80"
+gem "rubocop", "~> <%= config[:rubocop_version] %>"
 <%- end -%>
diff --git a/lib/bundler/templates/newgem/README.md.tt b/lib/bundler/templates/newgem/README.md.tt
index 315bc745a3..8fd87abe9a 100644
--- a/lib/bundler/templates/newgem/README.md.tt
+++ b/lib/bundler/templates/newgem/README.md.tt
@@ -29,19 +29,21 @@ TODO: Write usage instructions here
 After checking out the repo, run `bin/setup` to install dependencies.<% if config[:test] %> Then, run `rake <%= config[:test].sub('mini', '').sub('rspec', 'spec') %>` to run the tests.<% end %> You can also run `bin/console` for an interactive prompt that will allow you to experiment.<% if config[:bin] %> Run `bundle exec <%= config[:name] %>` to use the gem in this directory, ignoring other installed copies of this gem.<% end %>
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and the created tag, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+<% if config[:git] -%>
 
 ## Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/<%= config[:github_username] %>/<%= config[:name] %>.<% if config[:coc] %> This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/master/CODE_OF_CONDUCT.md).<% end %>
+Bug reports and pull requests are welcome on GitHub at https://github.com/<%= config[:github_username] %>/<%= config[:name] %>.<% if config[:coc] %> This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/<%= config[:git_default_branch] %>/CODE_OF_CONDUCT.md).<% end %>
+<% end -%>
 <% if config[:mit] -%>
 
 ## License
 
 The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
 <% end -%>
-<% if config[:coc] -%>
+<% if config[:git] && config[:coc] -%>
 
 ## Code of Conduct
 
-Everyone interacting in the <%= config[:constant_name] %> project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/master/CODE_OF_CONDUCT.md).
+Everyone interacting in the <%= config[:constant_name] %> project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/<%= config[:github_username] %>/<%= config[:name] %>/blob/<%= config[:git_default_branch] %>/CODE_OF_CONDUCT.md).
 <% end -%>
diff --git a/lib/bundler/templates/newgem/newgem.gemspec.tt b/lib/bundler/templates/newgem/newgem.gemspec.tt
index 4ed00bc749..5be20c7e4b 100644
--- a/lib/bundler/templates/newgem/newgem.gemspec.tt
+++ b/lib/bundler/templates/newgem/newgem.gemspec.tt
@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
 <%- if config[:mit] -%>
   spec.license       = "MIT"
 <%- end -%>
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= <%= config[:required_ruby_version] %>")
 
   spec.metadata["allowed_push_host"] = "TODO: Set to 'http://mygemserver.com'"
 
diff --git a/lib/bundler/templates/newgem/rubocop.yml.tt b/lib/bundler/templates/newgem/rubocop.yml.tt
index 00a72e3006..9ecec78807 100644
--- a/lib/bundler/templates/newgem/rubocop.yml.tt
+++ b/lib/bundler/templates/newgem/rubocop.yml.tt
@@ -1,3 +1,6 @@
+AllCops:
+  TargetRubyVersion: <%= ::Gem::Version.new(config[:required_ruby_version]).segments[0..1].join(".") %>
+
 Style/StringLiterals:
   Enabled: true
   EnforcedStyle: double_quotes
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider.rb b/lib/bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider.rb
index ec9c770a28..f8c695c1ed 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider.rb
@@ -26,6 +26,13 @@ module Bundler::Molinillo
         end
       end
 
+      # (see Bundler::Molinillo::SpecificationProvider#dependencies_equal?)
+      def dependencies_equal?(dependencies, other_dependencies)
+        with_no_such_dependency_error_handling do
+          specification_provider.dependencies_equal?(dependencies, other_dependencies)
+        end
+      end
+
       # (see Bundler::Molinillo::SpecificationProvider#name_for)
       def name_for(dependency)
         with_no_such_dependency_error_handling do
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
index d1d7045daf..936399ed2f 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'set'
 require 'tsort'
 
 require_relative 'dependency_graph/log'
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/vertex.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/vertex.rb
index 41bc013143..1185a8ab05 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/vertex.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/vertex.rb
@@ -59,7 +59,7 @@ module Bundler::Molinillo
       # @param [Set<Vertex>] vertices the set to add the predecessors to
       # @return [Set<Vertex>] the vertices of {#graph} where `self` is a
       #   {#descendent?}
-      def _recursive_predecessors(vertices = Set.new)
+      def _recursive_predecessors(vertices = new_vertex_set)
         incoming_edges.each do |edge|
           vertex = edge.origin
           next unless vertices.add?(vertex)
@@ -85,7 +85,7 @@ module Bundler::Molinillo
       # @param [Set<Vertex>] vertices the set to add the successors to
       # @return [Set<Vertex>] the vertices of {#graph} where `self` is an
       #   {#ancestor?}
-      def _recursive_successors(vertices = Set.new)
+      def _recursive_successors(vertices = new_vertex_set)
         outgoing_edges.each do |edge|
           vertex = edge.destination
           next unless vertices.add?(vertex)
@@ -128,7 +128,7 @@ module Bundler::Molinillo
 
       # Is there a path from `self` to `other` following edges in the
       # dependency graph?
-      # @return true iff there is a path following edges within this {#graph}
+      # @return whether there is a path following edges within this {#graph}
       def path_to?(other)
         _path_to?(other)
       end
@@ -138,7 +138,7 @@ module Bundler::Molinillo
       # @param [Vertex] other the vertex to check if there's a path to
       # @param [Set<Vertex>] visited the vertices of {#graph} that have been visited
       # @return [Boolean] whether there is a path to `other` from `self`
-      def _path_to?(other, visited = Set.new)
+      def _path_to?(other, visited = new_vertex_set)
         return false unless visited.add?(self)
         return true if equal?(other)
         successors.any? { |v| v._path_to?(other, visited) }
@@ -147,12 +147,18 @@ module Bundler::Molinillo
 
       # Is there a path from `other` to `self` following edges in the
       # dependency graph?
-      # @return true iff there is a path following edges within this {#graph}
+      # @return whether there is a path following edges within this {#graph}
       def ancestor?(other)
         other.path_to?(self)
       end
 
       alias is_reachable_from? ancestor?
+
+      def new_vertex_set
+        require 'set'
+        Set.new
+      end
+      private :new_vertex_set
     end
   end
 end
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb b/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
index 4d64d21072..e210202b69 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
@@ -34,7 +34,7 @@ module Bundler::Molinillo
 
   # An error caused by attempting to fulfil a dependency that was circular
   #
-  # @note This exception will be thrown iff a {Vertex} is added to a
+  # @note This exception will be thrown if and only if a {Vertex} is added to a
   #   {DependencyGraph} that has a {DependencyGraph::Vertex#path_to?} an
   #   existing {DependencyGraph::Vertex}
   class CircularDependencyError < ResolverError
@@ -121,7 +121,7 @@ module Bundler::Molinillo
           t = ''.dup
           depth = 2
           tree.each do |req|
-            t << '  ' * depth << req.to_s
+            t << '  ' * depth << printable_requirement.call(req)
             unless tree.last == req
               if spec = conflict.activated_by_name[name_for(req)]
                 t << %( was resolved to #{version_for_spec.call(spec)}, which)
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/modules/specification_provider.rb b/lib/bundler/vendor/molinillo/lib/molinillo/modules/specification_provider.rb
index fa094c1981..edf2366b7b 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/modules/specification_provider.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/modules/specification_provider.rb
@@ -45,6 +45,17 @@ module Bundler::Molinillo
       true
     end
 
+    # Determines whether two arrays of dependencies are equal, and thus can be
+    # grouped.
+    #
+    # @param [Array<Object>] dependencies
+    # @param [Array<Object>] other_dependencies
+    # @return [Boolean] whether `dependencies` and `other_dependencies` should
+    #   be considered equal.
+    def dependencies_equal?(dependencies, other_dependencies)
+      dependencies == other_dependencies
+    end
+
     # Returns the name for the given `dependency`.
     # @note This method should be 'pure', i.e. the return value should depend
     #   only on the `dependency` parameter.
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb b/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
index 26b8bc745c..c689ca7635 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
@@ -329,11 +329,11 @@ module Bundler::Molinillo
 
         # Look for past conflicts that could be unwound to affect the
         # requirement tree for the current conflict
+        all_reqs = last_detail_for_current_unwind.all_requirements
+        all_reqs_size = all_reqs.size
         relevant_unused_unwinds = unused_unwind_options.select do |alternative|
-          intersecting_requirements =
-            last_detail_for_current_unwind.all_requirements &
-            alternative.requirements_unwound_to_instead
-          next if intersecting_requirements.empty?
+          diff_reqs = all_reqs - alternative.requirements_unwound_to_instead
+          next if diff_reqs.size == all_reqs_size
           # Find the highest index unwind whilst looping through
           current_detail = alternative if alternative > current_detail
           alternative
@@ -344,8 +344,12 @@ module Bundler::Molinillo
         state.unused_unwind_options += unwind_details.reject { |detail| detail.state_index == -1 }
 
         # Update the requirements_unwound_to_instead on any relevant unused unwinds
-        relevant_unused_unwinds.each { |d| d.requirements_unwound_to_instead << current_detail.state_requirement }
-        unwind_details.each { |d| d.requirements_unwound_to_instead << current_detail.state_requirement }
+        relevant_unused_unwinds.each do |d|
+          (d.requirements_unwound_to_instead << current_detail.state_requirement).uniq!
+        end
+        unwind_details.each do |d|
+          (d.requirements_unwound_to_instead << current_detail.state_requirement).uniq!
+        end
 
         current_detail
       end
@@ -803,7 +807,7 @@ module Bundler::Molinillo
 
         possibilities.reverse_each do |possibility|
           dependencies = dependencies_for(possibility)
-          if current_possibility_set && current_possibility_set.dependencies == dependencies
+          if current_possibility_set && dependencies_equal?(current_possibility_set.dependencies, dependencies)
             current_possibility_set.possibilities.unshift(possibility)
           else
             possibility_sets.unshift(PossibilitySet.new(dependencies, [possibility]))
diff --git a/lib/bundler/vendor/thor/lib/thor.rb b/lib/bundler/vendor/thor/lib/thor.rb
index f2a03388cc..0794dbb522 100644
--- a/lib/bundler/vendor/thor/lib/thor.rb
+++ b/lib/bundler/vendor/thor/lib/thor.rb
@@ -1,7 +1,7 @@
-require "set"
 require_relative "thor/base"
 
 class Bundler::Thor
+  $thor_runner ||= false
   class << self
     # Allows for custom "Command" package naming.
     #
@@ -323,7 +323,7 @@ class Bundler::Thor
     # ==== Parameters
     # Symbol ...:: A list of commands that should be affected.
     def stop_on_unknown_option!(*command_names)
-      stop_on_unknown_option.merge(command_names)
+      @stop_on_unknown_option = stop_on_unknown_option | command_names
     end
 
     def stop_on_unknown_option?(command) #:nodoc:
@@ -337,7 +337,7 @@ class Bundler::Thor
     # ==== Parameters
     # Symbol ...:: A list of commands that should be affected.
     def disable_required_check!(*command_names)
-      disable_required_check.merge(command_names)
+      @disable_required_check = disable_required_check | command_names
     end
 
     def disable_required_check?(command) #:nodoc:
@@ -347,12 +347,12 @@ class Bundler::Thor
   protected
 
     def stop_on_unknown_option #:nodoc:
-      @stop_on_unknown_option ||= Set.new
+      @stop_on_unknown_option ||= []
     end
 
     # help command has the required check disabled by default.
     def disable_required_check #:nodoc:
-      @disable_required_check ||= Set.new([:help])
+      @disable_required_check ||= [:help]
     end
 
     # The method responsible for dispatching given the args.
@@ -398,7 +398,6 @@ class Bundler::Thor
     # the namespace should be displayed as arguments.
     #
     def banner(command, namespace = nil, subcommand = false)
-      $thor_runner ||= false
       command.formatted_usage(self, $thor_runner, subcommand).split("\n").map do |formatted_usage|
         "#{basename} #{formatted_usage}"
       end.join("\n")
diff --git a/lib/bundler/vendor/thor/lib/thor/actions.rb b/lib/bundler/vendor/thor/lib/thor/actions.rb
index a5368d07f3..de9323b2db 100644
--- a/lib/bundler/vendor/thor/lib/thor/actions.rb
+++ b/lib/bundler/vendor/thor/lib/thor/actions.rb
@@ -219,7 +219,7 @@ class Bundler::Thor
 
       contents = if is_uri
         require "open-uri"
-        open(path, "Accept" => "application/x-thor-template", &:read)
+        URI.open(path, "Accept" => "application/x-thor-template", &:read)
       else
         open(path, &:read)
       end
diff --git a/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb b/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb
index afdbd53dd0..62c82b3dba 100644
--- a/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb
+++ b/lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb
@@ -251,7 +251,8 @@ class Bundler::Thor
     # path<String>:: path of the file to be changed
     # flag<Regexp|String>:: the regexp or string to be replaced
     # replacement<String>:: the replacement, can be also given as a block
-    # config<Hash>:: give :verbose => false to not log the status.
+    # config<Hash>:: give :verbose => false to not log the status, and
+    #                :force => true, to force the replacement regardles of runner behavior.
     #
     # ==== Example
     #
@@ -262,9 +263,10 @@ class Bundler::Thor
     #   end
     #
     def gsub_file(path, flag, *args, &block)
-      return unless behavior == :invoke
       config = args.last.is_a?(Hash) ? args.pop : {}
 
+      return unless behavior == :invoke || config.fetch(:force, false)
+
       path = File.expand_path(path, destination_root)
       say_status :gsub, relative_to_original_destination_root(path), config.fetch(:verbose, true)
 
diff --git a/lib/bundler/vendor/thor/lib/thor/error.rb b/lib/bundler/vendor/thor/lib/thor/error.rb
index 1553afd201..7d57129b83 100644
--- a/lib/bundler/vendor/thor/lib/thor/error.rb
+++ b/lib/bundler/vendor/thor/lib/thor/error.rb
@@ -1,5 +1,5 @@
 class Bundler::Thor
-  Correctable = if defined?(DidYouMean::SpellChecker) && defined?(DidYouMean::Correctable)
+  Correctable = if defined?(DidYouMean::SpellChecker) && defined?(DidYouMean::Correctable) # rubocop:disable Naming/ConstantName
                   # In order to support versions of Ruby that don't have keyword
                   # arguments, we need our own spell checker class that doesn't take key
                   # words. Even though this code wouldn't be hit because of the check
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb b/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb
index d0f43e2d97..3a5d82cf29 100644
--- a/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb
+++ b/lib/bundler/vendor/thor/lib/thor/parser/arguments.rb
@@ -30,7 +30,11 @@ class Bundler::Thor
 
       arguments.each do |argument|
         if !argument.default.nil?
-          @assigns[argument.human_name] = argument.default
+          begin
+            @assigns[argument.human_name] = argument.default.dup
+          rescue TypeError  # Compatibility shim for un-dup-able Fixnum in Ruby < 2.4
+            @assigns[argument.human_name] = argument.default
+          end
         elsif argument.required?
           @non_assigned_required << argument
         end
diff --git a/lib/bundler/vendor/thor/lib/thor/parser/options.rb b/lib/bundler/vendor/thor/lib/thor/parser/options.rb
index 6d1342ee3c..3a8927d09c 100644
--- a/lib/bundler/vendor/thor/lib/thor/parser/options.rb
+++ b/lib/bundler/vendor/thor/lib/thor/parser/options.rb
@@ -133,15 +133,16 @@ class Bundler::Thor
 
   protected
 
-  def assign_result!(option, result)
-    if option.repeatable && option.type == :hash
-      (@assigns[option.human_name] ||= {}).merge!(result)
-    elsif option.repeatable
-      (@assigns[option.human_name] ||= []) << result
-    else
-      @assigns[option.human_name] = result
+    def assign_result!(option, result)
+      if option.repeatable && option.type == :hash
+        (@assigns[option.human_name] ||= {}).merge!(result)
+      elsif option.repeatable
+        (@assigns[option.human_name] ||= []) << result
+      else
+        @assigns[option.human_name] = result
+      end
     end
-  end
+
     # Check if the current value in peek is a registered switch.
     #
     # Two booleans are returned.  The first is true if the current value
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/basic.rb b/lib/bundler/vendor/thor/lib/thor/shell/basic.rb
index be48358cb1..2dddd4a53a 100644
--- a/lib/bundler/vendor/thor/lib/thor/shell/basic.rb
+++ b/lib/bundler/vendor/thor/lib/thor/shell/basic.rb
@@ -94,6 +94,8 @@ class Bundler::Thor
       # say("I know you knew that.")
       #
       def say(message = "", color = nil, force_new_line = (message.to_s !~ /( |\t)\Z/))
+        return if quiet?
+
         buffer = prepare_message(message, *color)
         buffer << "\n" if force_new_line && !message.to_s.end_with?("\n")
 
@@ -230,8 +232,9 @@ class Bundler::Thor
         paras = message.split("\n\n")
 
         paras.map! do |unwrapped|
-          counter = 0
-          unwrapped.split(" ").inject do |memo, word|
+          words = unwrapped.split(" ")
+          counter = words.first.length
+          words.inject do |memo, word|
             word = word.gsub(/\n\005/, "\n").gsub(/\005/, "\n")
             counter = 0 if word.include? "\n"
             if (counter + word.length + 1) < width
diff --git a/lib/bundler/vendor/thor/lib/thor/shell/color.rb b/lib/bundler/vendor/thor/lib/thor/shell/color.rb
index 29f280202d..dc167ed3cc 100644
--- a/lib/bundler/vendor/thor/lib/thor/shell/color.rb
+++ b/lib/bundler/vendor/thor/lib/thor/shell/color.rb
@@ -97,7 +97,11 @@ class Bundler::Thor
     protected
 
       def can_display_colors?
-        stdout.tty? && !are_colors_disabled?
+        are_colors_supported? && !are_colors_disabled?
+      end
+
+      def are_colors_supported?
+        stdout.tty? && ENV["TERM"] != "dumb"
       end
 
       def are_colors_disabled?
diff --git a/lib/bundler/vendor/thor/lib/thor/version.rb b/lib/bundler/vendor/thor/lib/thor/version.rb
index 1b222da995..a3efa9f762 100644
--- a/lib/bundler/vendor/thor/lib/thor/version.rb
+++ b/lib/bundler/vendor/thor/lib/thor/version.rb
@@ -1,3 +1,3 @@
 class Bundler::Thor
-  VERSION = "1.0.1"
+  VERSION = "1.1.0"
 end