Merge RubyGems-3.2.18 and Bundler-2.2.18

50 files changed, 377 insertions, 328 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index d370d8a53a..b2363a25f4 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -69,6 +69,7 @@ module Bundler
   autoload :SharedHelpers,          File.expand_path("bundler/shared_helpers", __dir__)
   autoload :Source,                 File.expand_path("bundler/source", __dir__)
   autoload :SourceList,             File.expand_path("bundler/source_list", __dir__)
+  autoload :SourceMap,              File.expand_path("bundler/source_map", __dir__)
   autoload :SpecSet,                File.expand_path("bundler/spec_set", __dir__)
   autoload :StubSpecification,      File.expand_path("bundler/stub_specification", __dir__)
   autoload :UI,                     File.expand_path("bundler/ui", __dir__)
diff --git a/lib/bundler/bundler.gemspec b/lib/bundler/bundler.gemspec
index f6cb02cea2..1a2ced54d3 100644
--- a/lib/bundler/bundler.gemspec
+++ b/lib/bundler/bundler.gemspec
@@ -34,13 +34,12 @@ Gem::Specification.new do |s|
   s.required_ruby_version     = ">= 2.3.0"
   s.required_rubygems_version = ">= 2.5.2"
 
-  s.files = Dir.glob("{lib,exe}/**/*", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
+  s.files = Dir.glob("lib/bundler{.rb,/**/*}", File::FNM_DOTMATCH).reject {|f| File.directory?(f) }
 
-  # Include the CHANGELOG.md, LICENSE.md, README.md manually
-  s.files += %w[CHANGELOG.md LICENSE.md README.md]
   # include the gemspec itself because warbler breaks w/o it
   s.files += %w[bundler.gemspec]
 
+  s.extra_rdoc_files = %w[CHANGELOG.md LICENSE.md README.md]
   s.bindir        = "exe"
   s.executables   = %w[bundle bundler]
   s.require_paths = ["lib"]
diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index d6e69afddf..45d4e62481 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -308,39 +308,19 @@ module Bundler
       end
     end
 
-    unless Bundler.feature_flag.bundler_3_mode?
-      desc "show GEM [OPTIONS]", "Shows all gems that are part of the bundle, or the path to a given gem"
-      long_desc <<-D
-        Show lists the names and versions of all gems that are required by your Gemfile.
-        Calling show with [GEM] will list the exact location of that gem on your machine.
-      D
-      method_option "paths", :type => :boolean,
-                             :banner => "List the paths of all gems that are required by your Gemfile."
-      method_option "outdated", :type => :boolean,
-                                :banner => "Show verbose output including whether gems are outdated."
-      def show(gem_name = nil)
-        if ARGV[0] == "show"
-          rest = ARGV[1..-1]
-
-          if flag = rest.find{|arg| ["--verbose", "--outdated"].include?(arg) }
-            Bundler::SharedHelpers.major_deprecation(2, "the `#{flag}` flag to `bundle show` was undocumented and will be removed without replacement")
-          else
-            new_command = rest.find {|arg| !arg.start_with?("--") } ? "info" : "list"
-
-            new_arguments = rest.map do |arg|
-              next arg if arg != "--paths"
-              next "--path" if new_command == "info"
-            end
-
-            old_argv = ARGV.join(" ")
-            new_argv = [new_command, *new_arguments.compact].join(" ")
-
-            Bundler::SharedHelpers.major_deprecation(2, "use `bundle #{new_argv}` instead of `bundle #{old_argv}`")
-          end
-        end
-        require_relative "cli/show"
-        Show.new(options, gem_name).run
-      end
+    desc "show GEM [OPTIONS]", "Shows all gems that are part of the bundle, or the path to a given gem"
+    long_desc <<-D
+      Show lists the names and versions of all gems that are required by your Gemfile.
+      Calling show with [GEM] will list the exact location of that gem on your machine.
+    D
+    method_option "paths", :type => :boolean,
+                           :banner => "List the paths of all gems that are required by your Gemfile."
+    method_option "outdated", :type => :boolean,
+                              :banner => "Show verbose output including whether gems are outdated."
+    def show(gem_name = nil)
+      SharedHelpers.major_deprecation(2, "the `--outdated` flag to `bundle show` was undocumented and will be removed without replacement") if ARGV.include?("--outdated")
+      require_relative "cli/show"
+      Show.new(options, gem_name).run
     end
 
     desc "list", "List all gems in the bundle"
diff --git a/lib/bundler/cli/outdated.rb b/lib/bundler/cli/outdated.rb
index e5d9af477c..d86ed2d002 100644
--- a/lib/bundler/cli/outdated.rb
+++ b/lib/bundler/cli/outdated.rb
@@ -146,17 +146,14 @@ module Bundler
     end
 
     def retrieve_active_spec(definition, current_spec)
-      if strict
-        active_spec = definition.find_resolved_spec(current_spec)
-      else
-        active_specs = definition.find_indexed_specs(current_spec)
-        if !current_spec.version.prerelease? && !options[:pre] && active_specs.size > 1
-          active_specs.delete_if {|b| b.respond_to?(:version) && b.version.prerelease? }
-        end
-        active_spec = active_specs.last
-      end
+      active_spec = definition.resolve.find_by_name_and_platform(current_spec.name, current_spec.platform)
+      return active_spec if strict
 
-      active_spec
+      active_specs = active_spec.source.specs.search(current_spec.name).select {|spec| spec.match_platform(current_spec.platform) }.sort_by(&:version)
+      if !current_spec.version.prerelease? && !options[:pre] && active_specs.size > 1
+        active_specs.delete_if {|b| b.respond_to?(:version) && b.version.prerelease? }
+      end
+      active_specs.last
     end
 
     def print_gems(gems_list)
diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index d4d3ce5a2d..bdf287b1e7 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -219,7 +219,6 @@ module Bundler
       Bundler.ui.debug "The definition is missing #{missing.map(&:full_name)}"
       true
     rescue BundlerError => e
-      @index = nil
       @resolve = nil
       @specs = nil
       @gem_version_promoter = nil
@@ -282,50 +281,6 @@ module Bundler
       end
     end
 
-    def index
-      @index ||= Index.build do |idx|
-        dependency_names = @dependencies.map(&:name)
-
-        sources.all_sources.each do |source|
-          source.dependency_names = dependency_names - pinned_spec_names(source)
-          idx.add_source source.specs
-          dependency_names.concat(source.unmet_deps).uniq!
-        end
-
-        double_check_for_index(idx, dependency_names)
-      end
-    end
-
-    # Suppose the gem Foo depends on the gem Bar.  Foo exists in Source A.  Bar has some versions that exist in both
-    # sources A and B.  At this point, the API request will have found all the versions of Bar in source A,
-    # but will not have found any versions of Bar from source B, which is a problem if the requested version
-    # of Foo specifically depends on a version of Bar that is only found in source B. This ensures that for
-    # each spec we found, we add all possible versions from all sources to the index.
-    def double_check_for_index(idx, dependency_names)
-      pinned_names = pinned_spec_names
-      loop do
-        idxcount = idx.size
-
-        names = :names # do this so we only have to traverse to get dependency_names from the index once
-        unmet_dependency_names = lambda do
-          return names unless names == :names
-          new_names = sources.all_sources.map(&:dependency_names_to_double_check)
-          return names = nil if new_names.compact!
-          names = new_names.flatten(1).concat(dependency_names)
-          names.uniq!
-          names -= pinned_names
-          names
-        end
-
-        sources.all_sources.each do |source|
-          source.double_check_for(unmet_dependency_names)
-        end
-
-        break if idxcount == idx.size
-      end
-    end
-    private :double_check_for_index
-
     def has_rubygems_remotes?
       sources.rubygems_sources.any? {|s| s.remotes.any? }
     end
@@ -532,14 +487,6 @@ module Bundler
       end
     end
 
-    def find_resolved_spec(current_spec)
-      specs.find_by_name_and_platform(current_spec.name, current_spec.platform)
-    end
-
-    def find_indexed_specs(current_spec)
-      index[current_spec.name].select {|spec| spec.match_platform(current_spec.platform) }.sort_by(&:version)
-    end
-
     attr_reader :sources
     private :sources
 
@@ -556,6 +503,10 @@ module Bundler
 
     private
 
+    def precompute_source_requirements_for_indirect_dependencies?
+      sources.non_global_rubygems_sources.all?(&:dependency_api_available?) && sources.no_aggregate_global_source?
+    end
+
     def current_ruby_platform_locked?
       return false unless generic_local_platform == Gem::Platform::RUBY
 
@@ -681,9 +632,9 @@ module Bundler
       changes = false
 
       # If there is a RubyGems source in both
-      locked_gem_sources.each do |locked_gem|
+      locked_gem_sources.each do |locked_gem_source|
         # Merge the remotes from the Gemfile into the Gemfile.lock
-        changes |= locked_gem.replace_remotes(actual_remotes, Bundler.settings[:allow_deployment_source_credential_changes])
+        changes |= locked_gem_source.replace_remotes(actual_remotes, Bundler.settings[:allow_deployment_source_credential_changes])
       end
 
       changes
@@ -902,26 +853,22 @@ module Bundler
     end
 
     def source_requirements
-      # Load all specs from remote sources
-      index
-
       # 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)
-      source_requirements = { :default => sources.default_source }.merge(dependency_source_requirements)
+      source_requirements = if precompute_source_requirements_for_indirect_dependencies?
+        { :default => sources.default_source }.merge(source_map.all_requirements)
+      else
+        { :default => Source::RubygemsAggregate.new(sources, source_map) }.merge(source_map.direct_requirements)
+      end
       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[:default_bundler] = source_requirements["bundler"] || sources.default_source
       source_requirements["bundler"] = sources.metadata_source # needs to come last to override
       source_requirements
     end
 
-    def pinned_spec_names(skip = nil)
-      dependency_source_requirements.reject {|_, source| source == skip }.keys
-    end
-
     def requested_groups
       groups - Bundler.settings[:without] - @optional_groups + Bundler.settings[:with]
     end
@@ -977,16 +924,8 @@ 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
+    def source_map
+      @source_map ||= SourceMap.new(sources, dependencies)
     end
   end
 end
diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index 3f9a502179..53d76b8ae8 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -32,7 +32,6 @@ module Bundler
     settings_flag(:cache_all) { bundler_3_mode? }
     settings_flag(:default_install_uses_path) { bundler_3_mode? }
     settings_flag(:deployment_means_frozen) { bundler_3_mode? }
-    settings_flag(:disable_multisource) { bundler_3_mode? }
     settings_flag(:forget_cli_options) { bundler_3_mode? }
     settings_flag(:global_gem_cache) { bundler_3_mode? }
     settings_flag(:path_relative_to_cwd) { bundler_3_mode? }
diff --git a/lib/bundler/friendly_errors.rb b/lib/bundler/friendly_errors.rb
index 5d0bb905bc..c5a19d3eea 100644
--- a/lib/bundler/friendly_errors.rb
+++ b/lib/bundler/friendly_errors.rb
@@ -112,7 +112,7 @@ module Bundler
         #{issues_url(e)}
 
         If there aren't any reports for this error yet, please create copy and paste the report template above into a new issue. Don't forget to anonymize any private data! The new issue form is located at:
-        https://github.com/rubygems/rubygems/issues/new?labels=Bundler
+        https://github.com/rubygems/rubygems/issues/new?labels=Bundler&template=bundler-related-issue.md
       EOS
     end
 
diff --git a/lib/bundler/index.rb b/lib/bundler/index.rb
index f945176037..36520c0a43 100644
--- a/lib/bundler/index.rb
+++ b/lib/bundler/index.rb
@@ -122,10 +122,9 @@ module Bundler
       names
     end
 
-    # returns a list of the dependencies
     def unmet_dependency_names
       dependency_names.select do |name|
-        name != "bundler" && search(name).empty?
+        search(name).empty?
       end
     end
 
diff --git a/lib/bundler/man/bundle-add.1 b/lib/bundler/man/bundle-add.1
index ffcd63bbcc..a8d3420d59 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" "April 2021" "" ""
+.TH "BUNDLE\-ADD" "1" "May 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 23c371b7de..3493770304 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" "April 2021" "" ""
+.TH "BUNDLE\-BINSTUBS" "1" "May 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 9bb8011a8a..7bfbaa6a4e 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" "April 2021" "" ""
+.TH "BUNDLE\-CACHE" "1" "May 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 6696479fef..bae888df27 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" "April 2021" "" ""
+.TH "BUNDLE\-CHECK" "1" "May 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 625d87c580..2e2bb615c4 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" "April 2021" "" ""
+.TH "BUNDLE\-CLEAN" "1" "May 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 3a1cee9b81..26e9418c0c 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" "April 2021" "" ""
+.TH "BUNDLE\-CONFIG" "1" "May 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\-config\fR \- Set bundler configuration options
@@ -56,9 +56,6 @@ Executing \fBbundle config unset \-\-local <name> <value>\fR will delete the con
 .P
 Executing bundle with the \fBBUNDLE_IGNORE_CONFIG\fR environment variable set will cause it to ignore all configuration\.
 .
-.P
-Executing \fBbundle config set \-\-local disable_multisource true\fR upgrades the warning about the Gemfile containing multiple primary sources to an error\. Executing \fBbundle config unset disable_multisource\fR downgrades this error to a warning\.
-.
 .SH "REMEMBERING OPTIONS"
 Flags passed to \fBbundle install\fR or the Bundler runtime, such as \fB\-\-path foo\fR or \fB\-\-without production\fR, are remembered between commands and saved to your local application\'s configuration (normally, \fB\./\.bundle/config\fR)\.
 .
@@ -184,9 +181,6 @@ The following is a list of all configuration keys and their purpose\. You can le
 \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
 \fBdisable_shared_gems\fR (\fBBUNDLE_DISABLE_SHARED_GEMS\fR): Stop Bundler from accessing gems installed to RubyGems\' normal location\.
 .
 .IP "\(bu" 4
diff --git a/lib/bundler/man/bundle-config.1.ronn b/lib/bundler/man/bundle-config.1.ronn
index 15bc5af778..cffd87a160 100644
--- a/lib/bundler/man/bundle-config.1.ronn
+++ b/lib/bundler/man/bundle-config.1.ronn
@@ -47,10 +47,6 @@ configuration only from the local application.
 Executing bundle with the `BUNDLE_IGNORE_CONFIG` environment variable set will
 cause it to ignore all configuration.
 
-Executing `bundle config set --local disable_multisource true` upgrades the warning about
-the Gemfile containing multiple primary sources to an error. Executing `bundle
-config unset disable_multisource` downgrades this error to a warning.
-
 ## REMEMBERING OPTIONS
 
 Flags passed to `bundle install` or the Bundler runtime, such as `--path foo` or
@@ -178,10 +174,6 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
 * `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.
-   Use `bundle config unset disable_multisource` to unset.
 * `disable_shared_gems` (`BUNDLE_DISABLE_SHARED_GEMS`):
    Stop Bundler from accessing gems installed to RubyGems' normal location.
 * `disable_version_check` (`BUNDLE_DISABLE_VERSION_CHECK`):
diff --git a/lib/bundler/man/bundle-doctor.1 b/lib/bundler/man/bundle-doctor.1
index 8e4c47c683..0c8ff27d3e 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" "April 2021" "" ""
+.TH "BUNDLE\-DOCTOR" "1" "May 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 863b76e4b7..c8d51cd4a2 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" "April 2021" "" ""
+.TH "BUNDLE\-EXEC" "1" "May 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 e71ccb4832..4b7e5a088c 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" "April 2021" "" ""
+.TH "BUNDLE\-GEM" "1" "May 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 168d021112..4039ec9c94 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" "April 2021" "" ""
+.TH "BUNDLE\-INFO" "1" "May 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 5d3e61d05b..f538b06bf6 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" "April 2021" "" ""
+.TH "BUNDLE\-INIT" "1" "May 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 37acabfa9a..85549b4585 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" "April 2021" "" ""
+.TH "BUNDLE\-INJECT" "1" "May 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 2dcb4d3ac6..867a41d70d 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" "April 2021" "" ""
+.TH "BUNDLE\-INSTALL" "1" "May 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 7c93b89dc3..0b67785a21 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" "April 2021" "" ""
+.TH "BUNDLE\-LIST" "1" "May 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 a4dfda9c86..860a2e07ef 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" "April 2021" "" ""
+.TH "BUNDLE\-LOCK" "1" "May 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 0511bc655b..b907e2d544 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" "April 2021" "" ""
+.TH "BUNDLE\-OPEN" "1" "May 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 268b4b157c..5427a2ab77 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" "April 2021" "" ""
+.TH "BUNDLE\-OUTDATED" "1" "May 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 77638b2b4b..2a80abb8d6 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" "April 2021" "" ""
+.TH "BUNDLE\-PLATFORM" "1" "May 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 0fcf9fdb39..7fff665de0 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" "April 2021" "" ""
+.TH "BUNDLE\-PRISTINE" "1" "May 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 ca366b81a9..17de5ed5a9 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" "April 2021" "" ""
+.TH "BUNDLE\-REMOVE" "1" "May 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 e403ae980f..fbbe18741f 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" "April 2021" "" ""
+.TH "BUNDLE\-SHOW" "1" "May 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 5546b51792..3c9af3dcc1 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" "April 2021" "" ""
+.TH "BUNDLE\-UPDATE" "1" "May 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 645c45b607..fbc48aa902 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" "April 2021" "" ""
+.TH "BUNDLE\-VIZ" "1" "May 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 5c1bc96572..5b6c9afe78 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" "April 2021" "" ""
+.TH "BUNDLE" "1" "May 2021" "" ""
 .
 .SH "NAME"
 \fBbundle\fR \- Ruby Dependency Management
diff --git a/lib/bundler/man/gemfile.5 b/lib/bundler/man/gemfile.5
index 480d38f39c..2497fad234 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" "April 2021" "" ""
+.TH "GEMFILE" "5" "May 2021" "" ""
 .
 .SH "NAME"
 \fBGemfile\fR \- A format for describing gem dependencies for Ruby programs
diff --git a/lib/bundler/plugin/api/source.rb b/lib/bundler/plugin/api/source.rb
index d70a16f4bc..f6f4ac4f0a 100644
--- a/lib/bundler/plugin/api/source.rb
+++ b/lib/bundler/plugin/api/source.rb
@@ -244,6 +244,20 @@ module Bundler
           specs.unmet_dependency_names
         end
 
+        # Used by definition.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def spec_names
+          specs.spec_names
+        end
+
+        # Used by definition.
+        #
+        # Note: Do not override if you don't know what you are doing.
+        def add_dependency_names(names)
+          @dependencies |= Array(names)
+        end
+
         # Note: Do not override if you don't know what you are doing.
         def can_lock?(spec)
           spec.source == self
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index 69899dc6c3..9a25e49d4b 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -21,17 +21,11 @@ module Bundler
       base = SpecSet.new(base) unless base.is_a?(SpecSet)
       resolver = new(source_requirements, base, gem_version_promoter, additional_base_requirements, platforms)
       result = resolver.start(requirements)
-      SpecSet.new(result)
+      SpecSet.new(result).for(requirements.reject{|dep| dep.name.end_with?("\0") })
     end
 
     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 = {}
@@ -45,10 +39,6 @@ module Bundler
       @resolving_only_for_ruby = platforms == [Gem::Platform::RUBY]
       @gem_version_promoter = gem_version_promoter
       @use_gvp = Bundler.feature_flag.use_gem_version_promoter_for_major_updates? || !@gem_version_promoter.major?
-      @no_aggregate_global_source = @source_requirements[:global].nil?
-
-      @variant_specific_names = []
-      @generic_names = ["Ruby\0", "RubyGems\0"]
     end
 
     def start(requirements)
@@ -58,7 +48,6 @@ module Bundler
       verify_gemfile_dependencies_are_found!(requirements)
       dg = @resolver.resolve(requirements, @base_dg)
       dg.
-        tap {|resolved| validate_resolved_specs!(resolved) }.
         map(&:payload).
         reject {|sg| sg.name.end_with?("\0") }.
         map(&:to_specs).
@@ -112,24 +101,14 @@ module Bundler
     include Molinillo::SpecificationProvider
 
     def dependencies_for(specification)
-      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
+      specification.dependencies_for_activated_platforms
     end
 
     def search_for(dependency_proxy)
       platform = dependency_proxy.__platform
       dependency = dependency_proxy.dep
       name = dependency.name
-      search_result = @search_for[dependency_proxy] ||= begin
+      @search_for[dependency_proxy] ||= begin
         results = results_for(dependency, @base[name])
 
         if vertex = @base_dg.vertex_named(name)
@@ -181,35 +160,14 @@ module Bundler
           @gem_version_promoter.sort_versions(dependency, spec_groups)
         end
       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
-      end
-
-      search_result
     end
 
     def index_for(dependency)
-      source = @index_requirements[dependency.name]
-      if source
-        source
-      elsif @no_aggregate_global_source
-        Index.build do |idx|
-          dependency.all_sources.each {|s| idx.add_source(s.specs) }
-        end
-      else
-        @index_requirements[:global]
-      end
+      source_for(dependency.name).specs
+    end
+
+    def source_for(name)
+      @source_requirements[name] || @source_requirements[:default]
     end
 
     def results_for(dependency, base)
@@ -240,23 +198,10 @@ module Bundler
       dependencies.map(&:dep) == other_dependencies.map(&:dep)
     end
 
-    def relevant_sources_for_vertex(vertex)
-      if vertex.root?
-        [@source_requirements[vertex.name]]
-      elsif @no_aggregate_global_source
-        vertex.recursive_predecessors.map do |v|
-          @source_requirements[v.name]
-        end.compact << @source_requirements[:default]
-      else
-        []
-      end
-    end
-
     def sort_dependencies(dependencies, activated, conflicts)
       dependencies.sort_by do |dependency|
         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,
@@ -398,7 +343,7 @@ module Bundler
             if other_bundler_required
               o << "\n\n"
 
-              candidate_specs = @index_requirements[:default_bundler].search(conflict_dependency)
+              candidate_specs = source_for(:default_bundler).specs.search(conflict_dependency)
               if candidate_specs.any?
                 target_version = candidate_specs.last.version
                 new_command = [File.basename($PROGRAM_NAME), "_#{target_version}_", *ARGV].join(" ")
@@ -415,11 +360,7 @@ module Bundler
           elsif !conflict.existing
             o << "\n"
 
-            relevant_sources = if conflict.requirement.source
-              [conflict.requirement.source]
-            else
-              conflict.requirement.all_sources
-            end.compact.map(&:to_s).uniq.sort
+            relevant_source = conflict.requirement.source || source_for(name)
 
             metadata_requirement = name.end_with?("\0")
 
@@ -432,12 +373,10 @@ module Bundler
             end
             o << " "
 
-            o << if relevant_sources.empty?
-              "in any of the sources.\n"
-            elsif metadata_requirement
-              "is not available in #{relevant_sources.join(" or ")}"
+            o << if metadata_requirement
+              "is not available in #{relevant_source}"
             else
-              "in any of the relevant sources:\n  #{relevant_sources * "\n  "}\n"
+              "in #{relevant_source}.\n"
             end
           end
         end,
@@ -451,27 +390,5 @@ module Bundler
         end
       )
     end
-
-    def validate_resolved_specs!(resolved_specs)
-      resolved_specs.each do |v|
-        name = v.name
-        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.search(name).empty? }
-        sources.uniq!
-        next if sources.size <= 1
-
-        msg = ["The gem '#{name}' was found in multiple relevant sources."]
-        msg.concat sources.map {|s| "  * #{s}" }.sort
-        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 @no_aggregate_global_source
-        Bundler.ui.warn "Warning: #{msg}"
-      end
-    end
   end
 end
diff --git a/lib/bundler/resolver/spec_group.rb b/lib/bundler/resolver/spec_group.rb
index 73ffec5838..8f4fd18c46 100644
--- a/lib/bundler/resolver/spec_group.rb
+++ b/lib/bundler/resolver/spec_group.rb
@@ -21,14 +21,10 @@ module Bundler
         @version = exemplary_spec.version
         @source = exemplary_spec.source
 
-        @all_platforms = relevant_platforms
         @activated_platforms = relevant_platforms
         @dependencies = Hash.new do |dependencies, platforms|
           dependencies[platforms] = dependencies_for(platforms)
         end
-        @partitioned_dependency_names = Hash.new do |partitioned_dependency_names, platforms|
-          partitioned_dependency_names[platforms] = partitioned_dependency_names_for(platforms)
-        end
         @specs = specs
       end
 
@@ -45,14 +41,6 @@ module Bundler
         end.flatten.compact.uniq
       end
 
-      def activate_platform!(platform)
-        self.activated_platforms = [platform]
-      end
-
-      def activate_all_platforms!
-        self.activated_platforms = @all_platforms
-      end
-
       def to_s
         activated_platforms_string = sorted_activated_platforms.join(", ")
         "#{name} (#{version}) (#{activated_platforms_string})"
@@ -62,10 +50,6 @@ module Bundler
         @dependencies[activated_platforms]
       end
 
-      def partitioned_dependency_names_for_activated_platforms
-        @partitioned_dependency_names[activated_platforms]
-      end
-
       def ==(other)
         return unless other.is_a?(SpecGroup)
         name == other.name &&
@@ -100,14 +84,6 @@ module Bundler
         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|
diff --git a/lib/bundler/rubygems_ext.rb b/lib/bundler/rubygems_ext.rb
index 2bd2dcb451..c95664965c 100644
--- a/lib/bundler/rubygems_ext.rb
+++ b/lib/bundler/rubygems_ext.rb
@@ -105,7 +105,7 @@ module Gem
   end
 
   class Dependency
-    attr_accessor :source, :groups, :all_sources
+    attr_accessor :source, :groups
 
     alias_method :eql?, :==
 
@@ -116,7 +116,7 @@ module Gem
     end
 
     def to_yaml_properties
-      instance_variables.reject {|p| ["@source", "@groups", "@all_sources"].include?(p.to_s) }
+      instance_variables.reject {|p| ["@source", "@groups"].include?(p.to_s) }
     end
 
     def to_lock
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 612c56f041..0702a80440 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -21,7 +21,6 @@ module Bundler
       disable_exec_load
       disable_local_branch_check
       disable_local_revision_check
-      disable_multisource
       disable_shared_gems
       disable_version_check
       force_ruby_platform
diff --git a/lib/bundler/source.rb b/lib/bundler/source.rb
index a3f4b09cce..f39072791c 100644
--- a/lib/bundler/source.rb
+++ b/lib/bundler/source.rb
@@ -7,6 +7,7 @@ module Bundler
     autoload :Metadata, File.expand_path("source/metadata", __dir__)
     autoload :Path,     File.expand_path("source/path", __dir__)
     autoload :Rubygems, File.expand_path("source/rubygems", __dir__)
+    autoload :RubygemsAggregate, File.expand_path("source/rubygems_aggregate", __dir__)
 
     attr_accessor :dependency_names
 
@@ -39,6 +40,10 @@ module Bundler
 
     def remote!; end
 
+    def add_dependency_names(names)
+      @dependency_names = Array(dependency_names) | Array(names)
+    end
+
     # it's possible that gems from one source depend on gems from some
     # other source, so now we download gemspecs and iterate over those
     # dependencies, looking for gems we don't have info on yet.
@@ -48,6 +53,10 @@ module Bundler
       specs.dependency_names
     end
 
+    def spec_names
+      specs.spec_names
+    end
+
     def include?(other)
       other == self
     end
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 2b7cfd53b9..a11a89cf72 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -259,8 +259,16 @@ module Bundler
         !equivalent
       end
 
+      def spec_names
+        if @allow_remote && dependency_api_available?
+          remote_specs.spec_names
+        else
+          []
+        end
+      end
+
       def unmet_deps
-        if @allow_remote && api_fetchers.any?
+        if @allow_remote && dependency_api_available?
           remote_specs.unmet_dependency_names
         else
           []
@@ -276,7 +284,7 @@ module Bundler
 
       def double_check_for(unmet_dependency_names)
         return unless @allow_remote
-        return unless api_fetchers.any?
+        return unless dependency_api_available?
 
         unmet_dependency_names = unmet_dependency_names.call
         unless unmet_dependency_names.nil?
@@ -298,17 +306,20 @@ module Bundler
         remote_specs.each do |spec|
           case spec
           when EndpointSpecification, Gem::Specification, StubSpecification, LazySpecification
-            names.concat(spec.runtime_dependencies)
+            names.concat(spec.runtime_dependencies.map(&:name))
           when RemoteSpecification # from the full index
             return nil
           else
             raise "unhandled spec type (#{spec.inspect})"
           end
         end
-        names.map!(&:name) if names
         names
       end
 
+      def dependency_api_available?
+        api_fetchers.any?
+      end
+
       protected
 
       def credless_remotes
diff --git a/lib/bundler/source/rubygems_aggregate.rb b/lib/bundler/source/rubygems_aggregate.rb
new file mode 100644
index 0000000000..685bf7e90a
--- /dev/null
+++ b/lib/bundler/source/rubygems_aggregate.rb
@@ -0,0 +1,64 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class RubygemsAggregate
+      attr_reader :source_map, :sources
+
+      def initialize(sources, source_map)
+        @sources = sources
+        @source_map = source_map
+
+        @index = build_index
+      end
+
+      def specs
+        @index
+      end
+
+      def to_s
+        "any of the sources"
+      end
+
+      private
+
+      def build_index
+        Index.build do |idx|
+          dependency_names = source_map.pinned_spec_names
+
+          sources.all_sources.each do |source|
+            source.dependency_names = dependency_names - source_map.pinned_spec_names(source)
+            idx.add_source source.specs
+            dependency_names.concat(source.unmet_deps).uniq!
+          end
+
+          double_check_for_index(idx, dependency_names)
+        end
+      end
+
+      # Suppose the gem Foo depends on the gem Bar.  Foo exists in Source A.  Bar has some versions that exist in both
+      # sources A and B.  At this point, the API request will have found all the versions of Bar in source A,
+      # but will not have found any versions of Bar from source B, which is a problem if the requested version
+      # of Foo specifically depends on a version of Bar that is only found in source B. This ensures that for
+      # each spec we found, we add all possible versions from all sources to the index.
+      def double_check_for_index(idx, dependency_names)
+        pinned_names = source_map.pinned_spec_names
+
+        names = :names # do this so we only have to traverse to get dependency_names from the index once
+        unmet_dependency_names = lambda do
+          return names unless names == :names
+          new_names = sources.all_sources.map(&:dependency_names_to_double_check)
+          return names = nil if new_names.compact!
+          names = new_names.flatten(1).concat(dependency_names)
+          names.uniq!
+          names -= pinned_names
+          names
+        end
+
+        sources.all_sources.each do |source|
+          source.double_check_for(unmet_dependency_names)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/source_list.rb b/lib/bundler/source_list.rb
index 6f5636f41e..f7eb3a1c03 100644
--- a/lib/bundler/source_list.rb
+++ b/lib/bundler/source_list.rb
@@ -21,15 +21,19 @@ module Bundler
       @rubygems_sources       = []
       @metadata_source        = Source::Metadata.new
 
-      @disable_multisource = true
+      @merged_gem_lockfile_sections = false
     end
 
-    def disable_multisource?
-      @disable_multisource
+    def merged_gem_lockfile_sections?
+      @merged_gem_lockfile_sections
     end
 
     def merged_gem_lockfile_sections!
-      @disable_multisource = false
+      @merged_gem_lockfile_sections = true
+    end
+
+    def no_aggregate_global_source?
+      global_rubygems_source.remotes.size <= 1
     end
 
     def add_path_source(options = {})
@@ -70,7 +74,11 @@ module Bundler
     end
 
     def rubygems_sources
-      @rubygems_sources + [global_rubygems_source]
+      non_global_rubygems_sources + [global_rubygems_source]
+    end
+
+    def non_global_rubygems_sources
+      @rubygems_sources
     end
 
     def rubygems_remotes
@@ -81,16 +89,27 @@ module Bundler
       path_sources + git_sources + plugin_sources + rubygems_sources + [metadata_source]
     end
 
+    def non_default_explicit_sources
+      all_sources - [default_source, metadata_source]
+    end
+
     def get(source)
       source_list_for(source).find {|s| equal_source?(source, s) || equivalent_source?(source, s) }
     end
 
     def lock_sources
-      lock_sources = (path_sources + git_sources + plugin_sources).sort_by(&:to_s)
-      if disable_multisource?
-        lock_sources + rubygems_sources.sort_by(&:to_s).uniq
+      lock_other_sources + lock_rubygems_sources
+    end
+
+    def lock_other_sources
+      (path_sources + git_sources + plugin_sources).sort_by(&:to_s)
+    end
+
+    def lock_rubygems_sources
+      if merged_gem_lockfile_sections?
+        [combine_rubygems_sources]
       else
-        lock_sources << combine_rubygems_sources
+        rubygems_sources.sort_by(&:to_s).uniq
       end
     end
 
@@ -104,7 +123,7 @@ module Bundler
         end
       end
 
-      replacement_rubygems = !disable_multisource? &&
+      replacement_rubygems = merged_gem_lockfile_sections? &&
         replacement_sources.detect {|s| s.is_a?(Source::Rubygems) }
       @global_rubygems_source = replacement_rubygems if replacement_rubygems
 
diff --git a/lib/bundler/source_map.rb b/lib/bundler/source_map.rb
new file mode 100644
index 0000000000..a554f26f76
--- /dev/null
+++ b/lib/bundler/source_map.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Bundler
+  class SourceMap
+    attr_reader :sources, :dependencies
+
+    def initialize(sources, dependencies)
+      @sources = sources
+      @dependencies = dependencies
+    end
+
+    def pinned_spec_names(skip = nil)
+      direct_requirements.reject {|_, source| source == skip }.keys
+    end
+
+    def all_requirements
+      requirements = direct_requirements.dup
+
+      unmet_deps = sources.non_default_explicit_sources.map do |source|
+        (source.spec_names - pinned_spec_names).each do |indirect_dependency_name|
+          previous_source = requirements[indirect_dependency_name]
+          if previous_source.nil?
+            requirements[indirect_dependency_name] = source
+          else
+            no_ambiguous_sources = Bundler.feature_flag.bundler_3_mode?
+
+            msg = ["The gem '#{indirect_dependency_name}' was found in multiple relevant sources."]
+            msg.concat [previous_source, source].map {|s| "  * #{s}" }.sort
+            msg << "You #{no_ambiguous_sources ? :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 no_ambiguous_sources
+            Bundler.ui.warn "Warning: #{msg}"
+          end
+        end
+
+        source.unmet_deps
+      end
+
+      sources.default_source.add_dependency_names(unmet_deps.flatten - requirements.keys)
+
+      requirements
+    end
+
+    def direct_requirements
+      @direct_requirements ||= begin
+        requirements = {}
+        default = sources.default_source
+        dependencies.each do |dep|
+          dep_source = dep.source || default
+          dep_source.add_dependency_names(dep.name)
+          requirements[dep.name] = dep_source
+        end
+        requirements
+      end
+    end
+  end
+end
diff --git a/lib/bundler/templates/newgem/newgem.gemspec.tt b/lib/bundler/templates/newgem/newgem.gemspec.tt
index 632b24dda9..7032004076 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(">= <%= config[:required_ruby_version] %>")
+  spec.required_ruby_version = ">= <%= config[:required_ruby_version] %>"
 
   spec.metadata["allowed_push_host"] = "TODO: Set to 'http://mygemserver.com'"
 
diff --git a/lib/bundler/version.rb b/lib/bundler/version.rb
index 735cb09c88..8e327e0951 100644
--- a/lib/bundler/version.rb
+++ b/lib/bundler/version.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 
 module Bundler
-  VERSION = "2.2.17".freeze
+  VERSION = "2.2.18".freeze
 
   def self.bundler_major_version
     @bundler_major_version ||= VERSION.split(".").first.to_i
diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index 48d0117efb..dec57f8309 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -8,7 +8,7 @@
 require 'rbconfig'
 
 module Gem
-  VERSION = "3.2.17".freeze
+  VERSION = "3.2.18".freeze
 end
 
 # Must be first since it unloads the prelude from 1.9.2
diff --git a/lib/rubygems/ext/ext_conf_builder.rb b/lib/rubygems/ext/ext_conf_builder.rb
index fede270417..1f73796351 100644
--- a/lib/rubygems/ext/ext_conf_builder.rb
+++ b/lib/rubygems/ext/ext_conf_builder.rb
@@ -23,11 +23,11 @@ class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
     # spaces do not work.
     #
     # Details: https://github.com/rubygems/rubygems/issues/977#issuecomment-171544940
-    tmp_dest = get_relative_path(tmp_dest, extension_dir)
+    tmp_dest_relative = get_relative_path(tmp_dest.clone, extension_dir)
 
     Tempfile.open %w[siteconf .rb], extension_dir do |siteconf|
       siteconf.puts "require 'rbconfig'"
-      siteconf.puts "dest_path = #{tmp_dest.dump}"
+      siteconf.puts "dest_path = #{tmp_dest_relative.dump}"
       %w[sitearchdir sitelibdir].each do |dir|
         siteconf.puts "RbConfig::MAKEFILE_CONFIG['#{dir}'] = dest_path"
         siteconf.puts "RbConfig::CONFIG['#{dir}'] = dest_path"
@@ -63,8 +63,8 @@ class Gem::Ext::ExtConfBuilder < Gem::Ext::Builder
 
         make dest_path, results, extension_dir
 
-        if tmp_dest
-          full_tmp_dest = File.join(extension_dir, tmp_dest)
+        if tmp_dest_relative
+          full_tmp_dest = File.join(extension_dir, tmp_dest_relative)
 
           # TODO remove in RubyGems 3
           if Gem.install_extension_in_lib and lib_dir
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index 6b569032ba..7206c3eaf0 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1558,7 +1558,6 @@ class Gem::Specification < Gem::BasicSpecification
   def build_extensions # :nodoc:
     return if default_gem?
     return if extensions.empty?
-    return if installed_by_version < Gem::Version.new('2.2.0.preview.2')
     return if File.exist? gem_build_complete_path
     return if !File.writable?(base_dir)
     return if !File.exist?(File.join(base_dir, 'extensions'))
@@ -2129,7 +2128,6 @@ class Gem::Specification < Gem::BasicSpecification
   def missing_extensions?
     return false if default_gem?
     return false if extensions.empty?
-    return false if installed_by_version < Gem::Version.new('2.2.0.preview.2')
     return false if File.exist? gem_build_complete_path
 
     true
diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb
index e2763561c6..b3e23360ed 100644
--- a/lib/rubygems/test_case.rb
+++ b/lib/rubygems/test_case.rb
@@ -12,7 +12,7 @@ if File.exist?(bundler_gemspec)
 end
 
 begin
-  gem 'minitest', '~> 5.13'
+  gem 'test-unit', '~> 3.0'
 rescue Gem::LoadError
 end
 
@@ -32,16 +32,7 @@ else
   require 'bundler'
 end
 
-# Enable server plugin needed for bisection
-if ENV["RG_BISECT_SERVER_PLUGIN"]
-  require ENV["RG_BISECT_SERVER_PLUGIN"]
-
-  Minitest.extensions << "server"
-end
-
-ENV["MT_NO_PLUGINS"] = "true"
-
-require 'minitest/autorun'
+require 'test/unit'
 
 ENV["JARS_SKIP"] = "true" if Gem.java_platform? # avoid unnecessary and noisy `jar-dependencies` post install hook
 
@@ -111,7 +102,7 @@ end
 # and uninstall gems, fetch remote gems through a stub fetcher and be assured
 # your normal set of gems is not affected.
 
-class Gem::TestCase < Minitest::Test
+class Gem::TestCase < Test::Unit::TestCase
   extend Gem::Deprecate
 
   attr_accessor :fetcher # :nodoc:
@@ -140,11 +131,48 @@ class Gem::TestCase < Minitest::Test
   end
 
   def assert_directory_exists(path, msg = nil)
-    msg = message(msg) { "Expected path '#{path}' to be a directory" }
-    assert_path_exists path
+    msg = build_message(msg, "Expected path '#{path}' to be a directory")
+    assert_path_exist path
     assert File.directory?(path), msg
   end
 
+  # https://github.com/seattlerb/minitest/blob/21d9e804b63c619f602f3f4ece6c71b48974707a/lib/minitest/assertions.rb#L188
+  def _synchronize
+    yield
+  end
+
+  # https://github.com/seattlerb/minitest/blob/21d9e804b63c619f602f3f4ece6c71b48974707a/lib/minitest/assertions.rb#L546
+  def capture_subprocess_io
+    _synchronize do
+      begin
+        require "tempfile"
+
+        captured_stdout, captured_stderr = Tempfile.new("out"), Tempfile.new("err")
+
+        orig_stdout, orig_stderr = $stdout.dup, $stderr.dup
+        $stdout.reopen captured_stdout
+        $stderr.reopen captured_stderr
+
+        yield
+
+        $stdout.rewind
+        $stderr.rewind
+
+        return captured_stdout.read, captured_stderr.read
+      ensure
+        captured_stdout.unlink
+        captured_stderr.unlink
+        $stdout.reopen orig_stdout
+        $stderr.reopen orig_stderr
+
+        orig_stdout.close
+        orig_stderr.close
+        captured_stdout.close
+        captured_stderr.close
+      end
+    end
+  end
+
   ##
   # Sets the ENABLE_SHARED entry in RbConfig::CONFIG to +value+ and restores
   # the original value when the block ends
@@ -262,19 +290,19 @@ class Gem::TestCase < Minitest::Test
 
   def assert_contains_make_command(target, output, msg = nil)
     if output.match(/\n/)
-      msg = message(msg) do
+      msg = build_message(msg,
         "Expected output containing make command \"%s\", but was \n\nBEGIN_OF_OUTPUT\n%sEND_OF_OUTPUT" % [
           ('%s %s' % [make_command, target]).rstrip,
           output,
         ]
-      end
+      )
     else
-      msg = message(msg) do
+      msg = build_message(msg,
         'Expected make command "%s": %s' % [
           ('%s %s' % [make_command, target]).rstrip,
           output,
         ]
-      end
+      )
     end
 
     assert scan_make_command_lines(output).any? {|line|
@@ -664,6 +692,28 @@ class Gem::TestCase < Minitest::Test
     path
   end
 
+  ##
+  # Load a YAML string, the psych 3 way
+
+  def load_yaml(yaml)
+    if YAML.respond_to?(:unsafe_load)
+      YAML.unsafe_load(yaml)
+    else
+      YAML.load(yaml)
+    end
+  end
+
+  ##
+  # Load a YAML file, the psych 3 way
+
+  def load_yaml_file(file)
+    if YAML.respond_to?(:unsafe_load_file)
+      YAML.unsafe_load_file(file)
+    else
+      YAML.load_file(file)
+    end
+  end
+
   def all_spec_names
     Gem::Specification.map(&:full_name)
   end
@@ -1519,4 +1569,38 @@ Also, a list:
   end if Gem::HAVE_OPENSSL
 end
 
+# https://github.com/seattlerb/minitest/blob/13c48a03d84a2a87855a4de0c959f96800100357/lib/minitest/mock.rb#L192
+class Object
+  def stub(name, val_or_callable, *block_args)
+    new_name = "__minitest_stub__#{name}"
+
+    metaclass = class << self; self; end
+
+    if respond_to? name and not methods.map(&:to_s).include? name.to_s
+      metaclass.send :define_method, name do |*args|
+        super(*args)
+      end
+    end
+
+    metaclass.send :alias_method, new_name, name
+
+    metaclass.send :define_method, name do |*args, &blk|
+      if val_or_callable.respond_to? :call
+        val_or_callable.call(*args, &blk)
+      else
+        blk.call(*block_args) if blk
+        val_or_callable
+      end
+    end
+
+    metaclass.send(:ruby2_keywords, name) if metaclass.respond_to?(:ruby2_keywords, true)
+
+    yield self
+  ensure
+    metaclass.send :undef_method, name
+    metaclass.send :alias_method, name, new_name
+    metaclass.send :undef_method, new_name
+  end
+end
+
 require 'rubygems/test_utilities'