diff --git a/ext/digest/lib/digest/version.rb b/ext/digest/lib/digest/version.rb
index 691323f1099fe0..a56e80c54ee84c 100644
--- a/ext/digest/lib/digest/version.rb
+++ b/ext/digest/lib/digest/version.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
 module Digest
+  # The version string
   VERSION = "3.2.1"
 end
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index d019891afeacae..7e319cae0de3cf 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -1456,6 +1456,7 @@ rb_zstream_finish(VALUE obj)
  * call-seq:
  *   flush_next_in -> input
  *
+ * Flushes input buffer and returns all data in that buffer.
  */
 static VALUE
 rb_zstream_flush_next_in(VALUE obj)
diff --git a/gem_prelude.rb b/gem_prelude.rb
index bcd2560fab52ca..1b78d80c726625 100644
--- a/gem_prelude.rb
+++ b/gem_prelude.rb
@@ -25,4 +25,3 @@
 rescue LoadError
   warn "`syntax_suggest' was not loaded."
 end if defined?(SyntaxSuggest)
-
diff --git a/lib/bundled_gems.rb b/lib/bundled_gems.rb
index 852d7c48e3a217..914c8465032fdc 100644
--- a/lib/bundled_gems.rb
+++ b/lib/bundled_gems.rb
@@ -1,5 +1,10 @@
 # -*- frozen-string-literal: true -*-
 
+# :stopdoc:
+module Gem
+end
+# :startdoc:
+
 module Gem::BUNDLED_GEMS # :nodoc:
   SINCE = {
     "racc" => "3.3.0",
diff --git a/lib/bundler/ruby_version.rb b/lib/bundler/ruby_version.rb
index 0ed5cbc6cacfa2..7f60dde4768ddd 100644
--- a/lib/bundler/ruby_version.rb
+++ b/lib/bundler/ruby_version.rb
@@ -43,7 +43,6 @@ def initialize(versions, patchlevel, engine, engine_version)
 
     def to_s(versions = self.versions)
       output = String.new("ruby #{versions_string(versions)}")
-      output << "p#{patchlevel}" if patchlevel && patchlevel != "-1"
       output << " (#{engine} #{versions_string(engine_versions)})" unless engine == "ruby"
 
       output
@@ -72,8 +71,7 @@ def single_version_string
     def ==(other)
       versions == other.versions &&
         engine == other.engine &&
-        engine_versions == other.engine_versions &&
-        patchlevel == other.patchlevel
+        engine_versions == other.engine_versions
     end
 
     def host
diff --git a/lib/delegate.rb b/lib/delegate.rb
index 824d02f28b0946..838de675f1f5e3 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -39,6 +39,7 @@
 # Be advised, RDoc will not detect delegated methods.
 #
 class Delegator < BasicObject
+  # The version string
   VERSION = "0.4.0"
 
   kernel = ::Kernel.dup
@@ -77,7 +78,7 @@ def initialize(obj)
   end
 
   #
-  # Handles the magic of delegation through \_\_getobj\_\_.
+  # Handles the magic of delegation through +__getobj__+.
   #
   ruby2_keywords def method_missing(m, *args, &block)
     r = true
@@ -94,7 +95,7 @@ def initialize(obj)
 
   #
   # Checks for a method provided by this the delegate object by forwarding the
-  # call through \_\_getobj\_\_.
+  # call through +__getobj__+.
   #
   def respond_to_missing?(m, include_private)
     r = true
@@ -107,7 +108,7 @@ def respond_to_missing?(m, include_private)
     r
   end
 
-  KERNEL_RESPOND_TO = ::Kernel.instance_method(:respond_to?)
+  KERNEL_RESPOND_TO = ::Kernel.instance_method(:respond_to?) # :nodoc:
   private_constant :KERNEL_RESPOND_TO
 
   # Handle BasicObject instances
@@ -126,7 +127,7 @@ def respond_to_missing?(m, include_private)
 
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ methods.
+  # of this object's and +__getobj__+ methods.
   #
   def methods(all=true)
     __getobj__.methods(all) | super
@@ -134,7 +135,7 @@ def methods(all=true)
 
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ public methods.
+  # of this object's and +__getobj__+ public methods.
   #
   def public_methods(all=true)
     __getobj__.public_methods(all) | super
@@ -142,7 +143,7 @@ def public_methods(all=true)
 
   #
   # Returns the methods available to this delegate object as the union
-  # of this object's and \_\_getobj\_\_ protected methods.
+  # of this object's and +__getobj__+ protected methods.
   #
   def protected_methods(all=true)
     __getobj__.protected_methods(all) | super
@@ -175,7 +176,7 @@ def eql?(obj)
   end
 
   #
-  # Delegates ! to the \_\_getobj\_\_
+  # Delegates ! to the +__getobj__+
   #
   def !
     !__getobj__
@@ -198,7 +199,7 @@ def __setobj__(obj)
   end
 
   #
-  # Serialization support for the object returned by \_\_getobj\_\_.
+  # Serialization support for the object returned by +__getobj__+.
   #
   def marshal_dump
     ivars = instance_variables.reject {|var| /\A@delegate_/ =~ var}
@@ -232,7 +233,7 @@ def initialize_dup(obj) # :nodoc:
 
   ##
   # :method: freeze
-  # Freeze both the object returned by \_\_getobj\_\_ and self.
+  # Freeze both the object returned by +__getobj__+ and self.
   #
   def freeze
     __getobj__.freeze
diff --git a/lib/erb/compiler.rb b/lib/erb/compiler.rb
index 08b5eb4ee1d220..8a4d85c6ea5d54 100644
--- a/lib/erb/compiler.rb
+++ b/lib/erb/compiler.rb
@@ -480,7 +480,6 @@ def initialize from
     end
   }.new(caller(0)).c
   private_constant :WARNING_UPLEVEL
-  # :startdoc:
 
   def warn_invalid_trim_mode(mode, uplevel:)
     warn "Invalid ERB trim mode: #{mode.inspect} (trim_mode: nil, 0, 1, 2, or String composed of '%' and/or '-', '>', '<>')", uplevel: uplevel + WARNING_UPLEVEL
diff --git a/lib/erb/util.rb b/lib/erb/util.rb
index efa8ca1d137cbd..9c3d186edefb62 100644
--- a/lib/erb/util.rb
+++ b/lib/erb/util.rb
@@ -19,6 +19,7 @@
   # A subset of ERB::Util. Unlike ERB::Util#html_escape, we expect/hope
   # Rails will not monkey-patch ERB::Escape#html_escape.
   module ERB::Escape
+    # :stopdoc:
     def html_escape(s)
       CGI.escapeHTML(s.to_s)
     end
diff --git a/lib/find.rb b/lib/find.rb
index 98a79cc76dad7c..8223eea4560319 100644
--- a/lib/find.rb
+++ b/lib/find.rb
@@ -27,6 +27,7 @@
 #
 module Find
 
+  # The version string
   VERSION = "0.2.0"
 
   #
diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index 71b4e6adad4d9a..5652e728642906 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -114,6 +114,8 @@ module Forwardable
   # Version of +forwardable.rb+
   VERSION = "1.3.3"
   VERSION.freeze
+
+  # Version for backward compatibility
   FORWARDABLE_VERSION = VERSION
   FORWARDABLE_VERSION.freeze
 
diff --git a/lib/open-uri.rb b/lib/open-uri.rb
index de710af261eaa9..5983c7368b1d35 100644
--- a/lib/open-uri.rb
+++ b/lib/open-uri.rb
@@ -91,8 +91,10 @@ def self.open(name, *rest, &block)
 
 module OpenURI
 
+  # The version string
   VERSION = "0.5.0"
 
+  # The default options
   Options = {
     :proxy => true,
     :proxy_http_basic_authentication => true,
@@ -394,24 +396,28 @@ def OpenURI.open_http(buf, target, proxy, options) # :nodoc:
     end
   end
 
+  # Raised on HTTP session failure
   class HTTPError < StandardError
-    def initialize(message, io)
+    def initialize(message, io) # :nodoc:
       super(message)
       @io = io
     end
+    # StringIO having the received data
     attr_reader :io
   end
 
   # Raised on redirection,
   # only occurs when +redirect+ option for HTTP is +false+.
   class HTTPRedirect < HTTPError
-    def initialize(message, io, uri)
+    def initialize(message, io, uri) # :nodoc:
       super(message, io)
       @uri = uri
     end
+    # URI to redirect
     attr_reader :uri
   end
 
+  # Raised on too many redirection,
   class TooManyRedirects < HTTPError
   end
 
diff --git a/lib/open3/version.rb b/lib/open3/version.rb
index bfcec44ccc920b..322dd71e2a3a46 100644
--- a/lib/open3/version.rb
+++ b/lib/open3/version.rb
@@ -1,3 +1,4 @@
 module Open3
+  # The version string
   VERSION = "0.2.1"
 end
diff --git a/lib/pp.rb b/lib/pp.rb
index 700a39cdc906a2..fcd33ba80e9e2e 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -174,7 +174,7 @@ def pop_inspect_key(id)
       Thread.current[:__recursive_key__][:inspect].delete id
     end
 
-    private def guard_inspect(object)
+    private def guard_inspect(object) # :nodoc:
       recursive_state = Thread.current[:__recursive_key__]
 
       if recursive_state&.key?(:inspect)
@@ -277,7 +277,7 @@ def seplist(list, sep=nil, iter_method=:each) # :yield: element
         kwsplat ? yield(*v, **kwsplat) : yield(*v)
       }
     end
-    EMPTY_KWHASH = if RUBY_VERSION >= "3.0"
+    EMPTY_KWHASH = if RUBY_VERSION >= "3.0" # :nodoc:
       {}.freeze
     end
     private_constant :EMPTY_KWHASH
diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb
index 6f50192f5daf29..a65407c1304df9 100644
--- a/lib/prettyprint.rb
+++ b/lib/prettyprint.rb
@@ -33,6 +33,7 @@
 #
 class PrettyPrint
 
+  # The version string
   VERSION = "0.2.0"
 
   # This is a convenience method which is same as follows:
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index b56d68cc45bb15..6b21ff1b953303 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -642,6 +642,8 @@ def verify
     raise Gem::Package::FormatError.new e.message, @gem
   end
 
+  private
+
   ##
   # Verifies the +checksums+ against the +digests+.  This check is not
   # cryptographically secure.  Missing checksums are ignored.
diff --git a/lib/singleton.rb b/lib/singleton.rb
index b8e43a7794891d..74aec8903cdc98 100644
--- a/lib/singleton.rb
+++ b/lib/singleton.rb
@@ -92,9 +92,10 @@
 #    p a.strip #  => nil
 #
 module Singleton
+  # The version string
   VERSION = "0.3.0"
 
-  module SingletonInstanceMethods
+  module SingletonInstanceMethods # :nodoc:
     # Raises a TypeError to prevent cloning.
     def clone
       raise TypeError, "can't clone instance of singleton #{self.class}"
@@ -143,11 +144,11 @@ def set_mutex(val)
     end
   end
 
-  def self.module_with_class_methods
+  def self.module_with_class_methods # :nodoc:
     SingletonClassMethods
   end
 
-  module SingletonClassProperties
+  module SingletonClassProperties # :nodoc:
 
     def self.included(c)
       # extending an object with Singleton is a bad idea
@@ -196,10 +197,10 @@ def included(klass)
 end
 
 if defined?(Ractor)
-  module RactorLocalSingleton
+  module RactorLocalSingleton # :nodoc:
     include Singleton::SingletonInstanceMethods
 
-    module RactorLocalSingletonClassMethods
+    module RactorLocalSingletonClassMethods # :nodoc:
       include Singleton::SingletonClassMethods
       def instance
         set_mutex(Thread::Mutex.new) if Ractor.current[mutex_key].nil?
diff --git a/lib/tempfile.rb b/lib/tempfile.rb
index 7292e72c252599..27ebb96439c7f3 100644
--- a/lib/tempfile.rb
+++ b/lib/tempfile.rb
@@ -564,6 +564,8 @@ def Tempfile.create(basename="", tmpdir=nil, mode: 0, anonymous: false, **option
 end
 
 class << Tempfile
+# :stopdoc:
+
 private def create_with_filename(basename="", tmpdir=nil, mode: 0, **options)
   tmpfile = nil
   Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
diff --git a/lib/weakref.rb b/lib/weakref.rb
index 0a09f7f9936d0f..c7274f96641d81 100644
--- a/lib/weakref.rb
+++ b/lib/weakref.rb
@@ -17,6 +17,7 @@
 #
 
 class WeakRef < Delegator
+  # The version string
   VERSION = "0.1.4"
 
   ##
diff --git a/lib/yaml.rb b/lib/yaml.rb
index 2cf11fc3dfb04e..c6f0f89fd2a1e0 100644
--- a/lib/yaml.rb
+++ b/lib/yaml.rb
@@ -66,5 +66,6 @@
 #
 # Syck can also be found on github: https://github.com/ruby/syck
 module YAML
+  # The version of YAML wrapper
   LOADER_VERSION = "0.4.0"
 end
diff --git a/spec/bundler/bundler/ruby_version_spec.rb b/spec/bundler/bundler/ruby_version_spec.rb
index 39d0571361ef93..b96893cefe8cc5 100644
--- a/spec/bundler/bundler/ruby_version_spec.rb
+++ b/spec/bundler/bundler/ruby_version_spec.rb
@@ -100,7 +100,7 @@
 
     describe "#to_s" do
       it "should return info string with the ruby version, patchlevel, engine, and engine version" do
-        expect(subject.to_s).to eq("ruby 2.0.0p645 (jruby 2.0.1)")
+        expect(subject.to_s).to eq("ruby 2.0.0 (jruby 2.0.1)")
       end
 
       context "no patchlevel" do
@@ -115,7 +115,7 @@
         let(:engine) { "ruby" }
 
         it "should return info string with the ruby version and patchlevel" do
-          expect(subject.to_s).to eq("ruby 2.0.0p645")
+          expect(subject.to_s).to eq("ruby 2.0.0")
         end
       end
 
@@ -149,12 +149,6 @@
         it_behaves_like "two ruby versions are not equal"
       end
 
-      context "the patchlevels do not match" do
-        let(:other_patchlevel) { "21" }
-
-        it_behaves_like "two ruby versions are not equal"
-      end
-
       context "the engines do not match" do
         let(:other_engine) { "ruby" }
 
diff --git a/spec/bundler/install/gemfile/ruby_spec.rb b/spec/bundler/install/gemfile/ruby_spec.rb
index 3e15d82bbe25cc..313babc81d7595 100644
--- a/spec/bundler/install/gemfile/ruby_spec.rb
+++ b/spec/bundler/install/gemfile/ruby_spec.rb
@@ -83,7 +83,7 @@ def locked_ruby_version
         myrack
 
       RUBY VERSION
-         ruby 2.1.4p422
+         ruby 2.1.4
 
       BUNDLED WITH
          #{Bundler::VERSION}
diff --git a/test/rubygems/test_gem_package.rb b/test/rubygems/test_gem_package.rb
index 8a9cc8558022b7..34fa65b1e03028 100644
--- a/test/rubygems/test_gem_package.rb
+++ b/test/rubygems/test_gem_package.rb
@@ -1247,71 +1247,25 @@ def test_verify_truncate
 
   # end #verify tests
 
-  def test_verify_entry
-    entry = Object.new
-    def entry.full_name
-      raise ArgumentError, "whatever"
-    end
-
-    package = Gem::Package.new @gem
-
-    _, err = use_ui @ui do
-      e = nil
-
-      out_err = capture_output do
-        e = assert_raise ArgumentError do
-          package.verify_entry entry
+  def test_missing_metadata
+    invalid_metadata = ["metadataxgz", "foobar\nmetadata", "metadata\nfoobar"]
+    invalid_metadata.each do |fname|
+      tar = StringIO.new
+
+      Gem::Package::TarWriter.new(tar) do |gem_tar|
+        gem_tar.add_file fname, 0o444 do |io|
+          gz_io = Zlib::GzipWriter.new io, Zlib::BEST_COMPRESSION
+          gz_io.write "bad metadata"
+          gz_io.close
         end
       end
 
-      assert_equal "whatever", e.message
-      assert_equal "full_name", e.backtrace_locations.first.label
-
-      out_err
-    end
-
-    assert_equal "Exception while verifying #{@gem}\n", err
-
-    valid_metadata = ["metadata", "metadata.gz"]
-    valid_metadata.each do |vm|
-      $spec_loaded = false
-      $good_name = vm
-
-      entry = Object.new
-      def entry.full_name
-        $good_name
-      end
+      tar.rewind
 
-      package = Gem::Package.new(@gem)
-      package.instance_variable_set(:@files, [])
-      def package.load_spec(entry)
-        $spec_loaded = true
-      end
-
-      package.verify_entry(entry)
-
-      assert $spec_loaded
-    end
-
-    invalid_metadata = ["metadataxgz", "foobar\nmetadata", "metadata\nfoobar"]
-    invalid_metadata.each do |vm|
-      $spec_loaded = false
-      $bad_name = vm
-
-      entry = Object.new
-      def entry.full_name
-        $bad_name
-      end
-
-      package = Gem::Package.new(@gem)
-      package.instance_variable_set(:@files, [])
-      def package.load_spec(entry)
-        $spec_loaded = true
+      package = Gem::Package.new(Gem::Package::IOSource.new(tar))
+      assert_raise Gem::Package::FormatError do
+        package.verify
       end
-
-      package.verify_entry(entry)
-
-      refute $spec_loaded
     end
   end
 
diff --git a/test/test_timeout.rb b/test/test_timeout.rb
index 01156867b05609..71d8e1f5c273c5 100644
--- a/test/test_timeout.rb
+++ b/test/test_timeout.rb
@@ -250,7 +250,7 @@ def test_fork
   end
 
   def test_threadgroup
-    assert_separately(%w[-rtimeout], <<-'end;')
+    assert_separately(%w[-W0 -rtimeout], <<-'end;')
       tg = ThreadGroup.new
       thr = Thread.new do
         tg.add(Thread.current)
@@ -263,7 +263,7 @@ def test_threadgroup
 
   # https://github.com/ruby/timeout/issues/24
   def test_handling_enclosed_threadgroup
-    assert_separately(%w[-rtimeout], <<-'end;')
+    assert_separately(%w[-W0 -rtimeout], <<-'end;')
       Thread.new {
         t = Thread.current
         group = ThreadGroup.new
diff --git a/tool/auto_review_pr.rb b/tool/auto_review_pr.rb
index c63640354d3593..07c98c7e0aed9e 100755
--- a/tool/auto_review_pr.rb
+++ b/tool/auto_review_pr.rb
@@ -46,7 +46,7 @@ def review(pr_number)
     changed_files = @client.get("/repos/#{REPO}/pulls/#{pr_number}/files").map { it.fetch(:filename) }
 
     # Build a Hash: { upstream_repo => files, ... }
-    upstream_repos = changed_files.group_by { |file| find_upstream_repo(file) }
+    upstream_repos = SyncDefaultGems::Repository.group(changed_files)
     upstream_repos.delete(nil) # exclude no-upstream files
     upstream_repos.delete('prism') if changed_files.include?('prism_compile.c') # allow prism changes in this case
     if upstream_repos.empty?
@@ -70,17 +70,6 @@ def review(pr_number)
 
   private
 
-  def find_upstream_repo(file)
-    SyncDefaultGems::REPOSITORIES.each do |repo_name, repository|
-      repository.mappings.each do |_src, dst|
-        if file.start_with?(dst)
-          return repo_name
-        end
-      end
-    end
-    nil
-  end
-
   # upstream_repos: { upstream_repo => files, ... }
   def format_comment(upstream_repos)
     comment = +''
diff --git a/tool/mkconfig.rb b/tool/mkconfig.rb
index ffa4c1c0b263e0..db741157303256 100755
--- a/tool/mkconfig.rb
+++ b/tool/mkconfig.rb
@@ -394,6 +394,7 @@ def RbConfig.ruby
     )
   end
 end
+# Non-nil if configured for cross compiling.
 CROSS_COMPILING = nil unless defined? CROSS_COMPILING
 EOS
 
diff --git a/tool/rdoc-srcdir b/tool/rdoc-srcdir
index f830fdc3027ffd..275f12fe421cd3 100755
--- a/tool/rdoc-srcdir
+++ b/tool/rdoc-srcdir
@@ -17,7 +17,7 @@ options.title = options.title.sub(/Ruby \K.*version/) {
     .sort # "MAJOR" < "MINOR", fortunately
     .to_h.values.join(".")
 }
-options.parse ARGV
+options.parse ARGV + ["#{invoked}/rbconfig.rb"]
 
 options.singleton_class.define_method(:finish) do
   super()
diff --git a/tool/sync_default_gems.rb b/tool/sync_default_gems.rb
index 997cd5eddc8f16..ff0518b1a599d4 100755
--- a/tool/sync_default_gems.rb
+++ b/tool/sync_default_gems.rb
@@ -293,6 +293,20 @@ def lib((upstream, branch), gemspec_in_subdir: false)
     ]),
   }.transform_keys(&:to_s)
 
+  class << Repository
+    def find_upstream(file)
+      REPOSITORIES.find do |repo_name, repository|
+        if repository.mappings.any? {|_src, dst| file.start_with?(dst) }
+          break repo_name
+        end
+      end
+    end
+
+    def group(files)
+      files.group_by {|file| find_upstream(file)}
+    end
+  end
+
   # Allow synchronizing commits up to this FETCH_DEPTH. We've historically merged PRs
   # with about 250 commits to ruby/ruby, so we use this depth for ruby/ruby in general.
   FETCH_DEPTH = 500