merge revision(s) b1c73f239fe9af97de837331849f55d67c27561e,bb570ce6d80d28cfc7131dcb72885eed2f989b30,b88d1e6b44164bca0c2b85ea6639469813e1e1d8,127f735c1e5e0771076caf2a74390757a42fb177,f3f1a666c77f8c528b0adc9ccf78e4b9910bd6e0,fa048a0f8523cefde5428805dd334691486319e6,d5d1c41728d65acfb8aa2cf95f2d8ac88f271cd1,52ebaf718e6a78297ceb0dff49815eeed28eae45,7fe22152fc28084f4395fece84ff6e5eb2d6b288,19e6d271266eca5925e66fc8ec39b251a2fa6bcd,05898c5b9001c0b1e8bd7bf0d12b42a8e7c388b8,3651f678a719ae3a35825bcb4e0dabbc7c60d8df,10b082064e6ab0943cce4ef43e567d8044c7096d,de8e6218a3257fe19b46ff0aa157e66f452ac8b7,971a0cd246db6578e1ea8760a903e1a23e3681f3,61a29a41e1d0d11a9963315aa86d25ed690124c0,ff9a00887161840eb8a34d53749a7d7962181cfe,fad3412d475b57055f426cf4e86eafeab516672b,54aa11efa8b1be2c5d20402890d6d2fa90aa19a8,e84d275fe6d0c14ba58ce73b13323879c060b7ae,61e1cf23ac0d122fba3ad4cbaa402c7c94ad54d3,a6948329f8f89fb390215086fe4a888915fd589e,64b991b0cd98ee8f23266b8cbea0fa34bdaab1ec,b1c73f239fe9af97de837331849f55d67c27561e,0ee24b4fab1a1faef600a42c29863e1c3edd8c61: [Backport #17877]

Synchronize rdoc with upstream version v6.3.1.

	[ruby/rdoc] Use File.open to fix the OS Command Injection
	 vulnerability in CVE-2021-31799

	https://github.com/ruby/rdoc/commit/a7f5d6ab88
	---
	 lib/rdoc/rdoc.rb            |  2 +-
	 test/rdoc/test_rdoc_rdoc.rb | 12 ++++++++++++
	 2 files changed, 13 insertions(+), 1 deletion(-)

	[ruby/rdoc] Support ChangeLog generated by `git log`

	https://github.com/ruby/rdoc/commit/5e0a123ca1
	---
	 lib/rdoc/parser/changelog.rb            | 35 +++++++++++++++++++++
	 test/rdoc/test_rdoc_parser_changelog.rb | 56 +++++++++++++++++++++++++++++++++
	 2 files changed, 91 insertions(+)

	[ruby/rdoc] Make each commit entries h3

	https://github.com/ruby/rdoc/commit/11eefb2ae9
	---
	 lib/rdoc/parser/changelog.rb            | 12 ++++++------
	 test/rdoc/test_rdoc_parser_changelog.rb | 12 ++++--------
	 2 files changed, 10 insertions(+), 14 deletions(-)

	[ruby/rdoc] Tweak log entry markdown

	* add 3 levels to headings
	* prefix commit log to labels to make unique IDs

	https://github.com/ruby/rdoc/commit/5074c13209
	---
	 lib/rdoc/parser/changelog.rb            | 20 +++++++++++++++++-
	 test/rdoc/test_rdoc_parser_changelog.rb | 36 ++++++++++++++++++++++++++++++++-
	 2 files changed, 54 insertions(+), 2 deletions(-)

	[ruby/rdoc] Shorten commit hashes

	https://github.com/ruby/rdoc/commit/5d3e153963
	---
	 lib/rdoc/parser/changelog.rb            | 2 +-
	 test/rdoc/test_rdoc_parser_changelog.rb | 2 +-
	 2 files changed, 2 insertions(+), 2 deletions(-)

	[ruby/rdoc] Add links to the commits

	https://github.com/ruby/rdoc/commit/1821628076
	---
	 lib/rdoc/parser/changelog.rb            | 107 +++++++++++++++++++++++++-------
	 test/rdoc/test_rdoc_parser_changelog.rb |  36 ++++++-----
	 2 files changed, 107 insertions(+), 36 deletions(-)

	[ruby/rdoc] Sort by CommitDate if available

	https://github.com/ruby/rdoc/commit/455715e930
	---
	 lib/rdoc/parser/changelog.rb            | 11 ++++++---
	 test/rdoc/test_rdoc_parser_changelog.rb | 40 +++++++++++++++++++++++++++++++++
	 2 files changed, 48 insertions(+), 3 deletions(-)

	[ruby/rdoc] Skip non-date logs by git-log

	`RDoc::Parser::ChangeLog` mis-parses ChangeLog generated by
	git-log, because of too heuristic `Time.parse`.

	For instance, "commit 8187228de0142d3ac7950b7d977c2849e934c637"
	results in "8187-08-16", that is, day 228 in the year 8187.

	https://github.com/ruby/rdoc/commit/9711e6f6d9
	---
	 lib/rdoc/parser/changelog.rb            | 36 ++++++++++++++++++++-------------
	 test/rdoc/test_rdoc_parser_changelog.rb |  2 ++
	 2 files changed, 24 insertions(+), 14 deletions(-)

	[ruby/rdoc] Support other date formats in git-log

	https://github.com/ruby/rdoc/commit/ad8cf37d72
	---
	 lib/rdoc/parser/changelog.rb            |  6 +++---
	 test/rdoc/test_rdoc_parser_changelog.rb | 22 ++++++++++++++++++++++
	 2 files changed, 25 insertions(+), 3 deletions(-)

	[ruby/rdoc] Support iso-strict format in git-log

	https://github.com/ruby/rdoc/commit/2a6c22da63
	---
	 lib/rdoc/parser/changelog.rb            |  6 +++---
	 test/rdoc/test_rdoc_parser_changelog.rb | 11 +++++++++++
	 2 files changed, 14 insertions(+), 3 deletions(-)

	[ruby/rdoc] Update Rdoc.css sidebar panel.

	Updates css so the sidebar look like a panel instead of looking like chopped edges.

	https://github.com/ruby/rdoc/commit/b0098c6d72
	---
	 lib/rdoc/generator/template/darkfish/css/rdoc.css | 1 +
	 1 file changed, 1 insertion(+)

	[ruby/rdoc] Support GFM table

	https://github.com/ruby/rdoc/commit/9dc933df16
	---
	 lib/rdoc/markdown.rb                    | 349 +++++++++++++++++++++++++++++++-
	 lib/rdoc/markup.rb                      |   1 +
	 lib/rdoc/markup/table.rb                |  47 +++++
	 lib/rdoc/markup/to_html.rb              |  23 +++
	 lib/rdoc/markup/to_joined_paragraph.rb  |   1 +
	 lib/rdoc/markup/to_rdoc.rb              |  28 +++
	 lib/rdoc/markup/to_table_of_contents.rb |   1 +
	 test/rdoc/test_rdoc_markdown.rb         |  23 +++
	 8 files changed, 471 insertions(+), 2 deletions(-)
	 create mode 100644 lib/rdoc/markup/table.rb

	[ruby/rdoc] Add table style

	https://github.com/ruby/rdoc/commit/2219c5ae80
	---
	 lib/rdoc/generator/template/darkfish/css/rdoc.css | 19 +++++++++++++++++++
	 1 file changed, 19 insertions(+)

	[ruby/rdoc] Fixed CodeFence without blank lines

	Currently a fenced code block needs a preceding blank line, it
	should not be required, as:
	https://github.github.com/gfm/#fenced-code-blocks
	> A fenced code block may interrupt a paragraph, and does not
	> require a blank line either before or after.

	Just recommended:
	https://docs.github.com/en/github/writing-on-github/creating-and-highlighting-code-blocks
	> We recommend placing a blank line before and after code blocks
	> to make the raw formatting easier to read.

	https://github.com/ruby/rdoc/commit/0e1776caf3
	---
	 lib/rdoc/markdown.rb            | 447 +++++++---------------------------------
	 test/rdoc/test_rdoc_markdown.rb |  36 +++-
	 2 files changed, 112 insertions(+), 371 deletions(-)

	[ruby/rdoc] Allow partial default values to be overridden with
	 .rdoc_options

	https://github.com/ruby/rdoc/commit/e14800891f
	---
	 lib/rdoc/options.rb         | 34 +++++++++++++++++++++++++++++++++-
	 lib/rdoc/rdoc.rb            |  7 ++++++-
	 test/rdoc/test_rdoc_rdoc.rb | 12 ++++++++++++
	 3 files changed, 51 insertions(+), 2 deletions(-)

	[ruby/rdoc] Allow empty .rdoc_options

	https://github.com/ruby/rdoc/commit/0c8cb25b50
	---
	 lib/rdoc/rdoc.rb            |  2 ++
	 test/rdoc/test_rdoc_rdoc.rb | 11 +++++++++++
	 2 files changed, 13 insertions(+)

	[ruby/rdoc] Suppress unused variable warning of "text"

	https://github.com/ruby/rdoc/commit/3a4120b155
	---
	 lib/rdoc/markdown.rb | 345 ++++++++++++++++++++++++++++++++++++++++++++++++++-
	 1 file changed, 343 insertions(+), 2 deletions(-)

	[ruby/rdoc] Get rid of a trailing space

	https://github.com/ruby/rdoc/commit/7b7b91768e
	---
	 lib/rdoc/markdown.rb | 7 +++----
	 1 file changed, 3 insertions(+), 4 deletions(-)

	[ruby/rdoc] Disable other notations in <code> tags

	https://github.com/ruby/rdoc/commit/0cd3b55210
	---
	 lib/rdoc/markup/attr_span.rb                    |  10 ++-
	 lib/rdoc/markup/attribute_manager.rb            | 102 ++++++++++++++++++------
	 test/rdoc/test_rdoc_markup_attribute_manager.rb |  24 +++++-
	 test/rdoc/test_rdoc_markup_to_html.rb           |   6 ++
	 4 files changed, 114 insertions(+), 28 deletions(-)

	[ruby/rdoc] Treat other tags as word boundaries

	https://github.com/ruby/rdoc/commit/8222f85a17
	---
	 lib/rdoc/markup/attribute_manager.rb  | 17 +++++++++++++----
	 test/rdoc/test_rdoc_markup_to_html.rb |  5 +++++
	 2 files changed, 18 insertions(+), 4 deletions(-)

	[ruby/rdoc] Treat emphasis tags as excluding other notations

	And exclusive notations don't exclude other exclusive notations.

	https://github.com/ruby/rdoc/commit/b8baa9a435
	---
	 lib/rdoc/markup/attr_span.rb                    |  2 +-
	 lib/rdoc/markup/attribute_manager.rb            | 10 +++++-----
	 test/rdoc/test_rdoc_markup_attribute_manager.rb |  1 +
	 3 files changed, 7 insertions(+), 6 deletions(-)

	[ruby/rdoc] Clarify that dots in URL are replaced

	The dots in all path components from the document root are
	replaced with underscores, not only in the basename.

	https://github.com/ruby/rdoc/commit/7a3417ea4c
	---
	 test/rdoc/test_rdoc_top_level.rb | 3 +++
	 1 file changed, 3 insertions(+)

	[ruby/rdoc] Links to document texts without "rdoc-ref:" prefix

	While links to generated HTML from RDoc file needs to be prefixed
	by "rdoc-ref:" currently, in case of explicit references this
	seems just redundant.

	Also GitHub RDoc support does not work with this prefix.

	This patch lets links to such document texts (".rb", ".rdoc" and
	".md" now) refer URLs generated by `RDoc::TopLevel#http_url`
	without the prefix.

	https://github.com/ruby/rdoc/commit/f18b27b69d
	---
	 lib/rdoc/markup/to_html.rb            |  4 ++++
	 test/rdoc/test_rdoc_markup_to_html.rb | 21 +++++++++++++++++++++
	 2 files changed, 25 insertions(+)

	[ruby/rdoc] Use File.open to fix the OS Command Injection
	 vulnerability in CVE-2021-31799

	https://github.com/ruby/rdoc/commit/a7f5d6ab88
	---
	 lib/rdoc/rdoc.rb            |  2 +-
	 test/rdoc/test_rdoc_rdoc.rb | 12 ++++++++++++
	 2 files changed, 13 insertions(+), 1 deletion(-)

	[ruby/rdoc] Version 6.3.1

	https://github.com/ruby/rdoc/commit/9307f932b7
	---
	 lib/rdoc/version.rb | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

1 files changed, 93 insertions, 28 deletions

diff --git a/lib/rdoc/markup/attribute_manager.rb b/lib/rdoc/markup/attribute_manager.rb
index f052bc8b01..50764510f3 100644
--- a/lib/rdoc/markup/attribute_manager.rb
+++ b/lib/rdoc/markup/attribute_manager.rb
@@ -59,6 +59,10 @@ class RDoc::Markup::AttributeManager
   attr_reader :regexp_handlings
 
   ##
+  # A bits of exclusive maps
+  attr_reader :exclusive_bitmap
+
+  ##
   # Creates a new attribute manager that understands bold, emphasized and
   # teletype text.
 
@@ -68,17 +72,18 @@ class RDoc::Markup::AttributeManager
     @protectable = %w[<]
     @regexp_handlings = []
     @word_pair_map = {}
+    @exclusive_bitmap = 0
     @attributes = RDoc::Markup::Attributes.new
 
-    add_word_pair "*", "*", :BOLD
-    add_word_pair "_", "_", :EM
-    add_word_pair "+", "+", :TT
+    add_word_pair "*", "*", :BOLD, true
+    add_word_pair "_", "_", :EM, true
+    add_word_pair "+", "+", :TT, true
 
-    add_html "em", :EM
-    add_html "i",  :EM
-    add_html "b",  :BOLD
-    add_html "tt",   :TT
-    add_html "code", :TT
+    add_html "em", :EM, true
+    add_html "i",  :EM, true
+    add_html "b",  :BOLD, true
+    add_html "tt",   :TT, true
+    add_html "code", :TT, true
   end
 
   ##
@@ -122,29 +127,67 @@ class RDoc::Markup::AttributeManager
     res
   end
 
+  def exclusive?(attr)
+    (attr & @exclusive_bitmap) != 0
+  end
+
+  NON_PRINTING_START = "\1" # :nodoc:
+  NON_PRINTING_END = "\2" # :nodoc:
+
   ##
   # Map attributes like <b>text</b>to the sequence
   # \001\002<char>\001\003<char>, where <char> is a per-attribute specific
   # character
 
-  def convert_attrs(str, attrs)
+  def convert_attrs(str, attrs, exclusive = false)
+    convert_attrs_matching_word_pairs(str, attrs, exclusive)
+    convert_attrs_word_pair_map(str, attrs, exclusive)
+  end
+
+  def convert_attrs_matching_word_pairs(str, attrs, exclusive)
     # first do matching ones
-    tags = @matching_word_pairs.keys.join("")
+    tags = @matching_word_pairs.select { |start, bitmap|
+      if exclusive && exclusive?(bitmap)
+        true
+      elsif !exclusive && !exclusive?(bitmap)
+        true
+      else
+        false
+      end
+    }.keys
+    return if tags.empty?
+    all_tags = @matching_word_pairs.keys
 
-    re = /(^|\W)([#{tags}])([#\\]?[\w:.\/-]+?\S?)\2(\W|$)/
+    re = /(^|\W|[#{all_tags.join("")}])([#{tags.join("")}])(\2*[#\\]?[\w:.\/\[\]-]+?\S?)\2(?!\2)([#{all_tags.join("")}]|\W|$)/
 
-    1 while str.gsub!(re) do
+    1 while str.gsub!(re) { |orig|
       attr = @matching_word_pairs[$2]
-      attrs.set_attrs($`.length + $1.length + $2.length, $3.length, attr)
-      $1 + NULL * $2.length + $3 + NULL * $2.length + $4
-    end
+      attr_updated = attrs.set_attrs($`.length + $1.length + $2.length, $3.length, attr)
+      if attr_updated
+        $1 + NULL * $2.length + $3 + NULL * $2.length + $4
+      else
+        $1 + NON_PRINTING_START + $2 + NON_PRINTING_END + $3 + NON_PRINTING_START + $2 + NON_PRINTING_END + $4
+      end
+    }
+    str.delete!(NON_PRINTING_START + NON_PRINTING_END)
+  end
 
+  def convert_attrs_word_pair_map(str, attrs, exclusive)
     # then non-matching
     unless @word_pair_map.empty? then
       @word_pair_map.each do |regexp, attr|
-        str.gsub!(regexp) {
-          attrs.set_attrs($`.length + $1.length, $2.length, attr)
-          NULL * $1.length + $2 + NULL * $3.length
+        if !exclusive
+          next if exclusive?(attr)
+        else
+          next if !exclusive?(attr)
+        end
+        1 while str.gsub!(regexp) { |orig|
+          updated = attrs.set_attrs($`.length + $1.length, $2.length, attr)
+          if updated
+            NULL * $1.length + $2 + NULL * $3.length
+          else
+            orig
+          end
         }
       end
     end
@@ -153,10 +196,18 @@ class RDoc::Markup::AttributeManager
   ##
   # Converts HTML tags to RDoc attributes
 
-  def convert_html(str, attrs)
-    tags = @html_tags.keys.join '|'
+  def convert_html(str, attrs, exclusive = false)
+    tags = @html_tags.select { |start, bitmap|
+      if exclusive && exclusive?(bitmap)
+        true
+      elsif !exclusive && !exclusive?(bitmap)
+        true
+      else
+        false
+      end
+    }.keys.join '|'
 
-    1 while str.gsub!(/<(#{tags})>(.*?)<\/\1>/i) {
+    1 while str.gsub!(/<(#{tags})>(.*?)<\/\1>/i) { |orig|
       attr = @html_tags[$1.downcase]
       html_length = $1.length + 2
       seq = NULL * html_length
@@ -168,8 +219,13 @@ class RDoc::Markup::AttributeManager
   ##
   # Converts regexp handling sequences to RDoc attributes
 
-  def convert_regexp_handlings str, attrs
+  def convert_regexp_handlings str, attrs, exclusive = false
     @regexp_handlings.each do |regexp, attribute|
+      if exclusive
+        next if !exclusive?(attribute)
+      else
+        next if exclusive?(attribute)
+      end
       str.scan(regexp) do
         capture = $~.size == 1 ? 0 : 1
 
@@ -205,7 +261,7 @@ class RDoc::Markup::AttributeManager
   #
   #   am.add_word_pair '*', '*', :BOLD
 
-  def add_word_pair(start, stop, name)
+  def add_word_pair(start, stop, name, exclusive = false)
     raise ArgumentError, "Word flags may not start with '<'" if
       start[0,1] == '<'
 
@@ -220,6 +276,8 @@ class RDoc::Markup::AttributeManager
 
     @protectable << start[0,1]
     @protectable.uniq!
+
+    @exclusive_bitmap |= bitmap if exclusive
   end
 
   ##
@@ -228,8 +286,10 @@ class RDoc::Markup::AttributeManager
   #
   #   am.add_html 'em', :EM
 
-  def add_html(tag, name)
-    @html_tags[tag.downcase] = @attributes.bitmap_for name
+  def add_html(tag, name, exclusive = false)
+    bitmap = @attributes.bitmap_for name
+    @html_tags[tag.downcase] = bitmap
+    @exclusive_bitmap |= bitmap if exclusive
   end
 
   ##
@@ -238,8 +298,10 @@ class RDoc::Markup::AttributeManager
   #
   #   @am.add_regexp_handling(/((https?:)\S+\w)/, :HYPERLINK)
 
-  def add_regexp_handling pattern, name
-    @regexp_handlings << [pattern, @attributes.bitmap_for(name)]
+  def add_regexp_handling pattern, name, exclusive = false
+    bitmap = @attributes.bitmap_for(name)
+    @regexp_handlings << [pattern, bitmap]
+    @exclusive_bitmap |= bitmap if exclusive
   end
 
   ##
@@ -250,8 +312,11 @@ class RDoc::Markup::AttributeManager
 
     mask_protected_sequences
 
-    @attrs = RDoc::Markup::AttrSpan.new @str.length
+    @attrs = RDoc::Markup::AttrSpan.new @str.length, @exclusive_bitmap
 
+    convert_attrs            @str, @attrs, true
+    convert_html             @str, @attrs, true
+    convert_regexp_handlings @str, @attrs, true
     convert_attrs            @str, @attrs
     convert_html             @str, @attrs
     convert_regexp_handlings @str, @attrs