patch 9.1.1568: need a few more default highlight groups

Problem:  need a few more default highlight groups
Solution: Add Bold, Italic and BoldItalic default highlight groups
          (Maxim Kim).

related: https://github.com/vim/vim/pull/17598#issuecomment-3007320523
closes: #17804

Signed-off-by: Maxim Kim <habamax@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2025 Jul 14
+*syntax.txt*	For Vim version 9.1.  Last change: 2025 Jul 20
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -262,6 +262,9 @@ you can see the actual color, except for "Ignore"):
 	 Debug		debugging statements
 
 	*Underlined	text that stands out, HTML links
+	*Bold		bold text
+	*Italic		italic text
+	*BoldItalic	bold and italic text
 
 	*Ignore		left blank, hidden  |hl-Ignore|
 

runtime/doc/version9.txt

@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2025 Jul 16
+*version9.txt*  For Vim version 9.1.  Last change: 2025 Jul 20
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41640,6 +41640,9 @@ Other new features ~
 
 - The new digraph "APPROACHES THE LIMIT" using ".=" has been added.
 
+- Add the new default highlighting groups "Bold", "Italic" and "BoldItalic"
+  for use in syntax scripts.
+
 							*changed-9.2*
 Changed~
 -------

runtime/syntax/help.vim

@@ -1,7 +1,7 @@
 " Vim syntax file
 " Language:		Vim help file
 " Maintainer:		Doug Kearns <dougkearns@gmail.com>
-" Last Change:		2025 Jul 12
+" Last Change:		2025 Jul 20
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Quit when a (custom) syntax file was already loaded
@@ -179,6 +179,9 @@ syn match helpDelimiter		"\t[* ]Delimiter\t\+[a-z].*"
 syn match helpSpecialComment	"\t[* ]SpecialComment\t\+[a-z].*"
 syn match helpDebug		"\t[* ]Debug\t\+[a-z].*"
 syn match helpUnderlined	"\t[* ]Underlined\t\+[a-z].*"
+syn match helpBold		"\t[* ]Bold\t\+[a-z].*"
+syn match helpItalic		"\t[* ]Italic\t\+[a-z].*"
+syn match helpBoldItalic	"\t[* ]BoldItalic\t\+[a-z].*"
 syn match helpError		"\t[* ]Error\t\+[a-z].*"
 syn match helpTodo		"\t[* ]Todo\t\+[a-z].*"
 
@@ -250,6 +253,9 @@ hi def link helpDelimiter	Delimiter
 hi def link helpSpecialComment	SpecialComment
 hi def link helpDebug		Debug
 hi def link helpUnderlined	Underlined
+hi def link helpBold		Bold
+hi def link helpItalic		Italic
+hi def link helpBoldItalic	BoldItalic
 hi def link helpError		Error
 hi def link helpTodo		Todo
 hi def link helpURL		String

runtime/syntax/syncolor.vim

@@ -62,6 +62,9 @@ else
 endif
 SynColor Error		term=reverse cterm=NONE ctermfg=White ctermbg=Red gui=NONE guifg=White guibg=Red
 SynColor Todo		term=standout cterm=NONE ctermfg=Black ctermbg=Yellow gui=NONE guifg=Blue guibg=Yellow
+SynColor Bold		term=bold cterm=bold ctermfg=NONE ctermbg=NONE gui=bold guifg=NONE guibg=NONE
+SynColor Italic		term=italic cterm=italic ctermfg=NONE ctermbg=NONE gui=italic guifg=NONE guibg=NONE
+SynColor BoldItalic	term=bold,italic cterm=bold,italic ctermfg=NONE ctermbg=NONE gui=bold,italic guifg=NONE guibg=NONE
 
 " Common groups that link to default highlighting.
 " You can specify other highlighting easily.

src/testdir/test_syntax.vim

@@ -191,14 +191,14 @@ func Test_syntax_completion()
   " Check that clearing "Aap" avoids it showing up before Boolean.
   hi Aap ctermfg=blue
   call feedkeys(":syn list \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_match('^"syn list Aap Added Boolean Changed Character ', @:)
+  call assert_match('^"syn list Aap Added Bold BoldItalic Boolean Changed Character ', @:)
   hi clear Aap
 
   call feedkeys(":syn list \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_match('^"syn list Added Boolean Changed Character ', @:)
+  call assert_match('^"syn list Added Bold BoldItalic Boolean Changed Character ', @:)
 
   call feedkeys(":syn match \<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_match('^"syn match Added Boolean Changed Character ', @:)
+  call assert_match('^"syn match Added Bold BoldItalic Boolean Changed Character ', @:)
 
   syn cluster Aax contains=Aap
   call feedkeys(":syn list @A\<C-A>\<C-B>\"\<CR>", 'tx')

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1568,
 /**/
     1567,
 /**/