patch 9.1.0013: Modula2 filetype support lackingv9.1.0013

Problem:  Modula2 filetype support lacking
Solution: Improve the Modula-2 runtime support, add additional modula2
          dialects, add compiler plugin, update syntax highlighting,
          include syntax tests, update Makefiles (Doug Kearns)

closes: #6796
closes: #8115

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Benjamin Kowarsch <trijezdci@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

46 files changed, 2354 insertions, 112 deletions

diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index af32d6a3ab..6ebaeda19e 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -13,6 +13,7 @@ runtime/autoload/freebasic.vim		@dkearns
 runtime/autoload/getscript.vim		@cecamp
 runtime/autoload/haskell.vim		@alx741
 runtime/autoload/javascript.vim		@jsit
+runtime/autoload/modula2.vim		@dkearns
 runtime/autoload/netrw.vim		@cecamp
 runtime/autoload/netrwFileHandlers.vim	@cecamp
 runtime/autoload/netrwSettings.vim	@cecamp
@@ -65,6 +66,7 @@ runtime/compiler/eruby.vim		@dkearns
 runtime/compiler/fbc.vim		@dkearns
 runtime/compiler/gawk.vim		@dkearns
 runtime/compiler/gjs.vim		@dkearns
+runtime/compiler/gm2.vim		@dkearns
 runtime/compiler/go.vim			@dbarnett
 runtime/compiler/haml.vim		@tpope
 runtime/compiler/hare.vim		@rsaihe
@@ -182,6 +184,7 @@ runtime/ftplugin/m3quake.vim		@dkearns
 runtime/ftplugin/markdown.vim		@tpope
 runtime/ftplugin/matlab.vim		@cecamp
 runtime/ftplugin/meson.vim		@Liambeguin
+runtime/ftplugin/modula2.vim		@dkearns
 runtime/ftplugin/modula3.vim		@dkearns
 runtime/ftplugin/nginx.vim		@chr4
 runtime/ftplugin/nroff.vim		@a-vrma
@@ -442,6 +445,10 @@ runtime/syntax/maple.vim		@cecamp
 runtime/syntax/markdown.vim		@tpope
 runtime/syntax/mason.vim		@petdance
 runtime/syntax/meson.vim		@Liambeguin
+runtime/syntax/modula2.vim		@dkearns
+runtime/syntax/modula2/opt/iso.vim	@trijezdci
+runtime/syntax/modula2/opt/pim.vim	@trijezdci
+runtime/syntax/modula2/opt/r10.vim	@trijezdci
 runtime/syntax/modula3.vim		@dkearns
 runtime/syntax/n1ql.vim			@pr3d4t0r
 runtime/syntax/netrw.vim		@cecamp
diff --git a/Filelist b/Filelist
index df188e8a5e..d4fbca342e 100644
--- a/Filelist
+++ b/Filelist
@@ -818,6 +818,7 @@ RT_SCRIPTS =	\
 		runtime/plugin/README.txt \
 		runtime/syntax/*.vim \
 		runtime/syntax/README.txt \
+		runtime/syntax/modula2/opt/*.vim \
 		runtime/syntax/shared/*.vim \
 		runtime/syntax/shared/README.txt \
 		runtime/syntax/Makefile \
diff --git a/runtime/autoload/dist/ft.vim b/runtime/autoload/dist/ft.vim
index 2423fd4469..9d0f2ee7af 100644
--- a/runtime/autoload/dist/ft.vim
+++ b/runtime/autoload/dist/ft.vim
@@ -2,8 +2,8 @@ vim9script
 
 # Vim functions for file type detection
 #
-# Maintainer:	The Vim Project <https://github.com/vim/vim>
-# Last Change:	2023 Aug 10
+# Maintainer:		The Vim Project <https://github.com/vim/vim>
+# Last Change:		2024 Jan 05
 # Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 # These functions are moved here from runtime/filetype.vim to make startup
@@ -279,6 +279,19 @@ export def DtraceCheck()
   endif
 enddef
 
+export def FTdef()
+  if get(g:, "filetype_def", "") == "modula2" || IsModula2()
+    SetFiletypeModula2()
+    return
+  endif
+
+  if exists("g:filetype_def")
+    exe "setf " .. g:filetype_def
+  else
+    setf def
+  endif
+enddef
+
 export def FTe()
   if exists('g:filetype_euphoria')
     exe 'setf ' .. g:filetype_euphoria
@@ -517,16 +530,53 @@ def IsLProlog(): bool
   return getline(lnum) =~ '\<module\s\+\w\+\s*\.\s*\(%\|$\)'
 enddef
 
+def IsModula2(): bool
+  return getline(nextnonblank(1)) =~ '\<MODULE\s\+\w\+\s*;\|^\s*(\*'
+enddef
+
+def SetFiletypeModula2()
+  const KNOWN_DIALECTS = ["iso", "pim", "r10"]
+  const KNOWN_EXTENSIONS = ["gm2"]
+  const LINE_COUNT = 200
+  const TAG = '(\*!m2\(\w\+\)\%(+\(\w\+\)\)\=\*)'
+
+  var dialect = get(g:, "modula2_default_dialect", "pim")
+  var extension = get(g:, "modula2_default_extension", "")
+
+  var matches = []
+
+  # ignore unknown dialects or badly formatted tags
+  for lnum in range(1, min([line("$"), LINE_COUNT]))
+    matches = matchlist(getline(lnum), TAG)
+    if !empty(matches)
+      if index(KNOWN_DIALECTS, matches[1]) >= 0
+         dialect = matches[1]
+      endif
+      if index(KNOWN_EXTENSIONS, matches[2]) >= 0
+         extension = matches[2]
+      endif
+      break
+    endif
+  endfor
+
+  modula2#SetDialect(dialect, extension)
+
+  setf modula2
+enddef
+
 # Determine if *.mod is ABB RAPID, LambdaProlog, Modula-2, Modsim III or go.mod
 export def FTmod()
+  if get(g:, "filetype_mod", "") == "modula2" || IsModula2()
+    SetFiletypeModula2()
+    return
+  endif
+
   if exists("g:filetype_mod")
     exe "setf " .. g:filetype_mod
   elseif expand("<afile>") =~ '\<go.mod$'
     setf gomod
   elseif IsLProlog()
     setf lprolog
-  elseif getline(nextnonblank(1)) =~ '\%(\<MODULE\s\+\w\+\s*;\|^\s*(\*\)'
-    setf modula2
   elseif IsRapid()
     setf rapid
   else
@@ -1243,4 +1293,4 @@ export def FTvba()
 enddef
 
 # Uncomment this line to check for compilation errors early
-# defcompile
+defcompile
diff --git a/runtime/autoload/modula2.vim b/runtime/autoload/modula2.vim
new file mode 100644
index 0000000000..284dc2768f
--- /dev/null
+++ b/runtime/autoload/modula2.vim
@@ -0,0 +1,31 @@
+" Vim filetype plugin file
+" Language:	Modula-2
+" Maintainer:	Doug Kearns <dougkearns@gmail.com>
+" Last Change:	2024 Jan 04
+
+" Dialect can be one of pim, iso, r10
+function modula2#GetDialect() abort
+
+  if exists("b:modula2.dialect")
+    return b:modula2.dialect
+  endif
+
+  if exists("g:modula2_default_dialect")
+    let dialect = g:modula2_default_dialect
+  else
+    let dialect = "pim"
+  endif
+
+  return dialect
+endfunction
+
+function modula2#SetDialect(dialect, extension = "") abort
+  if exists("b:modula2")
+    unlockvar! b:modula2
+  endif
+
+  let b:modula2 = #{ dialect: a:dialect, extension: a:extension }
+  lockvar! b:modula2
+endfunction
+
+" vim: nowrap sw=2 sts=2 ts=8 noet fdm=marker:
diff --git a/runtime/compiler/gm2.vim b/runtime/compiler/gm2.vim
new file mode 100644
index 0000000000..5053912200
--- /dev/null
+++ b/runtime/compiler/gm2.vim
@@ -0,0 +1,26 @@
+" Vim compiler file
+" Compiler:	GNU Modula-2 Compiler
+" Maintainer:	Doug Kearns <dougkearns@gmail.com>
+" Last Change:	2024 Jan 04
+
+if exists("current_compiler")
+  finish
+endif
+let current_compiler = "gm2"
+
+if exists(":CompilerSet") != 2		" older Vim always used :setlocal
+  command -nargs=* CompilerSet setlocal <args>
+endif
+
+let s:cpo_save = &cpo
+set cpo&vim
+
+CompilerSet makeprg=gm2
+CompilerSet errorformat=%-G%f:%l:%c:\ error:\ compilation\ failed,
+		       \%f:%l:%c:\ %trror:\ %m,
+		       \%f:%l:%c:\ %tarning:\ %m,
+		       \%f:%l:%c:\ %tote:\ %m,
+		       \%-G%.%#
+
+let &cpo = s:cpo_save
+unlet s:cpo_save
diff --git a/runtime/doc/filetype.txt b/runtime/doc/filetype.txt
index e8445db541..4876e3d754 100644
--- a/runtime/doc/filetype.txt
+++ b/runtime/doc/filetype.txt
@@ -1,4 +1,4 @@
-*filetype.txt*  For Vim version 9.1.  Last change: 2024 Jan 01
+*filetype.txt*	For Vim version 9.1.  Last change: 2024 Jan 04
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -148,6 +148,7 @@ variables can be used to overrule the filetype used for certain extensions:
 	*.cls		g:filetype_cls
 	*.csh		g:filetype_csh		|ft-csh-syntax|
 	*.dat		g:filetype_dat
+	*.def		g:filetype_def
 	*.f		g:filetype_f		|ft-forth-syntax|
 	*.frm		g:filetype_frm		|ft-form-syntax|
 	*.fs		g:filetype_fs		|ft-forth-syntax|
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index e3cac2e248..cc293a5979 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -2251,6 +2251,56 @@ have the following in your .vimrc: >
 	let filetype_m = "mma"
 
 
+MODULA2					*modula2.vim* *ft-modula2-syntax*
+
+Vim will recognise comments with dialect tags to automatically select a given
+dialect.
+
+The syntax for a dialect tag comment is: >
+
+	taggedComment :=
+	  '(*!' dialectTag '*)'
+	  ;
+
+	dialectTag :=
+	  m2pim | m2iso | m2r10
+	  ;
+
+	reserved words
+	  m2pim = 'm2pim', m2iso = 'm2iso', m2r10 = 'm2r10'
+
+A dialect tag comment is recognised by Vim if it occurs within the first 200
+lines of the source file. Only the very first such comment is recognised, any
+additional dialect tag comments are ignored.
+
+Example: >
+
+	DEFINITION MODULE FooLib; (*!m2pim*)
+	...
+
+Variable g:modula2_default_dialect sets the default Modula-2 dialect when the
+dialect cannot be determined from the contents of the Modula-2 file: if
+defined and set to 'm2pim', the default dialect is PIM.
+
+Example: >
+
+	let g:modula2_default_dialect = 'm2pim'
+
+
+Highlighting is further configurable for each dialect via the following
+variables.
+
+Variable			Highlight ~
+*modula2_iso_allow_lowline*	allow low line in identifiers
+*modula2_iso_disallow_octals*	disallow octal integer literals
+*modula2_iso_disallow_synonyms*	disallow "@", "&" and "~" synonyms
+
+*modula2_pim_allow_lowline*	allow low line in identifiers
+*modula2_pim_disallow_octals*	disallow octal integer literals
+*modula2_pim_disallow_synonyms*	disallow "&" and "~" synonyms
+
+*modula2_r10_allow_lowline*	allow low line in identifiers
+
 MOO						*moo.vim* *ft-moo-syntax*
 
 If you use C-style comments inside expressions and find it mangles your
diff --git a/runtime/doc/tags b/runtime/doc/tags
index 9af1ac0f64..5b9e5a9b64 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -7270,6 +7270,7 @@ ft-metapost-intro	ft_mp.txt	/*ft-metapost-intro*
 ft-metapost-mappings	ft_mp.txt	/*ft-metapost-mappings*
 ft-metapost-settings	ft_mp.txt	/*ft-metapost-settings*
 ft-mma-syntax	syntax.txt	/*ft-mma-syntax*
+ft-modula2-syntax	syntax.txt	/*ft-modula2-syntax*
 ft-moo-syntax	syntax.txt	/*ft-moo-syntax*
 ft-msql-syntax	syntax.txt	/*ft-msql-syntax*
 ft-n1ql-syntax	syntax.txt	/*ft-n1ql-syntax*
@@ -8659,6 +8660,14 @@ modeline	options.txt	/*modeline*
 modeline-local	options.txt	/*modeline-local*
 modeline-version	options.txt	/*modeline-version*
 modifyOtherKeys	map.txt	/*modifyOtherKeys*
+modula2.vim	syntax.txt	/*modula2.vim*
+modula2_iso_allow_lowline	syntax.txt	/*modula2_iso_allow_lowline*
+modula2_iso_disallow_octals	syntax.txt	/*modula2_iso_disallow_octals*
+modula2_iso_disallow_synonyms	syntax.txt	/*modula2_iso_disallow_synonyms*
+modula2_pim_allow_lowline	syntax.txt	/*modula2_pim_allow_lowline*
+modula2_pim_disallow_octals	syntax.txt	/*modula2_pim_disallow_octals*
+modula2_pim_disallow_synonyms	syntax.txt	/*modula2_pim_disallow_synonyms*
+modula2_r10_allow_lowline	syntax.txt	/*modula2_r10_allow_lowline*
 moo.vim	syntax.txt	/*moo.vim*
 more-compatible	version5.txt	/*more-compatible*
 more-prompt	message.txt	/*more-prompt*
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 30f8a1e16d..0c2869a017 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -619,8 +619,12 @@ au BufNewFile,BufRead *.intr			setf dylanintr
 " Dylan
 au BufNewFile,BufRead *.dylan			setf dylan
 
-" Microsoft Module Definition
-au BufNewFile,BufRead *.def			setf def
+" Microsoft Module Definition or Modula-2
+au BufNewFile,BufRead *.def			call dist#ft#FTdef()
+
+if has("fname_case")
+  au BufNewFile,BufRead *.DEF			setf modula2
+endif
 
 " Dracula
 au BufNewFile,BufRead *.drac,*.drc,*lvs,*lpe	setf dracula
@@ -1339,9 +1343,6 @@ au BufNewFile,BufRead *.mmp			setf mmp
 " ABB Rapid, Modula-2, Modsim III or LambdaProlog
 au BufNewFile,BufRead *.mod\c			call dist#ft#FTmod()
 
-" Modula-2  (.md removed in favor of Markdown, see dist#ft#FTmod for *.MOD)
-au BufNewFile,BufRead *.m2,*.DEF,*.mi		setf modula2
-
 " Modula-3 (.m3, .i3, .mg, .ig)
 au BufNewFile,BufRead *.[mi][3g]		setf modula3
 
diff --git a/runtime/ftplugin/modula2.vim b/runtime/ftplugin/modula2.vim
index 1d0e81ee70..e230636acc 100644
--- a/runtime/ftplugin/modula2.vim
+++ b/runtime/ftplugin/modula2.vim
@@ -11,28 +11,39 @@ let b:did_ftplugin = 1
 let s:cpo_save = &cpo
 set cpo&vim
 
-setlocal comments=s0:(*,mb:\ ,ex:*)
-setlocal commentstring=(*%s*)
+let s:dialect = modula2#GetDialect()
+
+if s:dialect ==# "r10"
+  setlocal comments=s:(*,m:\ ,e:*),:!
+  setlocal commentstring=!\ %s
+else
+  setlocal commentstring=(*%s*)
+  setlocal comments=s:(*,m:\ ,e:*)
+endif
 setlocal formatoptions-=t formatoptions+=croql
 
+let b:undo_ftplugin = "setl com< cms< fo<"
+
 if exists("loaded_matchit") && !exists("b:match_words")
-  " The second branch of the middle pattern is intended to match CASE labels
+  let b:match_ignorecase = 0
+  " the second branch of the middle pattern is intended to match CASE labels
   let b:match_words = '\<REPEAT\>:\<UNTIL\>,' ..
-		    \ '\<\%(BEGIN\|CASE\|FOR\|IF\|LOOP\|WHILE\|WITH\)\>' ..
-		    \	':' ..
-		    \	'\<\%(ELSIF\|ELSE\)\>\|\%(^\s*\)\@<=\w\+\%(\s*\,\s*\w\+\)\=\s*\:=\@!' ..
-		    \	':' ..
-		    \ '\<END\>'
+	\	      '\<\%(BEGIN\|CASE\|FOR\|IF\|LOOP\|WHILE\|WITH\|RECORD\)\>' ..
+	\		':' ..
+	\		'\<\%(ELSIF\|ELSE\)\>\|\%(^\s*\)\@<=\w\+\%(\s*\,\s*\w\+\)\=\s*\:=\@!' ..
+	\		':' ..
+	\	      '\<END\>,' ..
+	\	      '(\*:\*),<\*:\*>'
+  let b:match_skip = 's:Comment\|Pragma'
+  let b:undo_ftplugin ..= " | unlet! b:match_ignorecase b:match_skip b:match_words"
 endif
 
 if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
   let b:browsefilter = "Modula-2 Source Files (*.def *.mod)\t*.def;*.mod\n" ..
-		     \ "All Files (*.*)\t*.*\n"
+	\	       "All Files (*.*)\t*.*\n"
+  let b:undo_ftplugin ..= " | unlet! b:browsefilter"
 endif
 
-let b:undo_ftplugin = "setl com< cms< fo< " ..
-		    \ "| unlet! b:browsefilter b:match_words"
-
 let &cpo = s:cpo_save
 unlet s:cpo_save
 
diff --git a/runtime/makemenu.vim b/runtime/makemenu.vim
index 16af2035e3..6707f2b6a6 100644
--- a/runtime/makemenu.vim
+++ b/runtime/makemenu.vim
@@ -384,8 +384,10 @@ SynMenu M.MMIX:mmix
 SynMenu M.Modconf:modconf
 SynMenu M.Model:model
 SynMenu M.Modsim\ III:modsim3
-SynMenu M.Modula\ 2:modula2
-SynMenu M.Modula\ 3:modula3
+SynMenu M.Modula-2.R10\ (2010):modula2:r10
+SynMenu M.Modula-2.ISO\ (1994):modula2:iso
+SynMenu M.Modula-2.PIM\ (1985):modula2:pim
+SynMenu M.Modula-3:modula3
 SynMenu M.Monk:monk
 SynMenu M.Motorola\ S-Record:srec
 SynMenu M.Mplayer\ config:mplayerconf
diff --git a/runtime/synmenu.vim b/runtime/synmenu.vim
index eeede5f7ce..23c1c7b95b 100644
--- a/runtime/synmenu.vim
+++ b/runtime/synmenu.vim
@@ -1,8 +1,8 @@
 " Vim support file to define the syntax selection menu
 " This file is normally sourced from menu.vim.
 "
-" Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2023 Aug 10
+" Maintainer:		The Vim Project <https://github.com/vim/vim>
+" Last Change:		2024 Jan 04
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Define the SetSyn function, used for the Syntax menu entries.
@@ -13,6 +13,10 @@ def SetSyn(name: string)
     g:use_fvwm_1 = name == "fvwm1"
     g:use_fvwm_2 = name == "fvwm2"
     filetype = "fvwm"
+  elseif name =~ '^modula2:\w\+$'
+    var dialect: string
+    [filetype, dialect] = split(name, ":")
+    modula2#SetDialect(dialect)
   endif
   if name == "whitespace"
     # do not replace the filetype but add whitespace on top
@@ -359,25 +363,27 @@ an 50.70.340 &Syntax.M.MMIX :cal SetSyn("mmix")<CR>
 an 50.70.350 &Syntax.M.Modconf :cal SetSyn("modconf")<CR>
 an 50.70.360 &Syntax.M.Model :cal SetSyn("model")<CR>
 an 50.70.370 &Syntax.M.Modsim\ III :cal SetSyn("modsim3")<CR>
-an 50.70.380 &Syntax.M.Modula\ 2 :cal SetSyn("modula2")<CR>
-an 50.70.390 &Syntax.M.Modula\ 3 :cal SetSyn("modula3")<CR>
-an 50.70.400 &Syntax.M.Monk :cal SetSyn("monk")<CR>
-an 50.70.410 &Syntax.M.Motorola\ S-Record :cal SetSyn("srec")<CR>
-an 50.70.420 &Syntax.M.Mplayer\ config :cal SetSyn("mplayerconf")<CR>
-an 50.70.430 &Syntax.M.MOO :cal SetSyn("moo")<CR>
-an 50.70.440 &Syntax.M.Mrxvtrc :cal SetSyn("mrxvtrc")<CR>
-an 50.70.450 &Syntax.M.MS-DOS/Windows.4DOS\ \.bat\ file :cal SetSyn("btm")<CR>
-an 50.70.460 &Syntax.M.MS-DOS/Windows.\.bat\/\.cmd\ file :cal SetSyn("dosbatch")<CR>
-an 50.70.470 &Syntax.M.MS-DOS/Windows.\.ini\ file :cal SetSyn("dosini")<CR>
-an 50.70.480 &Syntax.M.MS-DOS/Windows.Message\ text :cal SetSyn("msmessages")<CR>
-an 50.70.490 &Syntax.M.MS-DOS/Windows.Module\ Definition :cal SetSyn("def")<CR>
-an 50.70.500 &Syntax.M.MS-DOS/Windows.Registry :cal SetSyn("registry")<CR>
-an 50.70.510 &Syntax.M.MS-DOS/Windows.Resource\ file :cal SetSyn("rc")<CR>
-an 50.70.520 &Syntax.M.Msql :cal SetSyn("msql")<CR>
-an 50.70.530 &Syntax.M.MuPAD :cal SetSyn("mupad")<CR>
-an 50.70.540 &Syntax.M.Murphi :cal SetSyn("murphi")<CR>
-an 50.70.550 &Syntax.M.MUSHcode :cal SetSyn("mush")<CR>
-an 50.70.560 &Syntax.M.Muttrc :cal SetSyn("muttrc")<CR>
+an 50.70.380 &Syntax.M.Modula-2.R10\ (2010) :cal SetSyn("modula2:r10")<CR>
+an 50.70.390 &Syntax.M.Modula-2.ISO\ (1994) :cal SetSyn("modula2:iso")<CR>
+an 50.70.400 &Syntax.M.Modula-2.PIM\ (1985) :cal SetSyn("modula2:pim")<CR>
+an 50.70.410 &Syntax.M.Modula-3 :cal SetSyn("modula3")<CR>
+an 50.70.420 &Syntax.M.Monk :cal SetSyn("monk")<CR>
+an 50.70.430 &Syntax.M.Motorola\ S-Record :cal SetSyn("srec")<CR>
+an 50.70.440 &Syntax.M.Mplayer\ config :cal SetSyn("mplayerconf")<CR>
+an 50.70.450 &Syntax.M.MOO :cal SetSyn("moo")<CR>
+an 50.70.460 &Syntax.M.Mrxvtrc :cal SetSyn("mrxvtrc")<CR>
+an 50.70.470 &Syntax.M.MS-DOS/Windows.4DOS\ \.bat\ file :cal SetSyn("btm")<CR>
+an 50.70.480 &Syntax.M.MS-DOS/Windows.\.bat\/\.cmd\ file :cal SetSyn("dosbatch")<CR>
+an 50.70.490 &Syntax.M.MS-DOS/Windows.\.ini\ file :cal SetSyn("dosini")<CR>
+an 50.70.500 &Syntax.M.MS-DOS/Windows.Message\ text :cal SetSyn("msmessages")<CR>
+an 50.70.510 &Syntax.M.MS-DOS/Windows.Module\ Definition :cal SetSyn("def")<CR>
+an 50.70.520 &Syntax.M.MS-DOS/Windows.Registry :cal SetSyn("registry")<CR>
+an 50.70.530 &Syntax.M.MS-DOS/Windows.Resource\ file :cal SetSyn("rc")<CR>
+an 50.70.540 &Syntax.M.Msql :cal SetSyn("msql")<CR>
+an 50.70.550 &Syntax.M.MuPAD :cal SetSyn("mupad")<CR>
+an 50.70.560 &Syntax.M.Murphi :cal SetSyn("murphi")<CR>
+an 50.70.570 &Syntax.M.MUSHcode :cal SetSyn("mush")<CR>
+an 50.70.580 &Syntax.M.Muttrc :cal SetSyn("muttrc")<CR>
 an 50.80.100 &Syntax.NO.N1QL :cal SetSyn("n1ql")<CR>
 an 50.80.110 &Syntax.NO.Nanorc :cal SetSyn("nanorc")<CR>
 an 50.80.120 &Syntax.NO.Nastran\ input/DMAP :cal SetSyn("nastran")<CR>
diff --git a/runtime/syntax/modula2.vim b/runtime/syntax/modula2.vim
index 4a14cf1f6f..6a9f4af6aa 100644
--- a/runtime/syntax/modula2.vim
+++ b/runtime/syntax/modula2.vim
@@ -1,73 +1,16 @@
 " Vim syntax file
-" Language:	Modula 2
-" Maintainer:	pf@artcom0.north.de (Peter Funk)
-"   based on original work of Bram Moolenaar <Bram@vim.org>
-" Last Change:	2001 May 09
+" Language:		Modula-2
+" Maintainer:		Doug Kearns <dougkearns@gmail.com>
+" Previous Maintainer:	pf@artcom0.north.de (Peter Funk)
+" Last Change:		2024 Jan 04
 
-" quit when a syntax file was already loaded
 if exists("b:current_syntax")
   finish
 endif
 
-" Don't ignore case (Modula-2 is case significant). This is the default in vim
-
-" Especially emphasize headers of procedures and modules:
-syn region modula2Header matchgroup=modula2Header start="PROCEDURE " end="(" contains=modula2Ident oneline
-syn region modula2Header matchgroup=modula2Header start="MODULE " end=";" contains=modula2Ident oneline
-syn region modula2Header matchgroup=modula2Header start="BEGIN (\*" end="\*)" contains=modula2Ident oneline
-syn region modula2Header matchgroup=modula2Header start="END " end=";" contains=modula2Ident oneline
-syn region modula2Keyword start="END" end=";" contains=ALLBUT,modula2Ident oneline
-
-" Some very important keywords which should be emphasized more than others:
-syn keyword modula2AttKeyword CONST EXIT HALT RETURN TYPE VAR
-" All other keywords in alphabetical order:
-syn keyword modula2Keyword AND ARRAY BY CASE DEFINITION DIV DO ELSE
-syn keyword modula2Keyword ELSIF EXPORT FOR FROM IF IMPLEMENTATION IMPORT
-syn keyword modula2Keyword IN LOOP MOD NOT OF OR POINTER QUALIFIED RECORD
-syn keyword modula2Keyword SET THEN TO UNTIL WHILE WITH
-
-syn keyword modula2Type ADDRESS BITSET BOOLEAN CARDINAL CHAR INTEGER REAL WORD
-syn keyword modula2StdFunc ABS CAP CHR DEC EXCL INC INCL ORD SIZE TSIZE VAL
-syn keyword modula2StdConst FALSE NIL TRUE
-" The following may be discussed, since NEW and DISPOSE are some kind of
-" special builtin macro functions:
-syn keyword modula2StdFunc NEW DISPOSE
-" The following types are added later on and may be missing from older
-" Modula-2 Compilers (they are at least missing from the original report
-" by N.Wirth from March 1980 ;-)  Highlighting should apply nevertheless:
-syn keyword modula2Type BYTE LONGCARD LONGINT LONGREAL PROC SHORTCARD SHORTINT
-" same note applies to min and max, which were also added later to m2:
-syn keyword modula2StdFunc MAX MIN
-" The underscore was originally disallowed in m2 ids, it was also added later:
-syn match   modula2Ident " [A-Z,a-z][A-Z,a-z,0-9,_]*" contained
-
-" Comments may be nested in Modula-2:
-syn region modula2Comment start="(\*" end="\*)" contains=modula2Comment,modula2Todo
-syn keyword modula2Todo	contained TODO FIXME XXX
-
-" Strings
-syn region modula2String start=+"+ end=+"+
-syn region modula2String start="'" end="'"
-syn region modula2Set start="{" end="}"
-
-" Define the default highlighting.
-" Only when an item doesn't have highlighting yet
-
-hi def link modula2Ident		Identifier
-hi def link modula2StdConst	Boolean
-hi def link modula2Type		Identifier
-hi def link modula2StdFunc		Identifier
-hi def link modula2Header		Type
-hi def link modula2Keyword		Statement
-hi def link modula2AttKeyword	PreProc
-hi def link modula2Comment		Comment
-" The following is just a matter of taste (you want to try this instead):
-" hi modula2Comment term=bold ctermfg=DarkBlue guifg=Blue gui=bold
-hi def link modula2Todo		Todo
-hi def link modula2String		String
-hi def link modula2Set		String
-
+let dialect = modula2#GetDialect()
+exe "runtime! syntax/modula2/opt/" .. dialect .. ".vim"
 
 let b:current_syntax = "modula2"
 
-" vim: ts=8
+" vim: nowrap sw=2 sts=2 ts=8 noet:
diff --git a/runtime/syntax/modula2/opt/iso.vim b/runtime/syntax/modula2/opt/iso.vim
new file mode 100644
index 0000000000..5bd24f6885
--- /dev/null
+++ b/runtime/syntax/modula2/opt/iso.vim
@@ -0,0 +1,380 @@
+" Vim syntax file
+" Language:    Modula-2 (ISO)
+" Maintainer:  B.Kowarsch <trijezdci@moc.liamg>
+" Last Change: 2016 August 22
+
+" ----------------------------------------------------
+" THIS FILE IS LICENSED UNDER THE VIM LICENSE
+" see https://github.com/vim/vim/blob/master/LICENSE
+" ----------------------------------------------------
+
+" Remarks:
+" Vim Syntax files are available for the following Modula-2 dialects:
+" * for the PIM dialect : m2pim.vim
+" * for the ISO dialect : m2iso.vim (this file)
+" * for the R10 dialect : m2r10.vim
+
+" -----------------------------------------------------------------------------
+" This syntax description follows ISO standard IS-10514 (aka ISO Modula-2)
+" with the addition of the following language extensions:
+" * non-standard types LONGCARD and LONGBITSET
+" * non-nesting code disabling tags ?< and >? at the start of a line
+" -----------------------------------------------------------------------------
+
+" Parameters:
+"
+" Vim's filetype sc