vim-patch:9.1.0013: Modula2 filetype support lacking (#27020)

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: vim/vim#6796
closes: vim/vim#8115

https://github.com/vim/vim/commit/68a89470693c7687d4e736ca056c05de632e3ac7

- Luaify the detection script:

  - Split the `(*!m2foo*)` and `(*!m2foo+bar*)` detection into two Lua patterns,
    as Lua capture groups cannot be used with `?` and friends (as they only work
    on character classes).

  - Use `vim.api.nvim_buf_call()` (ew) to call `modula2#SetDialect()` to ensure
    `b:modula2` is set for the given bufnr.

- Skip the syntax screendump tests. (A shame as they test some of the detection
  from `(*!m2foo+bar*)` tags, but I tested this locally and it seems to work)

- Port the synmenu.vim changes from Vim9 script. (Also tested this locally)

- (And also add the missing comma for `b:browsefilter` from earlier.)

Co-authored-by: Doug Kearns <dougkearns@gmail.com>

2 files changed, 51 insertions, 0 deletions

diff --git a/runtime/doc/filetype.txt b/runtime/doc/filetype.txt
index 6c2cddea54..29b929b8a5 100644
--- a/runtime/doc/filetype.txt
+++ b/runtime/doc/filetype.txt
@@ -146,6 +146,7 @@ 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 8cbb958e35..9164171152 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -2206,6 +2206,56 @@ 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