runtime(groff): Add compiler plugin for groff

Groff MOM (Macros for Manuscripts) is a macro package for the GNU
troff (groff) typesetting system, a light-weight alternative
to LaTeX for professional-quality documents.

closes: #15646

Signed-off-by: Konfekt <Konfekt@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

.github/MAINTAINERS

@@ -65,6 +65,7 @@ runtime/compiler/gawk.vim		@dkearns
 runtime/compiler/gjs.vim		@dkearns
 runtime/compiler/gm2.vim		@dkearns
 runtime/compiler/go.vim			@dbarnett
+runtime/compiler/groff.vim		@Konfekt
 runtime/compiler/haml.vim		@tpope
 runtime/compiler/hare.vim		@selenebun
 runtime/compiler/icon.vim		@dkearns

runtime/compiler/groff.vim

@@ -0,0 +1,45 @@
+" Vim compiler file
+" Compiler:     Groff
+" Maintainer:   Konfekt
+" Last Change:	2024 Sep 8
+"
+" Expects output file extension, say `:make html` or `:make pdf`.
+" Supported devices as of Sept 2024 are: (x)html, pdf, ps, dvi, lj4, lbp ...
+" Adjust command-line flags, language, encoding by buffer-local/global variables
+" groff_compiler_args, groff_compiler_lang, and groff_compiler_encoding,
+" which default to '', &spelllang and 'utf8'.
+
+if exists("current_compiler")
+  finish
+endif
+
+let s:keepcpo = &cpo
+set cpo&vim
+
+let current_compiler = 'groff'
+
+silent! function s:groff_compiler_lang()
+  let lang = get(b:, 'groff_compiler_lang',
+      \ &spell ? matchstr(&spelllang, '^\a\a') : '')
+  if lang ==# 'en' | let lang = '' | endif
+  return empty(lang) ? '' : '-m'..lang
+endfunction
+
+" Requires output format (= device) to be set by user after :make.
+execute 'CompilerSet makeprg=groff'..escape(
+    \ ' '..s:groff_compiler_lang()..
+    \ ' -K'..get(b:, 'groff_compiler_encoding', get(g:, 'groff_compiler_encoding', 'utf8'))..
+    \ ' '..get(b:, 'groff_compiler_args', get(g:, 'groff_compiler_args', ''))..
+    \ ' -mom -T$* -- %:S > %:r:S.$*', ' ')
+" From Gavin Freeborn's https://github.com/Gavinok/vim-troff under Vim License
+" https://github.com/Gavinok/vim-troff/blob/91017b1423caa80aba541c997909a4f810edd275/compiler/troff.vim#L39
+CompilerSet errorformat=%o:<standard\ input>\ (%f):%l:%m,
+			\%o:\ <standard\ input>\ (%f):%l:%m,
+			\%o:%f:%l:%m,
+			\%o:\ %f:%l:%m,
+			\%f:%l:\ macro\ %trror:%m,
+			\%f:%l:%m,
+			\%W%tarning:\ file\ '%f'\\,\ around\ line\ %l:,%Z%m
+
+let &cpo = s:keepcpo
+unlet s:keepcpo

runtime/doc/quickfix.txt

@@ -1,4 +1,4 @@
-*quickfix.txt*  For Vim version 9.1.  Last change: 2024 Aug 20
+*quickfix.txt*  For Vim version 9.1.  Last change: 2024 Sep 09
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1335,6 +1335,18 @@ If Vim was started from the compiler, the :sh and some :!  commands will not
 work, because Vim is then running in the same process as the compiler and
 stdin (standard input) will not be interactive.
 
+GROFF					*quickfix-groff* *compiler-groff*
+
+The GROFF compiler plugin uses the mom macro set (documented in the groff_mom
+manpage) as input and expects that the output file type extension is passed to
+make, say :make html or :make pdf.
+
+Additional arguments can be passed to groff by setting them in
+`b:groff_compiler_args` or `g:groff_compiler_args`. The `language` argument
+passed to groff is set using 'spelllang'; it can be overridden by setting
+`b:groff_compiler_lang`. The default enconding is `UTF-8` and can be changed
+by setting `b:groff_compiler_encoding` or `g:groff_compiler_encoding`.
+
 PANDOC					*quickfix-pandoc* *compiler-pandoc*
 
 The Pandoc compiler plugin expects that an output file type extension is

runtime/doc/tags

@@ -6545,6 +6545,7 @@ compiler-decada	ft_ada.txt	/*compiler-decada*
 compiler-dotnet	quickfix.txt	/*compiler-dotnet*
 compiler-gcc	quickfix.txt	/*compiler-gcc*
 compiler-gnat	ft_ada.txt	/*compiler-gnat*
+compiler-groff	quickfix.txt	/*compiler-groff*
 compiler-hpada	ft_ada.txt	/*compiler-hpada*
 compiler-javac	quickfix.txt	/*compiler-javac*
 compiler-manx	quickfix.txt	/*compiler-manx*
@@ -9640,6 +9641,7 @@ quickfix-directory-stack	quickfix.txt	/*quickfix-directory-stack*
 quickfix-error-lists	quickfix.txt	/*quickfix-error-lists*
 quickfix-functions	usr_41.txt	/*quickfix-functions*
 quickfix-gcc	quickfix.txt	/*quickfix-gcc*
+quickfix-groff	quickfix.txt	/*quickfix-groff*
 quickfix-index	quickfix.txt	/*quickfix-index*
 quickfix-manx	quickfix.txt	/*quickfix-manx*
 quickfix-pandoc	quickfix.txt	/*quickfix-pandoc*