vim-patch:9.1.0616: filetype: Make syntax highlighting off for MS Makefiles (#29874)

Problem:  filetype: Make syntax highlighting off for MS Makefiles
Solution: Try to detect MS Makefiles and adjust syntax rules to it.
          (Ken Takata)

Highlighting of variable expansion in Microsoft Makefile can be broken.
E.g.:
2979cfc262/src/Make_mvc.mak (L1331)

Don't use backslash as escape characters if `make_microsoft` is set.
Also fix that `make_no_comments` was not considered if `make_microsoft`
was set.

Also add description for `make_microsoft` and `make_no_comments` to the
documentation and include a very simple filetype test

closes: vim/vim#15341

eb4b903c9b

Co-authored-by: Ken Takata <kentkt@csc.jp>

runtime/lua/vim/filetype.lua

@@ -693,8 +693,8 @@ local extension = {
     return not (path:find('html%.m4$') or path:find('fvwm2rc')) and 'm4' or nil
   end,
   eml = 'mail',
-  mk = 'make',
-  mak = 'make',
+  mk = detect.make,
+  mak = detect.make,
   page = 'mallard',
   map = 'map',
   mws = 'maple',
@@ -2122,7 +2122,7 @@ local pattern = {
     ['^Containerfile%.'] = starsetf('dockerfile'),
     ['^Dockerfile%.'] = starsetf('dockerfile'),
     ['^[jJ]ustfile$'] = 'just',
-    ['[mM]akefile$'] = 'make',
+    ['[mM]akefile$'] = detect.make,
     ['^[mM]akefile'] = starsetf('make'),
     ['^[rR]akefile$'] = 'ruby',
     ['^[rR]akefile'] = starsetf('ruby'),

runtime/lua/vim/filetype/detect.lua

@@ -972,6 +972,24 @@ local function m4(contents)
   end
 end
 
+--- Check if it is a Microsoft Makefile
+--- @type vim.filetype.mapfn
+function M.make(_, bufnr)
+  vim.b.make_microsoft = nil
+  for _, line in ipairs(getlines(bufnr, 1, 1000)) do
+    if matchregex(line, [[\c^\s*!\s*\(ifn\=\(def\)\=\|include\|message\|error\)\>]]) then
+      vim.b.make_microsoft = 1
+      break
+    elseif
+      matchregex(line, [[^ *ifn\=\(eq\|def\)\>]])
+      or findany(line, { '^ *[-s]?%s', '^ *%w+%s*[!?:+]=' })
+    then
+      break
+    end
+  end
+  return 'make'
+end
+
 --- @type vim.filetype.mapfn
 function M.markdown(_, _)
   return vim.g.filetype_md or 'markdown'