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.:
https://github.com/vim/vim/blob/2979cfc2627d76a9c09cad46a1647dcd4aa73f5f/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

https://github.com/vim/vim/commit/eb4b903c9b238ebcc1d14cfcb207129b4931a33d

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

1 files changed, 18 insertions, 0 deletions

diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index 1fe7db0e1f..cb953f9d0c 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/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'