vim-patch:9.1.0505: filetype: Faust files are not recognized (#29426)

Problem:  filetype: Faust files are not recognized
Solution: Detect '*.lib' files as Faust filetype, add detection for
          '*.dsp' files (Faust or Make), remove '*.lib' from Cobol
          filetype (PowerUser64)

closes: vim/vim#14894

https://github.com/vim/vim/commit/aa61b8a9087e9cd999ef07e0d87b60f43d68f2c6

Co-authored-by: PowerUser64 <blake@blakenorth.net>

4 files changed, 67 insertions, 4 deletions

diff --git a/runtime/doc/filetype.txt b/runtime/doc/filetype.txt
index eddf14014a..70bbd02790 100644
--- a/runtime/doc/filetype.txt
+++ b/runtime/doc/filetype.txt
@@ -147,6 +147,7 @@ variables can be used to overrule the filetype used for certain extensions:
 	`*.csh`		g:filetype_csh		|ft-csh-syntax|
 	`*.dat`		g:filetype_dat
 	`*.def`		g:filetype_def
+	`*.dsp`		g:filetype_dsp
 	`*.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/lua/vim/filetype.lua b/runtime/lua/vim/filetype.lua
index 2bb50d8c0b..7373c403b5 100644
--- a/runtime/lua/vim/filetype.lua
+++ b/runtime/lua/vim/filetype.lua
@@ -281,7 +281,6 @@ local extension = {
   cook = 'cook',
   cmake = 'cmake',
   cmod = 'cmod',
-  lib = 'cobol',
   cob = 'cobol',
   cbl = 'cobol',
   atg = 'coco',
@@ -366,6 +365,7 @@ local extension = {
   gv = 'dot',
   drac = 'dracula',
   drc = 'dracula',
+  dsp = detect.dsp,
   dtd = 'dtd',
   d = detect.dtrace,
   dts = 'dts',
@@ -417,6 +417,7 @@ local extension = {
   fal = 'falcon',
   fan = 'fan',
   fwt = 'fan',
+  lib = 'faust',
   fnl = 'fennel',
   m4gl = 'fgl',
   ['4gl'] = 'fgl',
@@ -666,7 +667,6 @@ local extension = {
   eml = 'mail',
   mk = 'make',
   mak = 'make',
-  dsp = 'make',
   page = 'mallard',
   map = 'map',
   mws = 'maple',
diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index 997b53ba4b..b52dba7388 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/runtime/lua/vim/filetype/detect.lua
@@ -472,6 +472,41 @@ function M.def(_, bufnr)
 end
 
 --- @type vim.filetype.mapfn
+function M.dsp(path, bufnr)
+  if vim.g.filetype_dsp then
+    return vim.g.filetype_dsp
+  end
+
+  -- Test the filename
+  local file_name = fn.fnamemodify(path, ':t')
+  if file_name:find('^[mM]akefile.*$') then
+    return 'make'
+  end
+
+  -- Test the file contents
+  for _, line in ipairs(getlines(bufnr, 1, 200)) do
+    if
+      findany(line, {
+        -- Check for comment style
+        [[#.*]],
+        -- Check for common lines
+        [[^.*Microsoft Developer Studio Project File.*$]],
+        [[^!MESSAGE This is not a valid makefile\..+$]],
+        -- Check for keywords
+        [[^!(IF,ELSEIF,ENDIF).*$]],
+        -- Check for common assignments
+        [[^SOURCE=.*$]],
+      })
+    then
+      return 'make'
+    end
+  end
+
+  -- Otherwise, assume we have a Faust file
+  return 'faust'
+end
+
+--- @type vim.filetype.mapfn
 function M.e(_, bufnr)
   if vim.g.filetype_euphoria then
     return vim.g.filetype_euphoria
diff --git a/test/old/testdir/test_filetype.vim b/test/old/testdir/test_filetype.vim
index ec9d88d3bf..5d9e5a8a27 100644
--- a/test/old/testdir/test_filetype.vim
+++ b/test/old/testdir/test_filetype.vim
@@ -161,7 +161,7 @@ func s:GetFilenameChecks() abort
     \ 'cmakecache': ['CMakeCache.txt'],
     \ 'cmod': ['file.cmod'],
     \ 'cmusrc': ['any/.cmus/autosave', 'any/.cmus/rc', 'any/.cmus/command-history', 'any/.cmus/file.theme', 'any/cmus/rc', 'any/cmus/file.theme', '/.cmus/autosave', '/.cmus/command-history', '/.cmus/file.theme', '/.cmus/rc', '/cmus/file.theme', '/cmus/rc'],
-    \ 'cobol': ['file.cbl', 'file.cob', 'file.lib'],
+    \ 'cobol': ['file.cbl', 'file.cob'],
     \ 'coco': ['file.atg'],
     \ 'conaryrecipe': ['file.recipe'],
     \ 'conf': ['auto.master', 'file.conf', 'texdoc.cnf', '.x11vncrc', '.chktexrc', '.ripgreprc', 'ripgreprc', 'file.ctags', '.mbsyncrc'],
@@ -257,6 +257,7 @@ func s:GetFilenameChecks() abort
     \ 'factor': ['file.factor'],
     \ 'falcon': ['file.fal'],
     \ 'fan': ['file.fan', 'file.fwt'],
+    \ 'faust': ['file.dsp', 'file.lib'],
     \ 'fennel': ['file.fnl'],
     \ 'fetchmail': ['.fetchmailrc'],
     \ 'fgl': ['file.4gl', 'file.4gh', 'file.m4gl'],
@@ -421,7 +422,7 @@ func s:GetFilenameChecks() abort
     \ 'mail': ['snd.123', '.letter', '.letter.123', '.followup', '.article', '.article.123', 'pico.123', 'mutt-xx-xxx', 'muttng-xx-xxx', 'ae123.txt', 'file.eml', 'reportbug-file'],
     \ 'mailaliases': ['/etc/mail/aliases', '/etc/aliases', 'any/etc/aliases', 'any/etc/mail/aliases'],
     \ 'mailcap': ['.mailcap', 'mailcap'],
-    \ 'make': ['file.mk', 'file.mak', 'file.dsp', 'makefile', 'Makefile', 'makefile-file', 'Makefile-file', 'some-makefile', 'some-Makefile', 'Kbuild'],
+    \ 'make': ['file.mk', 'file.mak', 'makefile', 'Makefile', 'makefile-file', 'Makefile-file', 'some-makefile', 'some-Makefile', 'Kbuild'],
     \ 'mallard': ['file.page'],
     "\ 'man': ['file.man'],
     \ 'manconf': ['/etc/man.conf', 'man.config', 'any/etc/man.conf'],
@@ -2399,6 +2400,32 @@ func Test_typ_file()
   filetype off
 endfunc
 
+func Test_dsp_file()
+  filetype on
+
+  " Microsoft Developer Studio Project file
+
+  call writefile(['# Microsoft Developer Studio Project File'], 'Xfile.dsp', 'D')
+  split Xfile.dsp
+  call assert_equal('make', &filetype)
+  bwipe!
+
+  let g:filetype_dsp = 'make'
+  split test.dsp
+  call assert_equal('make', &filetype)
+  bwipe!
+  unlet g:filetype_dsp
+
+  " Faust
+
+  call writefile(['this is a fallback'], 'Xfile.dsp')
+  split Xfile.dsp
+  call assert_equal('faust', &filetype)
+  bwipe!
+
+  filetype off
+endfunc
+
 func Test_vba_file()
   filetype on