vim-patch:8.2.4274: Basic and form filetype detection is incomplete (#17259)

Problem:    Basic and form filetype detection is incomplete.
Solution:   Add a separate function for .frm files. (Doug Kearns, closes vim/vim#9675)
https://github.com/vim/vim/commit/c570e9cf68c0fe30366e82c96be460047dd659b9

4 files changed, 50 insertions, 6 deletions

diff --git a/runtime/autoload/dist/ft.vim b/runtime/autoload/dist/ft.vim
index f513a2ac8f..5d8734a625 100644
--- a/runtime/autoload/dist/ft.vim
+++ b/runtime/autoload/dist/ft.vim
@@ -67,7 +67,10 @@ func dist#ft#FTasmsyntax()
   endif
 endfunc
 
-func dist#ft#FTbas(alt = '')
+let s:ft_visual_basic_content = '\cVB_Name\|Begin VB\.\(Form\|MDIForm\|UserControl\)'
+
+" See FTfrm() for Visual Basic form file detection
+func dist#ft#FTbas()
   if exists("g:filetype_bas")
     exe "setf " . g:filetype_bas
     return
@@ -86,10 +89,8 @@ func dist#ft#FTbas(alt = '')
     setf freebasic
   elseif match(lines, qb64_preproc) > -1
     setf qb64
-  elseif match(lines, '\cVB_Name\|Begin VB\.\(Form\|MDIForm\|UserControl\)') > -1
+  elseif match(lines, s:ft_visual_basic_content) > -1
     setf vb
-  elseif a:alt != ''
-    exe 'setf ' .. a:alt
   else
     setf basic
   endif
@@ -237,6 +238,21 @@ func dist#ft#FTe()
   endif
 endfunc
 
+func dist#ft#FTfrm()
+  if exists("g:filetype_frm")
+    exe "setf " . g:filetype_frm
+    return
+  endif
+
+  let lines = getline(1, min([line("$"), 5]))
+
+  if match(lines, s:ft_visual_basic_content) > -1
+    setf vb
+  else
+    setf form
+  endif
+endfunc
+
 " Distinguish between Forth and F#.
 " Provided by Doug Kearns.
 func dist#ft#FTfs()
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 7c86809cb8..8b40b43a04 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -2050,7 +2050,7 @@ au BufRead,BufNewFile *.hw,*.module,*.pkg
 	\ endif
 
 " Visual Basic (also uses *.bas) or FORM
-au BufNewFile,BufRead *.frm			call dist#ft#FTbas('form')
+au BufNewFile,BufRead *.frm			call dist#ft#FTfrm()
 
 " SaxBasic is close to Visual Basic
 au BufNewFile,BufRead *.sba			setf vb
diff --git a/runtime/lua/vim/filetype.lua b/runtime/lua/vim/filetype.lua
index ff44f48195..e2cf408f3b 100644
--- a/runtime/lua/vim/filetype.lua
+++ b/runtime/lua/vim/filetype.lua
@@ -789,7 +789,7 @@ local extension = {
   ex = function() vim.fn["dist#ft#ExCheck"]() end,
   exu = function() vim.fn["dist#ft#EuphoriaCheck"]() end,
   exw = function() vim.fn["dist#ft#EuphoriaCheck"]() end,
-  frm = function() vim.fn["dist#ft#FTbas"]("form") end,
+  frm = function() vim.fn["dist#ft#FTfrm"]() end,
   fs = function() vim.fn["dist#ft#FTfs"]() end,
   h = function() vim.fn["dist#ft#FTheader"]() end,
   htm = function() vim.fn["dist#ft#FThtml"]() end,
diff --git a/src/nvim/testdir/test_filetype.vim b/src/nvim/testdir/test_filetype.vim
index dcf20e2c1b..d4e5563865 100644
--- a/src/nvim/testdir/test_filetype.vim
+++ b/src/nvim/testdir/test_filetype.vim
@@ -183,6 +183,7 @@ let s:filename_checks = {
     \ 'fgl': ['file.4gl', 'file.4gh', 'file.m4gl'],
     \ 'fish': ['file.fish'],
     \ 'focexec': ['file.fex', 'file.focexec'],
+    \ 'form': ['file.frm'],
     \ 'forth': ['file.ft', 'file.fth'],
     \ 'fortran': ['file.f', 'file.for', 'file.fortran', 'file.fpp', 'file.ftn', 'file.f77', 'file.f90', 'file.f95', 'file.f03', 'file.f08'],
     \ 'fpcmake': ['file.fpc'],
@@ -1249,4 +1250,31 @@ func Test_bas_file()
   filetype off
 endfunc
 
+func Test_frm_file()
+  filetype on
+
+  call writefile(['looks like FORM'], 'Xfile.frm')
+  split Xfile.frm
+  call assert_equal('form', &filetype)
+  bwipe!
+
+  " Test dist#ft#FTfrm()
+
+  let g:filetype_frm = 'form'
+  split Xfile.frm
+  call assert_equal('form', &filetype)
+  bwipe!
+  unlet g:filetype_frm
+
+  " Visual Basic
+
+  call writefile(['Begin VB.Form Form1'], 'Xfile.frm')
+  split Xfile.frm
+  call assert_equal('vb', &filetype)
+  bwipe!
+
+  call delete('Xfile.frm')
+  filetype off
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab