patch 9.0.0012: signature files not detected properly

Problem:    Signature files not detected properly.
Solution:   Add a function to better detect signature files. (Doug Kearns)

runtime/autoload/dist/ft.vim

@@ -459,7 +459,7 @@ export def FTmm()
   setf nroff
 enddef
 
-# Returns true if file content looks like LambdaProlog
+# Returns true if file content looks like LambdaProlog module
 def IsLProlog(): bool
   # skip apparent comments and blank lines, what looks like 
   # LambdaProlog comment may be RAPID header
@@ -848,6 +848,27 @@ export def FTperl(): number
   return 0
 enddef
 
+# LambdaProlog and Standard ML signature files
+export def FTsig()
+  if exists("g:filetype_sig")
+    exe "setf " .. g:filetype_sig
+    return
+  endif
+
+  var lprolog_comment = '^\s*\%(/\*\|%\)'
+  var lprolog_keyword = '^\s*sig\s\+\a'
+  var sml_comment = '^\s*(\*'
+  var sml_keyword = '^\s*\%(signature\|structure\)\s\+\a'
+
+  var line = getline(nextnonblank(1))
+
+  if line =~ lprolog_comment || line =~# lprolog_keyword
+    setf lprolog
+  elseif line =~ sml_comment || line =~# sml_keyword
+    setf sml
+  endif
+enddef
+
 export def FTsys()
   if exists("g:filetype_sys")
     exe "setf " .. g:filetype_sys

runtime/doc/filetype.txt

@@ -157,6 +157,7 @@ variables can be used to overrule the filetype used for certain extensions:
 	*.pp		g:filetype_pp	|ft-pascal-syntax|
 	*.prg		g:filetype_prg
 	*.r		g:filetype_r
+	*.sig		g:filetype_sig
 	*.sql		g:filetype_sql	|ft-sql-syntax|
 	*.src		g:filetype_src
 	*.sys		g:filetype_sys

runtime/filetype.vim

@@ -997,8 +997,8 @@ au BufNewFile,BufRead *.latte,*.lte		setf latte
 " Limits
 au BufNewFile,BufRead */etc/limits,*/etc/*limits.conf,*/etc/*limits.d/*.conf	setf limits
 
-" LambdaProlog (see dist#ft#FTmod for *.mod)
-au BufNewFile,BufRead *.sig			setf lprolog
+" LambdaProlog or SML (see dist#ft#FTmod for *.mod)
+au BufNewFile,BufRead *.sig			call dist#ft#FTsig()
 
 " LDAP LDIF
 au BufNewFile,BufRead *.ldif			setf ldif

src/testdir/test_filetype.vim

@@ -313,7 +313,6 @@ let s:filename_checks = {
     \ 'lotos': ['file.lot', 'file.lotos'],
     \ 'lout': ['file.lou', 'file.lout'],
     \ 'lpc': ['file.lpc', 'file.ulpc'],
-    \ 'lprolog': ['file.sig'],
     \ 'lsl': ['file.lsl'],
     \ 'lss': ['file.lss'],
     \ 'lua': ['file.lua', 'file.rockspec', 'file.nse'],
@@ -1760,4 +1759,59 @@ func Test_cls_file()
   filetype off
 endfunc
 
+func Test_sig_file()
+  filetype on
+
+  call writefile(['this is neither Lambda Prolog nor SML'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('', &filetype)
+  bwipe!
+
+  " Test dist#ft#FTsig()
+
+  let g:filetype_sig = 'sml'
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+  unlet g:filetype_sig
+
+  " Lambda Prolog
+
+  call writefile(['sig foo.'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  call writefile(['/* ... */'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  call writefile(['% ...'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  " SML signature file
+
+  call writefile(['signature FOO ='], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call writefile(['structure FOO ='], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call writefile(['(* ... *)'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call delete('Xfile.sig')
+  filetype off
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    12,
 /**/
     11,
 /**/