patch 9.0.1539: typst filetype is not recognized

Problem:    Typst filetype is not recognized.
Solution:   Distinguish between sql and typst. (Gaetan Lepage, closes #12363)

runtime/autoload/dist/ft.vim

@@ -470,7 +470,7 @@ enddef
 
 # Returns true if file content looks like LambdaProlog module
 def IsLProlog(): bool
-  # skip apparent comments and blank lines, what looks like 
+  # skip apparent comments and blank lines, what looks like
   # LambdaProlog comment may be RAPID header
   var l: number = nextnonblank(1)
   while l > 0 && l < line('$') && getline(l) =~ '^\s*%' # LambdaProlog comment
@@ -1106,6 +1106,31 @@ export def FTlsl()
   endif
 enddef
 
+export def FTtyp()
+  if exists("g:filetype_typ")
+    exe "setf " .. g:filetype_typ
+    return
+  endif
+
+  # Look for SQL type definition syntax
+  for line in getline(1, 200)
+    # SQL type files may define the casing
+    if line =~ '^CASE\s\==\s\=\(SAME\|LOWER\|UPPER\|OPPOSITE\)$'
+      setf sql
+      return
+    endif
+
+    # SQL type files may define some types as follows
+    if line =~ '^TYPE\s.*$'
+      setf sql
+      return
+    endif
+  endfor
+
+  # Otherwise, affect the typst filetype
+  setf typst
+enddef
+
 # Set the filetype of a *.v file to Verilog, V or Cog based on the first 200
 # lines.
 export def FTv()

runtime/doc/filetype.txt

@@ -164,6 +164,7 @@ variables can be used to overrule the filetype used for certain extensions:
 	*.sys		g:filetype_sys
 	*.sh		g:bash_is_sh	|ft-sh-syntax|
 	*.tex		g:tex_flavor	|ft-tex-plugin|
+	*.typ		g:filetype_typ
 	*.w		g:filetype_w	|ft-cweb-syntax|
 
 For a few filetypes the global variable is used only when the filetype could

runtime/filetype.vim

@@ -2058,7 +2058,10 @@ au BufNewFile,BufRead *.spy,*.spi		setf spyce
 au BufNewFile,BufRead squid.conf		setf squid
 
 " SQL for Oracle Designer
-au BufNewFile,BufRead *.tyb,*.typ,*.tyc,*.pkb,*.pks	setf sql
+au BufNewFile,BufRead *.tyb,*.tyc,*.pkb,*.pks	setf sql
+
+" *.typ can be either SQL or Typst files
+au BufNewFile,BufRead *.typ			call dist#ft#FTtyp()
 
 " SQL
 au BufNewFile,BufRead *.sql			call dist#ft#SQL()