patch 8.2.2576: Vim9: defining a :func function checks for white space

Problem:    Vim9: defining a :func function checks for white space after a
            comma in the arguments.
Solution:   Only check for white space in a :def function. (closes #7930)

src/testdir/test_vim9_func.vim

@@ -1136,6 +1136,23 @@ def Test_arg_type_wrong()
   CheckScriptFailure(['def Func5(items)', 'echo "a"'], 'E1077:')
 enddef
 
+def Test_white_space_after_comma()
+  var lines =<< trim END
+    vim9script
+    def Func(a: number,b: number)
+    enddef
+  END
+  CheckScriptFailure(lines, 'E1069:')
+
+  # OK in legacy function
+  lines =<< trim END
+    vim9script
+    func Func(a,b)
+    endfunc
+  END
+  CheckScriptSuccess(lines)
+enddef
+
 def Test_vim9script_call()
   var lines =<< trim END
     vim9script

src/userfunc.c

@@ -310,7 +310,8 @@ get_function_args(
 		++p;
 		// Don't give this error when skipping, it makes the "->" not
 		// found in "{k,v -> x}" and give a confusing error.
-		if (!skip && in_vim9script()
+		// Allow missing space after comma in legacy functions.
+		if (!skip && argtypes != NULL
 				      && !IS_WHITE_OR_NUL(*p) && *p != endchar)
 		{
 		    semsg(_(e_white_space_required_after_str_str), ",", p - 1);

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2576,
 /**/
     2575,
 /**/