patch 8.0.0004

Problem:    A string argument for function() that is not a function name
            results in an error message with NULL. (Christian Brabandt)
Solution:   Use the argument for the error message.

src/evalfunc.c

@@ -3612,7 +3612,7 @@ common_function(typval_T *argvars, typval_T *rettv, int is_funcref)
 
     if (s == NULL || *s == NUL || (use_string && VIM_ISDIGIT(*s))
 					 || (is_funcref && trans_name == NULL))
-	EMSG2(_(e_invarg2), s);
+	EMSG2(_(e_invarg2), use_string ? get_tv_string(&argvars[0]) : s);
     /* Don't check an autoload name for existence here. */
     else if (trans_name != NULL && (is_funcref
 				? find_func(trans_name) == NULL

src/testdir/test_expr.vim

@@ -439,6 +439,9 @@ func Test_function_with_funcref()
   let s:fref = function(s:f)
   call assert_equal(v:t_string, s:fref('x'))
   call assert_fails("call function('s:f')", 'E700:')
+
+  call assert_fails("call function('foo()')", 'E475:')
+  call assert_fails("call function('foo()')", 'foo()')
 endfunc
 
 func Test_funcref()

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4,
 /**/
     3,
 /**/