patch 7.4.1816

Problem:    Looping over a null list throws an error.
Solution:   Skip over the for loop.

src/eval.c

@@ -3292,11 +3292,16 @@ eval_for_line(
 	if (!skip)
 	{
 	    l = tv.vval.v_list;
-	    if (tv.v_type != VAR_LIST || l == NULL)
+	    if (tv.v_type != VAR_LIST)
 	    {
 		EMSG(_(e_listreq));
 		clear_tv(&tv);
 	    }
+	    else if (l == NULL)
+	    {
+		/* a null list is like an empty list: do nothing */
+		clear_tv(&tv);
+	    }
 	    else
 	    {
 		/* No need to increment the refcount, it's already set for the

src/testdir/test_expr.vim

@@ -83,3 +83,10 @@ func Test_getreg_empty_list()
   call add(x, 'foo')
   call assert_equal(['foo'], y)
 endfunc
+
+func Test_loop_over_null_list()
+  let null_list = submatch(1, 1)
+  for i in null_list
+    call assert_true(0, 'should not get here')
+  endfor
+endfunc

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1816,
 /**/
     1815,
 /**/