patch 9.1.0340: Problem: Error with matchaddpos() and empty list

Problem:  Error with matchaddpos() and empty list
          (@rickhow)
Solution: Return early for an empty list

fixes: #14525
closes: #14563

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/match.c

@@ -87,7 +87,7 @@ match_add(
     m = ALLOC_CLEAR_ONE(matchitem_T);
     if (m == NULL)
 	return -1;
-    if (pos_list != NULL)
+    if (pos_list != NULL && pos_list->lv_len > 0)
     {
 	m->mit_pos_array = ALLOC_CLEAR_MULT(llpos_T, pos_list->lv_len);
 	if (m->mit_pos_array == NULL)
@@ -1294,7 +1294,7 @@ f_matchaddpos(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
 	return;
     }
     l = argvars[1].vval.v_list;
-    if (l == NULL)
+    if (l == NULL || l->lv_len == 0)
 	return;
 
     if (argvars[2].v_type != VAR_UNKNOWN)

src/testdir/test_match.vim

@@ -307,6 +307,7 @@ func Test_matchaddpos_error()
   " Why doesn't the following error have an error code E...?
   call assert_fails("call matchaddpos('Error', [{}])", 'E290:')
   call assert_equal(-1, matchaddpos('Error', test_null_list()))
+  call assert_equal(-1, matchaddpos('Error', []))
   call assert_fails("call matchaddpos('Error', [1], [], 1)", 'E745:')
   call assert_equal(-1, matchaddpos('Search', [[]]))
   call assert_fails("call matchaddpos('Search', [[{}]])", 'E728:')
@@ -433,5 +434,4 @@ func Test_match_tab_with_linebreak()
   call StopVimInTerminal(buf)
 endfunc
 
-
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    340,
 /**/
     339,
 /**/