patch 8.2.2738: extending a list with itself can give wrong result
Problem: Extending a list with itself can give wrong result.
Solution: Remember the item before where the insertion happens and skip to
after the already inserted items. (closes #1112)
diff --git a/src/list.c b/src/list.c
index 873f9e6..76327ab 100644
--- a/src/list.c
+++ b/src/list.c
@@ -894,6 +894,7 @@
{
listitem_T *item;
int todo;
+ listitem_T *bef_prev;
// NULL list is equivalent to an empty list: nothing to do.
if (l2 == NULL || l2->lv_len == 0)
@@ -903,9 +904,15 @@
CHECK_LIST_MATERIALIZE(l1);
CHECK_LIST_MATERIALIZE(l2);
+ // When exending a list with itself, at some point we run into the item
+ // that was before "bef" and need to skip over the already inserted items
+ // to "bef".
+ bef_prev = bef == NULL ? NULL : bef->li_prev;
+
// We also quit the loop when we have inserted the original item count of
// the list, avoid a hang when we extend a list with itself.
- for (item = l2->lv_first; item != NULL && --todo >= 0; item = item->li_next)
+ for (item = l2->lv_first; item != NULL && --todo >= 0;
+ item = item == bef_prev ? bef : item->li_next)
if (list_insert_tv(l1, &item->li_tv, bef) == FAIL)
return FAIL;
return OK;
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 051a37c..1b0796d 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -862,6 +862,20 @@
" Extend g: dictionary with an invalid variable name
call assert_fails("call extend(g:, {'-!' : 10})", 'E461:')
+
+ " Extend a list with itself.
+ let l = [1, 5, 7]
+ call extend(l, l, 0)
+ call assert_equal([1, 5, 7, 1, 5, 7], l)
+ let l = [1, 5, 7]
+ call extend(l, l, 1)
+ call assert_equal([1, 1, 5, 7, 5, 7], l)
+ let l = [1, 5, 7]
+ call extend(l, l, 2)
+ call assert_equal([1, 5, 1, 5, 7, 7], l)
+ let l = [1, 5, 7]
+ call extend(l, l, 3)
+ call assert_equal([1, 5, 7, 1, 5, 7], l)
endfunc
func Test_listdict_extendnew()
diff --git a/src/version.c b/src/version.c
index 1a1f237..452565c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
static int included_patches[] =
{ /* Add new patch number below this line */
/**/
+ 2738,
+/**/
2737,
/**/
2736,