Commit: patch 9.2.0794: extend() and extendnew() don't handle NULL expr2 properly

[Christian Brabandt]

patch 9.2.0794: extend() and extendnew() don't handle NULL expr2 properly

Commit: https://github.com/vim/vim/commit/e397c82a04fc86ef9266e494a8c2ccc199159a93
Author: zeertzjq <zeer...@outlook.com>
Date: Sat Jul 18 13:57:04 2026 +0000

patch 9.2.0794: extend() and extendnew() don't handle NULL expr2 properly

Problem: extend() and extendnew() don't handle NULL expr2 properly
(Mao-Yining)
Solution: Still set the return value when expr2 is NULL (zeertzjq).

fixes: #20758
closes: #20759

Signed-off-by: zeertzjq <zeer...@outlook.com>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/src/dict.c b/src/dict.c
index 110639508..ac1fb3841 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -1335,9 +1335,6 @@ dict_extend_func(
emsg(_(e_cannot_extend_null_dict));
return;
}
- d2 = argvars[1].vval.v_dict;
- if (d2 == NULL)
- return;

if (!is_new && value_check_lock(d1->dv_lock, arg_errmsg, TRUE))
return;
@@ -1349,6 +1346,10 @@ dict_extend_func(
return;
}

+ d2 = argvars[1].vval.v_dict;
+ if (d2 == NULL)
+ goto theend;
+
// Check the third argument.
if (argvars[2].v_type != VAR_UNKNOWN)
{
@@ -1384,6 +1385,7 @@ dict_extend_func(
}
dict_extend(d1, d2, action, func_name);

+theend:
if (is_new)
{
rettv->v_type = VAR_DICT;
diff --git a/src/list.c b/src/list.c
index 3074bb93f..e400cb096 100644
--- a/src/list.c
+++ b/src/list.c
@@ -3014,9 +3014,7 @@ list_extend_func(
emsg(_(e_cannot_extend_null_list));
return;
}
- l2 = argvars[1].vval.v_list;
- if ((is_new || !value_check_lock(l1->lv_lock, arg_errmsg, TRUE))
- && l2 != NULL)
+ if (is_new || !value_check_lock(l1->lv_lock, arg_errmsg, TRUE))
{
if (is_new)
{
@@ -3025,6 +3023,10 @@ list_extend_func(
return;
}

+ l2 = argvars[1].vval.v_list;
+ if (l2 == NULL)
+ goto theend;
+
if (argvars[2].v_type != VAR_UNKNOWN)
{
before = (long)tv_get_number_chk(&argvars[2], &error);
@@ -3049,6 +3051,7 @@ list_extend_func(
goto cleanup;
list_extend(l1, l2, item);

+theend:
if (is_new)
{
rettv->v_type = VAR_LIST;
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 316e3614f..31b5f268d 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -1217,7 +1217,12 @@ func Test_listdict_extend()

LET l = [1, 2, 3]
call extend(l, [4, 5, 6], -3)
- call assert_equal([4, 5, 6, 1, 2, 3], l)
+ call assert_equal([4, 5, 6, 1, 2, 3], l)
+
+ LET l = [1, 2, 3]
+ call assert_equal([1, 2, 3], l->extend([]))
+ call assert_equal([1, 2, 3], l->extend(test_null_list()))
+ call assert_equal([1, 2, 3], l)
END
call v9.CheckLegacyAndVim9Success(lines)

@@ -1245,6 +1250,11 @@ func Test_listdict_extend()
LET d = {'a': 'A', 'b': 9}
call extend(d, {'b': 0, 'c': 'C'}, "keep")
call assert_equal({'a': 'A', 'b': 9, 'c': 'C'}, d)
+
+ LET d = {'a': 'A', 'b': 9}
+ call assert_equal({'a': 'A', 'b': 9}, d->extend({}))
+ call assert_equal({'a': 'A', 'b': 9}, d->extend(test_null_dict()))
+ call assert_equal({'a': 'A', 'b': 9}, d)
END
call v9.CheckLegacyAndVim9Success(lines)

@@ -1286,6 +1296,11 @@ func Test_listdict_extendnew()
call assert_equal([1, 2, 3], l)
lockvar l
call assert_equal([1, 2, 3, 4, 5], extendnew(l, [4, 5]))
+ let l2 = extendnew(l, test_null_list())
+ call assert_equal([1, 2, 3], l2)
+ let l2 += [4]
+ call assert_equal([1, 2, 3, 4], l2)
+ call assert_equal([1, 2, 3], l)

" Test extendnew() with dictionaries.
let d = {'a': {'b': 'B'}}
@@ -1293,6 +1308,11 @@ func Test_listdict_extendnew()
call assert_equal({'a': {'b': 'B'}}, d)
lockvar d
call assert_equal({'a': {'b': 'B'}, 'c': 'cc'}, extendnew(d, {'c': 'cc'}))
+ let d2 = extendnew(d, test_null_dict())
+ call assert_equal({'a': {'b': 'B'}}, d2)
+ let d2['c'] = 'C'
+ call assert_equal({'a': {'b': 'B'}, 'c': 'C'}, d2)
+ call assert_equal({'a': {'b': 'B'}}, d)
endfunc

func s:check_scope_dict(x, fixed)
diff --git a/src/version.c b/src/version.c
index 4e3ca0b5e..d2d3c45dc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -759,6 +759,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 794,
/**/
793,
/**/