Bug#34703610: Create view with subquery assertion error

The problem is a missing check for view context analysis mode
when resolving a GROUP_CONCAT aggregate function. Fixed by adding
the check.
Change-Id: Id2e4d6964b5a5f8e4154c7c7af38875149c2452f

Change-Id: Ic80259e754f42b56e42e36db9ab9b8d101016317

Author: roylyseng

mysql-test/r/func_gconcat.result

@@ -1371,3 +1371,6 @@ GROUP_CONCAT('32689,34068,34370,34930,37034,37638,38478,38643,38925,39889,40497,
 LENGTH(t.value)
 260
 SET SESSION group_concat_max_len=default;
+# Bug#34703610: Create view with subquery assertion error
+CREATE VIEW v(c0) AS SELECT group_concat((SELECT 1), 1);
+DROP VIEW v;

mysql-test/t/func_gconcat.test

@@ -1017,3 +1017,9 @@ SELECT LENGTH(t.value) FROM (SELECT
 GROUP_CONCAT('32689,34068,34370,34930,37034,37638,38478,38643,38925,39889,40497,41729,43085,43115,43500,44781,46344,46411,47173,47228,47623,48576,50293,50653,51794,54177,55347,55398,59492,59598,59804,59969,60612,62024,62754,62796,64647,68679,68974,69482,69625,70162,71100000') AS value ) t;
 
 SET SESSION group_concat_max_len=default;
+
+--echo # Bug#34703610: Create view with subquery assertion error
+
+CREATE VIEW v(c0) AS SELECT group_concat((SELECT 1), 1);
+
+DROP VIEW v;

sql/item_sum.cc

@@ -4464,7 +4464,8 @@ bool Item_func_group_concat::fix_fields(THD *thd, Item **ref) {
   for (uint i = 0; i < m_field_arg_count; i++) {
     Item *item = args[i];
     fields.push_back(item);
-    if (item->const_item() && item->is_null()) {
+    if (item->const_item() && !thd->lex->is_view_context_analysis() &&
+        item->is_null()) {
       // "is_null()" may cause error:
       if (thd->is_error()) return true;
       always_null = true;