Bug #22200984 ASSERTION IN FILESORT::MAKE_SORTORDER()

Problem: make_sortorder() asserts in debug mode: we are not supposed to be
sorting on outer references. If we switch off only_full_group_by then
this schenario may happen.

Solution: Relax the debug assert.

Author: Tor Didriksen

mysql-test/r/filesort_debug.result

@@ -114,3 +114,17 @@ FROM g
 GROUP BY b, a);
 1
 DROP TABLE t, g;
+#
+# Bug #22200984 ASSERTION IN FILESORT::MAKE_SORTORDER()
+#
+SET sql_mode="";
+Warnings:
+Warning	3090	Changing sql mode 'NO_AUTO_CREATE_USER' is deprecated. It will be removed in a future release.
+CREATE TABLE t1(a_t1 INT, c INT, d INT) ENGINE=INNODB;
+CREATE TABLE t2(a_t2 INT NOT NULL, UNIQUE KEY (a_t2)) ENGINE=INNODB;
+INSERT INTO t1 VALUES();
+SELECT (SELECT 1 FROM t2 GROUP BY d, a_t2 HAVING c) FROM t1 GROUP BY (1=2);
+(SELECT 1 FROM t2 GROUP BY d, a_t2 HAVING c)
+NULL
+DROP TABLE t1, t2;
+SET sql_mode=default;

mysql-test/t/filesort_debug.test

@@ -190,3 +190,18 @@ HAVING (SELECT a
       GROUP BY b, a);
 
 DROP TABLE t, g;
+
+--echo #
+--echo # Bug #22200984 ASSERTION IN FILESORT::MAKE_SORTORDER()
+--echo #
+
+# group by d below is incompatible with sql_mode=only_full_group_by
+SET sql_mode="";
+
+CREATE TABLE t1(a_t1 INT, c INT, d INT) ENGINE=INNODB;
+CREATE TABLE t2(a_t2 INT NOT NULL, UNIQUE KEY (a_t2)) ENGINE=INNODB;
+INSERT INTO t1 VALUES();
+SELECT (SELECT 1 FROM t2 GROUP BY d, a_t2 HAVING c) FROM t1 GROUP BY (1=2);
+DROP TABLE t1, t2;
+
+SET sql_mode=default;

sql/filesort.cc

@@ -622,12 +622,17 @@ uint Filesort::make_sortorder()
     pos->field= 0; pos->item= 0;
     if (real_item->type() == Item::FIELD_ITEM)
     {
-      // Could be a field, or Item_direct_view_ref/Item_ref wrapping a field
-      DBUG_ASSERT(item->type() == Item::FIELD_ITEM ||
-                  (item->type() == Item::REF_ITEM &&
-                   (down_cast<Item_ref*>(item)->ref_type() == Item_ref::VIEW_REF
-                    || down_cast<Item_ref*>(item)->ref_type() == Item_ref::REF)
-                    ));
+      /*
+        Could be a field, or Item_direct_view_ref/Item_ref wrapping a field
+        If it is an Item_outer_ref, only_full_group_by has been switched off.
+      */
+      DBUG_ASSERT
+        (item->type() == Item::FIELD_ITEM ||
+         (item->type() == Item::REF_ITEM &&
+          (down_cast<Item_ref*>(item)->ref_type() == Item_ref::VIEW_REF
+           || down_cast<Item_ref*>(item)->ref_type() == Item_ref::OUTER_REF
+           || down_cast<Item_ref*>(item)->ref_type() == Item_ref::REF)
+          ));
       pos->field= down_cast<Item_field*>(real_item)->field;
     }
     else if (real_item->type() == Item::SUM_FUNC_ITEM &&