Bug#36079456 Assertion `having_cond->has_subquery() || !(having_cond->used_tables() & ~(1 | PSEUDO_TABLE_BITS))' failed.

Server exit not seen in production builds, although even those are not
functioning correctly for this case.  In transforming subqueries to
derived tables (WL#12885), replacement of a subquery in a HAVING
condition failed to use an Item_ref, instead using an Item_field. This
leads to the assert seen cf. this quote in
JOIN::add_having_as_tmp_table_cond:

  "Pushing parts of HAVING to an internal temporary table.
   Fields in HAVING condition may have been replaced with fields in an
   internal temporary table. This table has map=1. "

For the above to work, the item replacing the subquery must be an item
ref, so the slice system can do its thing: allowing the having
condition to reference the temporary table, not the original derived
table (which has a map entry of 4 in the simplified repro, not 1 as
expected, hence the assert).

The code did not correctly detect that the subquery was part of a
HAVING condition. This is regression after commit

  ca2cd90bffb WL#9384: Prepare each DML statement once

although due to another error it didn't manifest for the repro until
later, in commit

  ca5275ff6e7 Bug#35060385 Item::update_used_tables should also
              update the PROP_SUBQUERY - for transforms

Change-Id: Iaddce7fddd7e08ebbb6fb0e683f81fc1a00f0d89

Author: Dag Wanvik

mysql-test/r/subquery_scalar_to_derived.result

@@ -4870,4 +4870,25 @@ a	MIN(f1)
 NULL	NULL
 DROP TABLE t1;
 SET SQL_MODE=default;
+#
+# Bug#36079456 Assertion `having_cond->has_subquery() ||
+#              !(having_cond->used_tables() & ~(1 | PSEUDO_TABLE_BITS))'
+#              failed.
+CREATE TABLE t(i INT);
+SELECT i FROM t
+HAVING i <> ( SELECT MIN(i)
+FROM t)
+ORDER BY i;
+i
+EXPLAIN SELECT i FROM t
+HAVING i <> ( SELECT MIN(i)
+FROM t)
+ORDER BY i;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t	NULL	ALL	NULL	NULL	NULL	NULL	1	100.00	Using temporary; Using filesort
+1	PRIMARY	<derived2>	NULL	ALL	NULL	NULL	NULL	NULL	1	100.00	Using where; Using join buffer (hash join)
+2	DERIVED	t	NULL	ALL	NULL	NULL	NULL	NULL	1	100.00	NULL
+Warnings:
+Note	1003	/* select#1 */ select `test`.`t`.`i` AS `i` from `test`.`t` left join (/* select#2 */ select min(`test`.`t`.`i`) AS `MIN(i)` from `test`.`t`) `derived_1_2` on(true) where true having (`test`.`t`.`i` <> `derived_1_2`.`MIN(i)`) order by `test`.`t`.`i`
+DROP TABLE t;
 SET optimizer_switch='subquery_to_derived=default';

mysql-test/t/subquery_scalar_to_derived.test

@@ -2549,4 +2549,21 @@ DROP TABLE t1;
 
 SET SQL_MODE=default;
 
+--echo #
+--echo # Bug#36079456 Assertion `having_cond->has_subquery() ||
+--echo #              !(having_cond->used_tables() & ~(1 | PSEUDO_TABLE_BITS))'
+--echo #              failed.
+CREATE TABLE t(i INT);
+
+let $query=
+SELECT i FROM t
+HAVING i <> ( SELECT MIN(i)
+              FROM t)
+ORDER BY i;
+
+eval $query;
+eval EXPLAIN $query;
+
+DROP TABLE t;
+
 SET optimizer_switch='subquery_to_derived=default';

sql/item_subselect.cc

@@ -3031,7 +3031,7 @@ Item *Item_singlerow_subselect::replace_scalar_subquery(uchar *arg) {
     ref = info->m_outer_query_block->add_hidden_item(scalar_item);
   }
   Item *result;
-  if (query_expr()->place() == CTX_HAVING) {
+  if (place() == CTX_HAVING) {
     result = new (mem_root)
         Item_ref(&info->m_outer_query_block->context, ref, scalar_item->db_name,
                  scalar_item->table_name, scalar_item->field_name);