MDEV-31296: Crash in Item_func::fix_fields when prepared statement with...

MDEV-31296: Crash in Item_func::fix_fields when prepared statement with subqueries and window function is executed with sql_mode = ONLY_FULL_GROUP_BY

Crash was caused by referencing a null pointer on getting
the number of the nesting levels of the set function for the current
select_lex at the method Item_field::fix_fields.

The current select for processing is taken from Name_resolution_context
that filled in at the function set_new_item_local_context() and
where initialization of the data member Name_resolution_context
was mistakenly removed by the commit
  d6ee351b
   (Revert "MDEV-24454 Crash at change_item_tree")

To fix the issue, correct initialization of data member
  Name_resolution_context::select_lex
that was removed by the commit d6ee351b
is restored.

mysql-test/main/win.result

@@ -4415,5 +4415,18 @@ NULL
 DROP FUNCTION f;
 DROP TABLE t;
 #
+# MDEV-31296: Crash in Item_func::fix_fields when prepared statement
+#             with subqueries and window function is executed with
+#             sql_mode = ONLY_FULL_GROUP_BY
+#
+CREATE TABLE t1 ( a INT, i INT) ;
+CREATE TABLE t2 ( a INT);
+INSERT INTO t2 VALUES (4000);
+SET SESSION sql_mode = "ONLY_FULL_GROUP_BY";
+EXECUTE IMMEDIATE "SELECT SUM(i) OVER (ORDER BY i) FROM t1 NATURAL JOIN t2";
+SUM(i) OVER (ORDER BY i)
+# Clean up
+DROP TABLE t1, t2;
+#
 # End of 10.6 tests
 #

mysql-test/main/win.test

@@ -2898,6 +2898,20 @@ EXECUTE IMMEDIATE "SELECT LEAD(c) OVER (ORDER BY c) FROM (SELECT 1 AS c) AS a NA
 DROP FUNCTION f;
 DROP TABLE t;
 
+--echo #
+--echo # MDEV-31296: Crash in Item_func::fix_fields when prepared statement
+--echo #             with subqueries and window function is executed with
+--echo #             sql_mode = ONLY_FULL_GROUP_BY
+--echo #
+CREATE TABLE t1 ( a INT, i INT) ;
+CREATE TABLE t2 ( a INT);
+INSERT INTO t2 VALUES (4000);
+SET SESSION sql_mode = "ONLY_FULL_GROUP_BY";
+EXECUTE IMMEDIATE "SELECT SUM(i) OVER (ORDER BY i) FROM t1 NATURAL JOIN t2";
+
+--echo # Clean up
+DROP TABLE t1, t2;
+
 --echo #
 --echo # End of 10.6 tests
 --echo #

mysql-test/suite/encryption/r/tempfiles_encrypted.result

@@ -4421,6 +4421,19 @@ NULL
 DROP FUNCTION f;
 DROP TABLE t;
 #
+# MDEV-31296: Crash in Item_func::fix_fields when prepared statement
+#             with subqueries and window function is executed with
+#             sql_mode = ONLY_FULL_GROUP_BY
+#
+CREATE TABLE t1 ( a INT, i INT) ;
+CREATE TABLE t2 ( a INT);
+INSERT INTO t2 VALUES (4000);
+SET SESSION sql_mode = "ONLY_FULL_GROUP_BY";
+EXECUTE IMMEDIATE "SELECT SUM(i) OVER (ORDER BY i) FROM t1 NATURAL JOIN t2";
+SUM(i) OVER (ORDER BY i)
+# Clean up
+DROP TABLE t1, t2;
+#
 # End of 10.6 tests
 #
 #

sql/sql_base.cc

@@ -6930,6 +6930,7 @@ set_new_item_local_context(THD *thd, Item_ident *item, TABLE_LIST *table_ref)
   if (!(context= new (thd->mem_root) Name_resolution_context))
     return TRUE;
   context->init();
+  context->select_lex= table_ref->select_lex;
   context->first_name_resolution_table=
     context->last_name_resolution_table= table_ref;
   item->context= context;