Merge 10.4 into 10.5

mysql-test/main/explain.test

@@ -339,3 +339,34 @@ explain replace into t2 select 100, (select a from t1);
 drop table t1, t2;
 
 --echo # End of 10.1 tests
+
+--echo #
+--echo # End of 10.2 test
+--echo #
+
+--echo #
+--echo # MDEV-25564: Server crashed on running some EXPLAIN statements
+--echo #
+
+EXPLAIN (SELECT 1,3) UNION (SELECT 2,1) ORDER BY (SELECT 2);
+
+--echo #
+--echo # MDEV-23160: SIGSEGV in Explain_node::print_explain_for_children on UNION SELECT
+--echo #
+
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (1),(2),(3);
+
+EXPLAIN
+SELECT *
+FROM t1
+WHERE
+  a IN (SELECT a FROM t1
+        UNION
+        SELECT a FROM t1 ORDER BY (SELECT a))
+UNION
+  SELECT * FROM t1 ORDER BY (SELECT a);
+drop table t1;
+
+explain
+VALUES ( (VALUES (2))) UNION VALUES ( (SELECT 3));