MDEV-10347 mysqld got signal 11

mysql-test/r/null.result

@@ -1572,6 +1572,23 @@ SELECT * FROM t1 WHERE NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(N
 i
 DROP TABLE t1;
 #
+# MDEV-10347 mysqld got signal 11
+#
+CREATE TABLE t1 (f1 VARCHAR(10), f2 VARCHAR(40));
+CREATE TABLE t2 (f3 VARCHAR(20));
+PREPARE stmt FROM "
+  SELECT (
+    SELECT IFNULL(f3,4) FROM t2
+    WHERE IFNULL(NULLIF(f1,''),1)
+  ) AS sq
+  FROM t1
+  GROUP BY f2
+";
+EXECUTE stmt;
+sq
+DEALLOCATE PREPARE stmt;
+DROP TABLE t2,t1;
+#
 # MDEV-10236 Where expression with NOT function gives incorrect result
 #
 CREATE TABLE t1 (c1 INT);

mysql-test/t/null.test

@@ -1006,6 +1006,23 @@ INSERT INTO t1 VALUES (1),(2);
 SELECT * FROM t1 WHERE NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(NULLIF(i = ROUND(0), 14), 13), 12), 11), 10), 9), 8), 7), 6), 5), 4), 3), 2), 1);
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-10347 mysqld got signal 11
+--echo #
+
+CREATE TABLE t1 (f1 VARCHAR(10), f2 VARCHAR(40));
+CREATE TABLE t2 (f3 VARCHAR(20));
+PREPARE stmt FROM "
+  SELECT (
+    SELECT IFNULL(f3,4) FROM t2
+    WHERE IFNULL(NULLIF(f1,''),1)
+  ) AS sq
+  FROM t1
+  GROUP BY f2
+";
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+DROP TABLE t2,t1;
 
 --echo #
 --echo # MDEV-10236 Where expression with NOT function gives incorrect result

sql/item_cmpfunc.h

@@ -1022,6 +1022,11 @@ class Item_func_nullif :public Item_func_hybrid_field_type
     Item_func_hybrid_field_type(thd, a, b, a),
     m_cache(NULL)
   { arg_count--; }
+  void cleanup()
+  {
+    Item_func_hybrid_field_type::cleanup();
+    arg_count= 2; // See the comment to the constructor
+  }
   bool date_op(MYSQL_TIME *ltime, uint fuzzydate);
   double real_op();
   longlong int_op();