MDEV-15950: LOAD DATA INTO compex_view crashed

For multi-table views with LOAD, updates are not allowed, so
we should just throw an error.

mysql-test/r/loaddata.result

@@ -574,3 +574,29 @@ a	b
 6	6
 DROP VIEW IF EXISTS v2,t2;
 DROP TABLE IF EXISTS t1;
+#
+# MDEV-15950: LOAD DATA INTO compex_view crashed
+#
+create table t1 (a int, b int);
+create table t0 (x int, y int);
+CREATE OR REPLACE VIEW v1 AS SELECT * FROM t1,t0;
+CREATE VIEW v2 AS SELECT * FROM v1;
+LOAD DATA INFILE '../../std_data/loaddata7.dat' INTO TABLE v1
+FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n';
+ERROR HY000: Incorrect usage of Multi-table VIEW and LOAD
+LOAD DATA INFILE '../../std_data/loaddata7.dat' INTO TABLE v2
+FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n';
+ERROR HY000: Incorrect usage of Multi-table VIEW and LOAD
+DROP VIEW IF EXISTS v2,v1;
+DROP TABLE IF EXISTS t1,t0;
+CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a), UNIQUE(b));
+INSERT INTO t1 VALUES (1,1);
+CREATE TABLE t2 (c INT);
+CREATE VIEW v AS SELECT t1.* FROM t1 JOIN t2;
+SELECT a, b FROM t1 INTO OUTFILE '15645.data';
+LOAD DATA INFILE '15645.data' IGNORE INTO TABLE v (a,b);
+ERROR HY000: Incorrect usage of Multi-table VIEW and LOAD
+LOAD DATA INFILE '15645.data' REPLACE INTO TABLE v (a,b);
+ERROR HY000: Incorrect usage of Multi-table VIEW and LOAD
+drop table t1,t2;
+drop view v;

mysql-test/t/loaddata.test

@@ -690,3 +690,34 @@ select * from v2;
 select * from t2;
 DROP VIEW IF EXISTS v2,t2;
 DROP TABLE IF EXISTS t1;
+
+--echo #
+--echo # MDEV-15950: LOAD DATA INTO compex_view crashed
+--echo #
+create table t1 (a int, b int);
+create table t0 (x int, y int);
+CREATE OR REPLACE VIEW v1 AS SELECT * FROM t1,t0;
+CREATE VIEW v2 AS SELECT * FROM v1;
+
+--error ER_WRONG_USAGE
+LOAD DATA INFILE '../../std_data/loaddata7.dat' INTO TABLE v1
+FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n';
+
+--error ER_WRONG_USAGE
+LOAD DATA INFILE '../../std_data/loaddata7.dat' INTO TABLE v2
+FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n';
+
+DROP VIEW IF EXISTS v2,v1;
+DROP TABLE IF EXISTS t1,t0;
+
+CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a), UNIQUE(b));
+INSERT INTO t1 VALUES (1,1);
+CREATE TABLE t2 (c INT);
+CREATE VIEW v AS SELECT t1.* FROM t1 JOIN t2;
+SELECT a, b FROM t1 INTO OUTFILE '15645.data';
+--error ER_WRONG_USAGE
+LOAD DATA INFILE '15645.data' IGNORE INTO TABLE v (a,b);
+--error ER_WRONG_USAGE
+LOAD DATA INFILE '15645.data' REPLACE INTO TABLE v (a,b);
+drop table t1,t2;
+drop view v;

sql/sql_load.cc

@@ -251,6 +251,11 @@ int mysql_load(THD *thd,sql_exchange *ex,TABLE_LIST *table_list,
     my_error(ER_NON_UPDATABLE_TABLE, MYF(0), table_list->alias, "LOAD");
     DBUG_RETURN(TRUE);
   }
+  if (table_list->is_multitable())
+  {
+    my_error(ER_WRONG_USAGE, MYF(0), "Multi-table VIEW", "LOAD");
+    DBUG_RETURN(TRUE);
+  }
   if (table_list->prepare_where(thd, 0, TRUE) ||
       table_list->prepare_check_option(thd))
   {