MDEV-26824 Can't add foreign key with empty referenced columns list

create_table_info_t::create_foreign_keys() expects equal number of
iterations through fk->columns and fk->ref_columns. If fk->ref_columns
is empty copy it from fk->columns.

2 files changed, 41 insertions, 0 deletions

diff --git a/mysql-test/suite/innodb/r/foreign_key.result b/mysql-test/suite/innodb/r/foreign_key.result
index ff0e025246e..1968661b45a 100644
--- a/mysql-test/suite/innodb/r/foreign_key.result
+++ b/mysql-test/suite/innodb/r/foreign_key.result
@@ -896,4 +896,27 @@ create or replace table t1 (a varchar(4096) unique) engine=innodb;
 create or replace table t2 (pk int primary key, a varchar(4096) unique, foreign key(a) references t1(a) on update cascade) engine=innodb;
 ERROR HY000: Can't create table `test`.`t2` (errno: 150 "Foreign key constraint is incorrectly formed")
 drop table t1;
+#
+# MDEV-26824 Can't add foreign key with empty referenced columns list
+#
+create table t2(a int primary key) engine=innodb;
+create table t1(a int primary key, b int) engine=innodb;
+alter table t2 add foreign key(a) references t1(a, b);
+ERROR 42000: Incorrect foreign key definition for 'foreign key without name': Key reference and table reference don't match
+create or replace table t1(a tinyint primary key) engine innodb;
+alter table t2 add foreign key(a) references t1;
+ERROR HY000: Can't create table `test`.`t2` (errno: 150 "Foreign key constraint is incorrectly formed")
+create or replace table t1(b int primary key) engine innodb;
+alter table t2 add foreign key(a) references t1;
+ERROR HY000: Can't create table `test`.`t2` (errno: 150 "Foreign key constraint is incorrectly formed")
+create or replace table t1(a int primary key, b int) engine innodb;
+alter table t2 add foreign key(a) references t1;
+show create table t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `a` int(11) NOT NULL,
+  PRIMARY KEY (`a`),
+  CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`a`) REFERENCES `t1` (`a`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+drop tables t2, t1;
 # End of 10.5 tests
diff --git a/mysql-test/suite/innodb/t/foreign_key.test b/mysql-test/suite/innodb/t/foreign_key.test
index be248a5bed4..1f25d995827 100644
--- a/mysql-test/suite/innodb/t/foreign_key.test
+++ b/mysql-test/suite/innodb/t/foreign_key.test
@@ -902,6 +902,24 @@ create or replace table t2 (pk int primary key, a varchar(4096) unique, foreign
 
 drop table t1;
 
+--echo #
+--echo # MDEV-26824 Can't add foreign key with empty referenced columns list
+--echo #
+create table t2(a int primary key) engine=innodb;
+create table t1(a int primary key, b int) engine=innodb;
+--error ER_WRONG_FK_DEF
+alter table t2 add foreign key(a) references t1(a, b);
+create or replace table t1(a tinyint primary key) engine innodb;
+--error ER_CANT_CREATE_TABLE
+alter table t2 add foreign key(a) references t1;
+create or replace table t1(b int primary key) engine innodb;
+--error ER_CANT_CREATE_TABLE
+alter table t2 add foreign key(a) references t1;
+create or replace table t1(a int primary key, b int) engine innodb;
+alter table t2 add foreign key(a) references t1;
+show create table t2;
+drop tables t2, t1;
+
 --echo # End of 10.5 tests
 
 --source include/wait_until_count_sessions.inc