INSERT .. RETURNING requires INSERT privilege on columns which only participate in RETURNING clause

create database db;

create table db.t (a int, b int);

create user foo;

grant insert (a) on db.t to foo;

grant select (b) on db.t to foo;

--connect (con1,localhost,foo,,)

insert into db.t (a) values (1) returning b;

# Cleanup

--disconnect con1

--connection default

drop database db;

drop user foo;

MariaDB [test]> insert into db.t (a) values (1) returning b;

ERROR 1143 (42000): INSERT command denied to user 'foo'@'localhost' for column 'b' in table 't'

MariaDB [test]> insert into db.t (a) values (1);

Query OK, 1 row affected (0.017 sec)