create user foo@localhost;
grant create user on *.* to foo@localhost;
connect  foo,localhost,foo,,;
drop user foo@localhost;
select * from information_schema.applicable_roles;
GRANTEE	ROLE_NAME	IS_GRANTABLE	IS_DEFAULT
show grants;
ERROR 42000: There is no such grant defined for user 'foo' on host 'localhost'
select current_user();
current_user()
foo@localhost