===description===
reports override widening return type
===file===
<?php
class Base {
    public function f(): int { return 1; }
}
class Child extends Base {
    public function f(): int|string { return 1; }
}
===expect===
MethodSignatureMismatch@6:4: Method Child::f() signature mismatch: return type 'int|string' is not a subtype of parent 'int'
===ignore===
TODO
