struct Foo {
}

fn (f Foo) no_ref() int {
	return 1
}

fn (f &Foo) ref() int {
	return 1
}

@[heap]
struct Bar {
}

fn (f &Bar) ref() int {
	return 1
}

fn main() {
	f := Foo{}
	_ := f.no_ref // no error
	_ := f.ref // error

	b := Bar{}
	_ := b.ref // no error
}