fn foo() ! {
	return error('something')
}

fn test_option_void() {
	foo() or {
		println(err)
		assert err.msg() == 'something'
		return
	}
}

fn bar() ! {
	return error('bar error')
}

fn test_option_void_only_question() {
	bar() or {
		println(err)
		assert err.msg() == 'bar error'
		return
	}
}

fn test_option_void_with_empty_or() {
	foo() or {}
	assert true
}

fn option_void(a int) ! {
	if a != 0 {
		return
	} else {
		return error('zero error')
	}
}

fn test_option_void_with_return() {
	option_void(0) or {
		println(err)
		assert err.msg() == 'zero error'
		return
	}
	option_void(-1) or {
		println(err)
		assert err.msg() == 'zero error'
		return
	}
	assert true
}

fn must_error_for_generic_result() ! {
	return error('boom')
}

fn never_returns_normally[T](value T) !T {
	must_error_for_generic_result()!
}

fn test_generic_result_propagation_from_always_error_fn_does_not_need_placeholder_return() {
	never_returns_normally(42) or {
		assert err.msg() == 'boom'
		return
	}
	assert false
}