type FnType = fn () bool

fn foo() int {
	return 0
}

fn bar() bool {
	return true
}

fn main() {
	// acceptable ones
	_ := unsafe { FnType(nil) }
	_ := unsafe { FnType(0) }
	_ := unsafe { FnType(foo) }
	_ := unsafe { FnType(bar) }
	_ := FnType(bar)
	_ := ?FnType(none)
	_ := ?FnType(bar)
	_ := unsafe { ?FnType(foo) }

	// wrong ones
	_ := FnType(foo)
	_ := FnType(nil)
	_ := FnType(0)
	_ := FnType('foo')
	_ := FnType(none)
	_ := ?FnType(0)
	_ := ?FnType(nil)
	_ := ?FnType(foo)
}