Void函数不能返回void函数？

Question

I wonder why this is not valid:

Class Foobar
{
    private function foo(): void {
        return;
    }

    public function bar(): void {
        return $this->foo(); // Compile Error: A void function must not return a value
    }

}

I know the RFC says this:

A function with a void return type, or void function, may either return implicitly, or have a return statement without a value

But IMHO foo is void, thus it should be allowed...

Answer 1

$this->foo() does not return void, but null. So in your bar function, you are actually explicitly returning null, which is not allowed.