Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:98092
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.215.50 as permitted sender)
MIME-Version: 1.0
Sender: morrison.levi@gmail.com
In-Reply-To: <CAFp73Xv0JumLQiaDgYAVVi0yEpONKUPnxJdN4djvhvdurit+cw@mail.gmail.com>
References: <CAFp73Xv0JumLQiaDgYAVVi0yEpONKUPnxJdN4djvhvdurit+cw@mail.gmail.com>
Date: Tue, 31 Jan 2017 13:47:52 -0700
Message-ID: <CAFMT4No-h=ZyUUT_0vFxO4F_uOYLMW2Cs7t5z4c3Ko5Hp4hHAA@mail.gmail.com>
To: "guilhermeblanco@gmail.com" <guilhermeblanco@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] PHP's support to contravariance and covariance
From: levim@php.net (Levi Morrison)

> Is there anything else that I am missing?

Sadly, yes. Consider the following snippet:

    class A {
        function method(): B;
    }

    class B extends A {
        function method(): C;
    }

    class C extends B {}

When checking that B::method satisfies the requirements of A::method
it must know if C extends B. At the time we check if B::method
satisfies A::method, C will *not* yet be in the symbol table.

You need to adjust the passes over the code to register symbols and
their declared relationships, and then in a separate pass validate
them. After that if the class isn't found then you trigger an
autoload.

It's doable, it just hasn't been done.