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Date: Sat, 07 Dec 2019 18:27:06 -0600
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Subject: Inconsistent class behavior and undocumented(?) BC change
From: larry@garfieldtech.com ("Larry Garfield")

I am not sure if this is a bug, a feature behaving in a desired but confusing way, or a feature behaving in a confusing and thus undesireable way.  I am therefore reporting it here in order to defer to those who know the answer to such questions better.

Consider the following:

class Ancestor {
    public function __construct(int $a, string $b) { }
}

class Child extends Ancestor {
    public function __construct(...$args) {
        parent::__construct(...$args);
    }
}

This works with no compile errors.  For any other method however:

class Ancestor {
    public function doStuff(int $a, string $b) { }
}

class Child extends Ancestor {
    public function doStuff(...$args) {
        parent::doStuff(...$args);
    }
}

I get:

Warning: Declaration of Child::doStuff(...$args) should be compatible with Ancestor::doStuff(int $a, string $b)

I am not clear on why __construct() is special in this case; I know __construct() is special where interfaces are concerned, but I didn't realize it was special with regards to basic inheritance.  It seems to happen regardless of the type information presented (or not).

Is this intentional?  Is there a logical way it could be made to work?  Are constructors actually wrong here?  (I hope not, because it's a neat trick.)

Additionally, according to 3v4l.org at least, the error message has changed.  On 7.1-7.3, the exact error message is:

Warning: Declaration of Child::doStuff(int ...$args) should be compatible with Ancestor::doStuff($a, $b) in /in/6NthP on line 15

On 7.4, it reports on a different line:

Warning: Declaration of Child::doStuff(int ...$args) should be compatible with Ancestor::doStuff($a, $b) in /in/6NthP on line 11

Specifically, prior to 7.4, it reports on the LAST line of the class (the closing brace).  As of 7.4 it reports on the line of the method that is inconsistent.

I don't think this is a bad change, per se.  It's actually a good change for debugging, IMO.  But I don't see it listed in the migration guide.  Should it be, in case some failure-mode tests or other automated error systems care?

https://www.php.net/manual/en/migration74.incompatible.php

-- 
  Larry Garfield
  larry@garfieldtech.com