Array destructuring should warn when used on a non-array

[tgr]

Description

This emits a warning:

<?php
['a'=>$b] = [];
var_dump($b);
// Warning: Undefined array key "a" in /in/D0WSJ on line 2
// NULL

This doesn't:

<?php
['a'=>$b] = 0;
var_dump($b);
// NULL

That seems unintuitive and error-prone.

(3v4l: first, second)

PHP Version

all supported versions + current master

Operating System

No response

[iluuu1994]

Hi. See https://wiki.php.net/rfc/warnings-php-8-5#destructuring_non-array_values, there will be a warning in 8.5.

[tgr]

Apparently I reported this a while ago in the doc repo (php/doc-en#3640) but forgot about it.