multiple issues in array destructuring

[azjezz]

Issue 1:

when spreading an array with keys that are no literal, psalm does not attempt to resolve the type of the key an access the index as you would manually ( since [$a => $b] = $c is the exact same as $b = $c[$a] ).

Issue 2:

PHP allows skipping elements when destructing, but, this is only allowed when the list/array on the lhs does not have keys, psalm allows this even when keys exist, it should warn/error instead because it will cause a fatal error at runtime.

Example: https://psalm.dev/r/c9cf653295

[psalm-github-bot[bot]]

I found these snippets:

https://psalm.dev/r/c9cf653295

<?php


$arr = ['a' => 1, 'b' => 2];
['a' => $a, 'b' => $b] = $arr;
/**
 * @psalm-trace $a
 * @psalm-trace $b
 */
echo $a;
echo $b;

$arr = ['a' => 1, 'b' => 2];
$ak = 'a';
$bk = 'b';
// fails to determine keys being accessed, assumes mixed values
[$ak => $a, $bk => $b] = $arr;

/**
 * @psalm-trace $a
 * @psalm-trace $b
 */
echo $a;
echo $b;

$arr = ['a' => 1, 'b' => 2];
// does not report an error regarding skipping items in keyed destruction
['a' => $a, /* skip */,'b' => $b] = $arr;

/**
 * @psalm-trace $a
 * @psalm-trace $b
 */
echo $a;
echo $b;

Psalm output (using commit 6670889):

INFO: Trace - 10:1 - $a: 1

INFO: Trace - 10:1 - $b: 2

INFO: MixedArgument - 23:6 - Argument 1 of echo cannot be mixed, expecting string

INFO: Trace - 23:1 - $a: mixed

INFO: Trace - 23:1 - $b: mixed

INFO: MixedArgument - 24:6 - Argument 1 of echo cannot be mixed, expecting string

INFO: Trace - 34:1 - $a: 1

INFO: Trace - 34:1 - $b: 2

INFO: UnusedVariable - 14:1 - $ak is never referenced or the value is not used

INFO: UnusedVariable - 15:1 - $bk is never referenced or the value is not used