PHPstan making bad assumption about array key

Question

PHPstan seems to incorrectly narrow type after if (empty(...)).

\PHPStan\dumpType($_GET); // array<mixed>
    
if (empty($_GET['ssid'])) { /* do nothing */ }

\PHPStan\dumpType($_GET); // non-empty-array&hasOffsetValue('ssid', mixed~(0|0.0|''|'0'|array{}|false|null))

In my opinion the type should remain array<mixed> even after the if test (which may result false). Does this narrowing make sense somehow or is it a bug?

(PHPstan 2.1.10, level 10)

Ondřej Mirtes · Accepted Answer · 2025-03-23 22:04:07Z

1

You are right. Please report this bug on PHPStan’s GitHub.

answered Mar 23 at 22:04

Ondřej Mirtes

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Arif Hassan · Accepted Answer · 2025-03-23 17:06:55Z

0

Your expectation that $_GET should remain array<mixed> makes sense in some cases because:

The empty() check only provides information about a single key (ssid), but PHPStan refines the entire $_GET array.
This could lead to incorrect inferences if the code is modified $_GET dynamically later.

-> Use isset() instead of empty(), which might not refine the type in the same way.

answered Mar 23 at 17:06

Arif Hassan

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