Incorrect type interpretation

[johnkhansrc]

Description

The following code:

<?php
    /**
     * @return array<string, string>
     */
    public function dict(): array
    {
        return [
            'foo' => 'bar',
            '1' => '1 year',
            '2' => '2 years',
            '3' => '3 years',
            '4' => '4 years',
            '5' => '5 years',
        ];
    }
?>

Resulted in this output (static warning):

should return array<string, string> but returns array<int|string, string>

But I expected this output instead:

array<string, string>

PHP Version

PHP8.3

Operating System

Ubuntu 24.01

As I am not sure that this comes from the interpreter I also published the issue on the static analysis tool repo (phpstan) : phpstan/phpstan#11880

[kallesommernielsen]

Hi

This has nothing to do with PHP itself as docblocks are irrelevant to how PHP interpret types (and on top of that PHP does not currently support Generics)

[damianwadley]

As mentioned in the other report, integer-ish string keys in arrays are always forced to actual integers.

https://www.php.net/manual/en/language.types.array.php

Additionally the following key casts will occur:

• Strings containing valid decimal ints, unless the number is preceded by a + sign, will be cast to the int type. E.g. the key "8" will actually be stored under 8. On the other hand "08" will not be cast, as it isn't a valid decimal integer.

So the warning is correct that the array keys will be int|string.