Null coalescence and casting precendence

[BackEndTea]

Given the following code:

<?php

function getContent(array $array) {
    return (string) $array['content'] ?? 'no content found';
}

var_dump(getContent(['content'=> 'aaaa']));
var_dump(getContent([]));

Psalm doens't error on this (besides the var_dumps).

This will however cause a notice for an undefined offset, as the casting takes place before the null coalescence.

The correct way would be as follows:

<?php

function getContent(array $array) {
    return (string) ($array['content'] ?? 'no content found');
}

https://phpstan.org/r/7cacfb28-6ef8-4d86-b915-825566c9c3bf

I would expect this to raise an error, that the coalescence is never used.

[ondrejmirtes]

PHPStan doesn't complain about specific keys existence on general arrays. It would be too annoying.

See: https://phpstan.org/r/4e0d98db-a8f7-4233-906e-8bbb830c45a0

Versus: https://phpstan.org/r/5f334a16-0f44-4b9f-981b-c326b8d0b474

You can use phpDocs for this purpose: https://phpstan.org/r/b28c885b-a896-4095-aad0-3b5d90828257

[BackEndTea]

I'm sorry i think i explained it wrong.

The issue is the fact that the coalescence is never used. And it is (most likely) a bug.

If no key is set you are writing

<?php

function getContent(array $array) {
    return "" ?? 'no content found';
}

Which would never trigger the coalescence either.

(Though that is also not an issue for phpstan) https://phpstan.org/r/6282f19b-1095-4b58-908d-bbc048340be8

[ondrejmirtes]

Yes, this is not yet implemented. I have it on my todolist.

[ondrejmirtes]

Implemented: phpstan/phpstan-src#36

If you re-run your playground examples, it shows the new error :)

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