Function with conditional types gives errors since 4.7.0

[Etherlord]

#5198 This bug is reproduced again since 4.7.0

https://psalm.dev/r/9449b708b5

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/9449b708b5

<?php

/**
 * @psalm-pure
 * @template TValue
 * @template TIterable of ?iterable<TValue>
 * @param TIterable $iterable
 * @return (TIterable is null ? null : list<TValue>)
 */
function toList(?iterable $iterable): ?array
{
    if (null === $iterable) {
        return null;
    }

    if (is_array($iterable)) {
        return array_values($iterable);
    }

    return iterator_to_array($iterable, false);
}

Psalm output (using commit d57dde0):

INFO: MixedReturnTypeCoercion - 17:16 - The type 'array<array-key, mixed>' is more general than the declared return type '(list<TValue:fn-tolist as mixed>)|null' for toList

INFO: MixedReturnTypeCoercion - 20:12 - The type 'array<array-key, mixed>' is more general than the declared return type '(list<TValue:fn-tolist as mixed>)|null' for toList

INFO: MixedReturnTypeCoercion - 8:12 - The declared return type '(list<TValue:fn-tolist as mixed>)|null' for toList is more specific than the inferred return type 'array<array-key, mixed>|null'

[muglug]

It's not since 4.7.0 – it's been an issue for a while, after an earlier commit fixed a false negative.