Function with conditional types gives errors since 4.5.0

[vudaltsov]

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

This function didn't throw any errors before 4.5.0

[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 257a1ca):

ERROR: DocblockTypeContradiction - 16:9 - Docblock-defined type TIterable:fn-tolist as iterable<mixed, TValue:fn-tolist as mixed> for $iterable is never array

INFO: MixedArgument - 17:29 - Argument 1 of array_values cannot be mixed, expecting array<array-key, mixed>

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]

A bugfix in 4.5 revealed the fixed issue. The other issues with mixed are also longstanding, ticketed here: #5208