iterator_to_array never returns mixed key, it throws TypeError instead

[vudaltsov]

https://psalm.dev/r/ce986a03b8

I think the issue raised by Psalm is not correct. While iterator_to_array does throw a TypeError in case of a non-scalar key (https://3v4l.org/BBOJF), the returned type of iterator_to_array(T, true) is never array<mixed, T>, it is array<array-key, T>.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/ce986a03b8

<?php

/**
 * @template TKey
 * @template TValue
 * @param Traversable<TKey, TValue> $traversable
 * @return array<TValue>
 */
function toArray(Traversable $traversable): array
{
    return iterator_to_array($traversable);
}

Psalm output (using commit dd4d970):

INFO: MixedReturnTypeCoercion - 11:12 - The type 'array<TKey:fn-toarray as mixed, TValue:fn-toarray as mixed>' is more general than the declared return type 'array<array-key, TValue:fn-toarray as mixed>' for toArray

INFO: MixedReturnTypeCoercion - 7:12 - The declared return type 'array<array-key, TValue:fn-toarray as mixed>' for toArray is more specific than the inferred return type 'array<TKey:fn-toarray as mixed, TValue:fn-toarray as mixed>'