Null coalesce operator on nested array returns unexpected error

[alexander-schranz]

Bug report

The ?? usage on a nested array which parent key does not exist throwns an error but I would not expect it e.g.:

/** @var mixed[] $test */
$test = [];

var_dump($test['hello'][0] ?? 'world');

Code snippet that reproduces the problem

https://phpstan.org/r/42618f11-503b-4ad6-ae43-0a2d642deff8

https://3v4l.org/hdYaB

Its a similar issue to isset but instead the ?? (Null coalesce operator) is used: #8068

Expected output

No error should be shown

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[ondrejmirtes]

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[rajyan]

This is an error caused by explicit mixed, because offset access to explicit mixed is not allowed.
The linked issue has a slightly different situation, It had offset access (false)no | (constant array)yes.

The only permitted operation for explicit mixed is passing to another mixed, so the solution is

change the doc as mixed[][]
https://phpstan.org/r/e872f721-8881-4e42-a901-84a7667afd28

or if it’s not possible, you need an explicit is_array check
https://phpstan.org/r/c6e34e77-b303-4677-b6c9-ce8a0cdef0aa

[rajyan]

but I think there were about two related issues before, and maybe supporting isset, coalesce with explicit mixed is reasonable.

[alexander-schranz]

@rajyan I understand thank you for the hint. So atleast I can go with mixed[][] now to fix my issues :)