non-empty-array seems to be incorrectly identified as possibly empty after unset

[cfahner]

Bug report

A property marked as non-empty-array seems to be incorrectly identified as possibly empty. This is after explicitly checking if the array has at least two items before using unset() on it.

Code snippet that reproduces the problem

https://phpstan.org/r/8d223a39-663d-42ba-803d-1ae7644ded48

Expected output

No errors as the array should have at least one item left.

Did PHPStan help you today? Did it make you happy in any way?

Very happy with PHPStan! Prevented a lot of headaches so far.

[ondrejmirtes]

PHPStan does not track specific array sizes above 1 yet.

[ondrejmirtes]

/cc @herndlm Hypothetical "AccessoryArraySizeType" would be really helpful for this and other cases. I'd be able to use it in phpstan/phpstan-src#3865 too which fixes about 5-6 issues now.

The accompanying Type::getArraySize() method is already there. The new type could be used to track the precise sizes of general arrays. Of course the biggest challenge would be to have it always up-to-date, after all operations.

Is this something you'd like to tackle?