fixed count() type after array_pop/array_shift

[staabm]

closes phpstan/phpstan#7804

[staabm]

just an initial idea on how this could be implemented. I am not sure its the right way to fix it, so figured I would submit it for review and further discussion.

I already realized that with this PR applied the following does not yet work:

/** @param array<int, string> $headers */
function pop1(array $headers): void
{
	if (count($headers) >= 4) {
		assertType('int<4, max>', count($headers));
		array_pop($headers);
		assertType('int<3, max>', sizeof($headers));
	}
}

/** @param array<int, string> $headers */
function foo(array $headers): void
{
	if (sizeof($headers) >= 4) {
		\PHPStan\dumpType(sizeof($headers));
		array_pop($headers);
		\PHPStan\dumpType(sizeof($headers));
	}
}

could be fixed - I guess - in a similar way as we already do for count here. but maybe there is a more elegant way?

---

array_push and array_unshift could be handled in a similar way.. will leave it for a separate PR though

[staabm]

atm this line depends on whether the code beeing analyzed is in a namespace or not

[ondrejmirtes]

We can't do this precisely without having some accessory type that would carry how many items are there in the array. Right now we only have NonEmptyArrayType which tells when it's int<0, max> and when it's int<1, max>. I don't want to do the count() computation anywhere but CountFunctionReturnTypeExtension.

I don't think this is worth fixing now, I removed the "Easy fixes" milestdone.

[ondrejmirtes]

See #1828 (comment)