Bug report

This can be quite tricky. Some functions may have side effects so that remembering return value doesn't make sense if next actions mutates the state

Code snippet that reproduces the problem

if (file_exists('foo')) {
	unlink('foo');
	if (file_exists('foo')) {
		echo "File still exists although it was deleted";
	}
}

https://phpstan.org/r/61c5bd5b-dc64-4562-aa3c-49cf7de51992

Expected output

No error