phpstan assumes file_exists always returns the same result

[uuf6429]

Consider the following code and failure:
https://phpstan.org/r/873e32ca-3b5b-46e9-a66f-08db3f883f25

Another case is when (before the final file_exists) other methods/functions are called that might affect the filesystem.

My current solution is to move the top file_exists to the caller:
https://phpstan.org/r/ad510bc9-5c7f-498f-b190-295614ea5b72

Edit: this also applies to similar functions, such as is_dir.
Another (hacky 🙈) solution is to use a different function for each condition (e.g. file_exists on top, is_dir on bottom).

[ondrejmirtes]

You need to call clearstatcachw between the calls: https://www.php.net/manual/en/function.clearstatcache.php

[uuf6429]

Thanks, funny to still learn something new in PHP after all these years. 😄

PS: Just found out that this is a duplicate of #10000