Fixed return value of substr according to its documentation

[Wosi]

Documentation says about substr:

Returns the extracted part of string; or FALSE on failure, or an empty string.

https://www.php.net/manual/en/function.substr.php

I fixed the return value in functionMap.

[ondrejmirtes]

Hi, this would be extra-annoying, substr almost never returns false so it would be annoying to force people on higher levels to always check for that. As you can see, it caused many false-positives in the build. See #1215.

[Wosi]

I understand.
My problem is that I'm currently working on a legacy code base that I want to clean up to PhpStan level 7. In that code base there are some checks if substr returned false. PhpStan creates false positives for them. How should PhpStan users deal with such checks?

[ondrejmirtes]

Please provide a code sample, I have no idea what message are you trying to avoid...

[Wosi]

It's this: https://phpstan.org/r/2164391a-f71b-4962-9022-d03d7b852cbe

[ondrejmirtes]

You can always persuade PHPStan with @var: https://phpstan.org/r/7bd2ed96-8e54-436d-8643-a206f62cf522

[Wosi]

Maybe I can stick with a type hint like this, thanks.

I see it's annoying to check the result always against false but if you use PhpStan to avoid bad surprises and enforce defensive programming then I think PhpStan should use correct method signatures.
Maybe we need separate rules for cases like this.

[ondrejmirtes]

Yes, I agree in most cases, but with gradual typing system that PHPStan it's also its job and the challenge not to annoy users with false positives, and string|false for substr would do that a lot.