[Downgrade PHP 7.0] Move Throwable out of type hints

[jtojnar]

It is only available on PHP 7.0+:
https://www.php.net/manual/en/class.throwable.php

[jtojnar]

This is a first part of work to be able to use latest Tracy on PHP 5.6. I need it for selfoss RSS reader, which still targets PHP 5.6 through 8.1. I also want to migrate try { … } catch (Throwable $e) { … } to try { … } catch (Throwable $e) { … } catch (Exception $e) { … } and … instanceof \Throwable to … instanceof \Throwable || … instanceof \Exception.

[TomasVotruba]

Hi, thanks for the new rule.

I wonder if RenameClassRector might help with this? E.g. Throwable to Exception

[jtojnar]

The issue is that it is not a straightforward renaming. Especially when we want the resulting code to support both PHP 5 and PHP 7. (I am not even sure if we should make it part of downgrade set.)

Though maybe we could have something like RenameClassRector that would change Throwable into Throwable|Exception and then have other rules resolve the other cases.

[TomasVotruba]

I see. In that way custom rule might be a way to go 👍

[jtojnar]

This does not preserve formatting (changes ?\Throwable to \Throwable|null. But that is probably fine.

[samsonasik]

that's actually fine https://phpstan.org/r/5c17f3ca-4b93-44e4-9597-b21bb9b784c5 , improvement maybe in separate PR.

[jtojnar]

Reading the docs again, we need to mention that it does params too.

[jtojnar]

And it looks like the examples are not tested since I based this on DowngradeSelfTypeDeclarationRector and it does not have the documentation comment either.

[samsonasik]

Thank you @jtojnar