Run static analysis on PHP 8.1

[greg0ire]

This will make it easier to add code that leverages features only
defined since that version of PHP.

[derrabus]

I agree that we should analyze the codebase on PHP 8.1. While PHP 7.1 is the lowest supported version, the repository contains features that require a more recent PHP version and we are currently hardly able to run static analysis on those parts.

Just raising the PHP interpreter version is not enough however. We need to toll both tools to apply PHP 8.1 rules. This is where you can do this for PHPStan:

orm/phpstan-params.neon

Line 11 in d30e748

phpVersion: 70100

For Psalm, you need to add the attribute phpVersion="8.1" to the top-level <psalm> element of psalm.xml. If you don't do that, Psalm will infer PHP 7.1 as language level from composer.json.

[derrabus]

Moreover, rasining the language level should allow us to drop some hacks from Psalm's configuration:

orm/psalm.xml

Lines 90 to 96 in d30e748

	<!-- Workaround for https://github.com/vimeo/psalm/issues/7026 -->
	<ReservedWord>
	<errorLevel type="suppress">
	<directory name="lib"/>
	<directory name="tests"/>
	</errorLevel>
	</ReservedWord>

orm/psalm.xml

Lines 103 to 108 in d30e748

	<UndefinedAttributeClass>
	<errorLevel type="suppress">
	<!-- The class was added in PHP 8.1 -->
	<referencedClass name="ReturnTypeWillChange"/>
	</errorLevel>
	</UndefinedAttributeClass>

[greg0ire]

@derrabus I'm not aiming at testing PHP 8.1 features with this PR, I'm aiming at preventing them from making the baseline grow. If we want to test our usage of PHP 8.1 features, while still checking that our code is compatible with our lowest supported version (we want to do that, right?), we will had to rework the static analysis jobs.

Do we still want to have jobs with 7.1 as a target version?

[derrabus]

@derrabus I'm not aiming at testing PHP 8.1 features with this PR, I'm aiming at preventing them from making the baseline grow.

Does it really make a difference if we bump the PHP runtime only? Both tools will still assume PHP 7.1 as language level.

Do we still want to have jobs with 7.1 as a target version?

Right now, letting the tools operate PHP 7.1 as language level causes more pain than it solves problems imho. Especially Psalm has a history of reporting funny errors if the dependencies are on a higher language level. I'd suggest to let the test suite cover PHP 7.1 support and let the SA tools operate on PHP 8.1.

[derrabus]

If you like, we can merge this PR as-is and I work out a PR for bumping the language level for the SA tools.

[beberlei]

Agree about PHPUnit covering 7.1 is good enough.

[derrabus]

I've implemented my suggestion as #9314.