Use short nullable for PHP<8 since union types are not supported

[kkmuffme]

Fix #1775

[kkmuffme]

Quick question before I fix the test: the test fails on 7.4, however this test should not ever have passed on 7.4, since this test is a fatal error in PHP 7.4
Can I just check the PHP_VERSION_ID and skip the test in that version? Or are there any other ways implemented to run tests version specific?

Any plans to add a php -l linting pipeline to CI to prevent tests that are actually fatal errors ending up in the codebase, as well as to become aware of any issues that might be fatal in newer/older PHP versions?

[kukulich]

PHPCS is parser so it does not run code. PHPCS on PHP 7.4 can parse and fix code with PHP 8.4 syntax.

[kkmuffme]

No, you misunderstood me: PHPCS on PHP 7.4 with config php_version 80400 can fix code with PHP 8.4 syntax - but "php84 -l file.php" should pass without errors
Similarly: PHPCS on 8.4 with config php_version 70400 can fix code with PHP 7.4 syntax - "php74 -l file.php" should pass without errors.
This is what I meant should be checked in the CI (like other tools e.g. psalm do)

Therefore:

Can I just check the PHP_VERSION_ID and skip the test in that version? Or are there any other ways implemented to run tests version specific?

using PHP_VERSION_ID would be wrong, I'd need to check the php_version of phpcs config for that case and skip the test in that case. It seems there are no other tests that are version specific? Does this mean I can just remove the failing test, since it's only failing in PHP 7.4?

[kukulich]

I don't usually test default values - only specific values of the options (yes and no here). However you can test it by standard ways of PHPUnit.

See other tests data for the lint check for specific PHP versions.

[kkmuffme]

Added tests, please merge