Enum assertions

[orklah]

This will fix #7654

It doesn't adress the collapsing issue, but it makes sure the assertions are correctly reconciled

[orklah]

I made a check that went a little too far so I had to revert it, but it saw this line as redundant. I couldn't find the reason for this, it seems redundant indeed

[weirdan]

Does it actually test reconciliation with Enum|Enum::Case? It doesn't seem like an individual enum case would ever appear in this test case.

[orklah]

what I wanted to test was the enum case not leaking to the negated if like in here: #7654 (comment)

The test would be cleaner without null values, (it showed Code|Code::Ok and never on the other var before) but assertions doesn't work if the var appears only in an if

[weirdan]

I mean, this test passes on 5.0a1 (I just tested that). So it doesn't cover changes introduced in this PR.

[orklah]

Ugh :( I'll try to design a better test then!

[weirdan]

What you could do instead is to abort (exit or throw) in the if body, and then assert the type as it was changed below the if. E.g.

[
            'EnumCaseReconciliation' => [
                'code' => '<?php
                    enum Code: int
                    {
                        case Ok = 0;
                        case Fatal = 1;
                    }

                    function foo(): Code|null|int
                    {
                        return null;
                    }

                    $code = foo() ?? Code::Ok;
                    if (!$code instanceof Code) throw new RuntimeException;
                    ',
                'assertions' => [
                    '$code===' => 'Code',
                ],
                'ignored_issues' => [],
                'php_version' => '8.1',
            ],
]