Check the #[\Override] attribute on class constants and enum cases

[Amoifr]

Closes phpstan/phpstan#15370

PHP 8.6 allows #[\Override] on class constants and enum cases (RFC). This follows what was done for properties in 8b85e62, 7f73847 and 64e9776:

• A constant or enum case with #[\Override] that overrides nothing is reported (classConstant.override, enum.caseOverride), regardless of the PHP version, like methods and properties. A private parent constant does not count, as the RFC says. The fix removes the attribute.
• A constant or enum case that overrides an inherited one without #[\Override] is reported (classConstant.missingOverride, enum.caseMissingOverride) when the new checkMissingOverrideConstantAttribute parameter is enabled. When it is null (the default), it follows checkMissingOverrideMethodAttribute on PHP 8.6+, like checkMissingOverridePropertyAttribute does on PHP 8.5+. The fix adds the attribute. Constants declared in traits are skipped, as for properties.

The shared logic lives in OverrideAttributeOnConstantCheck, used by OverridingConstantRule and a new OverridingEnumCaseRule (enum cases are EnumCase nodes, and their prototype can only come from an interface). For const A = 1, B = 2; the attribute applies to both constants, so no fix is offered there.

The new parameter mirrors the property one. If you would rather reuse checkMissingOverrideMethodAttribute without a dedicated parameter, I'm happy to change it. I have not touched the documentation on the website.

[VincentLanglet]

Parse error: tests/PHPStan/Rules/Constants/data/constant-override-attr.php:57
    55| {
    56| 	#[\Override]
  > 57| 	const FROM_PARENT = 5;
    58| 
    59| 	const PROTECTED_FROM_PARENT = 5;
Traits cannot have constants

I think you need // lint >= 8.2 rather than // lint >= 8.0.

[Amoifr]

Good catch, thanks! Trait constants need 8.2, so the fixture is now // lint >= 8.2 and both tests require PHP 8.2. I also added a test with a 8.5 to 8.6 version range for the missing attribute check.

[VincentLanglet]

Lint build is still failing ; check at

------------------------------------------------------------
Parse error: tests/PHPStan/Rules/Constants/data/constant-override-attr-fix.php:15
    13| 
    14| 	#[\Override]
  > 15| 	const BAR = 2;
    16| }
Attribute "Override" cannot target class constant (allowed targets: method, property)
------------------------------------------------------------
Parse error: tests/PHPStan/Rules/Constants/data/constant-override-attr.php:20
    18| {
    19| 	#[\Override]
  > 20| 	const FROM_INTERFACE = 2;
    21| 
    22| 	#[\Override]
Attribute "Override" cannot target class constant (allowed targets: method, property)
------------------------------------------------------------
Parse error: tests/PHPStan/Rules/EnumCases/data/enum-case-override-attr.php:13
    11| {
    12| 	#[\Override]
  > 13| 	case FOO = 'foo';
    14| 
    15| 	#[\Override]
Attribute "Override" cannot target class constant (allowed targets: method, property)

https://github.com/phpstan/phpstan-src/actions/runs/37407089096/job/112086933426?pr=6685

[Amoifr]

Thanks, and sorry for the second round! #[\Override] on a class constant only compiles on PHP 8.6, so the three fixtures are now // lint >= 8.6. I also checked them with php -l this time.

[Amoifr]

One more: PHP 8.6 itself rejects an #[\Override] that overrides nothing, so the two constant fixtures are now excluded from lint, like property-override-attr.php. I checked the whole lint target with the official php:8.6-rc-cli image this time. Sorry for the noise!