Abstract methods declared by traits and implemented by parent classes shouldn't raise errors

[Slamdunk]

Bug report

Abstract methods declared by traits and implemented by parent classes shouldn't raise errors, at least not on Level 0.

Code snippet that reproduces the problem

abstract class AbstractFoo {
	public function myFoo(): void {}
}
trait TraitFoo {
	abstract public function myFoo(): void;
}
final class ClassFoo extends AbstractFoo {
	use TraitFoo;
}

https://phpstan.org/r/12ccc2ea-b367-471b-9da9-7efd57b012a4

Expected output

No errors, at least not on Level 0, as this is valid code: https://3v4l.org/BOAEE

[danrot]

Any reason this should raise an error at all? IMO this is valid code, and it is completely valid to use traits like that, isn't it?

[ghost]

Any reason this should raise an error at all? IMO this is valid code, and it is completely valid to use traits like that, isn't it?

Sure, it is valid and I am facing the same issue. Lots of valid code is now marked as error

[ondrejmirtes]

Yes, it’s valid code, it’s just that this edge case wasn’t covered by any test. It will be fixed soon.

[marc-mabe]

I have the same issue with methods declared in traits : https://phpstan.org/r/1c7d4b55-9b31-4b71-94c9-caa14c699553

[freshp]

I got the same error with phpstan version 0.12.26.

I could not ignore these type of error, whether with --generate-baseline or by regex.

ignoreErrors:
    - '#Non-abstract class .* contains abstract method getView\(\) from class#'

The error: "cannot be ignored, use excludes_analyse instead." occured instead.

At the moment I have to exclude the files completly.

Does it belong to the same error?

At the moment I downgrade to 0.12.25 to prevent these error.

[phil-davis]

Does it belong to the same error?

I had this kind of thing start being reported by 0.12.26 and it was a genuine problem. The trait had code like:

trait LegacyDependencyCheckPolyfill {

	/**
	 * @return string
	 */
	abstract public function getStorageClass();
...

And the class had:

class DAV extends ExternalBackend {
	use LegacyDependencyCheckPolyfill;
...

and the error report is correct - someone who tries to instantiate that DAV class directly will find that there is no implementation of getStorageClass() available.

So when you have a "real" class that ends up having just an abstract method (not a real implementation of the method), the problem is being correctly reported.

For me, the error report is new, because IMO phpstan now analyses the content of traits properly.

[SamMousa]

But if ExternalBackend has an implementation it should not result in an error, which it does currently.

[ondrejmirtes]

Traits are so weird! Look at this example:

https://3v4l.org/1aQa0

Normal method from trait shadows the method from the parent class but abstract method from trait does not shadow the method from the parent class.

[Slamdunk]

Normal method from trait shadows the method from the parent class

That's ok as trait are copy-paste

but abstract method from trait does not shadow the method from the parent class.

Abstract methods in trait are just nonsense in fact, even thou are legit.
I would consider them errors in phpstan-strict-rules

[ondrejmirtes]

Fixed: ondrejmirtes/BetterReflection@aac16f0 + phpstan/phpstan-src@b79c08d

[dktapps]

This is still a problem with latest dev-master when the inheritance is not direct. See https://github.com/dktapps/phpstan-traits-abstract-bug-test

[ondrejmirtes]

@dktapps This issue is closed. Can you report this as a new issue?

[dktapps]

Sure, working on it right now.

[github-actions]

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