Add rule to detect redundant trait usage #279

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Closed

AronNovak wants to merge 2 commits into phpstan:2.0.x from AronNovak:add-no-redundant-trait-use-rule

Closed

Add rule to detect redundant trait usage #279

AronNovak wants to merge 2 commits into phpstan:2.0.x from AronNovak:add-no-redundant-trait-use-rule

Conversation

@AronNovak

Copy link

@AronNovak AronNovak commented Aug 27, 2025

This rule detects when a class uses both a trait A and trait B, where trait A already uses trait B (either directly or transitively).

Features

Detects direct redundancy (class uses A and B, A uses B)
Detects transitive redundancy (class uses A and C, A uses B, B uses C)
Configurable via strictRules.noRedundantTraitUse parameter

Example

trait BarTrait {}
trait FooTrait { use BarTrait; }
class MyClass {
 use FooTrait;
 use BarTrait; // Error: redundant, already included via FooTrait
}

AronNovak added 2 commits

August 27, 2025 14:24

@AronNovak


 Add NoRedundantTraitUseRule to detect redundant trait usage

1c557a8

@AronNovak


 Fix missing newlines at end of test data files

17e7463

@AronNovak AronNovak mentioned this pull request

Aug 27, 2025

Add rule to detect redundant trait usage mglaman/phpstan-drupal#912

Closed

@AronNovak AronNovak changed the title ~~(削除) Add NoRedundantTraitUseRule to detect redundant trait usage (削除ここまで)~~ (追記) Add rule to detect redundant trait usage (追記ここまで)

Aug 28, 2025

@ondrejmirtes

Copy link

Member

ondrejmirtes commented Aug 29, 2025

Hi,
I don't think this is a very common and bug-inducing problem. Additionally, there might be valid reasons to do this if you account for trait adaptations (with insteadof and as keywords).

As usual, feel free to publish this as your own package, or try to pitch this idea to other maintainers of strict rules packages like https://github.com/shipmonk-rnd/phpstan-rules or https://github.com/ergebnis/phpstan-rules 😊

@ondrejmirtes ondrejmirtes closed this

Aug 29, 2025

@AronNovak

Copy link

Author

AronNovak commented Aug 29, 2025

@ondrejmirtes It's problematic performance-wise. On a client project, phpstan needed 7 minutes to complete. After eliminating excessive redundant trait use, we were down to ~3 minutes. It can be a huge performance penalty for phpstan, and the reason is obvious, the trait is evaluated in every possible context where it appears. This redundant trait usage is problematic for this reason. Also it indicates bad design, but it's opinionated.