kapt is reported as unused plugin on an excluded unused annotation processor dependency

[ivanalvarado]

Is your feature request related to a problem? Please describe.

The plugin is raising an error that the kapt plugin is unused even when it's applied to an excluded unused dependency in a gradle project.

For example, in this project our dependency analysis plugin is configured to not fail if 'com.google.dagger:hilt-android-compiler' is unused for annotation processors: build-configuration/project-health.gradle

dependencyAnalysis {
    issues {
        onUnusedDependencies {
            severity('ignore')
        }
        onUsedTransitiveDependencies {
            severity('ignore')
        }
        onIncorrectConfiguration {
            severity('ignore')
        }
        onUnusedAnnotationProcessors {
            severity('fail')
            exclude('com.google.dagger:hilt-android-compiler')
        }
        onRedundantPlugins {
            severity('fail')
        }

        ignoreKtx(true)
    }
}

In the mylibrary/build.gradle we have 'com.google.dagger:hilt-android-compiler:2.43.2' configured with kapt:

apply plugin: "com.android.library"
apply plugin: "kotlin-android"
apply plugin: "kotlin-kapt"

...

dependencies {
    kapt 'com.google.dagger:hilt-android-compiler:2.43.2'
    ...
    implementation 'com.google.dagger:hilt-android:2.43.2'
}

When we run dependency analysis plugin by doing ./gradlew :mylibrary:projectHealth, the plugin correctly excludes 'com.google.dagger:hilt-android-compiler' from being reported as an unused annotation processor, but raises that the kapt plugin was applied but no annotation processors were used:

> Task :mylibrary:projectHealth FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':mylibrary:projectHealth'.
> Unused plugins that can be removed:
    kotlin-kapt: this project has the kotlin-kapt (org.jetbrains.kotlin.kapt) plugin applied, but there are no used annotation processors.

Describe the solution you'd like

We expect the plugin to detect that 'com.google.dagger:hilt-android-compiler' is excluded and because it's using the kapt plugin, the plugin shouldn't be reported as unused.

Describe alternatives you've considered

We are able to add a workaround for now by excluding kotlin-kapt as a redundant plugin in the dependency analysis configuration. However, we feel this is a bit aggressive:

onRedundantPlugins {
    severity('fail')
    exclude('kotlin-kapt')
}

Additional context

We assume that the plugin is detecting that because 'com.google.dagger:hilt-android-compiler' is unused and configured with kapt, then it effectively detects the kapt plugin as unused as well and thus raises this as an error.

We've create a project that easily reproduces this behavior: https://github.com/ivanalvarado/Dependency-Analysis-Plugin-Repro Simply run ./gradlew :mylibrary:projectHealth and observe the failure.

[autonomousapps]

Thanks for the issue. I'm a bit on the fence as to whether this is a bug or a feature request :) I'll certainly consider whether some improvement could be made in this area.

[ivanalvarado]

Thanks for the issue. I'm a bit on the fence as to whether this is a bug or a feature request :) I'll certainly consider whether some improvement could be made in this area.

Thanks for considering this. In the meantime, we've got a workaround where we apply a plugin configuration in the failing module like the following:

apply plugin: "com.android.library"
apply plugin: "kotlin-android"
apply plugin: "kotlin-kapt"

...

dependencies {
    kapt 'com.google.dagger:hilt-android-compiler:2.43.2'
    ...
    implementation 'com.google.dagger:hilt-android:2.43.2'
}

// Dependency Analysis returns the kotlin-kapt could be removed. However the test execution fails(kapt used in test
// implementation. Ignoring manually.
dependencyAnalysis {
    issues {
        onAny {
            severity('fail')
            exclude('kotlin-kapt')
        }
    }
}