Dependency-Analysis-Plugin-Repro

Reproduces an issue I'm experiencing using the Dependency Analysis Plugin where kapt plugin is reported as unused.

Issue

The Dependency Analysis 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.

According to the Hilt Android documentation, we need to configure the Hilt compiler with kapt:

dependencies {
    implementation "com.google.dagger:hilt-android:2.38.1"
    kapt "com.google.dagger:hilt-compiler:2.38.1"
}

Assumption

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.

Expected Behavior

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.

Workaround

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')
}