KSP error when upgrading Android project to Compose Compiler 2.0.0

Question

I am upgrading my project to use Kotlin 2.0.0 with the Compose Compiler of the same version. I ran the AGP upgrade assistant which upgraded the Gradle version to 8.7 and the com.android.application plugin to version 8.5. My build.gradle.kts files are as follows:

Project build.gradle.kts:

plugins {
    id("com.android.application") version "8.5.0" apply false
    id("org.jetbrains.kotlin.android") version "2.0.0" apply false
    id("com.google.dagger.hilt.android") version "2.51" apply false
    id("com.google.devtools.ksp") version "2.0.0-1.0.22" apply false
    id("org.jetbrains.kotlin.plugin.compose") version "2.0.0" apply false
    id("org.jetbrains.kotlin.plugin.serialization") version "1.8.10" apply false
}

App build.gradle.kts:

import com.google.protobuf.gradle.id

plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
    id("org.jetbrains.kotlin.plugin.compose")
    id("com.google.protobuf") version "0.9.4"
    id("com.google.dagger.hilt.android")
    id("com.google.devtools.ksp")
    id("kotlinx-serialization")
}

android {}

composeCompiler {
    enableStrongSkippingMode = true

    reportsDestination = layout.buildDirectory.dir("compose_compiler")
    stabilityConfigurationFile = rootProject.layout.projectDirectory.file("stability_config.conf")
}

dependencies {
    // Other dependencies omitted
    implementation("com.google.protobuf:protobuf-javalite:3.24.1")
}

protobuf {
    protoc {
        artifact = "com.google.protobuf:protoc:3.24.1"
    }

    generateProtoTasks {
        all().configureEach {
            builtins {
                id("java") {
                    option("lite")
                }
            }
        }
    }
}

The Gradle task :app:kspDebugKotlin is failing with the following error:

e: [ksp] InjectProcessingStep was unable to process 'UserPreferencesRepositoryImpl(androidx.datastore.core.DataStore<error.NonExistentClass>)' because 'error.NonExistentClass' could not be resolved.

Dependency trace:
    => element (CLASS): com.codejockie.wani.wk.data.repository.UserPreferencesRepositoryImpl
    => element (CONSTRUCTOR): UserPreferencesRepositoryImpl(androidx.datastore.core.DataStore<error.NonExistentClass>)
    => type (EXECUTABLE constructor): (androidx.datastore.core.DataStore<error.NonExistentClass>)void
    => type (DECLARED parameter type): androidx.datastore.core.DataStore<error.NonExistentClass>
    => type (ERROR type argument): error.NonExistentClass

If type 'error.NonExistentClass' is a generated type, check above for compilation errors that may have prevented the type from being generated. Otherwise, ensure that type 'error.NonExistentClass' is on your classpath.
e: [ksp] ModuleProcessingStep was unable to process 'com.codejockie.wani.di.DataStoreModule' because 'error.NonExistentClass' could not be resolved.

What could be wrong?

Answer 1

I was able to solve this issue after several hours of searching the internet. I came across a GitHub issue where someone mentioned a similar issue to mine. The fix required adding the below snippet to my app module build.gradle.kts file.

androidComponents {
    onVariants(selector().all()) { variant ->
        afterEvaluate {
            val capName = variant.name.capitalized()
            tasks.getByName<KotlinCompile>("ksp${capName}Kotlin") {
                setSource(tasks.getByName("generate${capName}Proto").outputs)
            }
        }
    }
}

Here is the link to the GitHub issue I referenced.