Hybrid mode fail without meaningful error message

[kevinguitar]

Hi again,

We're trying to prepare different Anvil setup to benchmark the build performance, including KSP-only mode and hybrid mode (mentioned in this blog post), but we couldn't get the hybrid mode working, it failed during kaptDebugKotlin task where dagger component lives (we're using MergeComponent here), and there is no meaningful error message, below is our setup for KSP-only and hybrid.

KSP-only (everything is working fine)

override fun apply(project: Project) {
    project.apply(plugin = project.libs.plugins.ksp.get().pluginId)
    project.dependencies {
        ksp(project.libs.google.dagger.compiler)
    }
}

Hybrid

override fun apply(project: Project) {
    project.apply(plugin = project.libs.plugins.kotlin.kapt.get().pluginId)
    project.dependencies {
        kapt(project.libs.google.dagger.compiler)
    }
    
    project.extensions.configure<ApplicationAndroidComponentsExtension> {
        onVariants(selector().all()) { variant ->
            project.connectKspOutputsToKaptInputs(variant.name)
        }
    }
}

private fun Project.connectKspOutputsToKaptInputs(variantName: String) {
    afterEvaluate {
        val buildType = variantName.replaceFirstChar { it.titlecaseChar() }
        val kspTaskName = "ksp${buildType}Kotlin"
        val useKSP2 = providers.gradleProperty("ksp.useKSP2").getOrElse("false").toBoolean()
        val generatedKspKotlinFiles =
            if (useKSP2) {
                val kspReleaseTask = tasks.named<KspAATask>(kspTaskName)
                kspReleaseTask.flatMap { it.kspConfig.kotlinOutputDir }
            } else {
                val kspReleaseTask = tasks.named<KspTaskJvm>(kspTaskName)
                kspReleaseTask.flatMap { it.destination }
            }
        tasks.named<KotlinCompile>("kaptGenerateStubs${buildType}Kotlin").configure {
            source(generatedKspKotlinFiles)
        }
    }
}

I understand that it's very vague without an error message, but we're stuck, we would appreciate if you have any guide or hunch where the issue could be, thank you! 🙏

[ZacSweers]

Sorry but this isn't enough information to help. Error message or ideally a minimally reproducing project are needed to advise

[kevinguitar]

Understood, let me spend more time on this and see if I can resolve it or provide something meaningful. Thanks!

[kevinguitar]

We managed to figure out the issue, it's related to KAPT4, we've reverted to KAPT2 and the issue is gone. 🎉
google/dagger#4373