Wire 7.0.0-alpha (1/2/3): Android variant Kotlin source set empty — KSP and compileKotlin see no user sources

[adrianczuczka]

Summary

After upgrading to Wire 7.0.0-alpha (any of alpha01, alpha02, alpha03), KSP runs against an Android library variant but receives zero Kotlin source files. The Kotlin compile task for the variant likewise does not see the user's .kt files under src/main/java. Both release and debug variants reproduce identically.

For projects using KSP-driven libraries (e.g. koin-ksp-compiler), this surfaces as missing generated symbols at consumer sites — e.g. Unresolved reference 'defaultModule' / Unresolved reference 'module' when importing org.koin.ksp.generated.*.

Versions

• Wire Gradle plugin: reproduced on 7.0.0-alpha01, alpha02, and alpha03
• Android Gradle Plugin: 9.2.1
• Kotlin: 2.2.21
• KSP: 2.3.7
• Gradle: 9.4.1
• KSP processor in use: io.insert-koin:koin-ksp-compiler:2.1.0
• Build target: com.android.library

(Wire 6.4.0 works for KSP but breaks sourceReleaseJar per #3558 — the fix for which is what landed in 7.x and triggered this regression.)

Module config

plugins {
    id("com.android.library")
    alias(libs.plugins.wire)
    alias(libs.plugins.ksp)
    alias(libs.plugins.kotlin.compose)
}

dependencies {
    implementation(libs.wire.runtime)
    implementation(libs.koin.annotations)
    ksp(libs.koin.ksp)
}

wire {
    kotlin { javaInterop = true }
    sourcePath { srcDir("src/main/proto") }
}

User Kotlin sources live under src/main/java/... (the conventional shared dir for Kotlin + Java co-located code in many Android codebases).

Symptom — diagnostic output

./gradlew :my-library:kspReleaseKotlin --rerun-tasks --info:

> Task :my-library:kspReleaseKotlin
Task ':my-library:kspReleaseKotlin' is not up-to-date because:
  The input changes require a full rebuild for incremental task ...
i: [ksp] loaded provider(s): [org.koin.compiler.BuilderProcessorProvider]
BUILD SUCCESSFUL

Note: every other Android library module in the project emits a Kotlin source files: <list> line at this point during --info. The Wire-using module emits nothing — KSP sees an empty source set.

my-library/build/generated/ksp/ is created but contains no release/ or debug/ subdirectory after the task runs (KSP only creates per-variant output dirs when it actually emits something).

The same is true for kspDebugKotlin — variant-independent.

What rules in / out

• Not specific to release variant — debug variant reproduces identically.
• Not specific to singleVariant("release") { withSourcesJar() } — the KSP failure happens regardless of that publishing config.
• Not a KSP / processor wiring issue — the processor loads cleanly (loaded provider(s): [...BuilderProcessorProvider]).
• Not a stale cache — reproduced after clean and with --rerun-tasks, configuration cache disabled.
• Specific to Wire 7.x — same project on Wire 6.4.0 has a populated Kotlin source set and KSP generates output normally (it just hits Wire v6 sourceReleaseJar task broken #3558 on sourceReleaseJar).

Hypothesis (best guess only)

The KotlinTarget source-root rework that closed #3558 / shipped via #3566 appears to leave the AGP variant's Kotlin source container in a state where the user's src/main/java .kt files are no longer visible to either compileKotlin or ksp{Variant}Kotlin. I suspect the variant API call that registers Wire's generated output is also displacing or overriding the variant's existing Kotlin source set rather than appending to it, but I haven't narrowed this down further — flagging in case the diagnosis is obvious to maintainers familiar with the AGP 9 variant API.

Repro

Happy to put together a minimal repro on a public Gist if useful — the shape is just any com.android.library module with wire + ksp + Kotlin sources under src/main/java.

[oldergod]

I was not able to repro. If you can create a repro project, I'll fix it right away 👍

[adrianczuczka]

Hi, thanks for the quick reply! With claude's help I believe I was able to reproduce with a minimal project, attached here.

repro.zip

The bug requires all of:

1. Wire plugin com.squareup.wire 7.0.0-alpha03 applied to a com.android.library module.
2. KSP applied with at least one processor that consumes the variant's Kotlin sources (the repro
   uses koin-ksp-compiler).
3. At least one Kotlin source file in the module that imports a Wire-generated proto type.

Remove condition 3 and KSP receives the variant's sources again and the build is green. So the bug isn't Wire + KSP by itself, it's specifically Wire's variant source-root rewiring becoming incorrect once downstream Kotlin sources reference Wire-generated types. At least that's what it seems like in the repro project.

Versions

Tool	Version
Gradle	9.4.1
AGP	9.2.1
Kotlin	2.2.21
KSP	2.3.7
Wire	7.0.0-alpha03
koin-annotations	2.1.0
koin-ksp	2.1.0
compileSdk	35
minSdk	28
JDK	21 toolchain

Reproduce (after unzipping):

  echo "sdk.dir=$HOME/Library/Android/sdk" > local.properties
  ./gradlew :library:clean :library:compileReleaseKotlin \
      --no-build-cache --no-configuration-cache