IssueTracker

(I'm creating this bug based on Internal Issue 234414461.)

Steps to reproduce

• In app, set minSdk >= 24 (when minSdk < 24, dexing transforms are not incremental)
• In lib, set compileOption.targetCompatibility = "11" (in lower Java versions, nest members do not exist)
• In lib, write a Java class with nested classes
• Copy this project to another location. Run ./gradlew :app:mergeLibDexDebug --build-cache at that location.
• Come back to the current project, run ./gradlew :app:mergeLibDexDebug --build-cache. Many tasks/transforms should have cache hits.
• Make a change to the Java class above or its nested classes.
• Run ./gradlew :app:mergeLibDexDebug --build-cache again. It will fail with:

* What went wrong:
Execution failed for task ':app:mergeLibDexDebug'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Failed to transform debug (project :lib) to match attributes {artifactType=android-dex, asm-transformed-variant=NONE, com.android.build.api.attributes.AgpVersionAttr=8.1.0-dev, com.android.build.api.attributes.BuildTypeAttr=debug, com.android.build.gradle.internal.attributes.VariantAttr=debug, dexing-enable-desugaring=true, dexing-enable-jacoco-instrumentation=false, dexing-is-debuggable=true, dexing-min-sdk=24, org.gradle.category=library, org.gradle.jvm.environment=android, org.gradle.libraryelements=classes, org.gradle.usage=java-runtime, org.jetbrains.kotlin.platform.type=androidJvm}.
      > Execution failed for DexingNoClasspathTransform: MyApplication/lib/build/intermediates/runtime_library_classes_dir/debug.
         > Error while dexing.
...
Caused by: com.android.builder.dexing.DexArchiveBuilderException: Error while dexing.
        at com.android.builder.dexing.D8DexArchiveBuilder.getExceptionToRethrow(D8DexArchiveBuilder.java:186)
        at com.android.builder.dexing.D8DexArchiveBuilder.convert(D8DexArchiveBuilder.java:125)
        at com.android.build.gradle.internal.dependency.BaseDexingTransform.process(DexingTransform.kt:316)
        at com.android.build.gradle.internal.dependency.BaseDexingTransform.processIncrementally(DexingTransform.kt:227)
        at com.android.build.gradle.internal.dependency.BaseDexingTransform.doTransform(DexingTransform.kt:137)
        at com.android.build.gradle.internal.dependency.BaseDexingTransform.transform(DexingTransform.kt:107)
...
Caused by: com.android.tools.r8.CompilationFailedException: Compilation failed to complete, origin: MyApplication/lib/build/intermediates/runtime_library_classes_dir/debug/com/example/lib/JavaClass.class
        at Version.fakeStackEntry(Version_8.1.8-dev.java:0)
...
        at com.android.builder.dexing.D8DexArchiveBuilder.convert(D8DexArchiveBuilder.java:123)
        ... 125 more
Caused by: com.android.tools.r8.utils.b: Compilation of classes com.example.lib.JavaClass requires its nest mates com.example.lib.JavaClass$NestedClass (unavailable) to be on program or class path.
...

Root cause

Dexing transforms use a desugaring graph to store dependencies among class files for incremental dexing/desugaring.

The desugaring graph's nodes are currently absolute paths, which means after a remote cache hit, it will not be usable and will result in subsequent failed incremental builds.

We were aware of this issue when designing the graph and used a workaround, but (I think) at some point Gradle changed the behavior and it no longer worked.

Potential fix

Make the desugaring graph relocatable. It is a bit difficult because there isn't one single root path to normalize the absolute file paths (instead, there are multiple root paths).

(If we can't work out a solution soon, the temporary measure is to ensure in the first build after a remote cache hit, affected transforms will be non-incremental.)