Gradle incremental compilation doesn't detect changes to transitively included modules

We have been using incremental compilation with Gradle for a few months, and we find it’s effective in a majority of cases. However, we found that it fails to detect changes to the types bound with @Binds or the elements in a multibound set or map. One simple way to repro is to build a Dagger module that contains a single binding like this:

@Module
abstract class DaggerModule {
  @Binds
  abstract Base provideBase(SubclassB subclass);
}

Replacing SubclassA with SubclassB here won’t cause the component to be regenerated. I created a small sample to facilitate a repro: https://github.com/cesar1000/dagger-incremental-bug.

I’m not sure whether this is a bug in Gradle or Dagger - @oehme and @autonomousapps, can you take a look?

[oehme]

This is a bug in Gradle. I’ve pushed a fix, which will be in 5.4. This doesn’t just affect Dagger, but is a general problem with how we handle transitive dependencies. I guess it was never detected because usually the intermediate project fails when you remove some API. But in this case it just removes one of many bindings, so everything was still valid.

[ronshapiro]

Thanks!