I have an FIR Checker that runs on `interface Exam...

# compiler

[Zac Sweers]

I have an FIR Checker that runs on interface ExampleGraph, which extends some other generated class Contribution. This supertype is generated during FIR as well

@DependencyGraph(AppScope::class)
interface ExampleGraph : Impl.Contribution

// another file
@Inject
@ContributesBinding(AppScope::class)
class Impl : Base {
  // Generated in FIR
  interface Contribution {
    @Binds fun Impl.bindImplAsBase(): Base
  }
}

My checker checks that Contribution has a compatible visibility with ExampleGraph, as I want to give a more meaningful error message where possible than the standard compiler error message that would happen. However, a user reported that in an incremental compilation scenario where Impl is changed to internal (and thus incompatible, the public ExampleGraph would extend an internal type) but only the Impl file is ever passed to the checker. As a result, the issue escapes it since ExampleGraph is not passed to the checker again.

Is this expected? It surprised me because I would expect a changed visibility of a class's supertype to trigger recompilation or at least FIR checks.

I tried explicitly copying the visibility of the parent when generating the nested Contribution class just in case but alas no dice. We do generate a function during IR that we make visible to metadata that helps us avoid some IC issues, but since it's IR-only it's too late in the pipeline to help

[Zac Sweers]

Actually, to my surprise this is actually legal in kotlinc

interface Base
internal class Impl : Base {
  internal interface Contribution
}
class Graph : Impl.Contribution

Whereas this would be an error

class Graph(
  val contribution: Impl.Contribution
) : Impl.Contribution

[Zac Sweers]

Filed KT-77938 kotlinc does not error on internal supertypes