I'm moving some testing code to a testing-support module in order to access from multiple modules. The code needs to access some internal APIs of the original module though. So I'm using

@file:Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")

to allow this, but I'm getting a compilation error for a specific internal API:

Compilation failed: Backend Internal error: Exception during IR lowering

The root cause org.jetbrains.kotlin.backend.common.CompilationException was thrown at: org.jetbrains.kotlin.ir.symbols.impl.IrBindablePublicSymbolBase.getOwner(IrPublicSymbolBase.kt:52)

Is this expected where some internal APIs can't be accessed in this way? It works on JVM, but not native targets.

you can use some Gradle config to allow different source sets to view internal members https://kotlinlang.org/docs/gradle-configure-project.html#associate-compiler-tasks, but I don’t think it’s possible across subprojects (well, it probably is possible somehow, but not simply!) As an alternative there are opt-in annotations https://kotlinlang.org/docs/opt-in-requirements.html#require-opt-in-for-api

I created an issue in YouTrack: https://youtrack.jetbrains.com/issue/KT-58949