Kotlin/Native codegen needs to deserialize all fields throughout the class hierarchy to build the proper binary class layout. That becomes impossible with the guard condition that prevents loading private top-level classes from another module in LazyIR (see https://github.com/JetBrains/kotlin/blob/2a4d8800374578c1aa9ec9c996b393a98f5a6e3b/kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanIrlinker.kt#L701). The guard suits well for the partial linkage needs, but it causes the codegen to fail with `Unbound public symbol IrClassPublicSymbolImpl: [ File '/file/in/the/library.kt' <- private.top.level/ClassDeclaration|null[0] ]` error.
To prevent this the guard is removed. This does not influence the partial linkage in general except for the different error message being generated: `Function 'foo' can not be called: Private function declared in module <A> can not be accessed in module <B>` instead of `Function 'foo' can not be called: No function found for symbol '<symbol>'`.
#KT-54469
Dmitriy Dolovov