The change in
`FirOptInUsageBaseChecker` is needed
to prevent `OPT_IN_OVERRIDE` on
intersection overrides where one
of the base functions requires opt-in.
We never designed this in such
a way that it's an error.
See:
`FirPsiOldFrontendDiagnosticsTestGenerated.testIncorrectTargetsForExperimentalAnnotation`.
According to KT-63741, the case like
`kt40510.fir.kt` should, in fact,
be an error. It will be addressed
separately.
Those descriptors may be empty in case user made a mistake and tried to
delegate implementation of abstract class instead of interface (and
we don't add functions from abstract class to overriden descriptors
of fake overrides in case of delegation by)
#KT-40510 Fixed
Nikolay Lunyak