This can happen e.g. if all supertypes were on the cycle (A : B, B : A)
-- then SupertypesLoopChecker will cut all supertypes that are on cycle,
leaving set of supertypes empty.
Some clients in the compiler are not ready to work with empty list of
supertypes -- notably, CommonSupertypes.
^KT-23029 Fixed
Mostly it's about detecting loops in supertypes
Test data changes:
- Loops are being disconnected in Java classes too
- functions.kt: loops disconnection mechanism runs supertypes calculation,
so when we start check T it forces F' supertypes calculation, that ends
with CYCLIC_GENERIC_UPPER_BOUND reported on F
#KT-11287 In Progress
Dmitry Savvinov