In this commit we drop less concrete members in intersection.
See for example change in test data: before the commit, we intersected
all three A.foo, B.foo and C.foo in diamond hierarchy. After the commit
we drop A.foo and intersect B.foo and C.foo only.
If some java class has multiple supertypes then we need to collect
overriddens from all those types directly, even if superTypeScope
(which is FirTypeIntersectionScope in this case) returns only
one symbol from one of this types (not intersection one)
This is needed to proper enhancement in cases when some type occurs
multiple times in supertypes graph with different nullability
of arguments:
class ConcurrentHashMap<K, V> : AbstractMap<K!, V!>, MutableMap<K, V>
If we try to find method `get(key: K): V` supertype scope returns
`AbstractMap.get(key: K!): V!` (because it actually overrides
`MutableMap(key: K): V?`), but we need to get both symbols to
properly enhance types for `ConcurrentHashMap.remove`
Previously we inferred "open" if there was at least one open member in the
hierarchy. However, that's not correct when that member is overridden by
another member in the hierarchy which is abstract. This led to incorrect code
being accepted by the front-end, and an exception during the bridge generation
#KT-12467 Fixed
Mikhail Glukhikh