When a type annotated with @PurelyImplements (explicitly or implicitly)
inherited some methods from a java supertype and the purely implemented
Kotlin supertype, it was inconsistent which of the signatures the
intersection override would have (with or without flexible types).
This commit adds support for the enhancement of intersection overrides.
If one of the overridden methods has non-flexible types, the enhanced
method will have non-flexible types.
This fixes some false negative nullability type mismatches.
#KT-59921 Fixed
That issue might be fixed via changing
TypeVariableMarker.shouldBeFlexible at ConeConstraintSystemUtilContext
but this and some other tricks have been added because of incorrect
handling of constraints where type variable has a flexible bound
^KT-51168 Fixed
This directive anyway does not make test run twice with OI, and with NI
It only once run the test with specific settings (// LANGUAGE)
and ignores irrelevant (OI or NI tags)