An overridden abstract member with a more specific "return type" than an overridden concrete member
should be explicitly overridden even if the class in question can have abstract members.
It helps to get rid of semantics duplicating and fixes known bugs
- SOE in OnlyAbstractMethodFinder.find
- type enhancement for SAM constructors
#KT-11287 Fixed
#KT-11322 Fixed
EA-77989 Fixed
Given overridden descriptors D = d[i].
1. Find D*, subset of D:
returnType(d* from D*) <: returnType(d) for each d from D.
Always prefer var to val.
2. Prefer non-flexible return type to flexible.
Check for var/val overrides properly
(NB: this will report PROPERTY_TYPE_MISMATCH_ON_OVERRIDE
for all properties, not just overrides involving vars as it was before).
- Tests.
- No need for a separate diagnostic message regarding
return/property type conflict on override by delegation:
it is always a conflict of inherited signatures.
Overridden signatures should have compatible return types
(equal types for 'var').
Only relevant overrides should be taken into account.
Refactor inherited signatures check,
introduce a strategy interface for problem reporting.
Mikhail Zarechenskiy