This commit introduces proper handling of recursion in scopes, which
could occur when some of companion object supertypes are members of
that companion owner:
```
class Container {
open class Base
companion object : Base()
}
```
To resolve `Base`, we have to build member scope for `Container`.
In the member scope of `Container`, we see all classifiers from
companion and his supertypes
So, we have to resolve companion objects supertype, which happens to be
`Base` again - therefore, we encounter recursion here.
Previously, we created `ThrowingLexicalScope` for such recursive calls,
but didn't checked for loop explicitly, which lead to a wide variety of
bugs (see https://jetbrains.quip.com/dc5aABhZoaQY and KT-10532).
To report such cyclic declarations properly, we first change
`ThrowingLexicalScope` to `ErrorLexicalScope` -- the main difference is
that latter doesn't throws ISE when someone tries to resolve type in it,
allowing us to report error instead of crashing with exception.
Then, we add additional fake edge in supertypes graph (from
host-class to companion object) which allows us to piggyback on existing
supertypes loops detection mechanism, and report such cycles for user.
When recursion is detected while computing
`ClassResolutionScopesSupport.scopeForMemberDeclarationResolution`,
create 'ThrowingLexicalScope' (as with other scopes), instead of
throwing ISE immediately. That allows to report error properly in cases
like in KT-18514
#KT-18514 Fixed
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
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
- when building a topsorted hierarchy, consider not only edges to the class'
superclasses, but also from inner/nested classes to their container. This
effectively means that a class cannot inherit from its nested class. Similar
cases (see the tests) are disallowed in Java.
- filter classes by their presence in TopDownAnalysisContext, not by being a
MutableClassDescriptor (otherwise analysis for local classes ends up trying
to do something with outer superclasses)
- delete outdated comment: topsort is needed not only for better diagnostics,
but also for correct order of fake overrides construction
Dmitry Savvinov