`getOrBuildFir` does not record `FirCheckedSafeCallSubject`
expression, and it would be impossible to get them anyway
since there are no PSI corresponding to "not null receiver"
in expressions like `foo?.bar` - there is only `foo`,
which is considered nullable by FIR
`FirCheckedSafeCallSubject` wrapper has non-null type during
resolve, and it becomes very important in
`KtFirCompletionCandidateChecker`. If we loose the wrapper,
then it would be impossible to call extensions on nullable
types using `?.` syntax
^KTIJ-21021 Fixed
Before all files were going to `getOrCreateSymbolLightFacade`. If there
were both compiled and source files, it caused exceptions later
(see `SymbolLightClassFacadeCache.getOrCreateFirLightFacadeNoCache`).
When grouped by the `KtModule`, each file group should contain either
only sources or only compiled classes.
^KTIJ-20637 Fixed
The IDE expects the super type calls to resolve to the constructor
invoked and not the class. The frontend itself resolves to the
class, so an extra layer is needed to adjust that to the constructor.
It's necessary to allow a?.b += v be interpreted as a?.(b += v)
But currently FirAssignmentOperatorStatement is not FirQualifiedAccess
^KT-41034 In Progress
Use-site substitution override happens in situations like this:
```
interface List<A> { fun get(i: Int): A }
fun take(list: List<String>) {
list.get(10) // this call
}
```
We want to have those overrides unwrapped, because we don't want
to deal with a different KtSymbol for each possible use-site
^KT-50862 Fixed
This cache wasn't working too well, because ConeTypes have
equals/hashCode implementations which do not account for types'
attributes (like annotations, for example).
Because of that, `String` and `@Annotated String` were considered the
same type, and the cache was remembering whichever came first.
This is a temporary fix to avoid crashes in FIR IDE
Of all stub types, only `ConeStubTypeForChainInference` is handled now,
so we can catch the other possible errors with stub types (in the
delegates' inference, for example)
The fix introduced in this commit should be reworked when KT-50916 is
fixed
^KTIJ-20826 Fixed
Roman Golyshev