If some function is not fake-override, then its type should be just
default type of containing class
For fake overrides the default type calculated in the following way:
1. Find first overridden function, which is not fake override
2. Take its containing class
3. Find supertype of current containing class with type constructor of
class from step 2
^KT-60252 Fixed
For type parameters of generic properties,
`DeclarationDescriptor#getContainingDeclaration` must return
the property descriptor instead of the accessor function descriptor.
^KT-57436 Fixed
The reason #1 for this feature is that we want to test IdSignatures
generated for declarations. Currently, there is no (easy) way to ensure
that a change in the signature building logic doesn't cause any breaking
changes wrt klibs.
Now, most IdSignatures include hashed mangled names in them, so even if
we catch a regression where the included hash changes, there would be no
way of knowing immediately what caused it, unless we'd also have mangled
names in the expectations.
The reason #2 is to test the manglers themselves. Currently, there are
no tests for them. They heavily duplicate each other, this is already
causing issues (see KT-57427) that would be very hard to catch without
these tests.
^KT-58238 Fixed
Dmitriy Novozhilov