Strip it of any "useful" information but a reference to the corresponding
symbol owner (file or a declaration).
TODO: add that useful information to declarations.
NB not all IrDeclarations have IrSymbols (IrProperty doesn't - at least now).
NB can't make 'override val descriptor: SimpleFunctionDescriptor' there,
because there are quite some FunctionDescriptors that are not
SimpleFunctionDescriptor, but actually belong to this category.
To get rid of pointless/confusing implementations in ModuleDescriptor,
PackageViewDescriptor, TypeParameterDescriptor and others.
Note that there are still implementations that do not make sense, for
example in those subclasses of VariableDescriptor which are not also
subclasses of CallableMemberDescriptor (e.g. ValueParameterDescriptor).
Those can be removed by making CallableMemberDescriptor (instead of
CallableDescriptor) inherit from Substitutable. However, that would
require more changes in the compiler because CallableDescriptor is used
rather often in places where in fact only CallableMemberDescriptor
instances can appear.
Explicit return types and casts are required in some places now because
there's no single non-trivial supertype for
ClassifierDescriptorWithTypeParameters and CallableDescriptor.
Previously it was DeclarationDescriptorWithVisibility, now it's both
that and Substitutable<...>
Expression '1.unaryMinus()' is resolved as Int::unaryMinus call with Int receiver.
However, this expression is implicitly coerced to a different integral type (Byte, Short, Long)
based on results of constant evaluation.
Introduce IMPLICIT_INTEGER_COERCION type operator to handle such cases.
TODO: should we use it for simple constant expressions like '1' and '-1'?
Update parser & descriptor renderer to handle parenthesized types and function types properly.
Resolve annotations in parenthesized types.
AnnotationsImpl.isEmpty() returned false for targeted annotations only
(e.g., 'fun @receiver:Ann C?.foo()').
Properly keep track of targeted annotations.
Dmitry Petrov