This handles optionality changes and type rewrites in function param and return types and constructor param and failability types.
Resolves rdar://problem/31766010
Parameter defs with a separate external argument label are marked with the 'Local' symbol property.
This ensures the indexer has enough information for clients to match up a function's argument labels with its child parameter definitions.
Resolves rdar://problem/31039915.
Also rename ASTWalker::shouldWalkIntoFunctionGenericParams() to shouldWalkIntoGenericParams() since it's now used when walking NominalTypeDecl (not just AbstractFunctionDecl).
Since the memory underlying returned USRs is guaranteed to last until
the indexing action completes, add a finish() hook so that clients can
trigger an action at the end of indexing but before the memory goes
away.
Fold UnitTest into the subkind, now that it's a bitself, and then remove
the unnecessary inheritance for IndexSymbol and its SourceKit indexing
equivalent.
Eventually we should just have one IndexSymbol, with all the
information. Once we kill FuncDeclIndexSymbol and can get rid of the
enum, we will regain most of the bytes we lost by inlining receiverUSR.
As a first step toward having more detailed "role" information, thread
through a SymbolRole bitset. For now it just contains the existing ref
vs. definition status.
Having a single interface for source files and modules and having to
pass in a buffer id was a crappy API. This splits the interface to take
either a Module or a SourceFile and handles the buffer id stuff
internally.
