TypeRefBuilder and MetadataReader had nearly identical symbolic reference resolvers,
but diverged because TypeRefBuilder had its own local/remote address management mechanism,
and because TypeRefBuilder tries to resolve opaque types to their underlying types, whereas
other MetadataReader clients want to preserve them as written in source. The first problem
has been addressed by making TypeRefBuilder use `RemoteRef` everywhere, and the second
can be handled with a flag (and might be able to be handled more elegantly with some more
refactoring of general opaque type handling in MetadataReader).
The Remote Mirror interop header now accepts an arbitrary number of remote mirror libraries so that it can have 4.1, 4.2, and 5.0 loaded side by side.
rdar://problem/45808282
Right now we expect that every class and protocol has a field
descriptor that tells us if the entity is @objc or not.
For imported types, the descriptor will not exist if we did not
directly emit a field whose concrete type contains the imported
type. For example, in lldb, we might have a generic type whose
runtime substituted type includes an imported type.
In this case, TypeLowering would fail to produce a layout because
it did not find a field descriptor for the imported type.
A better approach is to have the TypeDecoder call a different
factory method for imported types, and handle them specially in
TypeLowering, bypassing the field type metadata altogether.
TypeDecoder's interface with its builders already treated protocols as
a type (due to their being mangled as "protocol composition containing
one type"), and intermixed protocols with superclasses when forming
compositions. This makes for some awkwardness when working with
protocol descriptors, which are very much a distinct entity from a
type.
Separate out the notion of a "protocol declaration" (now represented
by the builder-provided BuiltProtocolDecl type) from "a protocol
composition containing a single type", similarly to the way we handle
nominal type declarations. Teach remote mirrors and remote AST to
handle the new contract.
Somehow ninja didn't rebuild everything, so I ended up pushing code
that didn't compile. I did a clean re-build and fixed a minor issue
in the logic, now the test passes.
When deriving substitutions from closure contexts, we end up with
a problem where we have an original type and a substituted type,
and the original type is not necessarily a type parameter.
We need to decompose the original and substituted types to derive
the substitutions that produced the substitution.
For example, deriveSubstitutions(Foo<T -> Int>, Foo<String -> Int>)
will give us a substitution of T := Int.
A TypeRef for C<T, U>, substituted to C<Int, Int>, should have the same
pointer identity as a C<Int, Int> created by other means. This prevents
repeating reflective layout work if we've already seen a particular
instantiation of a generic type.
We'd like to be able to compare TypeRefs with pointer equality,
but we can't link LLVMSupport, so make a lightweight TypeRefID
like FoldingSetID, that only supports the input types necessary
to unique TypeRefs.
rdar://problem/25924875
