This is yet another waypoint on the path towards the final
generic-metadata design. The immediate goal is to make the
pattern a private implementation detail and to give the runtime
more visibility into the allocation and caching of generic types.
The dumper method dumps:
1. The container's metadata pointer.
2. A pointer to the container's value.
3. Whether or not said value is stored inline in the container.
This provides a general overview that can be used even when working with SIL
code in the debugger by grabbing a pointer to swift Anys and then calling the
c++ any method upon them.
The verifier is intended to be used in conjunction with ASAN for maximum
effect to catch use-after-frees of existential boxes.
While implementing this I refactored some code from ExistentialTypeMetadata into
methods on OpaqueExistentialContainer. ExistentialTypeMetadata just calls these
methods now instead of implementing the code inline.
All of the information contained by this field (list of property names)
is already encoded as part of the field reflection metadata and
is accessible via `swift_getFieldAt` runtime method.
Use information from reflection section of the binary to lookup
type field info such as name and it's type and return it using
new `swift_getFieldAt` method based on nominal type and field index.
The old-style mirrors were the basis for non-custom, reflection based Mirrors. As part of removing old-style mirrors, reflection based Mirrors are reimplemented without them. Reflection.mm is deleted and replaced with ReflectionMirror.mm, which borrows a chunk of the old code but presents a simpler API to the Swift side. ReflectionMirror.swift then uses that API to implement a reflection-based Mirror init.
rdar://problem/20356017
@objc protocols don't have witness tables. However, both type metadata
(in the nominal type descriptors) and the runtime code to demangle
type names into metadata weren't acknowledging this. Fix type metadata
emission to not count an "extra argument" for @objc protocol
conformance requirements, and teach the runtime code to properly look
for conformances to @objc protocols (through the Objective-C runtime)
and not record witness tables for them.
This makes resolving mangled names to nominal types in the same module more efficient, and for eventual secrecy improvements, also allows types in the same module to be referenced from mangled typerefs without encoding any source-level name information about them.
