The compiler is generally free to not include pointers to metadata in
heap boxes, which are used for closure captures, if it knows you can get
to metadata through some other path. These MetadataSource classes will
describe a sequence of steps to get to metadata at runtime.
In the short term, this will be useful for describing the layout of
function/closure capture contexts, which can vary depending on what is
captured.
We will be handing pointers to typerefs over the SwiftRemoteMirrors C
API boundary, at which point it is unclear who will hold onto a shared
pointer. The useful lifetime of a typeref is tied to the
ReflectionContext for which they were created anyway so, when it goes
away, all of those typerefs can go away anyway.
We can't use LLVM's bump-pointer allocator here because we only build
the Support library for the host. As a compromise, stuff new typeref
pointers into a vector pool, where they will be taken down during
ReflectionContext's destructor.
Just drop labels when demangling TypeRefs. This is OK for now
since labels do not affect layout.
Vararg tuple types cannot appear directly as the type of
storage, however they can appear in function input types, and
therefore must be minimally supported. Since we don't plan on
doing function call reflection just yet, this doesn't matter
for now, but again we need to not crash.
With this patch, all TypeRefs in the Swift standard library now
successfully demangle and print.
swift-reflection-dump, a host-side tool, requires this library that
normally builds for the configured platform. So, if the host platform
isn't configured to build for some reason, swift-reflection-dump will
fail to link.
swift-reflection-test is now the test that forks a swift executable
and performs remote reflection, making it runnable on other targets,
such as the iOS simulator.
swift-reflection-dump is now a host-side tool that dumps the remote
reflection sections for any platform binary and will continue to
link in LLVM object file support.
This necessitates finally moving lib/Refleciton into stdlib/public,
since we're linking target-specific versions of the test tool and
we would eventually like to adopt some of this functionality in
the runtime anyway.
