It is expected that under enable-private-import internal/private symbols
become public. So that symbol-diffing would fail. Disable symbol diffing
under that test mode.
rdar://51304243
This comes with a fix for a null pointer dereference in _typeByName()
that would pop with foreign classes that do not have a
NominalTypeDescriptor.
Also, I decided to back out part of the change for now, where the
NominalTypeDescriptor references an accessor function instead of a
pattern, since this broke LLDB, which reaches into the pattern to
get the generic cache.
Soon we will split off the generic cache from the pattern, and at
that time we can change the NominalTypeDescriptor to point at the
cache. But for now, let's avoid needless churn in LLDB by keeping
that part of the setup unchanged.
Change conformance records to reference NominalTypeDescriptors instead of
metadata patterns for resilient or generic types.
For a resilient type, we don't know if the metadata is constant or not,
so we can't directly reference either constant metadata or the metadata
template.
Also, whereas previously NominalTypeDescriptors would point to the
metadata pattern, they now point to the metadata accessor function.
This allows the recently-added logic for instantiating concrete types
by name to continue working.
In turn, swift_initClassMetadata_UniversalStrategy() would reach into
the NominalTypeDescriptor to get the pattern out, so that its bump
allocator could be used to allocate ivar tables. Since the pattern is
no longer available this way, we have to pass it in as a parameter.
In the future, we will split off the read-write metadata cache entry
from the pattern; then swift_initClassMetadata_UniversalStrategy() can
just take a pointer to that, since it doesn't actually need anything
else from the pattern.
Since Clang doesn't guarantee alignment for function pointers, I had
to kill the cute trick that packed the NominalTypeKind into the low
bits of the relative pointer to the pattern; instead the kind is now
stored out of line. We could fix this by packing it with some other
field, or keep it this way in case we add new flags later.
Now that generic metadata is instantiated by calling accessor functions,
this change removes the last remaining place that metadata patterns were
referenced from outside the module they were defined in. Now, the layout
of the metadata pattern and the behavior of swift_getGenericMetadata()
is purely an implementation detail of generic metadata accessors.
This patch allows two previously-XFAIL'd tests to pass.
We now test four setups, with the four {before, after}^2 runs of each:
a) Client adds conformance -vs- library adds public conformance -- fixed-layout struct
b) Client adds conformance -vs- library removes internal conformance -- fixed-layout struct
c) Client adds conformance -vs- library adds public conformance -- resilient struct
d) Client adds conformance -vs- library removes internal conformance -- resilient struct
The first two pass, but a) requires a hack to ensure we don't
directly reference conformance table, otherwise the 'after_before'
version doesn't link. I think the right idea here is to weakly
reference conformance tables where the deployment target is
lower than the availability of the conformance.
The second two are XFAIL'd until protocol conformance tables can
reference resilient types from other modules. This requires emitting
indirect metadata symbols, since the client doesn't know if the
resilient type's metadata is direct or a template, and the
conformance table cannot use the metadata accessor either.
These tests will also become important if we decide to revisit
synthesized accessors, and make them lazy again for structs.
