When building with lazy initialization of the root conformance, we need
to ensure that we are invoking the accessor to initialize the
conformance record. We would previously generate a direct reference to
the conformance, which was uninitialized, resulting in a crash at
runtime.
The non-windows test changes here are to use/imply static linking for
the support modules. This should have no difference on the non-Windows
targets, but makes a difference on Windows where this implies that
everything will be built into a single module, which permits the
non-indirect access to types. Unfortunately, this does somewhat regress
the test coverage on Windows as we do not exercise as much of the shared
linkage paths which do change some of the code-generation to deal with
the moral equivalent of the GOT - the IAT.
Special thanks to @slavapestov for the pointer to
`isDependentConformance`. This should eliminate the last known issue
with cross-module protocol conformances.
Fixes: SR-14807
This adjusts the IRGen layer to accommodate the Windows linking model.
We assume dynamic linking by default. The static linking is enabled by
passing `-static` to the driver, which forwards it to the frontend when
building the module statically. This has already been required when
generating libraries, however, the non-Windows targets are more
forgiving and let it work. On those platforms, using this hint would
allow for more efficient code generation, reducing load times and some
runtime penalties from the PLT and GOT references formed to symbols
which are module local.
This corrects static linking on Windows, which is one of the last few
items that are missing on Windows. It also takes advantage of the hint
for the one peculiar difference between Windows and non-Windows:
protocol conformances that span module boundaries are not available as a
constant. However, when statically linking, we can enable those
conformances to be statically resolved. This should enable the last
known pattern to work when using static linking.
This support requires further work in the Swift Package Manager to
actually enable building libraries properly. However, when building
with CMake, this should be sufficient to enable static linking.
