PrintAsClang is supposed to emit declarations in the same order regardless of the compiler’s internal state, but we have repeatedly found that our current criteria are inadequate, resulting in non-functionality-affecting changes to generated header content. Add a diagnostic that’s emitted when this happens soliciting a bug report.
Since there *should* be no cases where the compiler fails to order declarations, this diagnostic is never actually emitted. Instead, we test this change by enabling `-verify` on nearly all PrintAsClang tests to make sure they are unaffected.
This did demonstrate a missing criterion that only mattered in C++ mode: extensions that varied only in their generic signature were not sorted stably. Add a sort criterion for this.
Currently, we do not support exporting zero-sized value types from Swift
to C++. It needs some work on our end as these types are not part of the
lowered signature. In the meantime, this PR makes sure that common (but
not all) zero sized types are properly marked as unavailable. This is
important as the proper diagnostic will give users a hint how to work
around this problem. Moreover, it is really easy to hit this when
someone is experimenting with interop, so it is important to not have a
cryptic failure mode.
rdar://138122545
Each emitted declaration is annotated with the external_source_symbol with its own USR, to allow Clang's indexer to recognize this declaration as a Swift declaration with a specific USR
This allows you to import a method that returns the type of the context in which the method is declared when such
type is a generic parameter in another type. This means that it's now possible to bridge the initializer for
RawRepresentable enums.
This change extends the clang header printer to start emitting C++ classes for Swift struct types with the correct struct layout in them (size + alignment)
