Explanation: Fixes an issue where the generated reverse interop header
would not compile for nested classes when library evolution is turned
off.
Scope: C++ reverse interop for nested classes for non-opaque types.
Issue: rdar://147882976
Risk: Low, the fix is fairly targeted. While it does affect other
(non-nested type) scenarios, those changes are fairly straightforward
making some names fully qualified. Moreover, that is well tested in our
test suite.
Testing: Added tests to test suite
Reviewer: @egorzhdan
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.
The generated header would not compile without these dependencies. Moreover
users probably expect all-public option to be the most permissive filter
including the maximal amount of declarations.
Swift-to-C++ thunk printing for functions didn’t really take into account Swift’s `Never` type. This type maps to `SWIFT_NORETURN`, but it also requires other tweaks to code generation, such as omitting the `return` keyword. (Removing that requires minor changes to many tests.)
Fixes rdar://124137073.
