This test is not executed by the pre-commit CI, so the failure went
unnoticed after #80495. This PR updates the test to make the CI pass.
rdar://148665873
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.
This is a fallout from emitting Swift StdLib dependencies when all
public decls are emitted. This was not found before because the test was
not executed by the CI.
rdar://131556373
