[clang/cxx-interop] Teach clang to ignore availability errors that come from CF_OPTIONS

[thakis]

Summary

This cherry-picks https://github.com/apple/llvm-project/pull/6431
since without it, macOS 14 SDK headers don't compile when targeting
catalyst.

Fixes #64438.

---

The github issue has all the details: https://github.com/llvm/llvm-project/issues/64438

The patch maybe looks a bit eh, but doing something different downstream also seems a bit eh. The system headers are precision matched to this patch.

(I'll commit this with @zoecarver as author to not steal attribution 🙂)

[hans]

lgtm

Maybe we want this for the release/17.x branch too?

[thakis]

bb58748e52ebd48a46de20525ef2c594db044a11

[thakis]

In D157245#4565166, @hans wrote:

lgtm

Thanks!

Maybe we want this for the release/17.x branch too?

Sure, trying that here: https://github.com/llvm/llvm-project/issues/64496

clang/lib/Sema/SemaAvailability.cpp

 /// the context of \c Ctx. For example, we should emit an unavailable diagnostic
 /// in a deprecated context, but not the other way around.
 static bool
 ShouldDiagnoseAvailabilityInContext(Sema &S, AvailabilityResult K,
                                     VersionTuple DeclVersion, Decl *Ctx,
                                     const NamedDecl *OffendingDecl) {
   assert(K != AR_Available && "Expected an unavailable declaration here!");
 
+  // If this was defined using CF_OPTIONS, etc. then ignore the diagnostic.
+  auto DeclLoc = Ctx->getBeginLoc();
+  // This is only a problem in Foundation's C++ implementation for CF_OPTIONS.
+  if (DeclLoc.isMacroID() && S.getLangOpts().CPlusPlus &&
+      isa<TypedefDecl>(OffendingDecl)) {
+    StringRef MacroName = S.getPreprocessor().getImmediateMacroName(DeclLoc);
+    if (MacroName == "CF_OPTIONS" || MacroName == "OBJC_OPTIONS" ||
+        MacroName == "SWIFT_OPTIONS" || MacroName == "NS_OPTIONS") {
+      return false;
+    }
+  }
+
   // Checks if we should emit the availability diagnostic in the context of C.
   auto CheckContext = [&](const Decl *C) {
     if (K == AR_NotYetIntroduced) {
       if (const AvailabilityAttr *AA = getAttrForPlatform(S.Context, C))
         if (AA->getIntroduced() >= DeclVersion)
           return true;
     } else if (K == AR_Deprecated) {
       if (C->isDeprecated())

clang/test/SemaCXX/suppress-availability-error-cf-options.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+#define CF_OPTIONS(_type, _name) __attribute__((availability(swift, unavailable))) _type _name; enum : _name
+
+__attribute__((availability(macOS, unavailable)))
+typedef CF_OPTIONS(unsigned, TestOptions) {
+  x
+};