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

Author: zoecarver

clang/lib/Sema/SemaAvailability.cpp

@@ -122,6 +122,18 @@ ShouldDiagnoseAvailabilityInContext(Sema &S, AvailabilityResult K,
                                     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) {

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

@@ -0,0 +1,9 @@
+// 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
+};