[cxx-interop] A little macros fix; breadcrumbs for future fixes.

Author: zoecarver

lib/ClangImporter/ImportMacro.cpp

@@ -328,6 +328,8 @@ static Optional<std::pair<llvm::APSInt, Type>>
     }
 
   // Macro identifier.
+  // TODO: for some reason when in C++ mode, "hasMacroDefinition" is often
+  // false: rdar://110071334
   } else if (token.is(clang::tok::identifier) &&
              token.getIdentifierInfo()->hasMacroDefinition()) {
 
@@ -422,7 +424,7 @@ static ValueDecl *importMacro(ClangImporter::Implementation &impl,
       auto diagState = impl.getClangSema().DelayedDiagnostics.push(diagPool);
       auto parsedType = impl.getClangSema().getTypeName(identifier,
                                                         clang::SourceLocation(),
-                                                        /*scope*/nullptr);
+                                                        impl.getClangSema().TUScope);
       impl.getClangSema().DelayedDiagnostics.popWithoutEmitting(diagState);
 
       if (parsedType && diagPool.empty()) {

test/ClangImporter/macros.swift

@@ -1,5 +1,8 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-objc-interop -typecheck -verify %s
 
+// Most of these don't pass: rdar://110071334
+// %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-experimental-cxx-interop -enable-objc-interop -typecheck -verify %s
+
 @_exported import macros
 
 func circle_area(_ radius: CDouble) -> CDouble {