[cxx-interop] Use translation unit scope when doing lookups

lib/ClangImporter/ClangAdapter.cpp

@@ -554,7 +554,7 @@ clang::TypedefNameDecl *importer::findSwiftNewtype(const clang::NamedDecl *decl,
     clang::LookupResult lookupResult(clangSema, notificationName,
                                      clang::SourceLocation(),
                                      clang::Sema::LookupOrdinaryName);
-    if (!clangSema.LookupName(lookupResult, nullptr))
+    if (!clangSema.LookupName(lookupResult, clangSema.TUScope))
       return nullptr;
     auto nsDecl = lookupResult.getAsSingle<clang::TypedefNameDecl>();
     if (!nsDecl)

lib/ClangImporter/ClangImporter.cpp

@@ -2757,7 +2757,7 @@ ClangImporter::Implementation::lookupTypedef(clang::DeclarationName name) {
                                    clang::SourceLocation(),
                                    clang::Sema::LookupOrdinaryName);
 
-  if (sema.LookupName(lookupResult, /*scope=*/nullptr)) {
+  if (sema.LookupName(lookupResult, sema.TUScope)) {
     for (auto decl : lookupResult) {
       if (auto typedefDecl =
           dyn_cast<clang::TypedefNameDecl>(decl->getUnderlyingDecl()))

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/cf.swift

@@ -1,5 +1,7 @@
 // RUN: %target-swift-frontend -disable-objc-attr-requires-foundation-module -typecheck -verify -import-cf-types -I %S/Inputs/custom-modules %s
 
+// RUN: %target-swift-frontend -disable-objc-attr-requires-foundation-module -typecheck -verify -import-cf-types -enable-experimental-cxx-interop -I %S/Inputs/custom-modules %s
+
 // REQUIRES: objc_interop
 
 import CoreCooling

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 {

test/Interop/Cxx/objc-correctness/Inputs/module.modulemap

@@ -12,3 +12,9 @@ module CxxClassWithNSStringInit [extern_c] {
 module NSOptionsMangling {
   header "NSOptionsMangling.h"
 }
+
+module NSNofiticationBridging {
+  header "nsnotification-bridging.h"
+  requires objc
+  requires cplusplus
+}

test/Interop/Cxx/objc-correctness/Inputs/nsnotification-bridging.h

@@ -0,0 +1,3 @@
+#import <Foundation/Foundation.h>
+
+extern NSString * const SpaceShipNotification;

test/Interop/Cxx/objc-correctness/nsnotification-bridging-ide-test.swift

@@ -0,0 +1,7 @@
+// RUN: %target-swift-ide-test -print-module -module-to-print=NSNofiticationBridging -I %S/Inputs -source-filename=x -enable-experimental-cxx-interop -enable-objc-interop | %FileCheck %s
+
+// REQUIRES: objc_interop
+
+// CHECK: import Foundation
+
+// CHECK: let SpaceShipNotification: String