[cxx-interop] Refactor: do not rely on Clang module importer being available

This makes sure that we can emit a pch from a C++ header that uses `CF_OPTIONS`.

rdar://112225263

include/swift/AST/ClangModuleLoader.h

@@ -306,9 +306,6 @@ public:
   virtual EffectiveClangContext getEffectiveClangContext(
       const NominalTypeDecl *nominal) = 0;
 
-  virtual const clang::TypedefType *
-  getTypeDefForCXXCFOptionsDefinition(const clang::Decl *candidateDecl) = 0;
-
   virtual SourceLoc importSourceLocation(clang::SourceLocation loc) = 0;
 };
 

include/swift/ClangImporter/ClangImporter.h

@@ -603,8 +603,8 @@ public:
   /// Enable the symbolic import experimental feature for the given callback.
   void withSymbolicFeatureEnabled(llvm::function_ref<void(void)> callback);
 
-  const clang::TypedefType *getTypeDefForCXXCFOptionsDefinition(
-      const clang::Decl *candidateDecl) override;
+  static const clang::TypedefType *getTypedefForCXXCFOptionsDefinition(
+      const clang::Decl *candidateDecl, const ASTContext &ctx);
 
   SourceLoc importSourceLocation(clang::SourceLocation loc) override;
 };

lib/AST/ASTMangler.cpp

@@ -2541,8 +2541,8 @@ ASTMangler::getTypeDefForCXXCFOptionsDefinition(const ValueDecl *decl) {
   if (!clangDecl)
     return nullptr;
 
-  const auto &clangModuleLoader = decl->getASTContext().getClangModuleLoader();
-  return clangModuleLoader->getTypeDefForCXXCFOptionsDefinition(clangDecl);
+  auto &ctx = decl->getASTContext();
+  return ClangImporter::getTypedefForCXXCFOptionsDefinition(clangDecl, ctx);
 }
 
 const clang::NamedDecl *

lib/ClangImporter/ClangImporter.cpp

@@ -7022,26 +7022,23 @@ void ClangImporter::withSymbolicFeatureEnabled(
       oldImportSymbolicCXXDecls.get());
 }
 
-const clang::TypedefType *ClangImporter::getTypeDefForCXXCFOptionsDefinition(
-    const clang::Decl *candidateDecl) {
-
-  if (!Impl.SwiftContext.LangOpts.EnableCXXInterop)
+const clang::TypedefType *ClangImporter::getTypedefForCXXCFOptionsDefinition(
+    const clang::Decl *candidateDecl, const ASTContext &ctx) {
+  if (!ctx.LangOpts.EnableCXXInterop)
     return nullptr;
 
   auto enumDecl = dyn_cast<clang::EnumDecl>(candidateDecl);
   if (!enumDecl)
     return nullptr;
-
   if (!enumDecl->getDeclName().isEmpty())
     return nullptr;
 
   const clang::ElaboratedType *elaboratedType =
-      dyn_cast<clang::ElaboratedType>(enumDecl->getIntegerType().getTypePtr());
+      enumDecl->getIntegerType()->getAs<clang::ElaboratedType>();
   if (auto typedefType =
           elaboratedType
               ? dyn_cast<clang::TypedefType>(elaboratedType->desugar())
-              : dyn_cast<clang::TypedefType>(
-                    enumDecl->getIntegerType().getTypePtr())) {
+              : enumDecl->getIntegerType()->getAs<clang::TypedefType>()) {
     auto enumExtensibilityAttr =
         elaboratedType
             ? enumDecl->getAttr<clang::EnumExtensibilityAttr>()
@@ -7054,8 +7051,13 @@ const clang::TypedefType *ClangImporter::getTypeDefForCXXCFOptionsDefinition(
         enumExtensibilityAttr->getExtensibility() ==
             clang::EnumExtensibilityAttr::Open &&
         hasFlagEnumAttr) {
-      return Impl.isUnavailableInSwift(typedefType->getDecl()) ? typedefType
-                                                               : nullptr;
+      // Make sure the typedef is marked as unavailable in Swift.
+      auto typedefDecl = typedefType->getDecl();
+      for (auto *attr :
+           typedefDecl->specific_attrs<clang::AvailabilityAttr>()) {
+        if (attr->getPlatform()->getName() == "swift")
+          return typedefType;
+      }
     }
   }
 

lib/ClangImporter/ImportType.cpp

@@ -2656,9 +2656,8 @@ ArgumentAttrs ClangImporter::Implementation::inferDefaultArgument(
     if (declIter != declsInContext.end()) {
       if (auto enumDecl = dyn_cast<clang::EnumDecl>(*declIter)) {
         if (auto cfOptionsTy =
-                nameImporter.getContext()
-                    .getClangModuleLoader()
-                    ->getTypeDefForCXXCFOptionsDefinition(enumDecl)) {
+                ClangImporter::getTypedefForCXXCFOptionsDefinition(
+                    enumDecl, nameImporter.getContext())) {
           if (cfOptionsTy->getDecl() == typedefDecl) {
             auto enumName = typedefDecl->getName();
             ArgumentAttrs argumentAttrs(DefaultArgumentKind::None, true,

test/Interop/Cxx/objc-correctness/custom-nsoptions.swift

@@ -1,7 +1,16 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/pch
+
 // RUN: %target-typecheck-verify-swift -verify-ignore-unknown -I %S/Inputs -enable-objc-interop -enable-experimental-cxx-interop
+
+// RUN: %target-swift-frontend -emit-pch -enable-objc-interop -enable-experimental-cxx-interop -o %t/pch/customNSOptions.pch %S/Inputs/customNSOptions.h
+// RUN: %target-typecheck-verify-swift -D BRIDGING_HEADER -I %S/Inputs -import-objc-header %t/pch/customNSOptions.pch -enable-objc-interop -enable-experimental-cxx-interop %s
+
 // REQUIRES: objc_interop
 
+#if !BRIDGING_HEADER
 import CustomNSOptions
+#endif
 
 let flags1: MyControlFlags = []
 let flags2: MyControlFlags = [.first]