[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

Author: egorzhdan

include/swift/AST/ASTContext.h

@@ -833,6 +833,9 @@ class ASTContext final {
   /// and results.
   const clang::Type *getClangTypeForIRGen(Type ty);
 
+  const clang::TypedefType *
+  getTypedefForCXXCFOptionsDefinition(const clang::Decl *candidateDecl);
+
   /// Determine whether the given Swift type is representable in a
   /// given foreign language.
   ForeignRepresentationInfo

include/swift/AST/ClangModuleLoader.h

@@ -306,9 +306,6 @@ class ClangModuleLoader : public ModuleLoader {
   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

@@ -603,9 +603,6 @@ class ClangImporter final : public ClangModuleLoader {
   /// 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;
-
   SourceLoc importSourceLocation(clang::SourceLocation loc) override;
 };
 

lib/AST/ASTContext.cpp

@@ -5732,6 +5732,48 @@ ASTContext::getClangTypeForIRGen(Type ty) {
   return getClangTypeConverter().convert(ty).getTypePtrOrNull();
 }
 
+const clang::TypedefType *ASTContext::getTypedefForCXXCFOptionsDefinition(
+    const clang::Decl *candidateDecl) {
+  if (!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 =
+      enumDecl->getIntegerType()->getAs<clang::ElaboratedType>();
+  if (auto typedefType =
+          elaboratedType
+              ? dyn_cast<clang::TypedefType>(elaboratedType->desugar())
+              : enumDecl->getIntegerType()->getAs<clang::TypedefType>()) {
+    auto enumExtensibilityAttr =
+        elaboratedType
+            ? enumDecl->getAttr<clang::EnumExtensibilityAttr>()
+            : typedefType->getDecl()->getAttr<clang::EnumExtensibilityAttr>();
+    const bool hasFlagEnumAttr =
+        elaboratedType ? enumDecl->hasAttr<clang::FlagEnumAttr>()
+                       : typedefType->getDecl()->hasAttr<clang::FlagEnumAttr>();
+
+    if (enumExtensibilityAttr &&
+        enumExtensibilityAttr->getExtensibility() ==
+            clang::EnumExtensibilityAttr::Open &&
+        hasFlagEnumAttr) {
+      // 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;
+      }
+    }
+  }
+
+  return nullptr;
+}
+
 GenericParamList *ASTContext::getSelfGenericParamList(DeclContext *dc) const {
   auto *theParamList = getImpl().SelfGenericParamList;
   if (theParamList)

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 ctx.getTypedefForCXXCFOptionsDefinition(clangDecl);
 }
 
 const clang::NamedDecl *

lib/ClangImporter/ClangImporter.cpp

@@ -7022,46 +7022,6 @@ void ClangImporter::withSymbolicFeatureEnabled(
       oldImportSymbolicCXXDecls.get());
 }
 
-const clang::TypedefType *ClangImporter::getTypeDefForCXXCFOptionsDefinition(
-    const clang::Decl *candidateDecl) {
-
-  if (!Impl.SwiftContext.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());
-  if (auto typedefType =
-          elaboratedType
-              ? dyn_cast<clang::TypedefType>(elaboratedType->desugar())
-              : dyn_cast<clang::TypedefType>(
-                    enumDecl->getIntegerType().getTypePtr())) {
-    auto enumExtensibilityAttr =
-        elaboratedType
-            ? enumDecl->getAttr<clang::EnumExtensibilityAttr>()
-            : typedefType->getDecl()->getAttr<clang::EnumExtensibilityAttr>();
-    const bool hasFlagEnumAttr =
-        elaboratedType ? enumDecl->hasAttr<clang::FlagEnumAttr>()
-                       : typedefType->getDecl()->hasAttr<clang::FlagEnumAttr>();
-
-    if (enumExtensibilityAttr &&
-        enumExtensibilityAttr->getExtensibility() ==
-            clang::EnumExtensibilityAttr::Open &&
-        hasFlagEnumAttr) {
-      return Impl.isUnavailableInSwift(typedefType->getDecl()) ? typedefType
-                                                               : nullptr;
-    }
-  }
-
-  return nullptr;
-}
-
 bool importer::requiresCPlusPlus(const clang::Module *module) {
   // The libc++ modulemap doesn't currently declare the requirement.
   if (module->getTopLevelModuleName() == "std")

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)) {
+                nameImporter.getContext().getTypedefForCXXCFOptionsDefinition(
+                    enumDecl)) {
           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]