Revert "[CxxInterop] Import C++ references." (#31777)

Author: compnerd

include/swift/AST/Types.h

@@ -2696,10 +2696,10 @@ enum class FunctionTypeRepresentation : uint8_t {
   /// A "thin" function that needs no context.
   Thin,
 
-  /// A C function pointer (or reference), which is thin and also uses the C
-  /// calling convention.
+  /// A C function pointer, which is thin and also uses the C calling
+  /// convention.
   CFunctionPointer,
-
+  
   /// The value of the greatest AST function representation.
   Last = CFunctionPointer,
 };
@@ -2980,8 +2980,8 @@ class AnyFunctionType : public TypeBase {
       // We preserve a full clang::Type *, not a clang::FunctionType * as:
       // 1. We need to keep sugar in case we need to present an error to the user.
       // 2. The actual type being stored is [ignoring sugar] either a
-      //    clang::PointerType, a clang::BlockPointerType, or a
-      //    clang::ReferenceType which points to a clang::FunctionType.
+      //    clang::PointerType or a clang::BlockPointerType which points to a
+      //    clang::FunctionType.
       const clang::Type *ClangFunctionType;
 
       bool empty() const { return !ClangFunctionType; }

lib/AST/Type.cpp

@@ -3376,8 +3376,7 @@ void AnyFunctionType::ExtInfo::Uncommon::printClangFunctionType(
 void
 AnyFunctionType::ExtInfo::assertIsFunctionType(const clang::Type *type) {
 #ifndef NDEBUG
-  if (!(type->isFunctionPointerType() || type->isBlockPointerType() ||
-        type->isFunctionReferenceType())) {
+  if (!(type->isFunctionPointerType() || type->isBlockPointerType())) {
     SmallString<256> buf;
     llvm::raw_svector_ostream os(buf);
     os << "Expected a Clang function type wrapped in a pointer type or "

lib/ClangImporter/ImportType.cpp

@@ -159,30 +159,6 @@ namespace {
     explicit operator bool() const { return (bool) AbstractType; }
   };
 
-  static ImportResult importFunctionPointerLikeType(const clang::Type &type,
-                                                    const Type &pointeeType) {
-    auto funcTy = pointeeType->castTo<FunctionType>();
-    return {FunctionType::get(
-                funcTy->getParams(), funcTy->getResult(),
-                funcTy->getExtInfo()
-                    .withRepresentation(
-                        AnyFunctionType::Representation::CFunctionPointer)
-                    .withClangFunctionType(&type)),
-            type.isReferenceType() ? ImportHint::None
-                                    : ImportHint::CFunctionPointer};
-  }
-
-  static ImportResult importOverAlignedFunctionPointerLikeType(
-      const clang::Type &type, ClangImporter::Implementation &Impl) {
-    auto opaquePointer = Impl.SwiftContext.getOpaquePointerDecl();
-    if (!opaquePointer) {
-      return Type();
-    }
-    return {opaquePointer->getDeclaredType(),
-            type.isReferenceType() ? ImportHint::None
-                                    : ImportHint::OtherPointer};
-  }
-
   class SwiftTypeConverter :
     public clang::TypeVisitor<SwiftTypeConverter, ImportResult>
   {
@@ -430,11 +406,23 @@ namespace {
       // alignment is greater than the maximum Swift alignment, import as
       // OpaquePointer.
       if (!pointeeType || Impl.isOverAligned(pointeeQualType)) {
-        return importOverAlignedFunctionPointerLikeType(*type, Impl);
+        auto opaquePointer = Impl.SwiftContext.getOpaquePointerDecl();
+        if (!opaquePointer)
+          return Type();
+        return {opaquePointer->getDeclaredType(),
+                ImportHint::OtherPointer};
       }
-
+      
       if (pointeeQualType->isFunctionType()) {
-        return importFunctionPointerLikeType(*type, pointeeType);
+        auto funcTy = pointeeType->castTo<FunctionType>();
+        return {
+          FunctionType::get(funcTy->getParams(), funcTy->getResult(),
+            funcTy->getExtInfo()
+              .withRepresentation(
+                AnyFunctionType::Representation::CFunctionPointer)
+              .withClangFunctionType(type)),
+          ImportHint::CFunctionPointer
+        };
       }
 
       PointerTypeKind pointerKind;
@@ -484,29 +472,7 @@ namespace {
     }
 
     ImportResult VisitReferenceType(const clang::ReferenceType *type) {
-      auto pointeeQualType = type->getPointeeType();
-      auto quals = pointeeQualType.getQualifiers();
-      Type pointeeType =
-          Impl.importTypeIgnoreIUO(pointeeQualType, ImportTypeKind::Value,
-                                   AllowNSUIntegerAsInt, Bridgeability::None);
-
-      if (pointeeQualType->isFunctionType()) {
-        return importFunctionPointerLikeType(*type, pointeeType);
-      }
-
-      if (Impl.isOverAligned(pointeeQualType)) {
-        return importOverAlignedFunctionPointerLikeType(*type, Impl);
-      }
-
-      PointerTypeKind pointerKind;
-      if (quals.hasConst()) {
-        pointerKind = PTK_UnsafePointer;
-      } else {
-        pointerKind = PTK_UnsafeMutablePointer;
-      }
-
-      return {pointeeType->wrapInPointer(pointerKind),
-              ImportHint::None};
+      return Type();
     }
 
     ImportResult VisitMemberPointer(const clang::MemberPointerType *type) {

lib/ClangImporter/ImporterImpl.h

@@ -135,10 +135,9 @@ enum class ImportTypeKind {
 
   /// Import the type of a function parameter.
   ///
-  /// Special handling:
-  /// * C and C++ pointers become `UnsafePointer?` or `UnsafeMutablePointer?`
-  /// * C++ references become `UnsafePointer` or `UnsafeMutablePointer`
-  /// * Bridging that requires type conversions is allowed.
+  /// This provides special treatment for C++ references (which become
+  /// [inout] parameters) and C pointers (which become magic [inout]-able types),
+  /// among other things, and enables the conversion of bridged types.
   /// Parameters are always considered CF-audited.
   Parameter,
 

lib/SIL/IR/AbstractionPattern.cpp

@@ -319,8 +319,6 @@ getClangFunctionType(const clang::Type *clangType) {
     clangType = ptrTy->getPointeeType().getTypePtr();
   } else if (auto blockTy = clangType->getAs<clang::BlockPointerType>()) {
     clangType = blockTy->getPointeeType().getTypePtr();
-  } else if (auto refTy = clangType->getAs<clang::ReferenceType>()) {
-    clangType = refTy->getPointeeType().getTypePtr();
   }
   return clangType->castAs<clang::FunctionType>();
 }