[interop][SwiftToCxx] Add a base ref counted Swift class type to _SwiftCxxInteroperability.h header

Author: hyp

lib/PrintAsClang/PrintClangClassType.cpp

@@ -31,53 +31,24 @@ void ClangClassTypePrinter::printClassTypeDecl(
                            os << ";\n";
                          });
 
+  StringRef baseClassName = "RefCountedClass";
+  StringRef baseClassQualifiedName = "swift::_impl::RefCountedClass";
+
   os << "class ";
   printer.printBaseName(typeDecl);
   // FIXME: Add support for inherintance.
-  os << " final";
+  os << " final : " << baseClassQualifiedName;
   os << " {\n";
   os << "public:\n";
 
-  // Destructor releases the object.
-  os << "  inline ~";
-  printer.printBaseName(typeDecl);
-  os << "() { swift::" << cxx_synthesis::getCxxImplNamespaceName()
-     << "::swift_release(_opaquePointer); }\n";
-
-  os << "  inline ";
-  printer.printBaseName(typeDecl);
-  os << "(const ";
-  printer.printBaseName(typeDecl);
-  os << "& other) noexcept : _opaquePointer(other._opaquePointer) { swift::"
-     << cxx_synthesis::getCxxImplNamespaceName()
-     << "::swift_retain(_opaquePointer); }\n";
-
-  os << "  inline ";
-  printer.printBaseName(typeDecl);
-  os << " & operator=(const ";
-  printer.printBaseName(typeDecl);
-  os << "& other) noexcept {\n    swift::"
-     << cxx_synthesis::getCxxImplNamespaceName()
-     << "::swift_retain(other._opaquePointer);\n";
-  os << "    swift::" << cxx_synthesis::getCxxImplNamespaceName()
-     << "::swift_release(_opaquePointer);\n";
-  os << "    _opaquePointer = other._opaquePointer;\n";
-  os << "    return *this;\n";
-  os << "  }\n";
-
-  // FIXME: move semantics should be restricted?
-  os << "  inline ";
-  printer.printBaseName(typeDecl);
-  os << "(";
-  printer.printBaseName(typeDecl);
-  os << "&&) noexcept = default;\n";
+  os << "  using " << baseClassName << "::" << baseClassName << ";\n";
+  os << "  using " << baseClassName << "::operator=;\n";
 
   os << "private:\n";
   os << "  inline ";
   printer.printBaseName(typeDecl);
-  os << "(void * _Nonnull ptr) noexcept : _opaquePointer(ptr) {}\n";
-  os << "\n  void * _Nonnull _opaquePointer;\n";
-  os << "  friend class " << cxx_synthesis::getCxxImplNamespaceName() << "::";
+  os << "(void * _Nonnull ptr) noexcept : " << baseClassName << "(ptr) {}\n";
+  os << "\n  friend class " << cxx_synthesis::getCxxImplNamespaceName() << "::";
   printCxxImplClassName(os, typeDecl);
   os << ";\n";
   os << "};\n\n";

stdlib/public/SwiftShims/_SwiftCxxInteroperability.h

@@ -53,6 +53,29 @@ inline void opaqueFree(void *_Nonnull p) noexcept {
 #endif
 }
 
+/// Base class for a Swift reference counted class value.
+class RefCountedClass {
+public:
+  inline ~RefCountedClass() { swift_release(_opaquePointer); }
+  inline RefCountedClass(const RefCountedClass &other) noexcept
+      : _opaquePointer(other._opaquePointer) {
+    swift_retain(_opaquePointer);
+  }
+  inline RefCountedClass &operator=(const RefCountedClass &other) noexcept {
+    swift_retain(other._opaquePointer);
+    swift_release(_opaquePointer);
+    _opaquePointer = other._opaquePointer;
+    return *this;
+  }
+  // FIXME: What to do in 'move'?
+  inline RefCountedClass(RefCountedClass &&) noexcept = default;
+
+protected:
+  inline RefCountedClass(void *_Nonnull ptr) noexcept : _opaquePointer(ptr) {}
+
+  void *_Nonnull _opaquePointer;
+};
+
 } // namespace _impl
 
 /// Swift's Int type.

test/Interop/SwiftToCxx/class/swift-class-in-cxx.swift

@@ -31,21 +31,13 @@ public final class ClassWithIntField {
 // CHECK-EMPTY:
 // CHECK-NEXT: } // namespace _impl
 // CHECK-EMPTY:
-// CHECK-NEXT: class ClassWithIntField final {
+// CHECK-NEXT: class ClassWithIntField final : swift::_impl::RefCountedClass {
 // CHECK-NEXT: public:
-// CHECK-NEXT:   inline ~ClassWithIntField() { swift::_impl::swift_release(_opaquePointer); }
-// CHECK-NEXT:   inline ClassWithIntField(const ClassWithIntField& other) noexcept : _opaquePointer(other._opaquePointer) { swift::_impl::swift_retain(_opaquePointer); }
-// CHECK-NEXT:   inline ClassWithIntField & operator=(const ClassWithIntField& other) noexcept {
-// CHECK-NEXT:     swift::_impl::swift_retain(other._opaquePointer);
-// CHECK-NEXT:     swift::_impl::swift_release(_opaquePointer);
-// CHECK-NEXT:     _opaquePointer = other._opaquePointer;
-// CHECK-NEXT:     return *this;
-// CHECK-NEXT:   }
-// CHECK-NEXT:   inline ClassWithIntField(ClassWithIntField&&) noexcept = default;
+// CHECK-NEXT:   using RefCountedClass::RefCountedClass;
+// CHECK-NEXT:   using RefCountedClass::operator=;
 // CHECK-NEXT: private:
-// CHECK-NEXT:   inline ClassWithIntField(void * _Nonnull ptr) noexcept : _opaquePointer(ptr) {}
+// CHECK-NEXT:   inline ClassWithIntField(void * _Nonnull ptr) noexcept : RefCountedClass(ptr) {}
 // CHECK-EMPTY:
-// CHECK-NEXT:   void * _Nonnull _opaquePointer;
 // CHECK-NEXT:   friend class _impl::_impl_ClassWithIntField;
 // CHECK-NEXT: };
 // CHECK-EMPTY:
@@ -66,7 +58,7 @@ public final class ClassWithIntField {
 
 public final class register { }
 
-// CHECK: class register_ final {
+// CHECK: class register_ final : swift::_impl::RefCountedClass {
 
 public func returnClassWithIntField() -> ClassWithIntField {
   return ClassWithIntField()