[interop][SwiftToCxx] retain & release class values when a C++ class reference is copy assigned

Author: hyp

lib/PrintAsClang/PrintClangClassType.cpp

@@ -52,6 +52,19 @@ void ClangClassTypePrinter::printClassTypeDecl(
      << 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);

test/Interop/SwiftToCxx/class/swift-class-execution.cpp

@@ -74,6 +74,24 @@ int main() {
     assert(getRetainCount(x) == 1);
   }
 // CHECK-NEXT: init ClassWithIntField
+// CHECK-NEXT: destroy ClassWithIntField
+
+  {
+    auto x = returnClassWithIntField();
+    {
+      auto x2 = returnClassWithIntField();
+      assert(getRetainCount(x2) == 1);
+      assert(getRetainCount(x) == 1);
+      x = x2;
+      assert(getRetainCount(x) == 2);
+    }
+    takeClassWithIntField(x);
+    assert(getRetainCount(x) == 1);
+  }
+// CHECK-NEXT: init ClassWithIntField
+// CHECK-NEXT: init ClassWithIntField
+// CHECK-NEXT: destroy ClassWithIntField
+// CHECK-NEXT: ClassWithIntField: 0;
 // CHECK-NEXT: destroy ClassWithIntField
   return 0;
 }

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

@@ -34,7 +34,13 @@ public final class ClassWithIntField {
 // CHECK-NEXT: class ClassWithIntField final {
 // 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(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: private:
 // CHECK-NEXT:   inline ClassWithIntField(void * _Nonnull ptr) noexcept : _opaquePointer(ptr) {}