[Interop][SwiftToCxx] Add class type support for enum with associated value

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -522,18 +522,24 @@ class DeclAndTypePrinter::Implementation
                   elementDecl->getParentEnum()->getModuleContext());
               outOfLineSyntaxPrinter.printBaseName(objectTypeDecl);
               outOfLineOS << ">::type";
-              outOfLineOS << "::returnNewValue([&](char * _Nonnull result) {\n";
-              outOfLineOS << "      swift::"
-                          << cxx_synthesis::getCxxImplNamespaceName();
-              outOfLineOS << "::implClassFor<";
-              outOfLineSyntaxPrinter.printModuleNamespaceQualifiersIfNeeded(
-                  objectTypeDecl->getModuleContext(),
-                  elementDecl->getParentEnum()->getModuleContext());
-              outOfLineSyntaxPrinter.printBaseName(objectTypeDecl);
-              outOfLineOS << ">::type";
-              outOfLineOS
-                  << "::initializeWithTake(result, payloadFromDestruction);\n";
-              outOfLineOS << "    });\n  ";
+              if (isa<ClassDecl>(objectTypeDecl)) {
+                outOfLineOS << "::makeRetained(*reinterpret_cast<void "
+                               "**>(payloadFromDestruction));\n  ";
+              } else {
+                outOfLineOS
+                    << "::returnNewValue([&](char * _Nonnull result) {\n";
+                outOfLineOS << "      swift::"
+                            << cxx_synthesis::getCxxImplNamespaceName();
+                outOfLineOS << "::implClassFor<";
+                outOfLineSyntaxPrinter.printModuleNamespaceQualifiersIfNeeded(
+                    objectTypeDecl->getModuleContext(),
+                    elementDecl->getParentEnum()->getModuleContext());
+                outOfLineSyntaxPrinter.printBaseName(objectTypeDecl);
+                outOfLineOS << ">::type";
+                outOfLineOS << "::initializeWithTake(result, "
+                               "payloadFromDestruction);\n";
+                outOfLineOS << "    });\n  ";
+              }
             }
           },
           ED, ED->getModuleContext(), outOfLineOS);
@@ -666,6 +672,13 @@ class DeclAndTypePrinter::Implementation
                     outOfLineOS
                         << "    memcpy(result._getOpaquePointer(), &val, "
                            "sizeof(val));\n";
+                  } else if (isa<ClassDecl>(objectTypeDecl)) {
+                    outOfLineOS
+                        << "    auto op = swift::"
+                        << cxx_synthesis::getCxxImplNamespaceName()
+                        << "::_impl_RefCountedClass::copyOpaquePointer(val);\n";
+                    outOfLineOS << "    memcpy(result._getOpaquePointer(), "
+                                   "&op, sizeof(op));\n";
                   } else {
                     objectTypeDecl =
                         paramType->getNominalOrBoundGenericNominal();

test/Interop/SwiftToCxx/enums/enum-associated-value-class-type-cxx.cpp

@@ -0,0 +1,57 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend %S/enum-associated-value-class-type-cxx.swift -typecheck -module-name Enums -clang-header-expose-decls=all-public -emit-clang-header-path %t/enums.h
+
+// RUN: %target-interop-build-clangxx -c %s -I %t -o %t/swift-enums-execution.o
+// RUN: %target-interop-build-swift %S/enum-associated-value-class-type-cxx.swift -o %t/swift-enums-execution -Xlinker %t/swift-enums-execution.o -module-name Enums -Xfrontend -entry-point-function-name -Xfrontend swiftMain
+
+// RUN: %target-codesign %t/swift-enums-execution
+// RUN: %target-run %t/swift-enums-execution
+
+// RUN: %empty-directory(%t-evo)
+
+// RUN: %target-swift-frontend %S/enum-associated-value-class-type-cxx.swift -typecheck -module-name Enums -clang-header-expose-decls=all-public -enable-library-evolution -emit-clang-header-path %t-evo/enums.h
+
+// RUN: %target-interop-build-clangxx -c %s -I %t-evo -o %t-evo/swift-enums-execution.o
+// RUN: %target-interop-build-swift %S/enum-associated-value-class-type-cxx.swift -o %t-evo/swift-enums-execution -Xlinker %t-evo/swift-enums-execution.o -module-name Enums -enable-library-evolution -Xfrontend -entry-point-function-name -Xfrontend swiftMain
+
+// RUN: %target-codesign %t-evo/swift-enums-execution
+// RUN: %target-run %t-evo/swift-enums-execution
+
+// REQUIRES: executable_test
+
+#include <cassert>
+#include "enums.h"
+
+using namespace Enums;
+
+extern "C" size_t swift_retainCount(void * _Nonnull obj);
+
+size_t getRetainCount(const C & obj) {
+  void *p = swift::_impl::_impl_RefCountedClass::getOpaquePointer(obj);
+  return swift_retainCount(p);
+}
+
+int main() {
+    auto c = C::init(1234);
+    assert(c.getX() == 1234);
+    assert(getRetainCount(c) == 1);
+
+    {
+        auto e = E::c(c);
+        assert(e.isC());
+        assert(getRetainCount(c) == 2);
+
+        auto extracted = e.getC();
+        assert(getRetainCount(c) == 3);
+        assert(getRetainCount(extracted) == 3);
+        assert(extracted.getX() == 1234);
+
+        extracted.setX(5678);
+        assert(extracted.getX() == 5678);
+        assert(c.getX() == 5678);
+    }
+
+    assert(getRetainCount(c) == 1);
+    return 0;
+}

test/Interop/SwiftToCxx/enums/enum-associated-value-class-type-cxx.swift

@@ -0,0 +1,31 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend %s -typecheck -module-name Enums -clang-header-expose-decls=all-public -emit-clang-header-path %t/enums.h
+// RUN: %FileCheck %s < %t/enums.h
+
+// RUN: %check-interop-cxx-header-in-clang(%t/enums.h -Wno-unused-private-field -Wno-unused-function)
+
+public class C {
+    public var x: Int
+    public init(x: Int) { self.x = x }
+}
+
+public enum E {
+    case c(C)
+    case i(Int)
+}
+
+// CHECK:      inline E E::_impl_c::operator()(const C& val) const {
+// CHECK-NEXT:   auto result = E::_make();
+// CHECK-NEXT:   auto op = swift::_impl::_impl_RefCountedClass::copyOpaquePointer(val);
+// CHECK-NEXT:   memcpy(result._getOpaquePointer(), &op, sizeof(op));
+// CHECK-NEXT:   result._destructiveInjectEnumTag(0);
+// CHECK-NEXT:   return result;
+// CHECK-NEXT: }
+
+// CHECK:      inline C E::getC() const {
+// CHECK-NEXT:   if (!isC()) abort();
+// CHECK-NEXT:   alignas(E) unsigned char buffer[sizeof(E)];
+// CHECK-NEXT:   auto *thisCopy = new(buffer) E(*this);
+// CHECK-NEXT:   char * _Nonnull payloadFromDestruction = thisCopy->_destructiveProjectEnumData();
+// CHECK-NEXT:   return swift::_impl::implClassFor<C>::type::makeRetained(*reinterpret_cast<void **>(payloadFromDestruction));
+// CHECK-NEXT: }