[interop][SwiftToCxx] support returning class values in enum's generic associated value getter

Author: hyp

lib/PrintAsClang/PrintClangFunction.cpp

@@ -928,26 +928,26 @@ void DeclAndTypeClangFunctionPrinter::printGenericReturnSequence(
   os << "  if constexpr (std::is_base_of<::swift::"
      << cxx_synthesis::getCxxImplNamespaceName() << "::RefCountedClass, "
      << resultTyName << ">::value) {\n";
+  os << "  void *returnValue;\n  ";
   if (!initializeWithTakeFromValue) {
-    os << "  void *returnValue;\n  ";
     invocationPrinter(/*additionalParam=*/StringRef(ros.str()));
+  } else {
+    os << "returnValue = *reinterpret_cast<void **>("
+       << *initializeWithTakeFromValue << ")";
+  }
     os << ";\n";
     os << "  return ::swift::" << cxx_synthesis::getCxxImplNamespaceName()
        << "::implClassFor<" << resultTyName
        << ">::type::makeRetained(returnValue);\n";
-  } else {
-    // FIXME: support taking a class pointer.
-    os << "abort();\n";
-  }
-  os << "  } else if constexpr (::swift::"
-     << cxx_synthesis::getCxxImplNamespaceName() << "::isValueType<"
-     << resultTyName << ">) {\n";
+    os << "  } else if constexpr (::swift::"
+       << cxx_synthesis::getCxxImplNamespaceName() << "::isValueType<"
+       << resultTyName << ">) {\n";
 
-  os << "  return ::swift::" << cxx_synthesis::getCxxImplNamespaceName()
-     << "::implClassFor<" << resultTyName
-     << ">::type::returnNewValue([&](void * _Nonnull returnValue) {\n";
-  if (!initializeWithTakeFromValue) {
-    invocationPrinter(/*additionalParam=*/StringRef("returnValue"));
+    os << "  return ::swift::" << cxx_synthesis::getCxxImplNamespaceName()
+       << "::implClassFor<" << resultTyName
+       << ">::type::returnNewValue([&](void * _Nonnull returnValue) {\n";
+    if (!initializeWithTakeFromValue) {
+      invocationPrinter(/*additionalParam=*/StringRef("returnValue"));
   } else {
     os << "  return ::swift::" << cxx_synthesis::getCxxImplNamespaceName()
        << "::implClassFor<" << resultTyName

test/Interop/SwiftToCxx/generics/generic-enum-execution.cpp

@@ -14,6 +14,13 @@
 #include <cassert>
 #include <cstdio>
 
+extern "C" size_t swift_retainCount(void * _Nonnull obj);
+
+size_t getRetainCount(const Generics::TracksDeinit & swiftClass) {
+  void *p = swift::_impl::_impl_RefCountedClass::getOpaquePointer(swiftClass);
+  return swift_retainCount(p);
+}
+
 int main() {
   using namespace Generics;
 
@@ -65,6 +72,21 @@ int main() {
     // CHECK-NEXT: init-TracksDeinit
     // CHECK-NEXT: destroy-TracksDeinit
   }
+  {
+    auto ptr = constructTracksDeinit();
+    // CHECK-NEXT: init-TracksDeinit
+    assert(getRetainCount(ptr) == 1);
+    {
+      auto x   = makeGenericOpt<TracksDeinit>(ptr);
+      assert(getRetainCount(ptr) == 2);
+      auto ptr2 = x.getSome();
+      assert(getRetainCount(ptr) == 3);
+    }
+    puts("after some");
+    assert(getRetainCount(ptr) == 1);
+    // CHECK-NEXT: after some
+    // CHECK-NEXT: destroy-TracksDeinit
+  }
   puts("EOF");
   // CHECK-NEXT: EOF
   return 0;

test/Interop/SwiftToCxx/generics/generic-enum-in-cxx.swift

@@ -10,7 +10,7 @@
 
 // FIXME: remove the need for -Wno-reserved-identifier
 
-class TracksDeinit {
+public class TracksDeinit {
     init() {
         print("init-TracksDeinit")
     }
@@ -19,6 +19,10 @@ class TracksDeinit {
     }
 }
 
+public func constructTracksDeinit() -> TracksDeinit {
+    return TracksDeinit()
+}
+
 @frozen
 public struct StructForEnum {
     let x: TracksDeinit