Merge pull request swiftlang#80270 from swiftlang/gaborh/opt-foreign-reference-type

[cxx-interop] Support foreing reference types in generic context

Author: Xazax-hun

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -579,8 +579,9 @@ class ModuleWriter {
           forwardDeclareCxxValueTypeIfNeeded(NTD);
         else if (isa<StructDecl>(TD) && NTD->hasClangNode())
           emitReferencedClangTypeMetadata(NTD);
-        else if (isa<ClassDecl>(TD) && TD->isObjC()) 
-          emitReferencedClangTypeMetadata(NTD);
+        else if (const auto *cd = dyn_cast<ClassDecl>(TD))
+          if (cd->isObjC() || cd->isForeignReferenceType())
+            emitReferencedClangTypeMetadata(NTD);
       } else if (auto TAD = dyn_cast<TypeAliasDecl>(TD)) {
         if (TAD->hasClangNode())
           emitReferencedClangTypeMetadata(TAD);

lib/PrintAsClang/PrintClangFunction.cpp

@@ -618,6 +618,15 @@ static bool isOptionalObjCExistential(Type ty) {
   return false;
 }
 
+static bool isOptionalForeignReferenceType(Type ty) {
+  if (auto obj = ty->getOptionalObjectType()) {
+    if (const auto *cd =
+            dyn_cast_or_null<ClassDecl>(obj->getNominalOrBoundGenericNominal()))
+      return cd->isForeignReferenceType();
+  }
+  return false;
+}
+
 // Returns false if the given direct type is not yet supported because
 // of its ABI.
 template <class T>
@@ -658,7 +667,8 @@ static bool printDirectReturnOrParamCType(
   if (isKnownCType(valueType, typeMapping) ||
       (Count == 1 && lastOffset.isZero() && !valueType->hasTypeParameter() &&
        (valueType->isAnyClassReferenceType() ||
-        isOptionalObjCExistential(valueType)))) {
+        isOptionalObjCExistential(valueType) ||
+        isOptionalForeignReferenceType(valueType)))) {
     prettifiedValuePrinter();
     return true;
   }
@@ -1506,10 +1516,9 @@ void DeclAndTypeClangFunctionPrinter::printCxxThunkBody(
   if (!nonOptResultType)
     nonOptResultType = resultTy;
   if (auto *classDecl = nonOptResultType->getClassOrBoundGenericClass();
-      classDecl || nonOptResultType->isObjCExistentialType()) {
+      (classDecl && isa<clang::ObjCContainerDecl>(classDecl->getClangDecl())) ||
+      nonOptResultType->isObjCExistentialType()) {
     assert(!classDecl || classDecl->hasClangNode());
-    assert(!classDecl ||
-           isa<clang::ObjCContainerDecl>(classDecl->getClangDecl()));
     os << "return (__bridge_transfer ";
     declPrinter.withOutputStream(os).print(nonOptResultType);
     os << ")(__bridge void *)";
@@ -1766,6 +1775,9 @@ bool DeclAndTypeClangFunctionPrinter::hasKnownOptionalNullableCxxMapping(
               optionalObjectType->getNominalOrBoundGenericNominal())) {
         return typeInfo->canBeNullable;
       }
+      if (const auto *cd = dyn_cast<ClassDecl>(nominal))
+        if (cd->isForeignReferenceType())
+          return true;
       return isa_and_nonnull<clang::ObjCInterfaceDecl>(nominal->getClangDecl());
     }
   }

lib/PrintAsClang/PrintClangValueType.cpp

@@ -641,7 +641,9 @@ void ClangValueTypePrinter::printTypeGenericTraits(
               typeDecl, typeMetadataFuncName, typeMetadataFuncRequirements);
         });
   }
-  bool addPointer = typeDecl->isObjC();
+  auto classDecl = dyn_cast<ClassDecl>(typeDecl);
+  bool addPointer =
+      typeDecl->isObjC() || (classDecl && classDecl->isForeignReferenceType());
 
   os << "#pragma clang diagnostic push\n";
   os << "#pragma clang diagnostic ignored \"-Wc++17-extensions\"\n";

test/Interop/CxxToSwiftToCxx/allow-shared-frt-back-to-cxx.swift

@@ -2,6 +2,9 @@
 // RUN: split-file %s %t
 
 // RUN: %target-swift-frontend %t/use-cxx-types.swift -module-name UseCxxTy -typecheck -verify -emit-clang-header-path %t/UseCxxTy.h -I %t -enable-experimental-cxx-interop -clang-header-expose-decls=all-public -disable-availability-checking
+// RUN: cat %t/header.h >> %t/full-header.h
+// RUN: cat %t/UseCxxTy.h >> %t/full-header.h
+// RUN: %target-interop-build-clangxx -std=c++20 -c -xc++-header %t/full-header.h -o %t/o.o
 
 // RUN: %FileCheck %s < %t/UseCxxTy.h
 
@@ -29,6 +32,11 @@ import CxxTest
 public func consumeSharedFRT(_ x: consuming SharedFRT) {}
 public func takeSharedFRT(_ x: SharedFRT) {}
 
+public func takeSharedFRTGeneric(_ x: [SharedFRT]) {}
+public func returnSharedFRTGeneric() -> [SharedFRT] { [] }
+public func takeSharedFRTOptional(_ x: SharedFRT?) {}
+public func returnSharedFRTOptional() -> SharedFRT? { nil }
+
 // CHECK: SWIFT_EXTERN void $s8UseCxxTy16consumeSharedFRTyySo0eF0VnF(SharedFRT *_Nonnull x) SWIFT_NOEXCEPT SWIFT_CALL; // consumeSharedFRT(_:)
 
 // CHECK: SWIFT_EXTERN void $s8UseCxxTy13takeSharedFRTyySo0eF0VF(SharedFRT *_Nonnull x) SWIFT_NOEXCEPT SWIFT_CALL; // takeSharedFRT(_:)