Make Objective-C objects shareable in Kotlin

Interop/Runtime/src/native/kotlin/kotlinx/cinterop/ObjectiveCImpl.kt

@@ -26,6 +26,7 @@ interface ObjCClassOf<T : ObjCObject> : ObjCClass // TODO: T should be added to
 typealias ObjCObjectMeta = ObjCClass
 
 @ExportTypeInfo("theForeignObjCObjectTypeInfo")
+@kotlin.native.internal.Frozen
 internal open class ForeignObjCObject : kotlin.native.internal.ObjCObjectWrapper
 
 abstract class ObjCObjectBase protected constructor() : ObjCObject {

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/descriptors/LegacyDescriptorUtils.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.backend.konan.descriptors
 
 import org.jetbrains.kotlin.backend.common.atMostOne
 import org.jetbrains.kotlin.backend.konan.binaryTypeIsReference
+import org.jetbrains.kotlin.backend.konan.isObjCClass
 import org.jetbrains.kotlin.backend.konan.serialization.isExported
 import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
 import org.jetbrains.kotlin.builtins.getFunctionalClassKind
@@ -241,8 +242,9 @@ private val frozenAnnotation = FqName("kotlin.native.internal.Frozen")
 
 internal val DeclarationDescriptor.isFrozen: Boolean
     get() = this.annotations.hasAnnotation(frozenAnnotation) ||
-            // RTTI is used for non-reference type box:
-            this is org.jetbrains.kotlin.descriptors.ClassDescriptor && !this.defaultType.binaryTypeIsReference()
+            (this is org.jetbrains.kotlin.descriptors.ClassDescriptor
+                    // RTTI is used for non-reference type box or Objective-C object wrapper:
+                    && (!this.defaultType.binaryTypeIsReference() || this.isObjCClass()))
 
 internal val FunctionDescriptor.isIntrinsic: Boolean
     get() = this.annotations.hasAnnotation(intrinsicAnnotation)

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/RTTIGenerator.kt

@@ -19,7 +19,7 @@ internal class RTTIGenerator(override val context: Context) : ContextUtils {
     private fun flagsFromClass(classDescriptor: ClassDescriptor): Int {
         var result = 0
         if (classDescriptor.isFrozen)
-           result = result or 1 /* TF_IMMUTABLE */
+           result = result or TF_IMMUTABLE
         return result
     }
 
@@ -291,7 +291,8 @@ internal class RTTIGenerator(override val context: Context) : ContextUtils {
     // TODO: extract more code common with generate().
     fun generateSyntheticInterfaceImpl(
             descriptor: ClassDescriptor,
-            methodImpls: Map<FunctionDescriptor, ConstPointer>
+            methodImpls: Map<FunctionDescriptor, ConstPointer>,
+            immutable: Boolean = false
     ): ConstPointer {
         assert(descriptor.isInterface)
 
@@ -346,7 +347,7 @@ internal class RTTIGenerator(override val context: Context) : ContextUtils {
                 fields = fieldsPtr, fieldsCount = fieldsCount,
                 packageName = reflectionInfo.packageName,
                 relativeName = reflectionInfo.relativeName,
-                flags = flagsFromClass(descriptor),
+                flags = flagsFromClass(descriptor) or (if (immutable) TF_IMMUTABLE else 0),
                 extendedInfo = NullPointer(runtime.extendedTypeInfoType),
                 writableTypeInfo = writableTypeInfo
               ), vtable)
@@ -376,3 +377,5 @@ internal class RTTIGenerator(override val context: Context) : ContextUtils {
         }
     }
 }
+
+private const val TF_IMMUTABLE = 1

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objcexport/ObjCExportCodeGenerator.kt

@@ -403,7 +403,8 @@ private fun ObjCExportCodeGenerator.generateKotlinFunctionAdapterToBlock(numberO
 
     return rttiGenerator.generateSyntheticInterfaceImpl(
             irInterface,
-            mapOf(invokeMethod to invokeImpl)
+            mapOf(invokeMethod to invokeImpl),
+            immutable = true
     )
 }
 

backend.native/tests/framework/values/values.kt

@@ -8,6 +8,7 @@
 
 package conversions
 
+import kotlin.native.concurrent.isFrozen
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
@@ -236,3 +237,6 @@ fun IC2?.getValueOrNull2() = this?.value
 
 fun IC3.getValue3() = value
 fun IC3?.getValueOrNull3() = this?.value
+
+fun isFrozen(obj: Any): Boolean = obj.isFrozen
+fun kotlinLambda(block: (Any) -> Any): Any = block

backend.native/tests/framework/values/values.swift

@@ -420,6 +420,27 @@ func testInlineClasses() throws {
     try assertEquals(actual: ValuesKt.getValueOrNull3(ic3N), expected: nil)
 }
 
+class TestSharedIImpl : NSObject, I {
+    func iFun() -> String {
+        return "TestSharedIImpl::iFun"
+    }
+}
+
+func testShared() throws {
+    func assertFrozen(_ obj: AnyObject) throws {
+        try assertTrue(ValuesKt.isFrozen(obj: obj), "isFrozen(\(obj))")
+    }
+
+    func assertNotFrozen(_ obj: AnyObject) throws {
+        try assertFalse(ValuesKt.isFrozen(obj: obj), "isFrozen(\(obj))")
+    }
+
+    try assertFrozen(NSObject())
+    try assertFrozen(TestSharedIImpl())
+    try assertFrozen(ValuesKt.kotlinLambda(block: { return $0 }) as AnyObject)
+    try assertNotFrozen(FinalClassExtOpen())
+}
+
 // -------- Execution of the test --------
 
 class ValuesTests : TestProvider {
@@ -453,6 +474,7 @@ class ValuesTests : TestProvider {
             TestCase(name: "TestDataClass", method: withAutorelease(testDataClass)),
             TestCase(name: "TestCompanionObj", method: withAutorelease(testCompanionObj)),
             TestCase(name: "TestInlineClasses", method: withAutorelease(testInlineClasses)),
+            TestCase(name: "TestShared", method: withAutorelease(testShared)),
         ]
     }
 }

runtime/src/main/cpp/ObjCExport.mm

@@ -669,11 +669,16 @@ static const TypeInfo* createTypeInfo(
   TypeInfo* result = (TypeInfo*)konanAllocMemory(sizeof(TypeInfo) + vtable.size() * sizeof(void*));
   result->typeInfo_ = result;
 
+  result->flags_ = 0;
+
   MakeGlobalHash(nullptr, 0, &result->name_);
   result->instanceSize_ = superType->instanceSize_;
   result->superType_ = superType;
   result->objOffsets_ = superType->objOffsets_;
-  result->objOffsetsCount_ = superType->objOffsetsCount_;
+  result->objOffsetsCount_ = superType->objOffsetsCount_; // So TF_IMMUTABLE can also be inherited:
+  if ((superType->flags_ & TF_IMMUTABLE) != 0) {
+    result->flags_ |= TF_IMMUTABLE;
+  }
 
   KStdVector<const TypeInfo*> implementedInterfaces(
     superType->implementedInterfaces_, superType->implementedInterfaces_ + superType->implementedInterfacesCount_