Add prelimitary support for using Objective-C types in framework API

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

@@ -23,9 +23,12 @@ interface ObjCClass : ObjCObject
 typealias ObjCObjectMeta = ObjCClass
 
 abstract class ObjCObjectBase protected constructor() : ObjCObject {
-    final override fun equals(other: Any?): Boolean = this.uncheckedCast<ObjCPointerHolder>().equals(other)
-    final override fun hashCode(): Int = ObjCHashCode(this.rawPtr)
-    final override fun toString(): String = ObjCToString(this.rawPtr)
+    final override fun equals(other: Any?): Boolean {
+        val thisAny: Any = this
+        return thisAny.equals(other) // Call it virtually because ObjCObjectBase is a fake type.
+    }
+    final override fun hashCode(): Int = ObjCHashCode(this.rawPtr())
+    final override fun toString(): String = ObjCToString(this.rawPtr())
 }
 
 abstract class ObjCObjectBaseMeta protected constructor() : ObjCObjectBase(), ObjCObjectMeta {}
@@ -43,7 +46,11 @@ class ObjCPointerHolder(inline val rawPtr: NativePtr) {
     }
 
     final override fun equals(other: Any?): Boolean =
-            (other is ObjCPointerHolder) && ObjCEquals(this.rawPtr, other.rawPtr)
+            if (other is ObjCPointerHolder) {
+                ObjCEquals(this.rawPtr, other.rawPtr)
+            } else {
+                other == this
+            }
 
     final override fun hashCode(): Int = ObjCHashCode(this.rawPtr)
     final override fun toString(): String = ObjCToString(this.rawPtr)
@@ -61,7 +68,7 @@ private fun ObjCObjectBase.superInitCheck(superInitCallResult: ObjCObject?) {
     if (superInitCallResult == null)
         throw RuntimeException("Super initialization failed")
 
-    if (superInitCallResult.rawPtr != this.rawPtr)
+    if (superInitCallResult.rawPtr() != this.rawPtr())
         throw UnsupportedOperationException("Super initializer has replaced object")
 }
 
@@ -79,18 +86,14 @@ inline fun <T : ObjCObject> interpretObjCPointer(rawPtr: NativePtr): T = if (raw
     throw NullPointerException()
 }
 
-inline val ObjCObject.rawPtr: NativePtr get() = (this.uncheckedCast<ObjCPointerHolder>()).rawPtr
-inline val ObjCObject?.rawPtr: NativePtr get() = if (this != null) {
-    (this.uncheckedCast<ObjCPointerHolder>()).rawPtr
-} else {
-    nativeNullPtr
-}
+@SymbolName("Kotlin_Interop_refToObjC")
+external fun ObjCObject?.rawPtr(): NativePtr
 
 @SymbolName("Kotlin_Interop_createKotlinObjectHolder")
 external fun createKotlinObjectHolder(any: Any?): NativePtr
 
 inline fun <reified T : Any> unwrapKotlinObjectHolder(holder: ObjCObject?): T {
-    return unwrapKotlinObjectHolderImpl(holder!!.rawPtr) as T
+    return unwrapKotlinObjectHolderImpl(holder!!.rawPtr()) as T
 }
 
 @PublishedApi

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

@@ -31,7 +31,7 @@ fun <T : ObjCObject> ObjCObject.reinterpret() = this.uncheckedCast<T>()
 // TODO: null checks
 var <T : ObjCObject?> ObjCObjectVar<T>.value: T
     get() = interpretObjCPointerOrNull<T>(nativeMemUtils.getNativePtr(this)).uncheckedCast<T>()
-    set(value) = nativeMemUtils.putNativePtr(this, value.rawPtr)
+    set(value) = nativeMemUtils.putNativePtr(this, value.rawPtr())
 
 /**
  * Makes Kotlin method in Objective-C class accessible through Objective-C dispatch

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/Mappings.kt

@@ -192,7 +192,7 @@ sealed class TypeInfo {
     }
 
     class ObjCPointerInfo(val kotlinType: KotlinType, val type: ObjCPointer) : TypeInfo() {
-        override fun argToBridged(expr: String) = "$expr.rawPtr"
+        override fun argToBridged(expr: String) = "$expr.rawPtr()"
 
         override fun argFromBridged(expr: KotlinExpression, scope: KotlinScope, nativeBacked: NativeBacked) =
                 "interpretObjCPointerOrNull<${kotlinType.render(scope)}>($expr)" +

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/ObjCStubs.kt

@@ -112,13 +112,13 @@ class ObjCMethodStub(stubGenerator: StubGenerator,
 
         if (method.nsConsumesSelf) {
             // TODO: do this later due to possible exceptions
-            bodyGenerator.out("objc_retain($kniReceiverParameter.rawPtr)")
+            bodyGenerator.out("objc_retain($kniReceiverParameter.rawPtr())")
         }
 
         kotlinObjCBridgeParameters.add(kniReceiverParameter to KotlinTypes.objCObject.type)
         nativeBridgeArguments.add(
                 TypedKotlinValue(voidPtr,
-                        "getReceiverOrSuper($kniReceiverParameter.rawPtr, $kniSuperClassParameter)"))
+                        "getReceiverOrSuper($kniReceiverParameter.rawPtr(), $kniSuperClassParameter)"))
 
         val kotlinParameterNames = method.getKotlinParameterNames()
 

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

@@ -172,10 +172,9 @@ internal class InteropBuiltIns(builtIns: KonanBuiltIns) {
 
     val getObjCClass = packageScope.getContributedFunctions("getObjCClass").single()
 
-    val objCObjectRawPtr = packageScope.getContributedVariables("rawPtr").single {
+    val objCObjectRawPtr = packageScope.getContributedFunctions("rawPtr").single {
         val extensionReceiverType = it.extensionReceiverParameter?.type
-        extensionReceiverType != null && !extensionReceiverType.isMarkedNullable &&
-                TypeUtils.getClassDescriptor(extensionReceiverType) == objCObject
+        extensionReceiverType != null && TypeUtils.getClassDescriptor(extensionReceiverType) == objCObject
     }
 
     val getObjCReceiverOrSuper = packageScope.getContributedFunctions("getReceiverOrSuper").single()

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

@@ -117,7 +117,7 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable): Sym
             symbolTable.referenceSimpleFunction(context.interopBuiltIns.objCObjectSuperInitCheck)
 
     val interopObjCObjectRawValueGetter =
-            symbolTable.referenceSimpleFunction(context.interopBuiltIns.objCObjectRawPtr.getter!!)
+            symbolTable.referenceSimpleFunction(context.interopBuiltIns.objCObjectRawPtr)
 
     val interopInvokeImpls = context.interopBuiltIns.invokeImpls.mapValues { (_, function) ->
         symbolTable.referenceSimpleFunction(function)

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

@@ -440,6 +440,15 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
         null
     }
 
+    val objCExportEnabled = if (context.config.produce.isNativeBinary) {
+        // Note: this defines the global declared in runtime (if any).
+        staticData.placeGlobal("objCExportEnabled", Int8(0), isExported = true).also {
+            it.setConstant(true)
+        }
+    } else {
+        null
+    }
+
     val tlsMode by lazy {
         when (target) {
             KonanTarget.WASM32, 

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

@@ -218,6 +218,7 @@ internal class ObjCExportCodeGenerator(
         emitSortedAdapters(placedInterfaceAdapters, "Kotlin_ObjCExport_sortedProtocolAdapters")
 
         context.llvm.kObjectReservedTailSize!!.setInitializer(Int32(runtime.pointerSize))
+        context.llvm.objCExportEnabled!!.setInitializer(Int8(1))
 
         dataGenerator.finishModule() // TODO: move to appropriate place.
     }
@@ -445,6 +446,11 @@ private fun ObjCExportCodeGenerator.emitSpecialClassesConvertions() {
         emitBoxConverter(it)
     }
 
+    setObjCExportTypeInfo(
+            context.interopBuiltIns.objCPointerHolder,
+            constPointer(codegen.llvmFunction(context.ir.symbols.objCPointerHolderValueGetter.owner))
+    )
+
     emitFunctionConverters()
 
     emitKotlinFunctionAdaptersToBlock()

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

@@ -92,8 +92,11 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
     private val kotlinAnyName = namer.kotlinAnyName
 
     private val stubs = mutableListOf<Stub>()
-    private val classToName = mutableMapOf<ClassDescriptor, String>()
-    private val interfaceToName = mutableMapOf<ClassDescriptor, String>()
+    private val classOrInterfaceToName = mutableMapOf<ClassDescriptor, String>()
+
+    internal val classForwardDeclarations = mutableSetOf<String>()
+    internal val protocolForwardDeclarations = mutableSetOf<String>()
+
     private val extensions = mutableMapOf<ClassDescriptor, MutableList<CallableMemberDescriptor>>()
     val extraClassesToTranslate = mutableSetOf<ClassDescriptor>()
 
@@ -154,17 +157,11 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
         }
     }
 
-    fun translateClassName(descriptor: ClassDescriptor): String {
-        val descriptorToName = if (descriptor.isInterface) interfaceToName else classToName
+    fun translateClassName(descriptor: ClassDescriptor): String = classOrInterfaceToName.getOrPut(descriptor) {
+        assert(mapper.shouldBeExposed(descriptor))
+        val forwardDeclarations = if (descriptor.isInterface) protocolForwardDeclarations else classForwardDeclarations
 
-        return descriptorToName.getOrPut(descriptor) {
-            if (!mapper.shouldBeExposed(descriptor)) {
-                context.reportCompilationError("Can't produce ${descriptor.fqNameSafe.asString()} to framework API")
-                throw KonanCompilationException()
-            }
-
-            namer.getClassOrProtocolName(descriptor)
-        }
+        namer.getClassOrProtocolName(descriptor).also { forwardDeclarations += it }
     }
 
     private fun translateInterface(descriptor: ClassDescriptor) {
@@ -555,13 +552,13 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
         add("#import <Foundation/Foundation.h>")
         add("")
 
-        if (classToName.isNotEmpty()) {
-            add("@class ${classToName.values.joinToString()};")
+        if (classForwardDeclarations.isNotEmpty()) {
+            add("@class ${classForwardDeclarations.joinToString()};")
             add("")
         }
 
-        if (interfaceToName.isNotEmpty()) {
-            add("@protocol ${interfaceToName.values.joinToString()};")
+        if (protocolForwardDeclarations.isNotEmpty()) {
+            add("@protocol ${protocolForwardDeclarations.joinToString()};")
             add("")
         }
 
@@ -790,6 +787,10 @@ private fun ObjCExportHeaderGenerator.mapReferenceTypeIgnoringNullability(
         return ObjCIdType
     }
 
+    if (classDescriptor.defaultType.isObjCObjectType()) {
+        return mapObjCObjectReferenceTypeIgnoringNullability(classDescriptor)
+    }
+
     scheduleClassToBeGenerated(classDescriptor)
 
     return if (classDescriptor.isInterface) {
@@ -799,6 +800,32 @@ private fun ObjCExportHeaderGenerator.mapReferenceTypeIgnoringNullability(
     }
 }
 
+private tailrec fun ObjCExportHeaderGenerator.mapObjCObjectReferenceTypeIgnoringNullability(
+        descriptor: ClassDescriptor
+): ObjCNonNullReferenceType {
+    // TODO: more precise types can be used.
+
+    if (descriptor.isObjCMetaClass()) return ObjCIdType
+
+    if (descriptor.isExternalObjCClass()) {
+        return if (descriptor.isInterface) {
+            val name = descriptor.name.asString().removeSuffix("Protocol")
+            protocolForwardDeclarations += name
+            ObjCProtocolType(name)
+        } else {
+            val name = descriptor.name.asString()
+            classForwardDeclarations += name
+            ObjCClassType(name)
+        }
+    }
+
+    if (descriptor.isKotlinObjCClass()) {
+        return mapObjCObjectReferenceTypeIgnoringNullability(descriptor.getSuperClassOrAny())
+    }
+
+    return ObjCIdType
+}
+
 private fun ObjCExportHeaderGenerator.scheduleClassToBeGenerated(classDescriptor: ClassDescriptor) {
     if (classDescriptor !in generatedClasses) {
         extraClassesToTranslate += classDescriptor

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

@@ -49,6 +49,8 @@ internal fun ObjCExportMapper.getClassIfCategory(descriptor: CallableMemberDescr
 
     val extensionReceiverType = descriptor.extensionReceiverParameter?.type ?: return null
 
+    if (extensionReceiverType.isObjCObjectType()) return null
+
     val erasedClass = extensionReceiverType.getErasedTypeClass()
     return if (this.isRepresentedAsObjCInterface(erasedClass)) {
         erasedClass

runtime/src/main/cpp/ObjCExport.mm

@@ -36,6 +36,9 @@
 #import "Utils.h"
 #import "Exceptions.h"
 
+// Note: defined by a compiler-generated bitcode.
+extern "C" const uint8_t objCExportEnabled;
+
 struct ObjCToKotlinMethodAdapter {
   const char* selector;
   const char* encoding;
@@ -513,6 +516,16 @@ extern "C" id Kotlin_ObjCExport_refToObjC(ObjHeader* obj) {
   return Kotlin_ObjCExport_refToObjC_slowpath(obj);
 }
 
+extern "C" ALWAYS_INLINE id Kotlin_Interop_refToObjC(ObjHeader* obj) {
+  if (obj == nullptr) {
+    return nullptr;
+  } else if (!objCExportEnabled || obj->type_info() == theObjCPointerHolderTypeInfo) {
+    return *reinterpret_cast<id*>(obj + 1); // First field.
+  } else {
+    return Kotlin_ObjCExport_refToObjC(obj);
+  }
+}
+
 extern "C" OBJ_GETTER(Kotlin_ObjCExport_refFromObjC, id obj) {
   if (obj == nullptr) RETURN_OBJ(nullptr);
   id convertible = (id<ConvertibleToKotlin>)obj;

runtime/src/main/cpp/ObjCInteropUtils.mm

@@ -78,7 +78,8 @@ OBJ_GETTER(Kotlin_Interop_ObjCToString, id <NSObject> ptr) {
 }
 
 KInt Kotlin_Interop_ObjCHashCode(id <NSObject> ptr) {
-  return (KInt) ptr.hash;
+  KLong hash = ptr.hash;
+  return (KInt)(hash ^ (hash >> 32));
 }
 
 KBoolean Kotlin_Interop_ObjCEquals(id <NSObject> ptr, id otherPtr) {