Disable inheriting Objective-C initializers by Kotlin classes

Unoverridden inherited Objective-C initializer can lead to
creating uninitialized Kotlin instances.
Throw exception when such an initializer gets called.

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

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.backend.konan
 import org.jetbrains.kotlin.backend.konan.descriptors.getStringValue
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.ExternalOverridabilityCondition
 import org.jetbrains.kotlin.resolve.descriptorUtil.*
@@ -163,6 +164,15 @@ class ObjCOverridabilityCondition : ExternalOverridabilityCondition {
 
 }
 
+fun ConstructorDescriptor.getObjCInitMethod(): FunctionDescriptor? {
+    return this.annotations.findAnnotation(FqName("kotlinx.cinterop.ObjCConstructor"))?.let {
+        val initSelector = it.getStringValue("initSelector")
+        this.constructedClass.unsubstitutedMemberScope.getContributedDescriptors().asSequence()
+                .filterIsInstance<FunctionDescriptor>()
+                .single { it.getExternalObjCMethodInfo()?.selector == initSelector }
+    }
+}
+
 fun inferObjCSelector(descriptor: FunctionDescriptor): String = if (descriptor.valueParameters.isEmpty()) {
     descriptor.name.asString()
 } else {

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

@@ -328,6 +328,7 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
 
     val createKotlinObjCClass by lazy { importRtFunction("CreateKotlinObjCClass") }
     val getObjCKotlinTypeInfo by lazy { importRtFunction("GetObjCKotlinTypeInfo") }
+    val missingInitImp by lazy { importRtFunction("MissingInitImp") }
 
     private val personalityFunctionName = when (context.config.targetManager.target) {
         KonanTarget.MINGW -> "__gxx_personality_seh0"

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

@@ -17,12 +17,11 @@
 package org.jetbrains.kotlin.backend.konan.llvm
 
 import llvm.LLVMStoreSizeOfType
-import org.jetbrains.kotlin.backend.konan.Context
-import org.jetbrains.kotlin.backend.konan.ObjCMethodInfo
+import llvm.LLVMValueRef
+import org.jetbrains.kotlin.backend.konan.*
 import org.jetbrains.kotlin.backend.konan.descriptors.contributedMethods
 import org.jetbrains.kotlin.backend.konan.descriptors.getStringValue
 import org.jetbrains.kotlin.backend.konan.descriptors.getStringValueOrNull
-import org.jetbrains.kotlin.backend.konan.getObjCMethodInfo
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ConstructorDescriptor
 import org.jetbrains.kotlin.descriptors.isFinalClass
@@ -39,7 +38,7 @@ internal class KotlinObjCClassInfoGenerator(override val context: Context) : Con
 
         val objCLLvmDeclarations = context.llvmDeclarations.forClass(descriptor).objCDeclarations!!
 
-        val instanceMethods = descriptor.generateOverridingMethodDescs() + irClass.generateImpMethodDescs()
+        val instanceMethods = generateInstanceMethodDescs(irClass)
 
         val companionObjectDescriptor = descriptor.companionObjectDescriptor
         val classMethods = companionObjectDescriptor?.generateOverridingMethodDescs() ?: emptyList()
@@ -80,6 +79,25 @@ internal class KotlinObjCClassInfoGenerator(override val context: Context) : Con
         objCLLvmDeclarations.bodyOffsetGlobal.setInitializer(Int32(0))
     }
 
+    private fun generateInstanceMethodDescs(
+            irClass: IrClass
+    ): List<ObjCMethodDesc> = mutableListOf<ObjCMethodDesc>().apply {
+        val descriptor = irClass.descriptor
+        addAll(descriptor.generateOverridingMethodDescs())
+        addAll(irClass.generateImpMethodDescs())
+        val allImplementedSelectors = this.map { it.selector }.toSet()
+
+        assert(descriptor.getSuperClassNotAny()!!.isExternalObjCClass())
+        val allInitMethodsInfo = descriptor.getSuperClassNotAny()!!.constructors
+                .mapNotNull { it.getObjCInitMethod()?.getExternalObjCMethodInfo() }
+                .filter { it.selector !in allImplementedSelectors }
+                .distinctBy { it.selector }
+
+        allInitMethodsInfo.mapTo(this) {
+            ObjCMethodDesc(it.selector, it.encoding, context.llvm.missingInitImp)
+        }
+    }
+
     private fun selectClassName(descriptor: ClassDescriptor): String? {
         val exportObjCClassAnnotation =
                 descriptor.annotations.findAnnotation(context.interopBuiltIns.exportObjCClass.fqNameSafe)
@@ -93,37 +111,37 @@ internal class KotlinObjCClassInfoGenerator(override val context: Context) : Con
         }
     }
 
-    private fun createMethodDesc(selector: String, encoding: String, imp: ConstPointer) = Struct(
+    private inner class ObjCMethodDesc(
+            val selector: String, val encoding: String, val impFunction: LLVMValueRef
+    ) : Struct(
             runtime.objCMethodDescription,
             staticData.cStringLiteral(selector),
             staticData.cStringLiteral(encoding),
-            imp
+            constPointer(impFunction).bitcast(int8TypePtr)
     )
 
-    private fun generateMethodDesc(info: ObjCMethodInfo): ConstValue {
-        return createMethodDesc(
-                info.selector,
-                info.encoding,
-                constPointer(context.llvm.externalFunction(info.imp, functionType(voidType))).bitcast(int8TypePtr)
-        )
-    }
+    private fun generateMethodDesc(info: ObjCMethodInfo) = ObjCMethodDesc(
+            info.selector,
+            info.encoding,
+            context.llvm.externalFunction(info.imp, functionType(voidType))
+    )
 
-    private fun ClassDescriptor.generateOverridingMethodDescs(): List<ConstValue> =
+    private fun ClassDescriptor.generateOverridingMethodDescs(): List<ObjCMethodDesc> =
             this.unsubstitutedMemberScope.contributedMethods.filter {
                 it.kind.isReal && it !is ConstructorDescriptor
             }.mapNotNull { it.getObjCMethodInfo() }.map { generateMethodDesc(it) }
 
-    private fun IrClass.generateImpMethodDescs(): List<ConstValue> = this.declarations
+    private fun IrClass.generateImpMethodDescs(): List<ObjCMethodDesc> = this.declarations
             .filterIsInstance<IrSimpleFunction>()
             .mapNotNull {
                 val annotation =
                         it.descriptor.annotations.findAnnotation(context.interopBuiltIns.objCMethodImp.fqNameSafe) ?:
                                 return@mapNotNull null
 
-                createMethodDesc(
+                ObjCMethodDesc(
                         annotation.getStringValue("selector"),
                         annotation.getStringValue("encoding"),
-                        it.descriptor.entryPointAddress
+                        it.descriptor.llvmFunction
                 )
             }
 }

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

@@ -389,7 +389,7 @@ internal class InteropLoweringPart1(val context: Context) : IrBuildingTransforme
 
             assert(constructedClassDescriptor.getSuperClassNotAny() == expression.descriptor.constructedClass)
 
-            val initMethod = getObjCInitMethod(expression.descriptor)!!
+            val initMethod = expression.descriptor.getObjCInitMethod()!!
             val initMethodInfo = initMethod.getExternalObjCMethodInfo()!!
 
             assert(expression.dispatchReceiver == null)
@@ -438,22 +438,13 @@ internal class InteropLoweringPart1(val context: Context) : IrBuildingTransforme
         }
     }
 
-    private fun getObjCInitMethod(descriptor: ConstructorDescriptor): FunctionDescriptor? {
-        return descriptor.annotations.findAnnotation(FqName("kotlinx.cinterop.ObjCConstructor"))?.let {
-            val initSelector = it.getStringValue("initSelector")
-            descriptor.constructedClass.unsubstitutedMemberScope.getContributedDescriptors().asSequence()
-                    .filterIsInstance<FunctionDescriptor>()
-                    .single { it.getExternalObjCMethodInfo()?.selector == initSelector }
-        }
-    }
-
     override fun visitCall(expression: IrCall): IrExpression {
         expression.transformChildrenVoid()
 
         val descriptor = expression.descriptor.original
 
         if (descriptor is ConstructorDescriptor) {
-            val initMethod = getObjCInitMethod(descriptor)
+            val initMethod = descriptor.getObjCInitMethod()
 
             if (initMethod != null) {
                 val arguments = descriptor.valueParameters.map { expression.getValueArgument(it)!! }

runtime/src/main/cpp/ObjCInteropUtils.mm

@@ -19,6 +19,7 @@
 #if KONAN_OBJC_INTEROP
 
 #import <objc/runtime.h>
+#import <Foundation/NSException.h>
 #import <Foundation/NSString.h>
 
 namespace {
@@ -34,6 +35,11 @@ namespace {
     }
     return result;
   }
+
+  // Note: using @"foo" string literals leads to linkage dependency on frameworks.
+  NSString* cStringToNS(const char* str) {
+    return [getNSStringClass() stringWithCString:str encoding:NSUTF8StringEncoding];
+  }
 }
 
 extern "C" {
@@ -67,6 +73,24 @@ OBJ_GETTER(CreateKStringFromNSString, NSString* str) {
   RETURN_OBJ(result->obj());
 }
 
+// Note: this body is used for init methods with signatures differing from this;
+// it is correct on arm64 and x86_64, because the body uses only the first two arguments which are fixed,
+// and returns pointers.
+id MissingInitImp(id self, SEL _cmd) {
+  const char* className = object_getClassName(self);
+  [self release]; // Since init methods receive ownership on the receiver.
+
+  // Lookup dynamically to avoid direct reference to Foundation:
+  Class nsExceptionClass = objc_getClass("NSException");
+  RuntimeAssert(nsExceptionClass != nullptr, "NSException class not found");
+
+  [nsExceptionClass raise:cStringToNS("Initializer is not implemented")
+    format:cStringToNS("%s is not implemented in %s"),
+    sel_getName(_cmd), className];
+
+  return nullptr;
+}
+
 } // extern "C"
 
 #else // KONAN_OBJC_INTEROP