Improve kotlin.Unit support in produced framework

Make the Objective-C wrapper unique, and provide the method to get it

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

@@ -398,6 +398,7 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
     val Kotlin_ObjCExport_refFromObjC by lazyRtFunction
     val Kotlin_Interop_CreateNSStringFromKString by lazyRtFunction
     val Kotlin_Interop_CreateNSArrayFromKList by lazyRtFunction
+    val Kotlin_ObjCExport_convertUnit by lazyRtFunction
     val Kotlin_ObjCExport_GetAssociatedObject by lazyRtFunction
     val Kotlin_ObjCExport_AbstractMethodCalled by lazyRtFunction
 

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

@@ -254,6 +254,7 @@ internal class ObjCExportCodeGenerator(
             methodTable: List<RTTIGenerator.MethodTableRecord>,
             val objCName: String,
             directAdapters: List<ObjCToKotlinMethodAdapter>,
+            classAdapters: List<ObjCToKotlinMethodAdapter>,
             virtualAdapters: List<ObjCToKotlinMethodAdapter>,
             reverseAdapters: List<KotlinToObjCMethodAdapter>
     ) : Struct(
@@ -275,6 +276,13 @@ internal class ObjCExportCodeGenerator(
             ),
             Int32(directAdapters.size),
 
+            staticData.placeGlobalConstArray(
+                    "",
+                    runtime.objCToKotlinMethodAdapter,
+                    classAdapters
+            ),
+            Int32(classAdapters.size),
+
             staticData.placeGlobalConstArray(
                     "",
                     runtime.objCToKotlinMethodAdapter,
@@ -611,7 +619,8 @@ private fun ObjCExportCodeGenerator.createTypeAdapterForPackage(
             vtableSize = -1,
             methodTable = emptyList(),
             objCName = name,
-            directAdapters = adapters,
+            directAdapters = emptyList(),
+            classAdapters = adapters,
             virtualAdapters = emptyList(),
             reverseAdapters = emptyList()
     )
@@ -719,6 +728,12 @@ private fun ObjCExportCodeGenerator.createTypeAdapter(
         emptyList()
     }
 
+    val classAdapters = mutableListOf<ObjCExportCodeGenerator.ObjCToKotlinMethodAdapter>()
+
+    if (descriptor.isUnit()) {
+        classAdapters += createUnitInstanceAdapter()
+    }
+
     return ObjCTypeAdapter(
             descriptor,
             typeInfo,
@@ -727,11 +742,26 @@ private fun ObjCExportCodeGenerator.createTypeAdapter(
             methodTable,
             objCName,
             adapters,
+            classAdapters,
             virtualAdapters,
             reverseAdapters
     )
 }
 
+private fun ObjCExportCodeGenerator.createUnitInstanceAdapter(): ObjCExportCodeGenerator.ObjCToKotlinMethodAdapter {
+    val selector = "unit"
+    val methodBridge = MethodBridge(ReferenceBridge, listOf(ReferenceBridge, ReferenceBridge))
+    val encoding = getEncoding(methodBridge)
+
+    val imp = generateFunction(codegen, objCFunctionType(methodBridge), "") {
+        ret(callFromBridge(context.llvm.Kotlin_ObjCExport_convertUnit, listOf(codegen.theUnitInstanceRef.llvm)))
+    }
+
+    LLVMSetLinkage(imp, LLVMLinkage.LLVMPrivateLinkage)
+
+    return ObjCToKotlinMethodAdapter(selector, encoding, constPointer(imp))
+}
+
 private fun List<CallableMemberDescriptor>.toMethods(): List<FunctionDescriptor> = this.flatMap {
     when (it) {
         is PropertyDescriptor -> listOfNotNull(it.getter, it.setter)

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

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.backend.konan.Context
 import org.jetbrains.kotlin.backend.konan.KonanCompilationException
 import org.jetbrains.kotlin.backend.konan.descriptors.getPackageFragments
 import org.jetbrains.kotlin.backend.konan.descriptors.isInterface
+import org.jetbrains.kotlin.backend.konan.descriptors.isUnit
 import org.jetbrains.kotlin.backend.konan.reportCompilationError
 import org.jetbrains.kotlin.builtins.getReceiverTypeFromFunctionType
 import org.jetbrains.kotlin.builtins.getReturnTypeFromFunctionType
@@ -201,6 +202,11 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
 
             +"@interface $name : $superName${descriptor.superProtocolsClause}"
 
+            if (descriptor.isUnit()) {
+                +"+ (instancetype)unit NS_SWIFT_NAME(init());"
+                +""
+            }
+
             val presentConstructors = mutableSetOf<String>()
 
             descriptor.constructors.filter { mapper.shouldBeExposed(it) }.forEach {

runtime/src/main/cpp/ObjCExport.mm

@@ -27,6 +27,7 @@
 #import <Foundation/NSMethodSignature.h>
 #import <Foundation/NSException.h>
 #import <objc/runtime.h>
+#import <dispatch/dispatch.h>
 #import "MemoryPrivate.hpp"
 #import "Runtime.h"
 #import "Utils.h"
@@ -58,6 +59,9 @@ struct ObjCTypeAdapter {
   const ObjCToKotlinMethodAdapter* directAdapters;
   int directAdapterNum;
 
+  const ObjCToKotlinMethodAdapter* classAdapters;
+  int classAdapterNum;
+
   const ObjCToKotlinMethodAdapter* virtualAdapters;
   int virtualAdapterNum;
 
@@ -107,6 +111,7 @@ inline static OBJ_GETTER(AllocInstanceWithAssociatedObject, const TypeInfo* type
   return result;
 }
 
+static Class getOrCreateClass(const TypeInfo* typeInfo);
 static void initializeClass(Class clazz);
 
 @protocol ConvertibleToKotlin
@@ -200,6 +205,16 @@ extern "C" void Kotlin_ObjCExport_releaseReservedObjectTail(ObjHeader* obj) {
   }
 }
 
+extern "C" id Kotlin_ObjCExport_convertUnit(ObjHeader* unitInstance) {
+  static dispatch_once_t onceToken;
+  static id instance = nullptr;
+  dispatch_once(&onceToken, ^{
+    Class unitClass = getOrCreateClass(unitInstance->type_info());
+    instance = [[unitClass createWrapper:unitInstance] retain];
+  });
+  return instance;
+}
+
 static const ObjCTypeAdapter* findAdapterByName(
       const char* name,
       const ObjCTypeAdapter** sortedAdapters,
@@ -279,8 +294,14 @@ static void initializeClass(Class clazz) {
   for (int i = 0; i < typeAdapter->directAdapterNum; ++i) {
     const ObjCToKotlinMethodAdapter* adapter = typeAdapter->directAdapters + i;
     SEL selector = sel_registerName(adapter->selector);
-    Class methodContainer = isClassForPackage ? object_getClass(clazz) : clazz;
+    BOOL added = class_addMethod(clazz, selector, adapter->imp, adapter->encoding);
-    BOOL added = class_addMethod(methodContainer, selector, adapter->imp, adapter->encoding);
+    RuntimeAssert(added, "Unexpected selector clash");
+  }
+
+  for (int i = 0; i < typeAdapter->classAdapterNum; ++i) {
+    const ObjCToKotlinMethodAdapter* adapter = typeAdapter->classAdapters + i;
+    SEL selector = sel_registerName(adapter->selector);
+    BOOL added = class_addMethod(object_getClass(clazz), selector, adapter->imp, adapter->encoding);
     RuntimeAssert(added, "Unexpected selector clash");
   }
 
@@ -570,8 +591,6 @@ extern "C" OBJ_GETTER(Kotlin_ObjCExport_refFromObjC, id obj) {
   return [convertible toKotlin:OBJ_RESULT];
 }
 
-static Class getOrCreateClass(const TypeInfo* typeInfo);
-
 static id convertKotlinObject(ObjHeader* obj) {
   Class clazz = obj->type_info()->writableInfo_->objCExport.objCClass;
   RuntimeAssert(clazz != nullptr, "");
@@ -589,7 +608,7 @@ static id Kotlin_ObjCExport_refToObjC_slowpath(ObjHeader* obj) {
 
   if (converter == nullptr) {
     getOrCreateClass(typeInfo);
-    converter = &convertKotlinObject;
+    converter = (typeInfo == theUnitTypeInfo) ? &Kotlin_ObjCExport_convertUnit : &convertKotlinObject;
   }
 
   typeInfo->writableInfo_->objCExport.convert = converter;

runtime/src/main/cpp/Types.h

@@ -83,6 +83,7 @@ extern const TypeInfo* theDoubleArrayTypeInfo;
 extern const TypeInfo* theBooleanArrayTypeInfo;
 extern const TypeInfo* theStringTypeInfo;
 extern const TypeInfo* theThrowableTypeInfo;
+extern const TypeInfo* theUnitTypeInfo;
 extern const TypeInfo* theObjCPointerHolderTypeInfo;
 
 KBoolean IsInstance(const ObjHeader* obj, const TypeInfo* type_info) RUNTIME_PURE;

runtime/src/main/kotlin/kotlin/Unit.kt

@@ -16,6 +16,7 @@
 
 package kotlin
 
+@ExportTypeInfo("theUnitTypeInfo")
 public object Unit {
     override fun toString() = "kotlin.Unit"
 }