Support handler parameter generation

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

@@ -16,9 +16,11 @@ import org.jetbrains.kotlin.util.OperatorNameConventions
 // This is what Context collects about IR.
 abstract class Ir<out T: CommonBackendContext>(val context: T, val irModule: IrModuleFragment) {
 
+    abstract val symbols: Symbols<T>
+
     val defaultParameterDeclarationsCache = mutableMapOf<FunctionDescriptor, IrFunction>()
 
-    abstract val symbols: Symbols<T>
+    open fun shouldGenerateHandlerParameterForDefaultBodyFun() = false
 }
 
 open class Symbols<out T: CommonBackendContext>(val context: T, private val symbolTable: SymbolTable) {

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/common/lower/DefaultArgumentStubGenerator.kt

@@ -368,6 +368,12 @@ private fun FunctionDescriptor.generateDefaultsFunction(context: CommonBackendCo
                     kConstructorMarkerName,
                     context.ir.symbols.defaultConstructorMarker.owner.defaultType)
         }
+        else if (context.ir.shouldGenerateHandlerParameterForDefaultBodyFun()) {
+            syntheticParameters += valueParameter(descriptor, syntheticParameters.last().index + 1,
+                    "handler".synthesizedName,
+                    context.ir.symbols.any.owner.defaultType)
+        }
+
         descriptor.initialize(
                 /* receiverParameterType         = */ extensionReceiverParameter?.type,
                 /* dispatchReceiverParameter     = */ dispatchReceiverParameter,