Primitive support for LocalVariables for function parameters

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ValueParameterDescriptorImpl.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeSubstitutor
+import org.jetbrains.kotlin.utils.join
 
 open class ValueParameterDescriptorImpl(
         containingDeclaration: CallableDescriptor,
@@ -60,6 +61,16 @@ open class ValueParameterDescriptorImpl(
                     WithDestructuringDeclaration(containingDeclaration, original, index, annotations, name, outType,
                                                  declaresDefaultValue, isCrossinline, isNoinline, varargElementType, source,
                                                  destructuringVariables)
+
+        @JvmStatic
+        fun getNameForDestructuredParameterOrNull(valueParameterDescriptor: ValueParameterDescriptor): String? {
+            val variablesOrNull = ValueParameterDescriptorImpl.getDestructuringVariablesOrNull(valueParameterDescriptor)
+            return if (variablesOrNull == null) null else
+                "$" + join(
+                    variablesOrNull.map { descriptor -> if (descriptor.name.isSpecial) "\$_\$" else descriptor.name.asString() },
+                    "_"
+                )
+        }
     }
 
     class WithDestructuringDeclaration internal constructor(
@@ -81,6 +92,13 @@ open class ValueParameterDescriptorImpl(
         // as value parameters.
         // Must be forced via ForceResolveUtil.forceResolveAllContents()
         val destructuringVariables by lazy(destructuringVariables)
+
+        override fun copy(newOwner: CallableDescriptor, newName: Name, newIndex: Int): ValueParameterDescriptor {
+            return WithDestructuringDeclaration(
+                newOwner, null, newIndex, annotations, newName, type, declaresDefaultValue(),
+                isCrossinline, isNoinline, varargElementType, SourceElement.NO_SOURCE
+            ) { destructuringVariables }
+        }
     }
 
     private val original: ValueParameterDescriptor = original ?: this