From e9588061d75a45cf6c1938dd98fc0051841159ea Mon Sep 17 00:00:00 2001
From: unconfident <30427068+unconfident@users.noreply.github.com>
Date: Fri, 18 Jan 2019 00:12:16 +0200
Subject: [PATCH] Copy "optional" property when cloning Identifier node (#9333)

Fixes #9331
---
 packages/babel-types/src/clone/cloneNode.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/babel-types/src/clone/cloneNode.js b/packages/babel-types/src/clone/cloneNode.js
index 1da6c930e0..f1e36d3ad0 100644
--- a/packages/babel-types/src/clone/cloneNode.js
+++ b/packages/babel-types/src/clone/cloneNode.js
@@ -38,6 +38,10 @@ export default function cloneNode<T: Object>(node: T, deep: boolean = true): T {
   if (type === "Identifier") {
     newNode.name = node.name;
 
+    if (has(node, "optional") && typeof node.optional === "boolean") {
+      newNode.optional = node.optional;
+    }
+
     if (has(node, "typeAnnotation")) {
       newNode.typeAnnotation = deep
         ? cloneIfNodeOrArray(node.typeAnnotation, true)