From 5c7f88a5fb3a7a9c99a764ebabfb9a751733c6b7 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Fri, 30 Oct 2015 17:39:57 +0000
Subject: [PATCH] fix parameters after defaults in arrow functions refering to
 the wrong `arguments` - fixes #2682

---
 .../es6.arrow-functions/default-parameters/actual.js      | 4 +++-
 .../es6.arrow-functions/default-parameters/expected.js    | 8 +++++++-
 .../src/default.js                                        | 4 ++--
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/actual.js b/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/actual.js
index 4eee9c372e..f9c9245ffe 100644
--- a/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/actual.js
+++ b/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/actual.js
@@ -2,4 +2,6 @@ var some = (count = "30") => {
   console.log("count", count);
 };
 
-some();
+var collect = (since = 0, userid) => {
+  console.log(userid);
+};
diff --git a/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/expected.js b/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/expected.js
index 7b03aac22d..4f89ccdd0d 100644
--- a/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/expected.js
+++ b/packages/babel-core/test/fixtures/transformation/es6.arrow-functions/default-parameters/expected.js
@@ -4,4 +4,10 @@ var some = function () {
   console.log("count", count);
 };
 
-some();
+
+var collect = function () {
+  let since = arguments.length <= 0 || arguments[0] === undefined ? 0 : arguments[0];
+  let userid = arguments[1];
+
+  console.log(userid);
+};
diff --git a/packages/babel-plugin-transform-es2015-parameters/src/default.js b/packages/babel-plugin-transform-es2015-parameters/src/default.js
index 9b99a3e475..6076c27b11 100644
--- a/packages/babel-plugin-transform-es2015-parameters/src/default.js
+++ b/packages/babel-plugin-transform-es2015-parameters/src/default.js
@@ -16,7 +16,7 @@ let buildDefaultParamAssign = template(`
 `);
 
 let buildCutOff = template(`
-  let $0 = arguments[$1];
+  let $0 = $1[$2];
 `);
 
 function hasDefaults(node) {
@@ -131,7 +131,7 @@ export let visitor = {
       let param = node.params[i];
       if (param._isDefaultPlaceholder) continue;
 
-      let declar = buildCutOff(param, t.numberLiteral(i));
+      let declar = buildCutOff(param, argsIdentifier, t.numberLiteral(i));
       declar._blockHoist = node.params.length - i;
       body.push(declar);
     }