fix rest parameters in arrow functions containing wrong arguments reference - fixes #11

lib/6to5/transformers/_alias-functions.js

@@ -35,6 +35,8 @@ var go = function (getBody, node, file) {
         }
       }
 
+      if (node._ignoreAliasFunctions) return;
+
       var getId;
 
       if (node.type === "Identifier" && node.name === "arguments") {

lib/6to5/transformers/rest-parameters.js

@@ -11,9 +11,14 @@ exports.Function = function (node, parent, file) {
   if (node.params.length) templateName += "-arg";
 
   util.ensureBlock(node);
-  node.body.body.unshift(util.template(templateName, {
+
+  var template = util.template(templateName, {
     SLICE_KEY: file.addDeclaration("slice"),
     VARIABLE_NAME: rest,
     SLICE_ARG: b.literal(node.params.length)
-  }));
+  });
+
+  template.declarations[0].init.arguments[0]._ignoreAliasFunctions = true;
+
+  node.body.body.unshift(template);
 };

test/fixtures/transformation/rest-parameters/arrow-functions/actual.js

@@ -0,0 +1,3 @@
+var concat = (...arrs) => {
+
+};

test/fixtures/transformation/rest-parameters/arrow-functions/expected.js

@@ -0,0 +1,5 @@
+"use strict";
+var _slice = Array.prototype.slice;
+var concat = function () {
+  var arrs = _slice.call(arguments);
+};