fix noOptimise state being incorrect when recursing into multiple nested functions - fixes #1815

src/babel/transformation/transformers/es6/parameters.rest.js

@@ -12,9 +12,10 @@ var memberExpressionOptimisationVisitor = {
   Function(node, parent, scope, state) {
     // skip over functions as whatever `arguments` we reference inside will refer
     // to the wrong function
+    var oldNoOptimise = state.noOptimise;
     state.noOptimise = true;
     this.traverse(memberExpressionOptimisationVisitor, state);
-    state.noOptimise = false;
+    state.noOptimise = oldNoOptimise;
     this.skip();
   },
 
@@ -27,7 +28,9 @@ var memberExpressionOptimisationVisitor = {
     // is this a referenced identifier and is it referencing the rest parameter?
     if (node.name !== state.name) return;
 
-    if (!state.noOptimise) {
+    if (state.noOptimise) {
+      state.deopted = true;
+    } else {
       if (this.parentPath.isMemberExpression({ computed: true, object: node })) {
         // if we know that this member expression is referencing a number then we can safely
         // optimise it
@@ -46,11 +49,7 @@ var memberExpressionOptimisationVisitor = {
           return;
         }
       }
-    }
 
-    if (state.noOptimise) {
-      state.deopted = true;
-    } else {
       state.references.push(this);
     }
   }

test/core/fixtures/transformation/es6.parameters.rest/deepest-common-ancestor-earliest-child/actual.js

@@ -41,3 +41,12 @@ function r(...rest){
   if (lol) rest;
   rest;
 }
+
+// nested functions
+function a(...args) {
+  return function() {
+    function b() {}
+
+    console.log("Shouldn't args be from a's scope?", args);
+  };
+}

test/core/fixtures/transformation/es6.parameters.rest/deepest-common-ancestor-earliest-child/expected.js

@@ -64,3 +64,16 @@ function r() {
   if (lol) rest;
   rest;
 }
+
+// nested functions
+function a() {
+  for (var _len6 = arguments.length, args = Array(_len6), _key6 = 0; _key6 < _len6; _key6++) {
+    args[_key6] = arguments[_key6];
+  }
+
+  return function () {
+    function b() {}
+
+    console.log("Shouldn't args be from a's scope?", args);
+  };
+}