Reland of Ship ES2015 sloppy-mode function hoisting, let, class

test/mjsunit/es6/block-eval-var-over-legacy-const.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-sloppy --harmony-sloppy-let --harmony-sloppy-function
+
+// Var-let conflict in a function throws, even if the var is in an eval
+
+// Throws at the top level of a function
+assertThrows(function() {
+  let x = 1;
+  eval('const x = 2');
+}, TypeError);
+
+// If the eval is in its own block scope, throws
+assertThrows(function() {
+  let y = 1;
+  { eval('const y = 2'); }
+}, TypeError);
+
+// If the let is in its own block scope, with the eval, throws
+assertThrows(function() {
+  {
+    let x = 1;
+    eval('const x = 2');
+  }
+}, TypeError);
+
+// Legal if the let is no longer visible
+assertDoesNotThrow(function() {
+  {
+    let x = 1;
+  }
+  eval('const x = 2');
+});
+
+// In global scope
+let caught = false;
+try {
+  let z = 1;
+  eval('const z = 2');
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// Let declarations beyond a function boundary don't conflict
+caught = false;
+try {
+  let a = 1;
+  (function() {
+    eval('const a');
+  })();
+} catch (e) {
+  caught = true;
+}
+assertFalse(caught);
+
+// var across with doesn't conflict
+caught = false;
+try {
+  (function() {
+    with ({x: 1}) {
+      eval("const x = 2;");
+    }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertFalse(caught);
+
+// var can still conflict with let across a with
+caught = false;
+try {
+  (function() {
+    let x;
+    with ({x: 1}) {
+      eval("const x = 2;");
+    }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);