Test for var declarations in eval which conflict with let

test/mjsunit/regress/regress-4454.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 --no-legacy-const

[adamk, 2015/10/05 17:20:36]

Nit: split this line into two "Flags: " lines to fit under 80 chars.

+
+// Var-let conflict in a function throws, even if the var is in an eval
+
+let caught = false;
+
+// Throws at the top level of a function
+try {
+  (function() {
+    let x = 1;
+    eval('var x = 2');

[adamk, 2015/10/05 17:20:36]

Can you add tests for function declarations (I'm not actually sure what ES6 says
eval of a sloppy function inside a block should do...)?

Also I'd ideally like to see tests for legacy const, though that'll have to be
in a separate file.

[Dan Ehrenberg, 2015/10/05 18:27:14]

The spec says that no hoisting out of lexical blocks happens in the top level of
eval, but I bet this is web-incompatible. I think the behavior needs to be that
it hoists out just like a var declaration and turns into assignments.

+  })()
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// If the eval is in its own block scope, throws
+caught = false;
+try {
+  (function() {
+    let y = 1;
+    { eval('var y = 2'); }
+  })()
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// If the let is in its own block scope, with the eval, throws
+caught = false
+try {
+  (function() {
+    {
+      let x = 1;
+      eval('var x = 2');
+    }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// Legal if the let is no longer visible
+caught = false
+try {
+  (function() {
+    {
+      let x = 1;
+    }
+    eval('var x = 2');
+  })();
+} catch (e) {
+  caught = true;
+}
+assertFalse(caught);
+
+// All the same works for const:
+// Throws at the top level of a function
+try {
+  (function() {
+    const x = 1;
+    eval('var x = 2');
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// If the eval is in its own block scope, throws
+caught = false;
+try {
+  (function() {
+    const y = 1;
+    { eval('var y = 2'); }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// If the const is in its own block scope, with the eval, throws
+caught = false
+try {
+  (function() {
+    {
+      const x = 1;
+      eval('var x = 2');
+    }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);
+
+// Legal if the const is no longer visible
+caught = false
+try {
+  (function() {
+    {
+      const x = 1;
+    }
+    eval('var x = 2');
+  })();
+} catch (e) {
+  caught = true;
+}
+assertFalse(caught);
+
+// In global scope
+caught = false;
+try {
+  let z = 1;
+  eval('var 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('var a');
+  })();
+} catch (e) {
+  caught = true;
+}
+assertFalse(caught);
+
+// var across with doesn't conflict
+caught = false;
+try {
+  (function() {
+    with ({x: 1}) {
+      eval("var 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("var x = 2;");
+    }
+  })();
+} catch (e) {
+  caught = true;
+}
+assertTrue(caught);