Parse harmony let declarations.

test/mjsunit/harmony/block-scoping.js

-// Copyright 2008 the V8 project authors. All rights reserved.
+// Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 20 matching lines @@
 function f1() {
   {
     var x = 1;
     var y;
   }
   assertEquals(1, x)
   assertEquals(undefined, y)
 }
 f1();
 
-// Dynamic lookup through block scopes.
+
+// Dynamic lookup in and through block contexts.
 function f2(one) {
   var x = one + 1;
-  // TODO(keuchel): introduce let
-  // let y = one + 2;
-  if (one == 1) {
-    // Parameter
+  let y = one + 2;
+  {
+    let z = one + 3;
     assertEquals(1, eval('one'));
-    // Function local var variable
     assertEquals(2, eval('x'));
-    // Function local let variable
-    // TODO(keuchel): introduce let
-    // assertEquals(3, eval('y'));
+    assertEquals(3, eval('y'));
+    assertEquals(4, eval('z'));
   }
 }
 f2(1);
 
+
+// Lookup in and through block contexts.

[rossberg, 2011/08/11 14:34:59]

It would be great if you could add tests for variable shadowing (between args,
catch, and let, in various combinations).

[Lasse Reichstein, 2011/08/12 08:08:33]

Agree. There is no test here that can distinguish a let from a hoisted var.

[Steven, 2011/08/16 09:05:32]

Added your for-loop test that distinguishes those.
On 2011/08/12 08:08:33, Lasse Reichstein wrote:

[Steven, 2011/08/16 09:05:32]

Done.

+function f3(one) {
+  var x = one + 1;
+  let y = one + 2;
+  {
+    let z = one + 3;
+    assertEquals(1, one);
+    assertEquals(2, x);
+    assertEquals(3, y);
+    assertEquals(4, z);
+  }
+}
+f3(1);
+
+
+// Dynamic lookup from closure.
+function f4(one) {
+  var x = one + 1;
+  let y = one + 2;
+  {
+    let z = one + 3;
+    function f() {
+      assertEquals(1, eval('one'));
+      assertEquals(2, eval('x'));
+      assertEquals(3, eval('y'));
+      assertEquals(4, eval('z'));
+    };
+  }
+}
+f4(1);
+
+
+// Lookup from closure.
+function f5(one) {
+  var x = one + 1;
+  let y = one + 2;
+  {
+    let z = one + 3;
+    function f() {
+      assertEquals(1, one);
+      assertEquals(2, x);
+      assertEquals(3, y);
+      assertEquals(4, z);
+    };
+  }

[Lasse Reichstein, 2011/08/12 08:08:33]

Try creating let variables in a loop. E.g.:

var accessors = [];
for (var i = 0; i < 10; i++) {
  let x = i;
  accessors[i] = function() { return x; }
}
for (var i = 0; i < 10; i++) {
  assertEquals(i, accessors[i]());
}

[Steven, 2011/08/16 09:05:32]

Done.

+}
+f5(1);
+
+// Return from block.
+function f6() {
+  let x = 1;
+  {
+    let y = 2;
+    return x + y;
+  }
+}
+assertEquals(3, f6(6));