Block scoped const variables.

test/mjsunit/harmony/block-scoping.js

 // 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
@@ skipping 26 matching lines @@
   assertEquals(1, x)
   assertEquals(undefined, y)
 }
 f1();
 
 
 // Dynamic lookup in and through block contexts.
 function f2(one) {
   var x = one + 1;
   let y = one + 2;
+  const u = one + 4;
   {
     let z = one + 3;
+    const v = one + 5;
     assertEquals(1, eval('one'));
     assertEquals(2, eval('x'));
     assertEquals(3, eval('y'));
     assertEquals(4, eval('z'));
+    assertEquals(5, eval('u'));
+    assertEquals(6, eval('v'));
   }
 }
 f2(1);
 
 
 // Lookup in and through block contexts.
 function f3(one) {
   var x = one + 1;
   let y = one + 2;
+  const u = one + 4;
   {
     let z = one + 3;
+    const v = one + 5;
     assertEquals(1, one);
     assertEquals(2, x);
     assertEquals(3, y);
     assertEquals(4, z);
+    assertEquals(5, u);
+    assertEquals(6, v);
+
   }
 }
 f3(1);
 
 
 // Dynamic lookup from closure.
 function f4(one) {
   var x = one + 1;
   let y = one + 2;
+  const u = one + 4;
   {
     let z = one + 3;
+    const v = one + 5;
     function f() {
       assertEquals(1, eval('one'));
       assertEquals(2, eval('x'));
       assertEquals(3, eval('y'));
       assertEquals(4, eval('z'));
+      assertEquals(5, eval('u'));
+      assertEquals(6, eval('v'));
     };
   }
 }
 f4(1);
 
 
 // Lookup from closure.
 function f5(one) {
   var x = one + 1;
   let y = one + 2;
+  const u = one + 4;
   {
     let z = one + 3;
+    const v = one + 5;
     function f() {
       assertEquals(1, one);
       assertEquals(2, x);
       assertEquals(3, y);
       assertEquals(4, z);
+      assertEquals(5, u);
+      assertEquals(6, v);
     };
   }
 }
 f5(1);
 
 
 // Return from block.
 function f6() {
   let x = 1;
+  const u = 3;
   {
     let y = 2;
+    const v = 4;
     return x + y;
   }
 }
 assertEquals(3, f6(6));
 
 
 // Variable shadowing and lookup.
 function f7(a) {
   let b = 1;
   var c = 1;
   var d = 1;
-  { // let variables shadowing argument, let and var variables
+  const e = 1;
+  { // let variables shadowing argument, let, const and var variables
     let a = 2;
     let b = 2;
     let c = 2;
+    let e = 2;
     assertEquals(2,a);
     assertEquals(2,b);
     assertEquals(2,c);
+    assertEquals(2,e);
+  }
+  { // const variables shadowing argument, let, const and var variables
+    const a = 2;
+    const b = 2;
+    const c = 2;
+    const e = 2;
+    assertEquals(2,a);
+    assertEquals(2,b);
+    assertEquals(2,c);
+    assertEquals(2,e);
   }
   try {
     throw 'stuff1';
   } catch (a) {
     assertEquals('stuff1',a);
     // catch variable shadowing argument
     a = 2;
     assertEquals(2,a);
     {
       // let variable shadowing catch variable
       let a = 3;
       assertEquals(3,a);
       try {
         throw 'stuff2';
       } catch (a) {
         assertEquals('stuff2',a);
         // catch variable shadowing let variable
         a = 4;
         assertEquals(4,a);
       }
       assertEquals(3,a);
     }
     assertEquals(2,a);
   }
   try {
     throw 'stuff3';
   } catch (c) {
     // catch variable shadowing var variable
     assertEquals('stuff3',c);
+    {
+      // const variable shadowing catch variable
+      const c = 3;
+      assertEquals(3,c);
+    }
+    assertEquals('stuff3',c);
     try {
       throw 'stuff4';
     } catch(c) {
       assertEquals('stuff4',c);
       // catch variable shadowing catch variable
       c = 3;
       assertEquals(3,c);
     }
     (function(c) {
       // argument shadowing catch variable
       c = 3;
       assertEquals(3,c);
     })();
     assertEquals('stuff3', c);
     (function() {
       // var variable shadowing catch variable
       var c = 3;
     })();
     assertEquals('stuff3', c);
     c = 2;
   }
   assertEquals(1,c);
-  (function(a,b,c) {
-    // arguments shadowing argument, let and var variable
+  (function(a,b,c,e) {
+    // arguments shadowing argument, let, const and var variable
     a = 2;
     b = 2;
     c = 2;
+    e = 2;
     assertEquals(2,a);
     assertEquals(2,b);
     assertEquals(2,c);
+    assertEquals(2,e);
     // var variable shadowing var variable
     var d = 2;
   })(1,1);
   assertEquals(1,a);
   assertEquals(1,b);
   assertEquals(1,c);
   assertEquals(1,d);
+  assertEquals(1,e);
 }
 f7(1);
 
 
-// Ensure let variables are block local and var variables function local.
+// Ensure let and const variables are block local
+// and var variables function local.
 function f8() {
   var let_accessors = [];
   var var_accessors = [];
+  var const_accessors = [];
   for (var i = 0; i < 10; i++) {
     let x = i;
     var y = i;
+    const z = i;
     let_accessors[i] = function() { return x; }
     var_accessors[i] = function() { return y; }
+    const_accessors[i] = function() { return z; }
   }
   for (var j = 0; j < 10; j++) {
     y = j + 10;
     assertEquals(j, let_accessors[j]());
     assertEquals(y, var_accessors[j]());
+    assertEquals(j, const_accessors[j]());
   }
 }
 f8();