ES6: Duplicate properties are no longer an error

test/cctest/test-parsing.cc

 // Copyright 2012 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 2464 matching lines @@
     {"\"use strict\"; var myobject = {", "};"},
     {"\"use strict\"; var myobject = {", ",};"},
     { NULL, NULL }
   };
   const char* non_strict_context_data[][2] = {
     {"var myobject = {", "};"},
     {"var myobject = {", ",};"},
     { NULL, NULL }
   };
 
-  // These are only errors in strict mode.
+  // ES6 allows duplicate properties even in strict mode.
   const char* statement_data[] = {
     "foo: 1, foo: 2",
     "\"foo\": 1, \"foo\": 2",
     "foo: 1, \"foo\": 2",
     "1: 1, 1: 2",
     "1: 1, \"1\": 2",
     "get: 1, get: 2",  // Not a getter for real, just a property called get.
     "set: 1, set: 2",  // Not a setter for real, just a property called set.
     NULL
   };
 
   RunParserSyncTest(non_strict_context_data, statement_data, kSuccess);
-  RunParserSyncTest(strict_context_data, statement_data, kError);
+  RunParserSyncTest(strict_context_data, statement_data, kSuccess);
 }
 
 
 TEST(ErrorsObjectLiteralChecking) {
   const char* context_data[][2] = {
     {"\"use strict\"; var myobject = {", "};"},
     {"var myobject = {", "};"},
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     ",",
-    "foo: 1, get foo() {}",
-    "foo: 1, set foo(v) {}",
-    "\"foo\": 1, get \"foo\"() {}",
-    "\"foo\": 1, set \"foo\"(v) {}",
-    "1: 1, get 1() {}",
-    "1: 1, set 1() {}",
-    // It's counter-intuitive, but these collide too (even in classic
-    // mode). Note that we can have "foo" and foo as properties in classic mode,
-    // but we cannot have "foo" and get foo, or foo and get "foo".
-    "foo: 1, get \"foo\"() {}",
-    "foo: 1, set \"foo\"(v) {}",
-    "\"foo\": 1, get foo() {}",
-    "\"foo\": 1, set foo(v) {}",
-    "1: 1, get \"1\"() {}",
-    "1: 1, set \"1\"() {}",
-    "\"1\": 1, get 1() {}"
-    "\"1\": 1, set 1(v) {}"
     // Wrong number of parameters
     "get bar(x) {}",
     "get bar(x, y) {}",
     "set bar() {}",
     "set bar(x, y) {}",
     // Parsing FunctionLiteral for getter or setter fails
     "get foo( +",
     "get foo() \"error\"",
     NULL
   };
@@ skipping 33 matching lines @@
     "\"foo\": 1, set \"bar\"(v) {}",
     "1: 1, get 2() {}",
     "1: 1, set 2(v) {}",
     // Keywords, future reserved and strict future reserved are also allowed as
     // property names.
     "if: 4",
     "interface: 5",
     "super: 6",
     "eval: 7",
     "arguments: 8",
+    // Duplicate property names are allowed in ES6.
+    "foo: 1, get foo() {}",
+    "foo: 1, set foo(v) {}",
+    "\"foo\": 1, get \"foo\"() {}",
+    "\"foo\": 1, set \"foo\"(v) {}",
+    "1: 1, get 1() {}",
+    "1: 1, set 1(v) {}",
+    // It's counter-intuitive, but these collide too (even in classic
+    // mode). Note that we can have "foo" and foo as properties in classic mode,
+    // but we cannot have "foo" and get foo, or foo and get "foo".
+    "foo: 1, get \"foo\"() {}",
+    "foo: 1, set \"foo\"(v) {}",
+    "\"foo\": 1, get foo() {}",
+    "\"foo\": 1, set foo(v) {}",
+    "1: 1, get \"1\"() {}",
+    "1: 1, set \"1\"(v) {}",
+    "\"1\": 1, get 1() {}",
+    "\"1\": 1, set 1(v) {}",
     NULL
   };
 
   RunParserSyncTest(context_data, statement_data, kSuccess);
 }
 
 
 TEST(TooManyArguments) {
   const char* context_data[][2] = {
     {"foo(", "0)"},
@@ skipping 745 matching lines @@
 
     // Arrow has more precedence, this is the same as: foo ? bar : (baz = {})
     "foo ? bar : baz => {}",
     NULL
   };
 
   static const ParserFlag always_flags[] = {kAllowArrowFunctions};
   RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
                     always_flags, ARRAY_SIZE(always_flags));
 }