Statically check for assignments to const in harmony mode.

src/parser.cc

 // 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 2671 matching lines @@
   if (expression == NULL || !expression->IsValidLeftHandSide()) {
     Handle<String> type =
         isolate()->factory()->invalid_lhs_in_assignment_symbol();
     expression = NewThrowReferenceError(type);
   }
 
   if (!top_scope_->is_classic_mode()) {
     // Assignment to eval or arguments is disallowed in strict mode.
     CheckStrictModeLValue(expression, "strict_lhs_assignment", CHECK_OK);
   }
+  MarkAsUsedAsLValue(expression);
 
   Token::Value op = Next();  // Get assignment operator.
   int pos = scanner().location().beg_pos;
   Expression* right = ParseAssignmentExpression(accept_IN, CHECK_OK);
 
   // TODO(1231235): We try to estimate the set of properties set by
   // constructors. We define a new property whenever there is an
   // assignment to a property of 'this'. We should probably only add
   // properties if we haven't seen them before. Otherwise we'll
   // probably overestimate the number of properties.
@@ skipping 213 matching lines @@
     if (expression == NULL || !expression->IsValidLeftHandSide()) {
       Handle<String> type =
           isolate()->factory()->invalid_lhs_in_prefix_op_symbol();
       expression = NewThrowReferenceError(type);
     }
 
     if (!top_scope_->is_classic_mode()) {
       // Prefix expression operand in strict mode may not be eval or arguments.
       CheckStrictModeLValue(expression, "strict_lhs_prefix", CHECK_OK);
     }
+    MarkAsUsedAsLValue(expression);
 
     int position = scanner().location().beg_pos;
     return new(zone()) CountOperation(isolate(),
                                       op,
                                       true /* prefix */,
                                       expression,
                                       position);
 
   } else {
     return ParsePostfixExpression(ok);
@@ skipping 15 matching lines @@
     if (expression == NULL || !expression->IsValidLeftHandSide()) {
       Handle<String> type =
           isolate()->factory()->invalid_lhs_in_postfix_op_symbol();
       expression = NewThrowReferenceError(type);
     }
 
     if (!top_scope_->is_classic_mode()) {
       // Postfix expression operand in strict mode may not be eval or arguments.
       CheckStrictModeLValue(expression, "strict_lhs_prefix", CHECK_OK);
     }
+    MarkAsUsedAsLValue(expression);
 
     Token::Value next = Next();
     int position = scanner().location().beg_pos;
     expression =
         new(zone()) CountOperation(isolate(),
                                    next,
                                    false /* postfix */,
                                    expression,
                                    position);
   }
@@ skipping 1338 matching lines @@
       next != Token::FUTURE_STRICT_RESERVED_WORD &&
       !Token::IsKeyword(next)) {
     ReportUnexpectedToken(next);
     *ok = false;
     return Handle<String>();
   }
   return GetSymbol(ok);
 }
 
 
+void Parser::MarkAsUsedAsLValue(Expression* expression) {
+  VariableProxy* lhs = expression != NULL
+      ? expression->AsVariableProxy()
+      : NULL;
+
+  if (lhs != NULL) lhs->MarkAsUsedAsLValue();
+}
+
+
 // Checks LHS expression for assignment and prefix/postfix increment/decrement
 // in strict mode.
 void Parser::CheckStrictModeLValue(Expression* expression,
                                    const char* error,
                                    bool* ok) {
   ASSERT(!top_scope_->is_classic_mode());
   VariableProxy* lhs = expression != NULL
       ? expression->AsVariableProxy()
       : NULL;
 
@@ skipping 1152 matching lines @@
       ASSERT(info->isolate()->has_pending_exception());
     } else {
       result = parser.ParseProgram(info);
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal