Simplify implementation of assignment-to-const checks.

Also, add test that assignment to function name is a syntax error with harmony scoping.

Does not fix issue 2243 directly, but with ES6, the required behaviour will change to what is implemented already anyway.

R=yangguo@chromium.org
BUG=v8:2243

Review URL: https://codereview.chromium.org/11607016

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13234 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/full-codegen-arm.cc

@@ -2031,7 +2031,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
-  // Invalid left-hand sides are rewritten to have a 'throw
+  // Invalid left-hand sides are rewritten by the parser to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);

src/ia32/full-codegen-ia32.cc

@@ -1977,7 +1977,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
-  // Invalid left-hand sides are rewritten to have a 'throw
+  // Invalid left-hand sides are rewritten by the parser to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);

src/mips/full-codegen-mips.cc

@@ -2047,7 +2047,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
-  // Invalid left-hand sides are rewritten to have a 'throw
+  // Invalid left-hand sides are rewritten by the parser to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);

src/parser.cc

@@ -3006,6 +3006,7 @@ Expression* Parser::ParseAssignmentExpression(bool accept_IN, bool* ok) {
   // side expression.  We could report this as a syntax error here but
   // for compatibility with JSC we choose to report the error at
   // runtime.
+  // TODO(ES5): Should change parsing for spec conformance.
   if (expression == NULL || !expression->IsValidLeftHandSide()) {
     Handle<String> type =
         isolate()->factory()->invalid_lhs_in_assignment_symbol();

src/scopes.cc

@@ -308,23 +308,6 @@ bool Scope::Analyze(CompilationInfo* info) {
   }
 #endif
 
-  if (FLAG_harmony_scoping) {
-    VariableProxy* proxy = scope->CheckAssignmentToConst();
-    if (proxy != NULL) {
-      // Found an assignment to const. Throw a syntax error.
-      MessageLocation location(info->script(),
-                               proxy->position(),
-                               proxy->position());
-      Isolate* isolate = info->isolate();
-      Factory* factory = isolate->factory();
-      Handle<JSArray> array = factory->NewJSArray(0);
-      Handle<Object> result =
-          factory->NewSyntaxError("harmony_const_assign", array);
-      isolate->Throw(*result, &location);
-      return false;
-    }
-  }
-
   info->SetScope(scope);
   return true;
 }
@@ -591,29 +574,6 @@ Declaration* Scope::CheckConflictingVarDeclarations() {
 }
 
 
-VariableProxy* Scope::CheckAssignmentToConst() {
-  // Check this scope.
-  if (is_extended_mode()) {
-    for (int i = 0; i < unresolved_.length(); i++) {
-      ASSERT(unresolved_[i]->var() != NULL);
-      if (unresolved_[i]->var()->is_const_mode() &&
-          unresolved_[i]->IsLValue()) {
-        return unresolved_[i];
-      }
-    }
-  }
-
-  // Check inner scopes.
-  for (int i = 0; i < inner_scopes_.length(); i++) {
-    VariableProxy* proxy = inner_scopes_[i]->CheckAssignmentToConst();
-    if (proxy != NULL) return proxy;
-  }
-
-  // No assignments to const found.
-  return NULL;
-}
-
-
 class VarAndOrder {
  public:
   VarAndOrder(Variable* var, int order) : var_(var), order_(order) { }
@@ -1102,6 +1062,20 @@ bool Scope::ResolveVariable(CompilationInfo* info,
 
   ASSERT(var != NULL);
 
+  if (FLAG_harmony_scoping && is_extended_mode() &&
+      var->is_const_mode() && proxy->IsLValue()) {
+    // Assignment to const. Throw a syntax error.
+    MessageLocation location(
+        info->script(), proxy->position(), proxy->position());
+    Isolate* isolate = Isolate::Current();
+    Factory* factory = isolate->factory();
+    Handle<JSArray> array = factory->NewJSArray(0);
+    Handle<Object> result =
+        factory->NewSyntaxError("harmony_const_assign", array);
+    isolate->Throw(*result, &location);
+    return false;
+  }
+
   if (FLAG_harmony_modules) {
     bool ok;
 #ifdef DEBUG
@@ -1122,9 +1096,8 @@ bool Scope::ResolveVariable(CompilationInfo* info,
 
       // Inconsistent use of module. Throw a syntax error.
       // TODO(rossberg): generate more helpful error message.
-      MessageLocation location(info->script(),
-                               proxy->position(),
-                               proxy->position());
+      MessageLocation location(
+          info->script(), proxy->position(), proxy->position());
       Isolate* isolate = Isolate::Current();
       Factory* factory = isolate->factory();
       Handle<JSArray> array = factory->NewJSArray(1);

src/scopes.h

@@ -224,11 +224,6 @@ class Scope: public ZoneObject {
   // scope over a let binding of the same name.
   Declaration* CheckConflictingVarDeclarations();
 
-  // For harmony block scoping mode: Check if the scope has variable proxies
-  // that are used as lvalues and point to const variables. Assumes that scopes
-  // have been analyzed and variables been resolved.
-  VariableProxy* CheckAssignmentToConst();
-
   // ---------------------------------------------------------------------------
   // Scope-specific info.
 

src/x64/full-codegen-x64.cc

@@ -1965,7 +1965,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
-  // Invalid left-hand sides are rewritten to have a 'throw
+  // Invalid left-hand sides are rewritten by the parser to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);

test/mjsunit/regress/regress-2243.js

@@ -0,0 +1,31 @@
+// 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --harmony-scoping
+
+assertThrows("'use strict'; (function f() { f = 123; })", SyntaxError);
+assertThrows("(function f() { 'use strict'; f = 123; })", SyntaxError);