Remove obsolete String + code

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
 #include "vm/growable_array.h"
 #include "vm/longjump.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
 #include "vm/scopes.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, enable_asserts, false, "Enable assert statements.");
 DEFINE_FLAG(bool, enable_type_checks, false, "Enable type checks.");
 DEFINE_FLAG(bool, trace_parser, false, "Trace parser operations.");
 DEFINE_FLAG(bool, warning_as_error, false, "Treat warnings as errors.");
 DEFINE_FLAG(bool, silent_warnings, false, "Silence warnings.");
-DEFINE_FLAG(bool, allow_string_plus, false, "Allow + operator on strings.");
 
 static void CheckedModeHandler(bool value) {
   FLAG_enable_asserts = value;
   FLAG_enable_type_checks = value;
 }
 
 DEFINE_FLAG_HANDLER(CheckedModeHandler,
                     enable_checked_mode,
                     "Enabled checked mode.");
 
@@ skipping 5891 matching lines @@
           || Token::IsEqualityOperator(op_kind)) {
         if (Token::IsInstanceofOperator(op_kind)) {
           if (!right_operand->AsTypeNode()->type().IsInstantiated()) {
             EnsureExpressionTemp();
           }
         }
         left_operand = new ComparisonNode(
             op_pos, op_kind, left_operand, right_operand);
         break;  // Equality and relational operators cannot be chained.
       } else {
-        StringConcatNode* str_concat = NULL;
-        if (op_kind == Token::kADD) {
-          if (left_operand->IsLiteralNode()) {
-            LiteralNode* lit = left_operand->AsLiteralNode();
-            if (lit->literal().IsString()) {
-              if (FLAG_allow_string_plus) {
-                str_concat = new StringConcatNode(lit->token_index());
-                str_concat->AddExpr(lit);
-              } else {
-                ErrorMsg(op_pos, "operator + on strings no longer allowed");
-              }
-            }
-          } else if (left_operand->IsStringConcatNode()) {
-            str_concat = left_operand->AsStringConcatNode();
-          }
-        }
-        if (str_concat != NULL) {
-          str_concat->AddExpr(right_operand);
-          left_operand = str_concat;
-        } else {
-          left_operand = OptimizeBinaryOpNode(
-              op_pos, op_kind, left_operand, right_operand);
-        }
+        left_operand = OptimizeBinaryOpNode(
+            op_pos, op_kind, left_operand, right_operand);
       }
     }
     current_preced--;
   }
   return left_operand;
 }
 
 
 bool Parser::IsAssignableExpr(AstNode* expr) {
   return expr->IsPrimaryNode()
@@ skipping 2613 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart