Remove support for legacy const, part 1

src/parsing/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 770 matching lines @@
   // Even though we were passed ParseInfo, we should not store it in
   // Parser - this makes sure that Isolate is not accidentally accessed via
   // ParseInfo during background parsing.
   DCHECK(!info->script().is_null() || info->source_stream() != NULL);
   set_allow_lazy(info->allow_lazy_parsing());
   set_allow_natives(FLAG_allow_natives_syntax || info->is_native());
   set_allow_tailcalls(FLAG_harmony_tailcalls && !info->is_native());
   set_allow_harmony_sloppy(FLAG_harmony_sloppy);
   set_allow_harmony_sloppy_function(FLAG_harmony_sloppy_function);
   set_allow_harmony_sloppy_let(FLAG_harmony_sloppy_let);
-  set_allow_legacy_const(FLAG_legacy_const);
   set_allow_harmony_do_expressions(FLAG_harmony_do_expressions);
   set_allow_harmony_function_name(FLAG_harmony_function_name);
   set_allow_harmony_function_sent(FLAG_harmony_function_sent);
   set_allow_harmony_restrictive_declarations(
       FLAG_harmony_restrictive_declarations);
   set_allow_harmony_exponentiation_operator(
       FLAG_harmony_exponentiation_operator);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
@@ skipping 1017 matching lines @@
                           : MessageTemplate::kSloppyFunction);
       *ok = false;
       return nullptr;
 
     case Token::DEBUGGER:
       return ParseDebuggerStatement(ok);
 
     case Token::VAR:
       return ParseVariableStatement(kStatement, NULL, ok);
 
-    case Token::CONST:
-      // In ES6 CONST is not allowed as a Statement, only as a
-      // LexicalDeclaration, however we continue to allow it in sloppy mode for
-      // backwards compatibility.
-      if (is_sloppy(language_mode()) && allow_legacy_const()) {
-        return ParseVariableStatement(kStatement, NULL, ok);
-      }
-
-    // Fall through.
     default:
       return ParseExpressionOrLabelledStatement(labels, ok);
   }
 }
 
 Statement* Parser::ParseStatementAsUnlabelled(
     ZoneList<const AstRawString*>* labels, bool* ok) {
   switch (peek()) {
     case Token::CONTINUE:
       return ParseContinueStatement(ok);
@@ skipping 63 matching lines @@
     // Declare the variable in the declaration scope.
     var = declaration_scope->LookupLocal(name);
     if (var == NULL) {
       // Declare the name.
       Variable::Kind kind = Variable::NORMAL;
       if (is_function_declaration) {
         kind = Variable::FUNCTION;
       }
       var = declaration_scope->DeclareLocal(
           name, mode, declaration->initialization(), kind, kNotAssigned);
-    } else if ((mode == CONST_LEGACY || var->mode() == CONST_LEGACY) &&
-               !declaration_scope->is_script_scope()) {
-      // Duplicate legacy const definitions throw at runtime.
-      DCHECK(is_sloppy(language_mode()));
-      Expression* expression = NewThrowSyntaxError(
-          MessageTemplate::kVarRedeclaration, name, declaration->position());
-      declaration_scope->SetIllegalRedeclaration(expression);
     } else if ((IsLexicalVariableMode(mode) ||
                 IsLexicalVariableMode(var->mode())) &&
                // Lexical bindings may appear for some parameters in sloppy
                // mode even with --harmony-sloppy off.
                (is_strict(language_mode()) || allow_harmony_sloppy())) {
       // Allow duplicate function decls for web compat, see bug 4693.
       if (is_sloppy(language_mode()) && is_function_declaration &&
           var->is_function()) {
         DCHECK(IsLexicalVariableMode(mode) &&
                IsLexicalVariableMode(var->mode()));
@@ skipping 352 matching lines @@
   Block* init_block = nullptr;
   if (var_context != kForStatement) {
     init_block = factory()->NewBlock(
         NULL, 1, true, parsing_result->descriptor.declaration_pos);
   }
 
   if (peek() == Token::VAR) {
     Consume(Token::VAR);
   } else if (peek() == Token::CONST && allow_const()) {
     Consume(Token::CONST);
-    if (is_sloppy(language_mode()) && allow_legacy_const()) {
-      parsing_result->descriptor.mode = CONST_LEGACY;
-      ++use_counts_[v8::Isolate::kLegacyConst];
-    } else {
-      DCHECK(is_strict(language_mode()) || allow_harmony_sloppy());
-      DCHECK(var_context != kStatement);
-      parsing_result->descriptor.mode = CONST;
-    }
+    DCHECK(is_strict(language_mode()) || allow_harmony_sloppy());
+    DCHECK(var_context != kStatement);
+    parsing_result->descriptor.mode = CONST;
   } else if (peek() == Token::LET && allow_let()) {
     Consume(Token::LET);
     DCHECK(var_context != kStatement);
     parsing_result->descriptor.mode = LET;
   } else {
     UNREACHABLE();  // by current callers
   }
 
   parsing_result->descriptor.scope = scope_;
   parsing_result->descriptor.hoist_scope = nullptr;
@@ skipping 2361 matching lines @@
   TRACE_EVENT0("v8", "V8.PreParse");
 
   DCHECK_EQ(Token::LBRACE, scanner()->current_token());
 
   if (reusable_preparser_ == NULL) {
     reusable_preparser_ = new PreParser(zone(), &scanner_, ast_value_factory(),
                                         NULL, stack_limit_);
     reusable_preparser_->set_allow_lazy(true);
 #define SET_ALLOW(name) reusable_preparser_->set_allow_##name(allow_##name());
     SET_ALLOW(natives);
-    SET_ALLOW(legacy_const);
     SET_ALLOW(harmony_sloppy);
     SET_ALLOW(harmony_sloppy_function);
     SET_ALLOW(harmony_sloppy_let);
     SET_ALLOW(harmony_do_expressions);
     SET_ALLOW(harmony_function_name);
     SET_ALLOW(harmony_function_sent);
     SET_ALLOW(harmony_exponentiation_operator);
     SET_ALLOW(harmony_restrictive_declarations);
 #undef SET_ALLOW
   }
@@ skipping 2178 matching lines @@
                         try_block, target);
     final_loop = target;
   }
 
   return final_loop;
 }
 
 
 }  // namespace internal
 }  // namespace v8