[es6] Initial support for let/const bindings in sloppy mode

src/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/v8.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/ast-literal-reindexer.h"
 #include "src/bailout-reason.h"
@@ skipping 1369 matching lines @@
       }
       return ParseClassDeclaration(NULL, ok);
     case Token::CONST:
       if (allow_const()) {
         return ParseVariableStatement(kStatementListItem, NULL, ok);
       }
       break;
     case Token::VAR:
       return ParseVariableStatement(kStatementListItem, NULL, ok);
     case Token::LET:
-      if (is_strict(language_mode())) {
+      if (allow_let()) {
         return ParseVariableStatement(kStatementListItem, NULL, ok);
       }
       break;
     default:
       break;
   }
   return ParseStatement(NULL, ok);
 }
 
 
@@ skipping 641 matching lines @@
       // functions. The function CheckConflictingVarDeclarations checks for
       // var and let bindings from different scopes whereas this is a check for
       // conflicting declarations within the same scope. This check also covers
       // the special case
       //
       // function () { let x; { var x; } }
       //
       // because the var declaration is hoisted to the function scope where 'x'
       // is already bound.
       DCHECK(IsDeclaredVariableMode(var->mode()));
-      if (is_strict(language_mode())) {
+      if (is_strict(language_mode()) || allow_harmony_sloppy()) {
         // In harmony we treat re-declarations as early errors. See
         // ES5 16 for a definition of early errors.
         if (declaration_kind == DeclarationDescriptor::NORMAL) {
           ParserTraits::ReportMessage(MessageTemplate::kVarRedeclaration, name);
         } else {
           ParserTraits::ReportMessage(MessageTemplate::kStrictParamDupe);
         }
         *ok = false;
         return nullptr;
       }
@@ skipping 137 matching lines @@
                            pos, FunctionLiteral::DECLARATION,
                            FunctionLiteral::NORMAL_ARITY, CHECK_OK);
   // Even if we're not at the top-level of the global or a function
   // scope, we treat it as such and introduce the function with its
   // initial value upon entering the corresponding scope.
   // In ES6, a function behaves as a lexical binding, except in
   // a script scope, or the initial scope of eval or another function.
   VariableMode mode =
       is_strong(language_mode())
           ? CONST
-          : is_strict(language_mode()) &&
+          : (is_strict(language_mode()) || allow_harmony_sloppy()) &&
                     !(scope_->is_script_scope() || scope_->is_eval_scope() ||
                       scope_->is_function_scope())
                 ? LET
                 : VAR;
   VariableProxy* proxy = NewUnresolved(name, mode);
   Declaration* declaration =
       factory()->NewFunctionDeclaration(proxy, mode, fun, scope_, pos);
   Declare(declaration, DeclarationDescriptor::NORMAL, true, CHECK_OK);
   if (names) names->Add(name, zone());
+
+  // In ES'15 sloppy mode inside a block a let binding and a var binding are
+  // created.
+  // TODO(arv): A var binding should only be created if it does not introduce a
+  // conflict.
+  // if (allow_harmony_sloppy() && !is_strict(language_mode()) &&
+  //     !(scope_->is_script_scope() || scope_->is_eval_scope() ||
+  //       scope_->is_function_scope())) {
+  //   Declaration* declaration =
+  //       factory()->NewFunctionDeclaration(proxy, VAR, fun, scope_, pos);
+  //   Declare(declaration, DeclarationDescriptor::NORMAL, true, CHECK_OK);
+  // }
+
   return factory()->NewEmptyStatement(RelocInfo::kNoPosition);
 }
 
 
 Statement* Parser::ParseClassDeclaration(ZoneList<const AstRawString*>* names,
                                          bool* ok) {
   // ClassDeclaration ::
   //   'class' Identifier ('extends' LeftHandExpression)? '{' ClassBody '}'
   //
   // A ClassDeclaration
@@ skipping 50 matching lines @@
       is_strong(language_mode()) ? Token::INIT_CONST : Token::INIT_LET;
   Assignment* assignment = factory()->NewAssignment(init_op, proxy, value, pos);
   Statement* assignment_statement =
       factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition);
   if (names) names->Add(name, zone());
   return assignment_statement;
 }
 
 
 Block* Parser::ParseBlock(ZoneList<const AstRawString*>* labels, bool* ok) {
-  if (is_strict(language_mode())) {
+  if (is_strict(language_mode()) || allow_harmony_sloppy()) {
     return ParseScopedBlock(labels, ok);
   }
 
   // Block ::
   //   '{' Statement* '}'
 
   // Note that a Block does not introduce a new execution scope!
   // (ECMA-262, 3rd, 12.2)
   //
   // Construct block expecting 16 statements.
@@ skipping 131 matching lines @@
       return;
     }
     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;
       parsing_result->descriptor.init_op = Token::INIT_CONST_LEGACY;
       ++use_counts_[v8::Isolate::kLegacyConst];
     } else {
-      DCHECK(is_strict(language_mode()));
+      DCHECK(is_strict(language_mode()) || allow_harmony_sloppy());
       DCHECK(var_context != kStatement);
       parsing_result->descriptor.mode = CONST;
       parsing_result->descriptor.init_op = Token::INIT_CONST;
     }
     parsing_result->descriptor.is_const = true;
     parsing_result->descriptor.needs_init = true;
-  } else if (peek() == Token::LET && is_strict(language_mode())) {
+  } else if (peek() == Token::LET && allow_let()) {
     Consume(Token::LET);
     DCHECK(var_context != kStatement);
     parsing_result->descriptor.mode = LET;
     parsing_result->descriptor.needs_init = true;
     parsing_result->descriptor.init_op = Token::INIT_LET;
   } else {
     UNREACHABLE();  // by current callers
   }
 
   parsing_result->descriptor.declaration_scope =
@@ skipping 1031 matching lines @@
   Scope* saved_scope = scope_;
   Scope* for_scope = NewScope(scope_, BLOCK_SCOPE);
   scope_ = for_scope;
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   for_scope->set_start_position(scanner()->location().beg_pos);
   bool is_let_identifier_expression = false;
   DeclarationParsingResult parsing_result;
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR || (peek() == Token::CONST && allow_const()) ||
-        (peek() == Token::LET && is_strict(language_mode()))) {
+        (peek() == Token::LET && allow_let())) {
       ParseVariableDeclarations(kForStatement, &parsing_result, CHECK_OK);
       is_const = parsing_result.descriptor.mode == CONST;
 
       int num_decl = parsing_result.declarations.length();
       bool accept_IN = num_decl >= 1;
       bool accept_OF = true;
       ForEachStatement::VisitMode mode;
       int each_beg_pos = scanner()->location().beg_pos;
       int each_end_pos = scanner()->location().end_pos;
 
@@ skipping 454 matching lines @@
   //   in all normal cases, function declarations are fully hoisted to a
   //   declaration scope and compiled relative to that.
   // - (2) is the case iff the current declaration scope is still the original
   //   one relative to the deserialized scope chain. Otherwise we must be
   //   compiling a function in an inner declaration scope in the eval, e.g. a
   //   nested function, and hoisting works normally relative to that.
   Scope* declaration_scope = scope_->DeclarationScope();
   Scope* original_declaration_scope = original_scope_->DeclarationScope();
   Scope* scope = function_type == FunctionLiteral::DECLARATION &&
                          is_sloppy(language_mode()) &&
+                         !allow_harmony_sloppy() &&
                          (original_scope_ == original_declaration_scope ||
                           declaration_scope != original_declaration_scope)
                      ? NewScope(declaration_scope, FUNCTION_SCOPE, kind)
                      : NewScope(scope_, FUNCTION_SCOPE, kind);
   ZoneList<Statement*>* body = NULL;
   int materialized_literal_count = -1;
   int expected_property_count = -1;
   DuplicateFinder duplicate_finder(scanner()->unicode_cache());
   ExpressionClassifier formals_classifier(&duplicate_finder);
   FunctionLiteral::EagerCompileHint eager_compile_hint =
@@ skipping 37 matching lines @@
 
     // If we have a named function expression, we add a local variable
     // declaration to the body of the function with the name of the
     // function and let it refer to the function itself (closure).
     // NOTE: We create a proxy and resolve it here so that in the
     // future we can change the AST to only refer to VariableProxies
     // instead of Variables and Proxis as is the case now.
     Variable* fvar = NULL;
     Token::Value fvar_init_op = Token::INIT_CONST_LEGACY;
     if (function_type == FunctionLiteral::NAMED_EXPRESSION) {
-      if (is_strict(language_mode())) {
+      bool use_strict_const = is_strict(language_mode()) ||
+                              (!allow_legacy_const() && allow_harmony_sloppy());
+      if (use_strict_const) {
         fvar_init_op = Token::INIT_CONST;
       }
-      VariableMode fvar_mode =
-          is_strict(language_mode()) ? CONST : CONST_LEGACY;
+      VariableMode fvar_mode = use_strict_const ? CONST : CONST_LEGACY;
       DCHECK(function_name != NULL);
       fvar = new (zone())
           Variable(scope_, function_name, fvar_mode, Variable::NORMAL,
                    kCreatedInitialized, kNotAssigned);
       VariableProxy* proxy = factory()->NewVariableProxy(fvar);
       VariableDeclaration* fvar_declaration = factory()->NewVariableDeclaration(
           proxy, fvar_mode, scope_, RelocInfo::kNoPosition);
       scope_->DeclareFunctionVar(fvar_declaration);
     }
 
@@ skipping 1894 matching lines @@
 Expression* Parser::SpreadCallNew(Expression* function,
                                   ZoneList<v8::internal::Expression*>* args,
                                   int pos) {
   args->InsertAt(0, function, zone());
 
   return factory()->NewCallRuntime(
       ast_value_factory()->reflect_construct_string(), NULL, args, pos);
 }
 }  // namespace internal
 }  // namespace v8