[strong] Declaration-after-use errors.

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/bailout-reason.h"
 #include "src/base/platform/platform.h"
@@ skipping 688 matching lines @@
       return factory->NewNumberLiteral(value, pos);
     }
     default:
       DCHECK(false);
   }
   return NULL;
 }
 
 
 Expression* ParserTraits::ExpressionFromIdentifier(const AstRawString* name,
-                                                   int pos, Scope* scope,
+                                                   int start_position,
+                                                   int end_position,
+                                                   Scope* scope,
                                                    AstNodeFactory* factory) {
   if (parser_->fni_ != NULL) parser_->fni_->PushVariableName(name);
 
   // Arrow function parameters are parsed as an expression. When
   // parsing lazily, it is enough to create a VariableProxy in order
   // for Traits::DeclareArrowParametersFromExpression() to be able to
   // pick the names of the parameters.
   return parser_->parsing_lazy_arrow_parameters_
-             ? factory->NewVariableProxy(name, false, pos)
-             : scope->NewUnresolved(factory, name, pos);
+             ? factory->NewVariableProxy(name, false, start_position,
+                                         end_position)
+             : scope->NewUnresolved(factory, name, start_position,
+                                    end_position);
 }
 
 
 Expression* ParserTraits::ExpressionFromString(int pos, Scanner* scanner,
                                                AstNodeFactory* factory) {
   const AstRawString* symbol = GetSymbol(scanner);
   if (parser_->fni_ != NULL) parser_->fni_->PushLiteralName(symbol);
   return factory->NewStringLiteral(symbol, pos);
 }
 
@@ skipping 1034 matching lines @@
 }
 
 
 VariableProxy* Parser::NewUnresolved(const AstRawString* name,
                                      VariableMode mode) {
   // If we are inside a function, a declaration of a var/const variable is a
   // truly local variable, and the scope of the variable is always the function
   // scope.
   // Let/const variables in harmony mode are always added to the immediately
   // enclosing scope.
-  return DeclarationScope(mode)->NewUnresolved(factory(), name, position());
+  return DeclarationScope(mode)->NewUnresolved(factory(), name,
+                                               scanner()->location().beg_pos,
+                                               scanner()->location().end_pos);
 }
 
 
-void Parser::Declare(Declaration* declaration, bool resolve, bool* ok) {
+Variable* Parser::Declare(Declaration* declaration, bool resolve, bool* ok) {
   VariableProxy* proxy = declaration->proxy();
   DCHECK(proxy->raw_name() != NULL);
   const AstRawString* name = proxy->raw_name();
   VariableMode mode = declaration->mode();
   Scope* declaration_scope = DeclarationScope(mode);
   Variable* var = NULL;
 
   // If a suitable scope exists, then we can statically declare this
   // variable and also set its mode. In any case, a Declaration node
   // will be added to the scope so that the declaration can be added
   // to the corresponding activation frame at runtime if necessary.
   // For instance declarations inside an eval scope need to be added
   // to the calling function context.
   // Similarly, strict mode eval scope does not leak variable declarations to
   // the caller's scope so we declare all locals, too.
   if (declaration_scope->is_function_scope() ||
       declaration_scope->is_strict_eval_scope() ||
       declaration_scope->is_block_scope() ||
       declaration_scope->is_module_scope() ||
       declaration_scope->is_script_scope()) {
     // Declare the variable in the declaration scope.
     var = declaration_scope->LookupLocal(name);
     if (var == NULL) {
       // Declare the name.
       var = declaration_scope->DeclareLocal(
-          name, mode, declaration->initialization(), kNotAssigned);
-    } else if (IsLexicalVariableMode(mode) || IsLexicalVariableMode(var->mode())
-               || ((mode == CONST_LEGACY || var->mode() == CONST_LEGACY) &&
-                   !declaration_scope->is_script_scope())) {
+          name, mode, declaration->initialization(),
+          declaration->IsFunctionDeclaration(), kNotAssigned);
+    } else if (IsLexicalVariableMode(mode) ||
+               IsLexicalVariableMode(var->mode()) ||
+               ((mode == CONST_LEGACY || var->mode() == CONST_LEGACY) &&
+                !declaration_scope->is_script_scope())) {
       // The name was declared in this scope before; check for conflicting
       // re-declarations. We have a conflict if either of the declarations is
       // not a var (in script scope, we also have to ignore legacy const for
       // compatibility). There is similar code in runtime.cc in the Declare
       // 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 (allow_harmony_scoping() && is_strict(language_mode())) {
         // In harmony we treat re-declarations as early errors. See
         // ES5 16 for a definition of early errors.
         ParserTraits::ReportMessage("var_redeclaration", name);
         *ok = false;
-        return;
+        return nullptr;
       }
       Expression* expression = NewThrowTypeError(
           "var_redeclaration", name, declaration->position());
       declaration_scope->SetIllegalRedeclaration(expression);
     } else if (mode == VAR) {
       var->set_maybe_assigned();
     }
   }
 
   // We add a declaration node for every declaration. The compiler
@@ skipping 53 matching lines @@
   // Note that if 'f' is accessed from inside the 'with' statement, it
   // will be allocated in the context (because we must be able to look
   // it up dynamically) but it will also be accessed statically, i.e.,
   // with a context slot index and a context chain length for this
   // initialization code. Thus, inside the 'with' statement, we need
   // both access to the static and the dynamic context chain; the
   // runtime needs to provide both.
   if (resolve && var != NULL) {
     proxy->BindTo(var);
   }
+  return var;
 }
 
 
 // Language extension which is only enabled for source files loaded
 // through the API's extension mechanism.  A native function
 // declaration is resolved by looking up the function through a
 // callback provided by the extension.
 Statement* Parser::ParseNativeDeclaration(bool* ok) {
   int pos = peek_position();
   Expect(Token::FUNCTION, CHECK_OK);
@@ skipping 100 matching lines @@
   const AstRawString* name =
       ParseIdentifierOrStrictReservedWord(&is_strict_reserved, CHECK_OK);
   ClassLiteral* value = ParseClassLiteral(name, scanner()->location(),
                                           is_strict_reserved, pos, CHECK_OK);
 
   VariableMode mode = is_strong(language_mode()) ? CONST : LET;
   VariableProxy* proxy = NewUnresolved(name, mode);
   Declaration* declaration =
       factory()->NewVariableDeclaration(proxy, mode, scope_, pos);
   Declare(declaration, true, CHECK_OK);
-  proxy->var()->set_initializer_position(pos);
+  proxy->var()->set_initializer_position(position());
 
   Token::Value init_op =
       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;
 }
 
@@ skipping 188 matching lines @@
     is_for_iteration_variable =
         var_context == kForStatement &&
         (peek() == Token::IN || PeekContextualKeyword(CStrVector("of")));
     if (is_for_iteration_variable && mode == CONST) {
       needs_init = false;
     }
 
     VariableProxy* proxy = NewUnresolved(name, mode);
     Declaration* declaration =
         factory()->NewVariableDeclaration(proxy, mode, scope_, pos);
-    Declare(declaration, mode != VAR, CHECK_OK);
+    Variable* var = Declare(declaration, mode != VAR, CHECK_OK);
+    DCHECK(var != nullptr);

[arv (Not doing code reviews), 2015/02/25 16:37:32]

DCHECK_NOT_NULL

[marja, 2015/02/26 12:55:42]

Done.

+    DCHECK(!proxy->is_resolved() || proxy->var() == var);
     nvars++;
     if (declaration_scope->num_var_or_const() > kMaxNumFunctionLocals) {
       ReportMessage("too_many_variables");
       *ok = false;
       return NULL;
     }
     if (names) names->Add(name, zone());
 
     // Parse initialization expression if present and/or needed. A
     // declaration of the form:
@@ skipping 33 matching lines @@
       value = ParseAssignmentExpression(var_context != kForStatement, CHECK_OK);
       // Don't infer if it is "a = function(){...}();"-like expression.
       if (fni_ != NULL &&
           value->AsCall() == NULL &&
           value->AsCallNew() == NULL) {
         fni_->Infer();
       } else {
         fni_->RemoveLastFunction();
       }
       if (decl_props != NULL) *decl_props = kHasInitializers;
-    }
-
-    // Record the end position of the initializer.
-    if (proxy->is_resolved()) {
-      proxy->var()->set_initializer_position(position());
+      // Record the end position of the initializer.
+      var->set_initializer_position(scanner()->location().end_pos);
+    } else {
+      // Record the end position of the initializer.

[arv (Not doing code reviews), 2015/02/25 16:37:32]

Maybe move this comment to before the if since it is same for both branches.

[marja, 2015/02/26 12:55:42]

Hmm, that's kinda far away... instead, I made these comments more useful by
clarifying why the end positions are different in these 2 cases.

+      var->set_initializer_position(position());
     }
 
     // Make sure that 'const x' and 'let x' initialize 'x' to undefined.
     if (value == NULL && needs_init) {
       value = GetLiteralUndefined(position());
     }
 
     // Global variable declarations must be compiled in a specific
     // way. When the script containing the global variable declaration
     // is entered, the global variable must be declared, so that if it
@@ skipping 484 matching lines @@
   if (tok == Token::CATCH) {
     Consume(Token::CATCH);
 
     Expect(Token::LPAREN, CHECK_OK);
     catch_scope = NewScope(scope_, CATCH_SCOPE);
     catch_scope->set_start_position(scanner()->location().beg_pos);
     name = ParseIdentifier(kDontAllowEvalOrArguments, CHECK_OK);
 
     Expect(Token::RPAREN, CHECK_OK);
 
-    catch_variable = catch_scope->DeclareLocal(name, VAR, kCreatedInitialized);
+    catch_variable =
+        catch_scope->DeclareLocal(name, VAR, kCreatedInitialized, false);
     BlockState block_state(&scope_, catch_scope);
     catch_block = ParseBlock(NULL, CHECK_OK);
 
     catch_scope->set_end_position(scanner()->location().end_pos);
     tok = peek();
   }
 
   Block* finally_block = NULL;
   DCHECK(tok == Token::FINALLY || catch_block != NULL);
   if (tok == Token::FINALLY) {
@@ skipping 271 matching lines @@
 
   Block* inner_block = factory()->NewBlock(NULL, names->length() + 4, false,
                                            RelocInfo::kNoPosition);
   int pos = scanner()->location().beg_pos;
   ZoneList<Variable*> inner_vars(names->length(), zone());
 
   // For each let variable x:
   //    make statement: let x = temp_x.
   for (int i = 0; i < names->length(); i++) {
     VariableProxy* proxy = NewUnresolved(names->at(i), LET);
-    Declaration* declaration =
-        factory()->NewVariableDeclaration(proxy, LET, scope_, pos);
+    Declaration* declaration = factory()->NewVariableDeclaration(
+        proxy, LET, scope_, RelocInfo::kNoPosition);
     Declare(declaration, true, CHECK_OK);
     inner_vars.Add(declaration->proxy()->var(), zone());
     VariableProxy* temp_proxy = factory()->NewVariableProxy(temps.at(i));
     Assignment* assignment = factory()->NewAssignment(
         Token::INIT_LET, proxy, temp_proxy, pos);
-    Statement* assignment_statement = factory()->NewExpressionStatement(
-        assignment, pos);
-    proxy->var()->set_initializer_position(pos);
+    Statement* assignment_statement =
+        factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition);
+    proxy->var()->set_initializer_position(init->position());
     inner_block->AddStatement(assignment_statement, zone());
   }
 
   // Make statement: if (first == 1) { first = 0; } else { next; }
   if (next) {
     DCHECK(first);
     Expression* compare = NULL;
     // Make compare expression: first == 1.
     {
       Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition);
@@ skipping 127 matching lines @@
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR ||
         (peek() == Token::CONST && is_sloppy(language_mode()))) {
       const AstRawString* name = NULL;
       VariableDeclarationProperties decl_props = kHasNoInitializers;
       Block* variable_statement =
           ParseVariableDeclarations(kForStatement, &decl_props, NULL, &name,
                                     CHECK_OK);
       bool accept_OF = decl_props == kHasNoInitializers;
       ForEachStatement::VisitMode mode;
-      int each_pos = position();
+      int each_beg_pos = scanner()->location().beg_pos;
+      int each_end_pos = scanner()->location().end_pos;
 
       if (name != NULL && CheckInOrOf(accept_OF, &mode, ok)) {
         if (!*ok) return nullptr;
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(factory(), name, each_pos);
+        VariableProxy* each =
+            scope_->NewUnresolved(factory(), name, each_beg_pos, each_end_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         InitializeForEachStatement(loop, each, enumerable, body);
         Block* result =
             factory()->NewBlock(NULL, 2, false, RelocInfo::kNoPosition);
         result->AddStatement(variable_statement, zone());
         result->AddStatement(loop, zone());
         scope_ = saved_scope;
         for_scope->set_end_position(scanner()->location().end_pos);
         for_scope = for_scope->FinalizeBlockScope();
         DCHECK(for_scope == NULL);
         // Parsed for-in loop w/ variable/const declaration.
         return result;
       } else {
         init = variable_statement;
       }
     } else if ((peek() == Token::LET || peek() == Token::CONST) &&
                is_strict(language_mode())) {
       bool is_const = peek() == Token::CONST;
       const AstRawString* name = NULL;
       VariableDeclarationProperties decl_props = kHasNoInitializers;
       Block* variable_statement =
           ParseVariableDeclarations(kForStatement, &decl_props, &let_bindings,
                                     &name, CHECK_OK);
       bool accept_IN = name != NULL && decl_props != kHasInitializers;
       bool accept_OF = decl_props == kHasNoInitializers;
       ForEachStatement::VisitMode mode;
-      int each_pos = position();
+      int each_beg_pos = scanner()->location().beg_pos;
+      int each_end_pos = scanner()->location().end_pos;
 
       if (accept_IN && CheckInOrOf(accept_OF, &mode, ok)) {
         if (!*ok) return nullptr;
 
         // Rewrite a for-in statement of the form
         //
         //   for (let/const x in e) b
         //
         // into
         //
         //   <let x' be a temporary variable>
         //   for (x' in e) {
         //     let/const x;
         //     x = x';
         //     b;
         //   }
 
         // TODO(keuchel): Move the temporary variable to the block scope, after
         // implementing stack allocated block scoped variables.
         Variable* temp = scope_->DeclarationScope()->NewTemporary(
             ast_value_factory()->dot_for_string());
-        VariableProxy* temp_proxy = factory()->NewVariableProxy(temp, each_pos);
+        VariableProxy* temp_proxy =
+            factory()->NewVariableProxy(temp, each_beg_pos, each_end_pos);
         ForEachStatement* loop =
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
         // The expression does not see the loop variable.
         scope_ = saved_scope;
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         scope_ = for_scope;
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(factory(), name, each_pos);
+        VariableProxy* each =
+            scope_->NewUnresolved(factory(), name, each_beg_pos, each_end_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         Block* body_block =
             factory()->NewBlock(NULL, 3, false, RelocInfo::kNoPosition);
         Token::Value init_op = is_const ? Token::INIT_CONST : Token::ASSIGN;
         Assignment* assignment = factory()->NewAssignment(
             init_op, each, temp_proxy, RelocInfo::kNoPosition);
         Statement* assignment_statement = factory()->NewExpressionStatement(
             assignment, RelocInfo::kNoPosition);
         body_block->AddStatement(variable_statement, zone());
         body_block->AddStatement(assignment_statement, zone());
@@ skipping 763 matching lines @@
     block_scope->set_start_position(scanner()->location().end_pos);
   }
 
 
   ClassLiteralChecker checker(this);
   ZoneList<ObjectLiteral::Property*>* properties = NewPropertyList(4, zone());
   FunctionLiteral* constructor = NULL;
   bool has_seen_constructor = false;
 
   Expect(Token::LBRACE, CHECK_OK);
+  int body_beg_pos = scanner()->location().beg_pos;
+
   const bool has_extends = extends != nullptr;
   while (peek() != Token::RBRACE) {
     if (Check(Token::SEMICOLON)) continue;
     if (fni_ != NULL) fni_->Enter();
     const bool in_class = true;
     const bool is_static = false;
     bool is_computed_name = false;  // Classes do not care about computed
                                     // property names here.
     ObjectLiteral::Property* property = ParsePropertyDefinition(
         &checker, in_class, has_extends, is_static, &is_computed_name,
@@ skipping 19 matching lines @@
     constructor =
         DefaultConstructor(extends != NULL, block_scope, pos, end_pos);
   }
 
   block_scope->set_end_position(end_pos);
   block_scope = block_scope->FinalizeBlockScope();
 
   if (name != NULL) {
     DCHECK_NOT_NULL(proxy);
     DCHECK_NOT_NULL(block_scope);
-    proxy->var()->set_initializer_position(end_pos);
+    proxy->var()->set_initializer_position(body_beg_pos);
   }
 
   return factory()->NewClassLiteral(name, block_scope, proxy, extends,
                                     constructor, properties, pos, end_pos);
 }
 
 
 Expression* Parser::ParseV8Intrinsic(bool* ok) {
   // CallRuntime ::
   //   '%' Identifier Arguments
@@ skipping 1267 matching lines @@
     } else {
       const uc16* data = reinterpret_cast<const uc16*>(raw_string->raw_data());
       running_hash = StringHasher::ComputeRunningHash(running_hash, data,
                                                       raw_string->length());
     }
   }
 
   return running_hash;
 }
 } }  // namespace v8::internal