Handle future reserved keywords in parameters

If, after parsing the function body, we changed from non strict to strict mode
we go through the parameters to ensure we do not have an future reserved
keywords.

Part of google#242

Review URL: google#256

Closes google#256.

Author: arv

bin/traceur.js

@@ -0,0 +1,43 @@
+// Copyright 2013 Traceur Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import {ParseTreeVisitor} from '../syntax/ParseTreeVisitor.js';
+import {isStrictKeyword} from '../syntax/Keywords.js';
+
+/**
+ * This matches the "Static Semantics: BoundNames" in the ES6 spec.
+ */
+export class StrictParams extends ParseTreeVisitor {
+
+  /**
+   * @param {ErrorReporter} errorReporter
+   */
+  constructor(errorReporter) {
+    super();
+    this.errorReporter = errorReporter;
+  }
+
+  visitBindingIdentifier(tree) {
+    var name = tree.identifierToken.value;
+    if (isStrictKeyword(name)) {
+      this.errorReporter.reportError(tree.location.start,
+                                     `${name} is a reserved identifier`);
+    }
+  }
+
+  static visit(tree, errorReporter) {
+    new StrictParams(errorReporter).visitAny(tree);
+  }
+}
+

src/staticsemantics/StrictParams.js

@@ -90,4 +90,8 @@ strictKeywords.forEach((value) => {
 
 export function getKeywordType(value) {
   return keywordsByName[value];
-};
+}
+
+export function isStrictKeyword(value) {
+  return getKeywordType(value) === STRICT_KEYWORD;
+}

src/syntax/Keywords.js

@@ -50,6 +50,7 @@ import {
 } from './PredefinedName.js';
 import {Scanner} from './Scanner.js';
 import {SourceRange} from '../util/SourceRange.js';
+import {StrictParams} from '../staticsemantics/StrictParams.js';
 import {
   Token,
   isAssignmentOperator
@@ -514,7 +515,11 @@ export class Parser {
   }
 
   peekId_(type) {
-    return type === IDENTIFIER;
+    if (type === IDENTIFIER)
+      return true;
+    if (this.strictMode_)
+      return false;
+    return this.peekToken_().isStrictKeyword();
   }
 
   peekIdName_(token) {
@@ -803,7 +808,8 @@ export class Parser {
     this.eat_(OPEN_PAREN);
     var formalParameterList = this.parseFormalParameterList_();
     this.eat_(CLOSE_PAREN);
-    var functionBody = this.parseFunctionBody_(isGenerator);
+    var functionBody = this.parseFunctionBody_(isGenerator,
+                                               formalParameterList);
     return new FunctionDeclaration(this.getTreeLocation_(start), name,
                                    isGenerator, formalParameterList,
                                    functionBody);
@@ -824,7 +830,8 @@ export class Parser {
     this.eat_(OPEN_PAREN);
     var formalParameterList = this.parseFormalParameterList_();
     this.eat_(CLOSE_PAREN);
-    var functionBody = this.parseFunctionBody_(isGenerator);
+    var functionBody = this.parseFunctionBody_(isGenerator,
+                                               formalParameterList);
     return new FunctionExpression(this.getTreeLocation_(start), name,
                                   isGenerator, formalParameterList,
                                   functionBody);
@@ -894,7 +901,7 @@ export class Parser {
    * @return {Block}
    * @private
    */
-  parseFunctionBody_(isGenerator) {
+  parseFunctionBody_(isGenerator, params) {
     var start = this.getTreeStartLocation_();
     this.eat_(OPEN_CURLY);
 
@@ -904,6 +911,9 @@ export class Parser {
 
     var result = this.parseStatementList_(!strictMode);
 
+    if (!strictMode && this.strictMode_ && params)
+      StrictParams.visit(params, this.errorReporter_);
+
     this.strictMode_ = strictMode;
     this.allowYield_ = allowYield;
 
@@ -2044,7 +2054,8 @@ export class Parser {
     this.eat_(OPEN_PAREN);
     var formalParameterList = this.parseFormalParameterList_();
     this.eat_(CLOSE_PAREN);
-    var functionBody = this.parseFunctionBody_(isGenerator);
+    var functionBody = this.parseFunctionBody_(isGenerator,
+                                               formalParameterList);
     return new PropertyMethodAssignment(this.getTreeLocation_(start),
         isStatic, isGenerator, name, formalParameterList, functionBody);
   }
@@ -2072,7 +2083,7 @@ export class Parser {
     var name = this.parsePropertyName_();
     this.eat_(OPEN_PAREN);
     this.eat_(CLOSE_PAREN);
-    var body = this.parseFunctionBody_(isGenerator);
+    var body = this.parseFunctionBody_(isGenerator, null);
     return new GetAccessor(this.getTreeLocation_(start), isStatic, name, body);
   }
 
@@ -2082,7 +2093,7 @@ export class Parser {
     this.eat_(OPEN_PAREN);
     var parameter = this.parsePropertySetParameterList_();
     this.eat_(CLOSE_PAREN);
-    var body = this.parseFunctionBody_(isGenerator);
+    var body = this.parseFunctionBody_(isGenerator, parameter);
     return new SetAccessor(this.getTreeLocation_(start), isStatic, name,
                            parameter, body);
   }

src/syntax/Parser.js

@@ -25,18 +25,16 @@ export class ErrorReporter {
    * @param {SourcePosition} location
    * @param {string} format
    */
-  reportError(location, format, var_args) {
+  reportError(location, format, ...args) {
     this.hadError_ = true;
-    var args = Array.prototype.slice.call(arguments, 2);
     this.reportMessageInternal(location, 'error', format, args);
   }
 
   /**
    * @param {SourcePosition} location
    * @param {string} format
    */
-  reportWarning(location, format, var_args) {
-    var args = Array.prototype.slice.call(arguments, 2);
+  reportWarning(location, format, ...args) {
     this.reportMessageInternal(location, 'warn', format, args);
   }
 

src/util/ErrorReporter.js

@@ -0,0 +1,7 @@
+// Should not compile.
+// Error: :4:25: implements is a reserved identifier
+
+function testImplements(implements) {
+  'use strict';
+  return 42;
+}

test/feature/Syntax/Error_StrictKeywordsInArguments.js

@@ -0,0 +1,7 @@
+// Should not compile.
+// Error: :4:26: implements is a reserved identifier
+
+function testImplements({implements}) {
+  'use strict';
+  return 42;
+}