Add missing compile-time errors for async/await.

pkg/compiler/lib/src/parser/parser.dart

 // 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.
 
 library dart2js.parser;
 
 import '../common.dart';
 import '../tokens/keyword.dart' show
     Keyword;
 import '../tokens/precedence.dart' show
@@ skipping 80 matching lines @@
  *
  * Parse methods are generally named parseGrammarProductionSuffix. The
  * suffix can be one of "opt", or "star". "opt" means zero or one
  * matches, "star" means zero or more matches. For example,
  * [parseMetadataStar] corresponds to this grammar snippet: [:
  * metadata* :], and [parseTypeOpt] corresponds to: [: type? :].
  */
 class Parser {
   final Listener listener;
   bool mayParseFunctionExpressions = true;
-  bool yieldIsKeyword;
-  bool awaitIsKeyword;
+  bool asyncAwaitKeywordsEnabled;
 
   Parser(this.listener,
-         {this.yieldIsKeyword: false, this.awaitIsKeyword: false});
+         {this.asyncAwaitKeywordsEnabled: false});
 
   Token parseUnit(Token token) {
     listener.beginCompilationUnit(token);
     int count = 0;
     while (!identical(token.kind, EOF_TOKEN)) {
       token = parseTopLevelDeclaration(token);
       listener.endTopLevelDeclaration(token);
       count++;
     }
     listener.endCompilationUnit(count, token);
@@ skipping 845 matching lines @@
     }
 
     if (type == null) {
       listener.handleNoType(name);
     } else {
       parseReturnTypeOpt(type);
     }
     Token token = parseIdentifier(name);
 
     token = parseFormalParametersOpt(token);
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
+    bool previousAsyncAwaitKeywordsEnabled = asyncAwaitKeywordsEnabled;
     token = parseAsyncModifier(token);
     token = parseFunctionBody(token, false, externalModifier != null);
-    yieldIsKeyword = previousYieldIsKeyword;
-    awaitIsKeyword = previousAwaitIsKeyword;
+    asyncAwaitKeywordsEnabled = previousAsyncAwaitKeywordsEnabled;
     Token endToken = token;
     token = token.next;
     if (token.kind == BAD_INPUT_TOKEN) {
       token = listener.unexpected(token);
     }
     listener.endTopLevelMethod(start, getOrSet, endToken);
     return token;
   }
 
   /// Looks ahead to find the name of a member. Returns a link of the modifiers,
@@ skipping 386 matching lines @@
             staticModifier, MessageKind.EXTRANEOUS_MODIFIER,
             {'modifier': staticModifier});
       }
     } else {
       token = parseIdentifier(name);
     }
 
     token = parseQualifiedRestOpt(token);
     token = parseFormalParametersOpt(token);
     token = parseInitializersOpt(token);
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
+    bool previousAsyncAwaitKeywordsEnabled = asyncAwaitKeywordsEnabled;
     token = parseAsyncModifier(token);
     if (optional('=', token)) {
       token = parseRedirectingFactoryBody(token);
     } else {
       token = parseFunctionBody(
           token, false, staticModifier == null || externalModifier != null);
     }
-    yieldIsKeyword = previousYieldIsKeyword;
-    awaitIsKeyword = previousAwaitIsKeyword;
+    asyncAwaitKeywordsEnabled = previousAsyncAwaitKeywordsEnabled;
     listener.endMethod(getOrSet, start, token);
     return token.next;
   }
 
   Token parseFactoryMethod(Token token) {
     assert(isFactoryDeclaration(token));
     Token start = token;
     Token externalModifier;
     if (identical(token.stringValue, 'external')) {
       externalModifier = token;
@@ skipping 57 matching lines @@
       if (optional('operator', token)) {
         token = parseOperatorName(token);
       } else {
         token = parseIdentifier(token);
       }
     }
     token = parseQualifiedRestOpt(token);
     listener.endFunctionName(token);
     token = parseFormalParametersOpt(token);
     token = parseInitializersOpt(token);
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
+    bool previousAsyncAwaitKeywordsEnabled = asyncAwaitKeywordsEnabled;
     token = parseAsyncModifier(token);
     if (optional('=', token)) {
       token = parseRedirectingFactoryBody(token);
     } else {
       token = parseFunctionBody(token, false, true);
     }
-    yieldIsKeyword = previousYieldIsKeyword;
-    awaitIsKeyword = previousAwaitIsKeyword;
+    asyncAwaitKeywordsEnabled = previousAsyncAwaitKeywordsEnabled;
     listener.endFunction(getOrSet, token);
     return token.next;
   }
 
   Token parseUnnamedFunction(Token token) {
     listener.beginUnnamedFunction(token);
     token = parseFormalParameters(token);
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
+    bool previousAsyncAwaitKeywordsEnabled = asyncAwaitKeywordsEnabled;
     token = parseAsyncModifier(token);
     bool isBlock = optional('{', token);
     token = parseFunctionBody(token, true, false);
-    yieldIsKeyword = previousYieldIsKeyword;
-    awaitIsKeyword = previousAwaitIsKeyword;
+    asyncAwaitKeywordsEnabled = previousAsyncAwaitKeywordsEnabled;
     listener.endUnnamedFunction(token);
     return isBlock ? token.next : token;
   }
 
   Token parseFunctionDeclaration(Token token) {
     listener.beginFunctionDeclaration(token);
     token = parseFunction(token, null);
     listener.endFunctionDeclaration(token);
     return token;
   }
 
   Token parseFunctionExpression(Token token) {
     listener.beginFunction(token);
     listener.handleModifiers(0);
     token = parseReturnTypeOpt(token);
     listener.beginFunctionName(token);
     token = parseIdentifier(token);
     listener.endFunctionName(token);
     token = parseFormalParameters(token);
     listener.handleNoInitializers();
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
+    bool previousAsyncAwaitKeywordsEnabled = asyncAwaitKeywordsEnabled;
     token = parseAsyncModifier(token);
     bool isBlock = optional('{', token);
     token = parseFunctionBody(token, true, false);
-    yieldIsKeyword = previousYieldIsKeyword;
-    awaitIsKeyword = previousAwaitIsKeyword;
+    asyncAwaitKeywordsEnabled = previousAsyncAwaitKeywordsEnabled;
     listener.endFunction(null, token);
     return isBlock ? token.next : token;
   }
 
   Token parseConstructorReference(Token token) {
     Token start = token;
     listener.beginConstructorReference(start);
     token = parseIdentifier(token);
     token = parseQualifiedRestOpt(token);
     token = parseTypeArgumentsOpt(token);
@@ skipping 48 matching lines @@
       ++statementCount;
     }
     listener.endFunctionBody(statementCount, begin, token);
     expect('}', token);
     return token;
   }
 
   Token parseAsyncModifier(Token token) {
     Token async;
     Token star;
-    awaitIsKeyword = false;
-    yieldIsKeyword = false;
+    asyncAwaitKeywordsEnabled = false;
     if (optional('async', token)) {
-      awaitIsKeyword = true;
+      asyncAwaitKeywordsEnabled = true;
       async = token;
       token = token.next;
       if (optional('*', token)) {
-        yieldIsKeyword = true;
         star = token;
         token = token.next;
       }
     } else if (optional('sync', token)) {
       async = token;
       token = token.next;
       if (optional('*', token)) {
-        yieldIsKeyword = true;
+        asyncAwaitKeywordsEnabled = true;
         star = token;
         token = token.next;
       } else {
         listener.reportError(async,
             MessageKind.INVALID_SYNC_MODIFIER);
       }
     }
     listener.handleAsyncModifier(async, star);
     return token;
   }
 
   Token parseStatement(Token token) {
     final value = token.stringValue;
     if (identical(token.kind, IDENTIFIER_TOKEN)) {
       return parseExpressionStatementOrDeclaration(token);
     } else if (identical(value, '{')) {
       return parseBlock(token);
     } else if (identical(value, 'return')) {
       return parseReturnStatement(token);
     } else if (identical(value, 'var') || identical(value, 'final')) {
       return parseVariablesDeclaration(token);
     } else if (identical(value, 'if')) {
       return parseIfStatement(token);
-    } else if (awaitIsKeyword && identical(value, 'await')) {
+    } else if (asyncAwaitKeywordsEnabled && identical(value, 'await')) {
       if (identical(token.next.stringValue, 'for')) {
         return parseForStatement(token, token.next);
       } else {
         return parseExpressionStatement(token);
       }
     } else if (identical(value, 'for')) {
       return parseForStatement(null, token);
     } else if (identical(value, 'rethrow')) {
       return parseRethrowStatement(token);
     } else if (identical(value, 'throw') && optional(';', token.next)) {
@@ skipping 10 matching lines @@
     } else if (identical(value, 'switch')) {
       return parseSwitchStatement(token);
     } else if (identical(value, 'break')) {
       return parseBreakStatement(token);
     } else if (identical(value, 'continue')) {
       return parseContinueStatement(token);
     } else if (identical(value, 'assert')) {
       return parseAssertStatement(token);
     } else if (identical(value, ';')) {
       return parseEmptyStatement(token);
-    } else if (yieldIsKeyword && identical(value, 'yield')) {
+    } else if (asyncAwaitKeywordsEnabled && identical(value, 'yield')) {
       return parseYieldStatement(token);
     } else if (identical(value, 'const')) {
       return parseExpressionStatementOrConstDeclaration(token);
     } else if (token.isIdentifier()) {
       return parseExpressionStatementOrDeclaration(token);
     } else {
       return parseExpressionStatement(token);
     }
   }
 
@@ skipping 261 matching lines @@
       token = parseExpressionWithoutCascade(token.next);
       listener.handleAssignmentExpression(assignment);
     }
     listener.endCascade();
     return token;
   }
 
   Token parseUnaryExpression(Token token, bool allowCascades) {
     String value = token.stringValue;
     // Prefix:
-    if (awaitIsKeyword && optional('await', token)) {
+    if (asyncAwaitKeywordsEnabled && optional('await', token)) {
       return parseAwaitExpression(token, allowCascades);
     } else if (identical(value, '+')) {
       // Dart no longer allows prefix-plus.
       listener.reportError(token, MessageKind.UNSUPPORTED_PREFIX_PLUS);
       return parseUnaryExpression(token.next, allowCascades);
     } else if ((identical(value, '!')) ||
                (identical(value, '-')) ||
                (identical(value, '~'))) {
       Token operator = token;
       // Right associative, so we recurse at the same precedence
@@ skipping 30 matching lines @@
         listener.endSend(token);
       } else {
         break;
       }
     }
     return token;
   }
 
   Token parsePrimary(Token token) {
     final kind = token.kind;
-    if (identical(kind, IDENTIFIER_TOKEN)) {
+    if (kind == IDENTIFIER_TOKEN) {
       return parseSendOrFunctionLiteral(token);
-    } else if (identical(kind, INT_TOKEN)
-        || identical(kind, HEXADECIMAL_TOKEN)) {
+    } else if (kind == INT_TOKEN
+        || kind == HEXADECIMAL_TOKEN) {
       return parseLiteralInt(token);
-    } else if (identical(kind, DOUBLE_TOKEN)) {
+    } else if (kind == DOUBLE_TOKEN) {
       return parseLiteralDouble(token);
-    } else if (identical(kind, STRING_TOKEN)) {
+    } else if (kind == STRING_TOKEN) {
       return parseLiteralString(token);
-    } else if (identical(kind, HASH_TOKEN)) {
+    } else if (kind == HASH_TOKEN) {
       return parseLiteralSymbol(token);
-    } else if (identical(kind, KEYWORD_TOKEN)) {
+    } else if (kind == KEYWORD_TOKEN) {
       final value = token.stringValue;
-      if ((identical(value, 'true')) || (identical(value, 'false'))) {
+      if (value == 'true' || value == 'false') {
         return parseLiteralBool(token);
-      } else if (identical(value, 'null')) {
+      } else if (value == 'null') {
         return parseLiteralNull(token);
-      } else if (identical(value, 'this')) {
+      } else if (value == 'this') {
         return parseThisExpression(token);
-      } else if (identical(value, 'super')) {
+      } else if (value == 'super') {
         return parseSuperExpression(token);
-      } else if (identical(value, 'new')) {
+      } else if (value == 'new') {
         return parseNewExpression(token);
-      } else if (identical(value, 'const')) {
+      } else if (value == 'const') {
         return parseConstExpression(token);
-      } else if (identical(value, 'void')) {
+      } else if (value == 'void') {
         return parseFunctionExpression(token);
+      } else if (asyncAwaitKeywordsEnabled &&
+                 (value == 'yield' || value == 'async')) {
+        return listener.expectedExpression(token);
       } else if (token.isIdentifier()) {
         return parseSendOrFunctionLiteral(token);
       } else {
         return listener.expectedExpression(token);
       }
-    } else if (identical(kind, OPEN_PAREN_TOKEN)) {
+    } else if (kind == OPEN_PAREN_TOKEN) {
       return parseParenthesizedExpressionOrFunctionLiteral(token);
-    } else if ((identical(kind, LT_TOKEN)) ||
-               (identical(kind, OPEN_SQUARE_BRACKET_TOKEN)) ||
-               (identical(kind, OPEN_CURLY_BRACKET_TOKEN)) ||
-               identical(token.stringValue, '[]')) {
+    } else if ((kind == LT_TOKEN) ||
+               (kind == OPEN_SQUARE_BRACKET_TOKEN) ||
+               (kind == OPEN_CURLY_BRACKET_TOKEN) ||
+               token.stringValue == '[]') {
       return parseLiteralListOrMap(token);
     } else {
       return listener.expectedExpression(token);
     }
   }
 
   Token parseParenthesizedExpressionOrFunctionLiteral(Token token) {
     BeginGroupToken beginGroup = token;
     Token nextToken = beginGroup.endGroup.next;
     int kind = nextToken.kind;
@@ skipping 703 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }