Various semantic checks on field initializers.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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 fasta.body_builder;
 
 import '../fasta_codes.dart'
-    show FastaMessage, codeExpectedButGot, codeExpectedFunctionBody;
+    show
+        FastaMessage,
+        codeConstFieldWithoutInitializer,
+        codeExpectedButGot,
+        codeExpectedFunctionBody,
+        codeFinalFieldWithoutInitializer;
 
 import '../parser/parser.dart'
     show Assert, FormalParameterType, MemberKind, optional;
 
 import '../parser/identifier_context.dart' show IdentifierContext;
 
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart';
 
 import 'package:front_end/src/fasta/kernel/utils.dart' show offsetForToken;
 
@@ skipping 959 matching lines @@
 
   /// Look up [name] in [scope] using [token] as location information (both to
   /// report problems and as the file offset in the generated kernel code).
   /// [isQualified] should be true if [name] is a qualified access
   /// (which implies that it shouldn't be turned into a [ThisPropertyAccessor]
   /// if the name doesn't resolve in the scope).
   @override
   scopeLookup(Scope scope, String name, Token token,
       {bool isQualified: false, PrefixBuilder prefix}) {
     Builder builder = scope.lookup(name, offsetForToken(token), uri);
+    if (builder != null && member.isField && builder.isInstanceMember) {
+      return new IncompleteError(this, token,
+          "Can't access 'this' in a field initializer to read '$name'.");
+    }
     if (builder == null || (!isInstanceContext && builder.isInstanceMember)) {
       Name n = new Name(name, library.library);
       if (prefix != null &&
           prefix.deferred &&
           builder == null &&
           "loadLibrary" == name) {
         return buildCompileTimeError(
             "Deferred loading isn't implemented yet.", offsetForToken(token));
       } else if (!isQualified && isInstanceContext) {
         assert(builder == null);
-        if (constantExpressionRequired) {
+        if (constantExpressionRequired || member.isField) {
           return new UnresolvedAccessor(this, n, token);
         }
         return new ThisPropertyAccessor(this, token, n, null, null);
       } else if (isBuiltinLibrary &&
           name == "main" &&
           member?.name == "_getMainClosure") {
         // TODO(ahe): https://github.com/dart-lang/sdk/issues/28989
         return new KernelNullLiteral()..fileOffset = offsetForToken(token);
       } else {
         return new UnresolvedAccessor(this, n, token);
@@ skipping 274 matching lines @@
   void endFieldInitializer(Token assignmentOperator, Token token) {
     debugEvent("FieldInitializer");
     assert(assignmentOperator.stringValue == "=");
     push(popForValue());
   }
 
   @override
   void handleNoFieldInitializer(Token token) {
     debugEvent("NoFieldInitializer");
     if (constantExpressionRequired) {
-      addCompileTimeError(
-          token.charOffset, "const field must have initializer.");
       // Creating a null value to prevent the Dart VM from crashing.
       push(new KernelNullLiteral()..fileOffset = offsetForToken(token));
     } else {
       push(NullValue.FieldInitializer);
     }
   }
 
   @override
   void endInitializedIdentifier(Token nameToken) {
     // TODO(ahe): Use [InitializedIdentifier] here?
@@ skipping 1514 matching lines @@
 
   @override
   void handleModifiers(int count) {
     debugEvent("Modifiers");
     // TODO(ahe): Copied from outline_builder.dart.
     push(popList(count) ?? NullValue.Modifiers);
   }
 
   @override
   void handleRecoverableError(Token token, FastaMessage message) {
-    bool silent = hasParserError;
+    bool silent = hasParserError ||
+        message.code == codeFinalFieldWithoutInitializer ||
+        message.code == codeConstFieldWithoutInitializer;
     addCompileTimeError(message.charOffset, message.message, silent: silent);
   }
 
   @override
   Token handleUnrecoverableError(Token token, FastaMessage message) {
     if (enableNative && message.code == codeExpectedFunctionBody) {
       Token recover = library.loader.target.skipNativeClause(token);
       if (recover != null) return recover;
     } else if (message.code == codeExpectedButGot) {
       String expected = message.arguments["string"];
@@ skipping 702 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }