Various issues with duplicated names.

pkg/front_end/lib/src/fasta/kernel/kernel_enum_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.kernel_enum_builder;
 
 import 'package:kernel/ast.dart'
     show
         Arguments,
         Class,
@@ skipping 12 matching lines @@
         ProcedureKind,
         ReturnStatement,
         StaticGet,
         StringLiteral,
         SuperInitializer,
         ThisExpression,
         VariableGet;
 
 import 'package:front_end/src/scanner/token.dart' show Token;
 
-import '../errors.dart' show inputError;
-
 import '../modifier.dart' show constMask, finalMask, staticMask;
 
 import '../names.dart' show indexGetName;
 
 import '../source/source_class_builder.dart' show SourceClassBuilder;
 
 import 'kernel_builder.dart'
     show
         Builder,
         EnumBuilder,
@@ skipping 123 matching lines @@
         parent,
         charOffset,
         charOffset,
         charEndOffset);
     members["toString"] = toStringBuilder;
     String className = name;
     for (int i = 0; i < constantNamesAndOffsets.length; i += 2) {
       String name = constantNamesAndOffsets[i];
       int charOffset = constantNamesAndOffsets[i + 1];
       if (members.containsKey(name)) {
-        inputError(null, null, "Duplicated name: $name");
+        parent.addCompileTimeError(charOffset, "Duplicated name: '$name'.");
+        constantNamesAndOffsets[i] = null;
+        continue;
+      }
+      if (name == className) {
+        parent.addCompileTimeError(
+            charOffset,
+            "Name of enum constant '$name' can't be the same as the enum's "
+            "own name.");
+        constantNamesAndOffsets[i] = null;
         continue;
       }
       KernelFieldBuilder fieldBuilder = new KernelFieldBuilder(
           null,
           selfType,
           name,
           constMask | staticMask,
           parent,
           charOffset,
           // Synthetic token to signal this field is initialized.
@@ skipping 54 matching lines @@
     KernelProcedureBuilder toStringBuilder = this["toString"];
     toStringBuilder.body = new ReturnStatement(new MethodInvocation(
         toStringMap,
         indexGetName,
         new Arguments(<Expression>[
           new DirectPropertyGet(new ThisExpression(), indexField)
         ])));
     List<Expression> values = <Expression>[];
     for (int i = 0; i < constantNamesAndOffsets.length; i += 2) {
       String name = constantNamesAndOffsets[i];
-      KernelFieldBuilder builder = this[name];
-      values.add(new StaticGet(builder.build(libraryBuilder)));
+      if (name != null) {
+        KernelFieldBuilder builder = this[name];
+        values.add(new StaticGet(builder.build(libraryBuilder)));
+      }
     }
     KernelFieldBuilder valuesBuilder = this["values"];
     valuesBuilder.build(libraryBuilder);
     valuesBuilder.initializer =
         new ListLiteral(values, typeArgument: cls.rawType, isConst: true);
     KernelConstructorBuilder constructorBuilder = constructorScopeBuilder[""];
     Constructor constructor = constructorBuilder.build(libraryBuilder);
     constructor.initializers.insert(
         0,
         new FieldInitializer(indexField,
             new VariableGet(constructor.function.positionalParameters.single))
           ..parent = constructor);
     KernelClassBuilder objectClass = objectType.builder;
     MemberBuilder superConstructor = objectClass.findConstructorOrFactory(
         "", charOffset, fileUri, libraryBuilder);
     if (superConstructor == null || !superConstructor.isConstructor) {
       // TODO(ahe): Ideally, we would also want to check that [Object]'s
       // unnamed constructor requires no arguments. But that information isn't
       // always available at this point, and it's not really a situation that
       // can happen unless you start modifying the SDK sources.
       addCompileTimeError(-1, "'Object' has no unnamed constructor.");
     } else {
       constructor.initializers.add(
           new SuperInitializer(superConstructor.target, new Arguments.empty())
             ..parent = constructor);
     }
     int index = 0;
     for (int i = 0; i < constantNamesAndOffsets.length; i += 2) {
       String constant = constantNamesAndOffsets[i];
-      KernelFieldBuilder field = this[constant];
-      field.build(libraryBuilder);
-      Arguments arguments =
-          new Arguments(<Expression>[new IntLiteral(index++)]);
-      field.initializer =
-          new ConstructorInvocation(constructor, arguments, isConst: true);
+      if (constant != null) {
+        KernelFieldBuilder field = this[constant];
+        field.build(libraryBuilder);
+        Arguments arguments =
+            new Arguments(<Expression>[new IntLiteral(index++)]);
+        field.initializer =
+            new ConstructorInvocation(constructor, arguments, isConst: true);
+      }
     }
     return super.build(libraryBuilder, coreLibrary);
   }
 
   @override
   Builder findConstructorOrFactory(
       String name, int charOffset, Uri uri, LibraryBuilder library) {
     return null;
   }
 }