Merge pull request #1401 from jskeet/enum-casing

Enum casing in C#

Makefile.am

@@ -154,6 +154,7 @@ csharp_EXTRA_DIST=                                                           \
   csharp/src/Google.Protobuf/Reflection/MethodDescriptor.cs                  \
   csharp/src/Google.Protobuf/Reflection/OneofAccessor.cs                     \
   csharp/src/Google.Protobuf/Reflection/OneofDescriptor.cs                   \
+  csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs             \
   csharp/src/Google.Protobuf/Reflection/PackageDescriptor.cs                 \
   csharp/src/Google.Protobuf/Reflection/PartialClasses.cs                    \
   csharp/src/Google.Protobuf/Reflection/ReflectionUtil.cs                    \

csharp/src/AddressBook/AddPerson.cs

@@ -73,13 +73,13 @@ namespace Google.Protobuf.Examples.AddressBook
                 switch (type)
                 {
                     case "mobile":
-                        phoneNumber.Type = Person.Types.PhoneType.MOBILE;
+                        phoneNumber.Type = Person.Types.PhoneType.Mobile;
                         break;
                     case "home":
-                        phoneNumber.Type = Person.Types.PhoneType.HOME;
+                        phoneNumber.Type = Person.Types.PhoneType.Home;
                         break;
                     case "work":
-                        phoneNumber.Type = Person.Types.PhoneType.WORK;
+                        phoneNumber.Type = Person.Types.PhoneType.Work;
                         break;
                     default:
                         output.Write("Unknown phone type. Using default.");

csharp/src/AddressBook/Addressbook.cs

@@ -228,9 +228,9 @@ namespace Google.Protobuf.Examples.AddressBook {
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
       public enum PhoneType {
-        MOBILE = 0,
-        HOME = 1,
-        WORK = 2,
+        [pbr::OriginalName("MOBILE")] Mobile = 0,
+        [pbr::OriginalName("HOME")] Home = 1,
+        [pbr::OriginalName("WORK")] Work = 2,
       }
 
       [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
@@ -273,7 +273,7 @@ namespace Google.Protobuf.Examples.AddressBook {
 
         /// <summary>Field number for the "type" field.</summary>
         public const int TypeFieldNumber = 2;
-        private global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType type_ = global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.MOBILE;
+        private global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType type_ = 0;
         public global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType Type {
           get { return type_; }
           set {
@@ -300,7 +300,7 @@ namespace Google.Protobuf.Examples.AddressBook {
         public override int GetHashCode() {
           int hash = 1;
           if (Number.Length != 0) hash ^= Number.GetHashCode();
-          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.MOBILE) hash ^= Type.GetHashCode();
+          if (Type != 0) hash ^= Type.GetHashCode();
           return hash;
         }
 
@@ -313,7 +313,7 @@ namespace Google.Protobuf.Examples.AddressBook {
             output.WriteRawTag(10);
             output.WriteString(Number);
           }
-          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.MOBILE) {
+          if (Type != 0) {
             output.WriteRawTag(16);
             output.WriteEnum((int) Type);
           }
@@ -324,7 +324,7 @@ namespace Google.Protobuf.Examples.AddressBook {
           if (Number.Length != 0) {
             size += 1 + pb::CodedOutputStream.ComputeStringSize(Number);
           }
-          if (Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.MOBILE) {
+          if (Type != 0) {
             size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Type);
           }
           return size;
@@ -337,7 +337,7 @@ namespace Google.Protobuf.Examples.AddressBook {
           if (other.Number.Length != 0) {
             Number = other.Number;
           }
-          if (other.Type != global::Google.Protobuf.Examples.AddressBook.Person.Types.PhoneType.MOBILE) {
+          if (other.Type != 0) {
             Type = other.Type;
           }
         }

csharp/src/AddressBook/ListPeople.cs

@@ -55,13 +55,13 @@ namespace Google.Protobuf.Examples.AddressBook
                 {
                     switch (phoneNumber.Type)
                     {
-                        case Person.Types.PhoneType.MOBILE:
+                        case Person.Types.PhoneType.Mobile:
                             Console.Write("  Mobile phone #: ");
                             break;
-                        case Person.Types.PhoneType.HOME:
+                        case Person.Types.PhoneType.Home:
                             Console.Write("  Home phone #: ");
                             break;
-                        case Person.Types.PhoneType.WORK:
+                        case Person.Types.PhoneType.Work:
                             Console.Write("  Work phone #: ");
                             break;
                     }

csharp/src/Google.Protobuf.Conformance/Conformance.cs

@@ -199,15 +199,15 @@ namespace Conformance {
   }
   #region Enums
   public enum WireFormat {
-    UNSPECIFIED = 0,
-    PROTOBUF = 1,
-    JSON = 2,
+    [pbr::OriginalName("UNSPECIFIED")] Unspecified = 0,
+    [pbr::OriginalName("PROTOBUF")] Protobuf = 1,
+    [pbr::OriginalName("JSON")] Json = 2,
   }
 
   public enum ForeignEnum {
-    FOREIGN_FOO = 0,
-    FOREIGN_BAR = 1,
-    FOREIGN_BAZ = 2,
+    [pbr::OriginalName("FOREIGN_FOO")] ForeignFoo = 0,
+    [pbr::OriginalName("FOREIGN_BAR")] ForeignBar = 1,
+    [pbr::OriginalName("FOREIGN_BAZ")] ForeignBaz = 2,
   }
 
   #endregion
@@ -278,7 +278,7 @@ namespace Conformance {
 
     /// <summary>Field number for the "requested_output_format" field.</summary>
     public const int RequestedOutputFormatFieldNumber = 3;
-    private global::Conformance.WireFormat requestedOutputFormat_ = global::Conformance.WireFormat.UNSPECIFIED;
+    private global::Conformance.WireFormat requestedOutputFormat_ = 0;
     /// <summary>
     ///  Which format should the testee serialize its message to?
     /// </summary>
@@ -328,7 +328,7 @@ namespace Conformance {
       int hash = 1;
       if (payloadCase_ == PayloadOneofCase.ProtobufPayload) hash ^= ProtobufPayload.GetHashCode();
       if (payloadCase_ == PayloadOneofCase.JsonPayload) hash ^= JsonPayload.GetHashCode();
-      if (RequestedOutputFormat != global::Conformance.WireFormat.UNSPECIFIED) hash ^= RequestedOutputFormat.GetHashCode();
+      if (RequestedOutputFormat != 0) hash ^= RequestedOutputFormat.GetHashCode();
       hash ^= (int) payloadCase_;
       return hash;
     }
@@ -346,7 +346,7 @@ namespace Conformance {
         output.WriteRawTag(18);
         output.WriteString(JsonPayload);
       }
-      if (RequestedOutputFormat != global::Conformance.WireFormat.UNSPECIFIED) {
+      if (RequestedOutputFormat != 0) {
         output.WriteRawTag(24);
         output.WriteEnum((int) RequestedOutputFormat);
       }
@@ -360,7 +360,7 @@ namespace Conformance {
       if (payloadCase_ == PayloadOneofCase.JsonPayload) {
         size += 1 + pb::CodedOutputStream.ComputeStringSize(JsonPayload);
       }
-      if (RequestedOutputFormat != global::Conformance.WireFormat.UNSPECIFIED) {
+      if (RequestedOutputFormat != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) RequestedOutputFormat);
       }
       return size;
@@ -370,7 +370,7 @@ namespace Conformance {
       if (other == null) {
         return;
       }
-      if (other.RequestedOutputFormat != global::Conformance.WireFormat.UNSPECIFIED) {
+      if (other.RequestedOutputFormat != 0) {
         RequestedOutputFormat = other.RequestedOutputFormat;
       }
       switch (other.PayloadCase) {
@@ -1044,7 +1044,7 @@ namespace Conformance {
 
     /// <summary>Field number for the "optional_nested_enum" field.</summary>
     public const int OptionalNestedEnumFieldNumber = 21;
-    private global::Conformance.TestAllTypes.Types.NestedEnum optionalNestedEnum_ = global::Conformance.TestAllTypes.Types.NestedEnum.FOO;
+    private global::Conformance.TestAllTypes.Types.NestedEnum optionalNestedEnum_ = 0;
     public global::Conformance.TestAllTypes.Types.NestedEnum OptionalNestedEnum {
       get { return optionalNestedEnum_; }
       set {
@@ -1054,7 +1054,7 @@ namespace Conformance {
 
     /// <summary>Field number for the "optional_foreign_enum" field.</summary>
     public const int OptionalForeignEnumFieldNumber = 22;
-    private global::Conformance.ForeignEnum optionalForeignEnum_ = global::Conformance.ForeignEnum.FOREIGN_FOO;
+    private global::Conformance.ForeignEnum optionalForeignEnum_ = 0;
     public global::Conformance.ForeignEnum OptionalForeignEnum {
       get { return optionalForeignEnum_; }
       set {
@@ -2079,8 +2079,8 @@ namespace Conformance {
       if (OptionalBytes.Length != 0) hash ^= OptionalBytes.GetHashCode();
       if (optionalNestedMessage_ != null) hash ^= OptionalNestedMessage.GetHashCode();
       if (optionalForeignMessage_ != null) hash ^= OptionalForeignMessage.GetHashCode();
-      if (OptionalNestedEnum != global::Conformance.TestAllTypes.Types.NestedEnum.FOO) hash ^= OptionalNestedEnum.GetHashCode();
-      if (OptionalForeignEnum != global::Conformance.ForeignEnum.FOREIGN_FOO) hash ^= OptionalForeignEnum.GetHashCode();
+      if (OptionalNestedEnum != 0) hash ^= OptionalNestedEnum.GetHashCode();
+      if (OptionalForeignEnum != 0) hash ^= OptionalForeignEnum.GetHashCode();
       if (OptionalStringPiece.Length != 0) hash ^= OptionalStringPiece.GetHashCode();
       if (OptionalCord.Length != 0) hash ^= OptionalCord.GetHashCode();
       if (recursiveMessage_ != null) hash ^= RecursiveMessage.GetHashCode();
@@ -2247,11 +2247,11 @@ namespace Conformance {
         output.WriteRawTag(154, 1);
         output.WriteMessage(OptionalForeignMessage);
       }
-      if (OptionalNestedEnum != global::Conformance.TestAllTypes.Types.NestedEnum.FOO) {
+      if (OptionalNestedEnum != 0) {
         output.WriteRawTag(168, 1);
         output.WriteEnum((int) OptionalNestedEnum);
       }
-      if (OptionalForeignEnum != global::Conformance.ForeignEnum.FOREIGN_FOO) {
+      if (OptionalForeignEnum != 0) {
         output.WriteRawTag(176, 1);
         output.WriteEnum((int) OptionalForeignEnum);
       }
@@ -2492,10 +2492,10 @@ namespace Conformance {
       if (optionalForeignMessage_ != null) {
         size += 2 + pb::CodedOutputStream.ComputeMessageSize(OptionalForeignMessage);
       }
-      if (OptionalNestedEnum != global::Conformance.TestAllTypes.Types.NestedEnum.FOO) {
+      if (OptionalNestedEnum != 0) {
         size += 2 + pb::CodedOutputStream.ComputeEnumSize((int) OptionalNestedEnum);
       }
-      if (OptionalForeignEnum != global::Conformance.ForeignEnum.FOREIGN_FOO) {
+      if (OptionalForeignEnum != 0) {
         size += 2 + pb::CodedOutputStream.ComputeEnumSize((int) OptionalForeignEnum);
       }
       if (OptionalStringPiece.Length != 0) {
@@ -2719,10 +2719,10 @@ namespace Conformance {
         }
         OptionalForeignMessage.MergeFrom(other.OptionalForeignMessage);
       }
-      if (other.OptionalNestedEnum != global::Conformance.TestAllTypes.Types.NestedEnum.FOO) {
+      if (other.OptionalNestedEnum != 0) {
         OptionalNestedEnum = other.OptionalNestedEnum;
       }
-      if (other.OptionalForeignEnum != global::Conformance.ForeignEnum.FOREIGN_FOO) {
+      if (other.OptionalForeignEnum != 0) {
         OptionalForeignEnum = other.OptionalForeignEnum;
       }
       if (other.OptionalStringPiece.Length != 0) {
@@ -3448,13 +3448,13 @@ namespace Conformance {
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
       public enum NestedEnum {
-        FOO = 0,
-        BAR = 1,
-        BAZ = 2,
+        [pbr::OriginalName("FOO")] Foo = 0,
+        [pbr::OriginalName("BAR")] Bar = 1,
+        [pbr::OriginalName("BAZ")] Baz = 2,
         /// <summary>
         ///  Intentionally negative.
         /// </summary>
-        NEG = -1,
+        [pbr::OriginalName("NEG")] Neg = -1,
       }
 
       [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]

csharp/src/Google.Protobuf.Conformance/Program.cs

@@ -109,10 +109,10 @@ namespace Google.Protobuf.Conformance
             {
                 switch (request.RequestedOutputFormat)
                 {
-                    case global::Conformance.WireFormat.JSON:
+                    case global::Conformance.WireFormat.Json:
                         var formatter = new JsonFormatter(new JsonFormatter.Settings(false, typeRegistry));
                         return new ConformanceResponse { JsonPayload = formatter.Format(message) };
-                    case global::Conformance.WireFormat.PROTOBUF:
+                    case global::Conformance.WireFormat.Protobuf:
                         return new ConformanceResponse { ProtobufPayload = message.ToByteString() };
                     default:
                         throw new Exception("Unsupported request output format: " + request.PayloadCase);

csharp/src/Google.Protobuf.Test/FieldCodecTest.cs

@@ -58,7 +58,7 @@ namespace Google.Protobuf
             new FieldCodecTestData<float>(FieldCodec.ForFloat(100), 1234.5f, "Float"),
             new FieldCodecTestData<double>(FieldCodec.ForDouble(100), 1234567890.5d, "Double"),
             new FieldCodecTestData<ForeignEnum>(
-                FieldCodec.ForEnum(100, t => (int) t, t => (ForeignEnum) t), ForeignEnum.FOREIGN_BAZ, "Enum"),
+                FieldCodec.ForEnum(100, t => (int) t, t => (ForeignEnum) t), ForeignEnum.ForeignBaz, "Enum"),
             new FieldCodecTestData<ForeignMessage>(
                 FieldCodec.ForMessage(100, ForeignMessage.Parser), new ForeignMessage { C = 10 }, "Message"),
         };

csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs

@@ -66,13 +66,13 @@ namespace Google.Protobuf
             Assert.AreEqual(0, message.SingleFixed32);
             Assert.AreEqual(0L, message.SingleFixed64);
             Assert.AreEqual(0.0f, message.SingleFloat);
-            Assert.AreEqual(ForeignEnum.FOREIGN_UNSPECIFIED, message.SingleForeignEnum);
+            Assert.AreEqual(ForeignEnum.ForeignUnspecified, message.SingleForeignEnum);
             Assert.IsNull(message.SingleForeignMessage);
-            Assert.AreEqual(ImportEnum.IMPORT_ENUM_UNSPECIFIED, message.SingleImportEnum);
+            Assert.AreEqual(ImportEnum.Unspecified, message.SingleImportEnum);
             Assert.IsNull(message.SingleImportMessage);
             Assert.AreEqual(0, message.SingleInt32);
             Assert.AreEqual(0L, message.SingleInt64);
-            Assert.AreEqual(TestAllTypes.Types.NestedEnum.NESTED_ENUM_UNSPECIFIED, message.SingleNestedEnum);
+            Assert.AreEqual(TestAllTypes.Types.NestedEnum.Unspecified, message.SingleNestedEnum);
             Assert.IsNull(message.SingleNestedMessage);
             Assert.IsNull(message.SinglePublicImportMessage);
             Assert.AreEqual(0, message.SingleSfixed32);
@@ -145,13 +145,13 @@ namespace Google.Protobuf
                 SingleFixed32 = 23,
                 SingleFixed64 = 1234567890123,
                 SingleFloat = 12.25f,
-                SingleForeignEnum = ForeignEnum.FOREIGN_BAR,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
                 SingleForeignMessage = new ForeignMessage { C = 10 },
-                SingleImportEnum = ImportEnum.IMPORT_BAZ,
+                SingleImportEnum = ImportEnum.ImportBaz,
                 SingleImportMessage = new ImportMessage { D = 20 },
                 SingleInt32 = 100,
                 SingleInt64 = 3210987654321,
-                SingleNestedEnum = TestAllTypes.Types.NestedEnum.FOO,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
                 SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
                 SinglePublicImportMessage = new PublicImportMessage { E = 54 },
                 SingleSfixed32 = -123,
@@ -179,13 +179,13 @@ namespace Google.Protobuf
                 RepeatedFixed32 = { uint.MaxValue, 23 },
                 RepeatedFixed64 = { ulong.MaxValue, 1234567890123 },
                 RepeatedFloat = { 100f, 12.25f },
-                RepeatedForeignEnum = { ForeignEnum.FOREIGN_FOO, ForeignEnum.FOREIGN_BAR },
+                RepeatedForeignEnum = { ForeignEnum.ForeignFoo, ForeignEnum.ForeignBar },
                 RepeatedForeignMessage = { new ForeignMessage(), new ForeignMessage { C = 10 } },
-                RepeatedImportEnum = { ImportEnum.IMPORT_BAZ, ImportEnum.IMPORT_ENUM_UNSPECIFIED },
+                RepeatedImportEnum = { ImportEnum.ImportBaz, ImportEnum.Unspecified },
                 RepeatedImportMessage = { new ImportMessage { D = 20 }, new ImportMessage { D = 25 } },
                 RepeatedInt32 = { 100, 200 },
                 RepeatedInt64 = { 3210987654321, long.MaxValue },
-                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.FOO, TestAllTypes.Types.NestedEnum.NEG },
+                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.Foo, TestAllTypes.Types.NestedEnum.Neg },
                 RepeatedNestedMessage = { new TestAllTypes.Types.NestedMessage { Bb = 35 }, new TestAllTypes.Types.NestedMessage { Bb = 10 } },
                 RepeatedPublicImportMessage = { new PublicImportMessage { E = 54 }, new PublicImportMessage { E = -1 } },
                 RepeatedSfixed32 = { -123, 123 },
@@ -224,8 +224,8 @@ namespace Google.Protobuf
                     { 5, new ForeignMessage() },
                 },
                 MapInt32Enum = {
-                    { 1, MapEnum.MAP_ENUM_BAR },
-                    { 2000, MapEnum.MAP_ENUM_FOO }
+                    { 1, MapEnum.Bar },
+                    { 2000, MapEnum.Foo }
                 }
             };
 
@@ -449,7 +449,7 @@ namespace Google.Protobuf
                 SingleFloat = 12.25f,
                 SingleInt32 = 100,
                 SingleInt64 = 3210987654321,
-                SingleNestedEnum = TestAllTypes.Types.NestedEnum.FOO,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
                 SingleSfixed32 = -123,
                 SingleSfixed64 = -12345678901234,
                 SingleSint32 = -456,
@@ -479,7 +479,7 @@ namespace Google.Protobuf
                 RepeatedFloat = { 100f, 12.25f },
                 RepeatedInt32 = { 100, 200 },
                 RepeatedInt64 = { 3210987654321, long.MaxValue },
-                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.FOO, TestAllTypes.Types.NestedEnum.NEG },
+                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.Foo, TestAllTypes.Types.NestedEnum.Neg },
                 RepeatedSfixed32 = { -123, 123 },
                 RepeatedSfixed64 = { -12345678901234, 12345678901234 },
                 RepeatedSint32 = { -456, 100 },

csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs

@@ -75,13 +75,13 @@ namespace Google.Protobuf
                 SingleFixed32 = 23,
                 SingleFixed64 = 1234567890123,
                 SingleFloat = 12.25f,
-                SingleForeignEnum = ForeignEnum.FOREIGN_BAR,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
                 SingleForeignMessage = new ForeignMessage { C = 10 },
-                SingleImportEnum = ImportEnum.IMPORT_BAZ,
+                SingleImportEnum = ImportEnum.ImportBaz,
                 SingleImportMessage = new ImportMessage { D = 20 },
                 SingleInt32 = 100,
                 SingleInt64 = 3210987654321,
-                SingleNestedEnum = TestAllTypes.Types.NestedEnum.FOO,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
                 SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
                 SinglePublicImportMessage = new PublicImportMessage { E = 54 },
                 SingleSfixed32 = -123,
@@ -174,14 +174,14 @@ namespace Google.Protobuf
         [Test]
         public void UnknownEnumValueNumeric_RepeatedField()
         {
-            var message = new TestAllTypes { RepeatedForeignEnum = { ForeignEnum.FOREIGN_BAZ, (ForeignEnum) 100, ForeignEnum.FOREIGN_FOO } };
+            var message = new TestAllTypes { RepeatedForeignEnum = { ForeignEnum.ForeignBaz, (ForeignEnum) 100, ForeignEnum.ForeignFoo } };
             AssertJson("{ 'repeatedForeignEnum': [ 'FOREIGN_BAZ', 100, 'FOREIGN_FOO' ] }", JsonFormatter.Default.Format(message));
         }
 
         [Test]
         public void UnknownEnumValueNumeric_MapField()
         {
-            var message = new TestMap { MapInt32Enum = { { 1, MapEnum.MAP_ENUM_FOO }, { 2, (MapEnum) 100 }, { 3, MapEnum.MAP_ENUM_BAR } } };
+            var message = new TestMap { MapInt32Enum = { { 1, MapEnum.Foo }, { 2, (MapEnum) 100 }, { 3, MapEnum.Bar } } };
             AssertJson("{ 'mapInt32Enum': { '1': 'MAP_ENUM_FOO', '2': 100, '3': 'MAP_ENUM_BAR' } }", JsonFormatter.Default.Format(message));
         }
 

csharp/src/Google.Protobuf.Test/JsonParserTest.cs

@@ -142,8 +142,8 @@ namespace Google.Protobuf
         [TestCase(typeof(DoubleValue), "1.5", 1.5d)]
         public void Wrappers_Standalone(System.Type wrapperType, string json, object expectedValue)
         {
-            IMessage parsed = (IMessage) Activator.CreateInstance(wrapperType);
-            IMessage expected = (IMessage) Activator.CreateInstance(wrapperType);
+            IMessage parsed = (IMessage)Activator.CreateInstance(wrapperType);
+            IMessage expected = (IMessage)Activator.CreateInstance(wrapperType);
             JsonParser.Default.Merge(parsed, "null");
             Assert.AreEqual(expected, parsed);
 
@@ -886,9 +886,9 @@ namespace Google.Protobuf
         }
 
         [Test]
-        [TestCase("\"FOREIGN_BAR\"", ForeignEnum.FOREIGN_BAR)]
-        [TestCase("5", ForeignEnum.FOREIGN_BAR)]
-        [TestCase("100", (ForeignEnum) 100)]
+        [TestCase("\"FOREIGN_BAR\"", ForeignEnum.ForeignBar)]
+        [TestCase("5", ForeignEnum.ForeignBar)]
+        [TestCase("100", (ForeignEnum)100)]
         public void EnumValid(string value, ForeignEnum expectedValue)
         {
             string json = "{ \"singleForeignEnum\": " + value + " }";

csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs

@@ -195,7 +195,7 @@ namespace Google.Protobuf.Reflection
             Assert.AreEqual(value, enumType.Values[1]);
             Assert.AreEqual("FOREIGN_FOO", value.Name);
             Assert.AreEqual(4, value.Number);
-            Assert.AreEqual((int) ForeignEnum.FOREIGN_FOO, value.Number);
+            Assert.AreEqual((int) ForeignEnum.ForeignFoo, value.Number);
             Assert.AreEqual(value, enumType.FindValueByNumber(4));
             Assert.Null(enumType.FindValueByName("NO_SUCH_VALUE"));
             for (int i = 0; i < enumType.Values.Count; i++)

csharp/src/Google.Protobuf.Test/Reflection/FieldAccessTest.cs

@@ -128,7 +128,7 @@ namespace Google.Protobuf.Reflection
             fields[TestAllTypes.SingleInt32FieldNumber].Accessor.SetValue(message, 500);
             fields[TestAllTypes.SingleStringFieldNumber].Accessor.SetValue(message, "It's a string");
             fields[TestAllTypes.SingleBytesFieldNumber].Accessor.SetValue(message, ByteString.CopyFrom(99, 98, 97));
-            fields[TestAllTypes.SingleForeignEnumFieldNumber].Accessor.SetValue(message, ForeignEnum.FOREIGN_FOO);
+            fields[TestAllTypes.SingleForeignEnumFieldNumber].Accessor.SetValue(message, ForeignEnum.ForeignFoo);
             fields[TestAllTypes.SingleForeignMessageFieldNumber].Accessor.SetValue(message, new ForeignMessage { C = 12345 });
             fields[TestAllTypes.SingleDoubleFieldNumber].Accessor.SetValue(message, 20150701.5);
 
@@ -138,7 +138,7 @@ namespace Google.Protobuf.Reflection
                 SingleInt32 = 500,
                 SingleString = "It's a string",
                 SingleBytes = ByteString.CopyFrom(99, 98, 97),
-                SingleForeignEnum = ForeignEnum.FOREIGN_FOO,
+                SingleForeignEnum = ForeignEnum.ForeignFoo,
                 SingleForeignMessage = new ForeignMessage { C = 12345 },
                 SingleDouble = 20150701.5
             };

csharp/src/Google.Protobuf.Test/SampleMessages.cs

@@ -54,13 +54,13 @@ namespace Google.Protobuf
                 SingleFixed32 = 23,
                 SingleFixed64 = 1234567890123,
                 SingleFloat = 12.25f,
-                SingleForeignEnum = ForeignEnum.FOREIGN_BAR,
+                SingleForeignEnum = ForeignEnum.ForeignBar,
                 SingleForeignMessage = new ForeignMessage { C = 10 },
-                SingleImportEnum = ImportEnum.IMPORT_BAZ,
+                SingleImportEnum = ImportEnum.ImportBaz,
                 SingleImportMessage = new ImportMessage { D = 20 },
                 SingleInt32 = 100,
                 SingleInt64 = 3210987654321,
-                SingleNestedEnum = TestAllTypes.Types.NestedEnum.FOO,
+                SingleNestedEnum = TestAllTypes.Types.NestedEnum.Foo,
                 SingleNestedMessage = new TestAllTypes.Types.NestedMessage { Bb = 35 },
                 SinglePublicImportMessage = new PublicImportMessage { E = 54 },
                 SingleSfixed32 = -123,
@@ -76,13 +76,13 @@ namespace Google.Protobuf
                 RepeatedFixed32 = { UInt32.MaxValue, 23 },
                 RepeatedFixed64 = { UInt64.MaxValue, 1234567890123 },
                 RepeatedFloat = { 100f, 12.25f },
-                RepeatedForeignEnum = { ForeignEnum.FOREIGN_FOO, ForeignEnum.FOREIGN_BAR },
+                RepeatedForeignEnum = { ForeignEnum.ForeignFoo, ForeignEnum.ForeignBar },
                 RepeatedForeignMessage = { new ForeignMessage(), new ForeignMessage { C = 10 } },
-                RepeatedImportEnum = { ImportEnum.IMPORT_BAZ, ImportEnum.IMPORT_ENUM_UNSPECIFIED },
+                RepeatedImportEnum = { ImportEnum.ImportBaz, ImportEnum.Unspecified },
                 RepeatedImportMessage = { new ImportMessage { D = 20 }, new ImportMessage { D = 25 } },
                 RepeatedInt32 = { 100, 200 },
                 RepeatedInt64 = { 3210987654321, Int64.MaxValue },
-                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.FOO, TestAllTypes.Types.NestedEnum.NEG },
+                RepeatedNestedEnum = { TestAllTypes.Types.NestedEnum.Foo, TestAllTypes.Types.NestedEnum.Neg },
                 RepeatedNestedMessage = { new TestAllTypes.Types.NestedMessage { Bb = 35 }, new TestAllTypes.Types.NestedMessage { Bb = 10 } },
                 RepeatedPublicImportMessage = { new PublicImportMessage { E = 54 }, new PublicImportMessage { E = -1 } },
                 RepeatedSfixed32 = { -123, 123 },

csharp/src/Google.Protobuf.Test/TestCornerCases.cs

@@ -43,8 +43,8 @@ namespace Google.Protobuf
             NegativeEnumMessage msg = new NegativeEnumMessage
             {
                 Value = NegativeEnum.MinusOne,
-                Values = { NegativeEnum.NEGATIVE_ENUM_ZERO, NegativeEnum.MinusOne, NegativeEnum.FiveBelow },
-                PackedValues = { NegativeEnum.NEGATIVE_ENUM_ZERO, NegativeEnum.MinusOne, NegativeEnum.FiveBelow }
+                Values = { NegativeEnum.Zero, NegativeEnum.MinusOne, NegativeEnum.FiveBelow },
+                PackedValues = { NegativeEnum.Zero, NegativeEnum.MinusOne, NegativeEnum.FiveBelow }
             };
 
             Assert.AreEqual(58, msg.CalculateSize());

csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs

@@ -164,9 +164,9 @@ namespace Google.Protobuf.TestProtos {
   }
   #region Enums
   public enum MapEnum {
-    MAP_ENUM_FOO = 0,
-    MAP_ENUM_BAR = 1,
-    MAP_ENUM_BAZ = 2,
+    [pbr::OriginalName("MAP_ENUM_FOO")] Foo = 0,
+    [pbr::OriginalName("MAP_ENUM_BAR")] Bar = 1,
+    [pbr::OriginalName("MAP_ENUM_BAZ")] Baz = 2,
   }
 
   #endregion
@@ -1358,7 +1358,7 @@ namespace Google.Protobuf.TestProtos {
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     public static partial class Types {
       public enum Type {
-        TYPE_FOO = 0,
+        [pbr::OriginalName("TYPE_FOO")] Foo = 0,
       }
 
     }

csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs

@@ -42,10 +42,10 @@ namespace Google.Protobuf.TestProtos {
   }
   #region Enums
   public enum ImportEnum {
-    IMPORT_ENUM_UNSPECIFIED = 0,
-    IMPORT_FOO = 7,
-    IMPORT_BAR = 8,
-    IMPORT_BAZ = 9,
+    [pbr::OriginalName("IMPORT_ENUM_UNSPECIFIED")] Unspecified = 0,
+    [pbr::OriginalName("IMPORT_FOO")] ImportFoo = 7,
+    [pbr::OriginalName("IMPORT_BAR")] ImportBar = 8,
+    [pbr::OriginalName("IMPORT_BAZ")] ImportBaz = 9,
   }
 
   #endregion

csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs

@@ -66,14 +66,14 @@ namespace UnitTest.Issues.TestProtos {
   }
   #region Enums
   public enum NegativeEnum {
-    NEGATIVE_ENUM_ZERO = 0,
-    FiveBelow = -5,
-    MinusOne = -1,
+    [pbr::OriginalName("NEGATIVE_ENUM_ZERO")] Zero = 0,
+    [pbr::OriginalName("FiveBelow")] FiveBelow = -5,
+    [pbr::OriginalName("MinusOne")] MinusOne = -1,
   }
 
   public enum DeprecatedEnum {
-    DEPRECATED_ZERO = 0,
-    one = 1,
+    [pbr::OriginalName("DEPRECATED_ZERO")] DeprecatedZero = 0,
+    [pbr::OriginalName("one")] One = 1,
   }
 
   #endregion
@@ -356,7 +356,7 @@ namespace UnitTest.Issues.TestProtos {
 
     /// <summary>Field number for the "value" field.</summary>
     public const int ValueFieldNumber = 1;
-    private global::UnitTest.Issues.TestProtos.NegativeEnum value_ = global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO;
+    private global::UnitTest.Issues.TestProtos.NegativeEnum value_ = 0;
     public global::UnitTest.Issues.TestProtos.NegativeEnum Value {
       get { return value_; }
       set {
@@ -401,7 +401,7 @@ namespace UnitTest.Issues.TestProtos {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) hash ^= Value.GetHashCode();
+      if (Value != 0) hash ^= Value.GetHashCode();
       hash ^= values_.GetHashCode();
       hash ^= packedValues_.GetHashCode();
       return hash;
@@ -412,7 +412,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) {
+      if (Value != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) Value);
       }
@@ -422,7 +422,7 @@ namespace UnitTest.Issues.TestProtos {
 
     public int CalculateSize() {
       int size = 0;
-      if (Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) {
+      if (Value != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Value);
       }
       size += values_.CalculateSize(_repeated_values_codec);
@@ -434,7 +434,7 @@ namespace UnitTest.Issues.TestProtos {
       if (other == null) {
         return;
       }
-      if (other.Value != global::UnitTest.Issues.TestProtos.NegativeEnum.NEGATIVE_ENUM_ZERO) {
+      if (other.Value != 0) {
         Value = other.Value;
       }
       values_.Add(other.values_);
@@ -620,7 +620,7 @@ namespace UnitTest.Issues.TestProtos {
 
     /// <summary>Field number for the "EnumValue" field.</summary>
     public const int EnumValueFieldNumber = 5;
-    private global::UnitTest.Issues.TestProtos.DeprecatedEnum enumValue_ = global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO;
+    private global::UnitTest.Issues.TestProtos.DeprecatedEnum enumValue_ = 0;
     [global::System.ObsoleteAttribute()]
     public global::UnitTest.Issues.TestProtos.DeprecatedEnum EnumValue {
       get { return enumValue_; }
@@ -665,7 +665,7 @@ namespace UnitTest.Issues.TestProtos {
       hash ^= primitiveArray_.GetHashCode();
       if (messageValue_ != null) hash ^= MessageValue.GetHashCode();
       hash ^= messageArray_.GetHashCode();
-      if (EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) hash ^= EnumValue.GetHashCode();
+      if (EnumValue != 0) hash ^= EnumValue.GetHashCode();
       hash ^= enumArray_.GetHashCode();
       return hash;
     }
@@ -685,7 +685,7 @@ namespace UnitTest.Issues.TestProtos {
         output.WriteMessage(MessageValue);
       }
       messageArray_.WriteTo(output, _repeated_messageArray_codec);
-      if (EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) {
+      if (EnumValue != 0) {
         output.WriteRawTag(40);
         output.WriteEnum((int) EnumValue);
       }
@@ -702,7 +702,7 @@ namespace UnitTest.Issues.TestProtos {
         size += 1 + pb::CodedOutputStream.ComputeMessageSize(MessageValue);
       }
       size += messageArray_.CalculateSize(_repeated_messageArray_codec);
-      if (EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) {
+      if (EnumValue != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) EnumValue);
       }
       size += enumArray_.CalculateSize(_repeated_enumArray_codec);
@@ -724,7 +724,7 @@ namespace UnitTest.Issues.TestProtos {
         MessageValue.MergeFrom(other.MessageValue);
       }
       messageArray_.Add(other.messageArray_);
-      if (other.EnumValue != global::UnitTest.Issues.TestProtos.DeprecatedEnum.DEPRECATED_ZERO) {
+      if (other.EnumValue != 0) {
         EnumValue = other.EnumValue;
       }
       enumArray_.Add(other.enumArray_);
@@ -1435,7 +1435,7 @@ namespace UnitTest.Issues.TestProtos {
     public const int NameFieldNumber = 1;
     private string name_ = "";
     /// <summary>
-    ///  json_name field options are not properly handled during deserialization
+    ///  Message for testing the effects for of the json_name option
     /// </summary>
     public string Name {
       get { return name_; }

csharp/src/Google.Protobuf/Google.Protobuf.csproj

@@ -117,6 +117,7 @@
     <Compile Include="Reflection\MethodDescriptor.cs" />
     <Compile Include="Reflection\OneofAccessor.cs" />
     <Compile Include="Reflection\OneofDescriptor.cs" />
+    <Compile Include="Reflection\OriginalNameAttribute.cs" />
     <Compile Include="Reflection\PackageDescriptor.cs" />
     <Compile Include="Reflection\PartialClasses.cs" />
     <Compile Include="Reflection\ReflectionUtil.cs" />

csharp/src/Google.Protobuf/Google.Protobuf.nuspec

@@ -33,10 +33,12 @@
         <dependency id="System.Linq.Expressions" version="4.0.0" />
         <dependency id="System.ObjectModel" version="4.0.0" />
         <dependency id="System.Reflection" version="4.0.0" />
+        <dependency id="System.Reflection.Extensions" version="4.0.0" />
         <dependency id="System.Runtime" version="4.0.0" />
         <dependency id="System.Runtime.Extensions" version="4.0.0" />
         <dependency id="System.Text.Encoding" version="4.0.0" />
         <dependency id="System.Text.RegularExpressions" version="4.0.0" />
+        <dependency id="System.Threading" version="4.0.0" />
       </group>
     </dependencies>
   </metadata>

csharp/src/Google.Protobuf/JsonFormatter.cs

@@ -39,6 +39,7 @@ using Google.Protobuf.WellKnownTypes;
 using System.IO;
 using System.Linq;
 using System.Collections.Generic;
+using System.Reflection;
 
 namespace Google.Protobuf
 {
@@ -420,9 +421,10 @@ namespace Google.Protobuf
             }
             else if (value is System.Enum)
             {
-                if (System.Enum.IsDefined(value.GetType(), value))
+                string name = OriginalEnumValueHelper.GetOriginalName(value);
+                if (name != null)
                 {
-                    WriteString(writer, value.ToString());
+                    WriteString(writer, name);
                 }
                 else
                 {
@@ -877,5 +879,44 @@ namespace Google.Protobuf
                 TypeRegistry = ProtoPreconditions.CheckNotNull(typeRegistry, nameof(typeRegistry));
             }
         }
+
+        // Effectively a cache of mapping from enum values to the original name as specified in the proto file,
+        // fetched by reflection.
+        // The need for this is unfortunate, as is its unbounded size, but realistically it shouldn't cause issues.
+        private static class OriginalEnumValueHelper
+        {
+            // TODO: In the future we might want to use ConcurrentDictionary, at the point where all
+            // the platforms we target have it.
+            private static readonly Dictionary<System.Type, Dictionary<object, string>> dictionaries
+                = new Dictionary<System.Type, Dictionary<object, string>>();
+            
+            internal static string GetOriginalName(object value)
+            {
+                var enumType = value.GetType();
+                Dictionary<object, string> nameMapping;
+                lock (dictionaries)
+                {
+                    if (!dictionaries.TryGetValue(enumType, out nameMapping))
+                    {
+                        nameMapping = GetNameMapping(enumType);
+                        dictionaries[enumType] = nameMapping;
+                    }
+                }
+
+                string originalName;
+                // If this returns false, originalName will be null, which is what we want.
+                nameMapping.TryGetValue(value, out originalName);
+                return originalName;
+            }
+
+            private static Dictionary<object, string> GetNameMapping(System.Type enumType) =>
+                enumType.GetTypeInfo().DeclaredFields
+                    .Where(f => f.IsStatic)
+                    .ToDictionary(f => f.GetValue(null),
+                                  f => f.GetCustomAttributes<OriginalNameAttribute>()
+                                        .FirstOrDefault()
+                                        // If the attribute hasn't been applied, fall back to the name of the field.
+                                        ?.Name ?? f.Name);
+        }
     }
 }

csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs

@@ -133,41 +133,41 @@ namespace Google.Protobuf.Reflection
         {
             switch (type)
             {
-                case FieldDescriptorProto.Types.Type.TYPE_DOUBLE:
+                case FieldDescriptorProto.Types.Type.Double:
                     return FieldType.Double;
-                case FieldDescriptorProto.Types.Type.TYPE_FLOAT:
+                case FieldDescriptorProto.Types.Type.Float:
                     return FieldType.Float;
-                case FieldDescriptorProto.Types.Type.TYPE_INT64:
+                case FieldDescriptorProto.Types.Type.Int64:
                     return FieldType.Int64;
-                case FieldDescriptorProto.Types.Type.TYPE_UINT64:
+                case FieldDescriptorProto.Types.Type.Uint64:
                     return FieldType.UInt64;
-                case FieldDescriptorProto.Types.Type.TYPE_INT32:
+                case FieldDescriptorProto.Types.Type.Int32:
                     return FieldType.Int32;
-                case FieldDescriptorProto.Types.Type.TYPE_FIXED64:
+                case FieldDescriptorProto.Types.Type.Fixed64:
                     return FieldType.Fixed64;
-                case FieldDescriptorProto.Types.Type.TYPE_FIXED32:
+                case FieldDescriptorProto.Types.Type.Fixed32:
                     return FieldType.Fixed32;
-                case FieldDescriptorProto.Types.Type.TYPE_BOOL:
+                case FieldDescriptorProto.Types.Type.Bool:
                     return FieldType.Bool;
-                case FieldDescriptorProto.Types.Type.TYPE_STRING:
+                case FieldDescriptorProto.Types.Type.String:
                     return FieldType.String;
-                case FieldDescriptorProto.Types.Type.TYPE_GROUP:
+                case FieldDescriptorProto.Types.Type.Group:
                     return FieldType.Group;
-                case FieldDescriptorProto.Types.Type.TYPE_MESSAGE:
+                case FieldDescriptorProto.Types.Type.Message:
                     return FieldType.Message;
-                case FieldDescriptorProto.Types.Type.TYPE_BYTES:
+                case FieldDescriptorProto.Types.Type.Bytes:
                     return FieldType.Bytes;
-                case FieldDescriptorProto.Types.Type.TYPE_UINT32:
+                case FieldDescriptorProto.Types.Type.Uint32:
                     return FieldType.UInt32;
-                case FieldDescriptorProto.Types.Type.TYPE_ENUM:
+                case FieldDescriptorProto.Types.Type.Enum:
                     return FieldType.Enum;
-                case FieldDescriptorProto.Types.Type.TYPE_SFIXED32:
+                case FieldDescriptorProto.Types.Type.Sfixed32:
                     return FieldType.SFixed32;
-                case FieldDescriptorProto.Types.Type.TYPE_SFIXED64:
+                case FieldDescriptorProto.Types.Type.Sfixed64:
                     return FieldType.SFixed64;
-                case FieldDescriptorProto.Types.Type.TYPE_SINT32:
+                case FieldDescriptorProto.Types.Type.Sint32:
                     return FieldType.SInt32;
-                case FieldDescriptorProto.Types.Type.TYPE_SINT64:
+                case FieldDescriptorProto.Types.Type.Sint64:
                     return FieldType.SInt64;
                 default:
                     throw new ArgumentException("Invalid type specified");
@@ -177,7 +177,7 @@ namespace Google.Protobuf.Reflection
         /// <summary>
         /// Returns <c>true</c> if this field is a repeated field; <c>false</c> otherwise.
         /// </summary>
-        public bool IsRepeated => Proto.Label == FieldDescriptorProto.Types.Label.LABEL_REPEATED;
+        public bool IsRepeated => Proto.Label == FieldDescriptorProto.Types.Label.Repeated;
 
         /// <summary>
         /// Returns <c>true</c> if this field is a map field; <c>false</c> otherwise.

csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs

+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+
+namespace Google.Protobuf.Reflection
+{
+    /// <summary>
+    /// Specifies the original name (in the .proto file) of a named element,
+    /// such as an enum value.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Field)]
+    public class OriginalNameAttribute : Attribute
+    {
+        /// <summary>
+        /// The name of the element in the .proto file.
+        /// </summary>
+        public string Name { get; set; }
+
+        /// <summary>
+        /// Constructs a new attribute instance for the given name.
+        /// </summary>
+        /// <param name="name">The name of the element in the .proto file.</param>
+        public OriginalNameAttribute(string name)
+        {
+            Name = ProtoPreconditions.CheckNotNull(name, nameof(name));
+        }
+    }
+}
\ No newline at end of file

csharp/src/Google.Protobuf/WellKnownTypes/Api.cs

@@ -185,7 +185,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "syntax" field.</summary>
     public const int SyntaxFieldNumber = 7;
-    private global::Google.Protobuf.WellKnownTypes.Syntax syntax_ = global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2;
+    private global::Google.Protobuf.WellKnownTypes.Syntax syntax_ = 0;
     /// <summary>
     ///  The source syntax of the service.
     /// </summary>
@@ -225,7 +225,7 @@ namespace Google.Protobuf.WellKnownTypes {
       if (Version.Length != 0) hash ^= Version.GetHashCode();
       if (sourceContext_ != null) hash ^= SourceContext.GetHashCode();
       hash ^= mixins_.GetHashCode();
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) hash ^= Syntax.GetHashCode();
+      if (Syntax != 0) hash ^= Syntax.GetHashCode();
       return hash;
     }
 
@@ -249,7 +249,7 @@ namespace Google.Protobuf.WellKnownTypes {
         output.WriteMessage(SourceContext);
       }
       mixins_.WriteTo(output, _repeated_mixins_codec);
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         output.WriteRawTag(56);
         output.WriteEnum((int) Syntax);
       }
@@ -269,7 +269,7 @@ namespace Google.Protobuf.WellKnownTypes {
         size += 1 + pb::CodedOutputStream.ComputeMessageSize(SourceContext);
       }
       size += mixins_.CalculateSize(_repeated_mixins_codec);
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Syntax);
       }
       return size;
@@ -294,7 +294,7 @@ namespace Google.Protobuf.WellKnownTypes {
         SourceContext.MergeFrom(other.SourceContext);
       }
       mixins_.Add(other.mixins_);
-      if (other.Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (other.Syntax != 0) {
         Syntax = other.Syntax;
       }
     }
@@ -458,7 +458,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "syntax" field.</summary>
     public const int SyntaxFieldNumber = 7;
-    private global::Google.Protobuf.WellKnownTypes.Syntax syntax_ = global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2;
+    private global::Google.Protobuf.WellKnownTypes.Syntax syntax_ = 0;
     /// <summary>
     ///  The source syntax of this method.
     /// </summary>
@@ -498,7 +498,7 @@ namespace Google.Protobuf.WellKnownTypes {
       if (ResponseTypeUrl.Length != 0) hash ^= ResponseTypeUrl.GetHashCode();
       if (ResponseStreaming != false) hash ^= ResponseStreaming.GetHashCode();
       hash ^= options_.GetHashCode();
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) hash ^= Syntax.GetHashCode();
+      if (Syntax != 0) hash ^= Syntax.GetHashCode();
       return hash;
     }
 
@@ -528,7 +528,7 @@ namespace Google.Protobuf.WellKnownTypes {
         output.WriteBool(ResponseStreaming);
       }
       options_.WriteTo(output, _repeated_options_codec);
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         output.WriteRawTag(56);
         output.WriteEnum((int) Syntax);
       }
@@ -552,7 +552,7 @@ namespace Google.Protobuf.WellKnownTypes {
         size += 1 + 1;
       }
       size += options_.CalculateSize(_repeated_options_codec);
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Syntax);
       }
       return size;
@@ -578,7 +578,7 @@ namespace Google.Protobuf.WellKnownTypes {
         ResponseStreaming = other.ResponseStreaming;
       }
       options_.Add(other.options_);
-      if (other.Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (other.Syntax != 0) {
         Syntax = other.Syntax;
       }
     }

csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs

@@ -59,7 +59,7 @@ namespace Google.Protobuf.WellKnownTypes {
     /// <summary>
     ///  Null value.
     /// </summary>
-    NULL_VALUE = 0,
+    [pbr::OriginalName("NULL_VALUE")] NullValue = 0,
   }
 
   #endregion
@@ -234,7 +234,7 @@ namespace Google.Protobuf.WellKnownTypes {
     ///  Represents a null value.
     /// </summary>
     public global::Google.Protobuf.WellKnownTypes.NullValue NullValue {
-      get { return kindCase_ == KindOneofCase.NullValue ? (global::Google.Protobuf.WellKnownTypes.NullValue) kind_ : global::Google.Protobuf.WellKnownTypes.NullValue.NULL_VALUE; }
+      get { return kindCase_ == KindOneofCase.NullValue ? (global::Google.Protobuf.WellKnownTypes.NullValue) kind_ : 0; }
       set {
         kind_ = value;
         kindCase_ = KindOneofCase.NullValue;

src/google/protobuf/compiler/csharp/csharp_enum.cc

@@ -41,6 +41,7 @@
 #include <google/protobuf/compiler/csharp/csharp_doc_comment.h>
 #include <google/protobuf/compiler/csharp/csharp_enum.h>
 #include <google/protobuf/compiler/csharp/csharp_helpers.h>
+#include <google/protobuf/compiler/csharp/csharp_options.h>
 
 using google::protobuf::internal::scoped_ptr;
 
@@ -64,10 +65,23 @@ void EnumGenerator::Generate(io::Printer* printer) {
                  "access_level", class_access_level(),
                  "name", descriptor_->name());
   printer->Indent();
+  std::set<string> used_names;
   for (int i = 0; i < descriptor_->value_count(); i++) {
       WriteEnumValueDocComment(printer, descriptor_->value(i));
-      printer->Print("$name$ = $number$,\n",
-                   "name", descriptor_->value(i)->name(),
+      string original_name = descriptor_->value(i)->name();
+      string name = options()->legacy_enum_values
+          ? descriptor_->value(i)->name()
+          : GetEnumValueName(descriptor_->name(), descriptor_->value(i)->name());
+      // Make sure we don't get any duplicate names due to prefix removal.
+      while (!used_names.insert(name).second) {
+        // It's possible we'll end up giving this warning multiple times, but that's better than not at all.
+        GOOGLE_LOG(WARNING) << "Duplicate enum value " << name << " (originally " << original_name
+          << ") in " << descriptor_->name() << "; adding underscore to distinguish";
+        name += "_";
+      }
+      printer->Print("[pbr::OriginalName(\"$original_name$\")] $name$ = $number$,\n",
+         "original_name", original_name,
+         "name", name,
          "number", SimpleItoa(descriptor_->value(i)->number()));         
   }
   printer->Outdent();

src/google/protobuf/compiler/csharp/csharp_field_base.cc

@@ -306,7 +306,9 @@ std::string FieldGeneratorBase::default_value() {
 std::string FieldGeneratorBase::default_value(const FieldDescriptor* descriptor) {
   switch (descriptor->type()) {
     case FieldDescriptor::TYPE_ENUM:
-      return type_name() + "." + descriptor->default_value_enum()->name();
+      // All proto3 enums have a default value of 0, and there's an implicit conversion from the constant 0 to
+      // any C# enum. This means we don't need to work out what we actually mapped the enum value name to.
+     return "0";
     case FieldDescriptor::TYPE_MESSAGE:
     case FieldDescriptor::TYPE_GROUP:
       if (IsWrapperType(descriptor)) {

src/google/protobuf/compiler/csharp/csharp_generator.cc

@@ -83,6 +83,9 @@ bool Generator::Generate(
       cli_options.base_namespace_specified = true;
     } else if (options[i].first == "internal_access") {
       cli_options.internal_access = true;
+    } else if (options[i].first == "legacy_enum_values") {
+      // TODO: Remove this before final release
+      cli_options.legacy_enum_values = true;
     } else {
       *error = "Unknown generator option: " + options[i].first;
       return false;

src/google/protobuf/compiler/csharp/csharp_generator_unittest.cc

@@ -30,8 +30,8 @@
 
 #include <memory>
 
-#include <google/protobuf/compiler/ruby/ruby_generator.h>
 #include <google/protobuf/compiler/command_line_interface.h>
+#include <google/protobuf/compiler/csharp/csharp_helpers.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/io/printer.h>
 
@@ -45,7 +45,23 @@ namespace compiler {
 namespace csharp {
 namespace {
 
-// TODO(jtattermusch): add some tests.
+TEST(CSharpEnumValue, PascalCasedPrefixStripping) {
+  EXPECT_EQ("Bar", GetEnumValueName("Foo", "BAR"));
+  EXPECT_EQ("BarBaz", GetEnumValueName("Foo", "BAR_BAZ"));
+  EXPECT_EQ("Bar", GetEnumValueName("Foo", "FOO_BAR"));
+  EXPECT_EQ("Bar", GetEnumValueName("Foo", "FOO__BAR"));
+  EXPECT_EQ("BarBaz", GetEnumValueName("Foo", "FOO_BAR_BAZ"));
+  EXPECT_EQ("BarBaz", GetEnumValueName("Foo", "Foo_BarBaz"));
+  EXPECT_EQ("Bar", GetEnumValueName("FO_O", "FOO_BAR"));
+  EXPECT_EQ("Bar", GetEnumValueName("FOO", "F_O_O_BAR"));
+  EXPECT_EQ("Bar", GetEnumValueName("Foo", "BAR"));
+  EXPECT_EQ("BarBaz", GetEnumValueName("Foo", "BAR_BAZ"));
+  EXPECT_EQ("Foo", GetEnumValueName("Foo", "FOO"));
+  EXPECT_EQ("Foo", GetEnumValueName("Foo", "FOO___"));
+  // Identifiers can't start with digits
+  EXPECT_EQ("_2Bar", GetEnumValueName("Foo", "FOO_2_BAR"));
+  EXPECT_EQ("_2", GetEnumValueName("Foo", "FOO___2"));
+}
 
 }  // namespace
 }  // namespace csharp

src/google/protobuf/compiler/csharp/csharp_helpers.cc

@@ -178,6 +178,104 @@ std::string UnderscoresToPascalCase(const std::string& input) {
   return UnderscoresToCamelCase(input, true);
 }
 
+// Convert a string which is expected to be SHOUTY_CASE (but may not be *precisely* shouty)
+// into a PascalCase string. Precise rules implemented:
+
+// Previous input character      Current character         Case
+// Any                           Non-alphanumeric          Skipped
+// None - first char of input    Alphanumeric              Upper
+// Non-letter (e.g. _ or 1)      Alphanumeric              Upper
+// Numeric                       Alphanumeric              Upper
+// Lower letter                  Alphanumeric              Same as current
+// Upper letter                  Alphanumeric              Lower
+std::string ShoutyToPascalCase(const std::string& input) {
+  string result;
+  // Simple way of implementing "always start with upper"
+  char previous = '_';
+  for (int i = 0; i < input.size(); i++) {
+    char current = input[i];
+    if (!ascii_isalnum(current)) {
+      previous = current;
+      continue;      
+    }
+    if (!ascii_isalnum(previous)) {
+      result += ascii_toupper(current);
+    } else if (ascii_isdigit(previous)) {
+      result += ascii_toupper(current);
+    } else if (ascii_islower(previous)) {
+      result += current;
+    } else {
+      result += ascii_tolower(current);
+    }
+    previous = current;
+  }
+  return result;
+}
+
+// Attempt to remove a prefix from a value, ignoring casing and skipping underscores.
+// (foo, foo_bar) => bar - underscore after prefix is skipped
+// (FOO, foo_bar) => bar - casing is ignored
+// (foo_bar, foobarbaz) => baz - underscore in prefix is ignored
+// (foobar, foo_barbaz) => baz - underscore in value is ignored
+// (foo, bar) => bar - prefix isn't matched; return original value
+std::string TryRemovePrefix(const std::string& prefix, const std::string& value) {
+  // First normalize to a lower-case no-underscores prefix to match against
+  std::string prefix_to_match = "";
+  for (size_t i = 0; i < prefix.size(); i++) {
+    if (prefix[i] != '_') {
+      prefix_to_match += ascii_tolower(prefix[i]);
+    }
+  }
+  
+  // This keeps track of how much of value we've consumed
+  size_t prefix_index, value_index;
+  for (prefix_index = 0, value_index = 0;
+      prefix_index < prefix_to_match.size() && value_index < value.size();
+      value_index++) {
+    // Skip over underscores in the value
+    if (value[value_index] == '_') {
+      continue;
+    }
+    if (ascii_tolower(value[value_index]) != prefix_to_match[prefix_index++]) {
+      // Failed to match the prefix - bail out early.
+      return value;
+    }
+  }
+
+  // If we didn't finish looking through the prefix, we can't strip it.
+  if (prefix_index < prefix_to_match.size()) {
+    return value;
+  }
+
+  // Step over any underscores after the prefix
+  while (value_index < value.size() && value[value_index] == '_') {
+    value_index++;
+  }
+
+  // If there's nothing left (e.g. it was a prefix with only underscores afterwards), don't strip.
+  if (value_index == value.size()) {
+    return value;
+  }
+
+  return value.substr(value_index);
+}
+
+// Format the enum value name in a pleasant way for C#:
+// - Strip the enum name as a prefix if possible
+// - Convert to PascalCase.
+// For example, an enum called Color with a value of COLOR_BLUE should
+// result in an enum value in C# called just Blue
+std::string GetEnumValueName(const std::string& enum_name, const std::string& enum_value_name) {
+  std::string stripped = TryRemovePrefix(enum_name, enum_value_name);
+  std::string result = ShoutyToPascalCase(stripped);
+  // Just in case we have an enum name of FOO and a value of FOO_2... make sure the returned
+  // string is a valid identifier.
+  if (ascii_isdigit(result[0])) {
+    result = "_" + result;
+  }
+  return result;
+}
+
 std::string ToCSharpName(const std::string& name, const FileDescriptor* file) {
   std::string result = GetFileNamespace(file);
   if (result != "") {

src/google/protobuf/compiler/csharp/csharp_helpers.h

@@ -36,6 +36,7 @@
 #define GOOGLE_PROTOBUF_COMPILER_CSHARP_HELPERS_H__
 
 #include <string>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/compiler/code_generator.h>
@@ -93,6 +94,10 @@ inline std::string UnderscoresToCamelCase(const std::string& input, bool cap_nex
 
 std::string UnderscoresToPascalCase(const std::string& input);
 
+// Note that we wouldn't normally want to export this (we're not expecting
+// it to be used outside libprotoc itself) but this exposes it for testing.
+std::string LIBPROTOBUF_EXPORT GetEnumValueName(const std::string& enum_name, const std::string& enum_value_name);
+
 // TODO(jtattermusch): perhaps we could move this to strutil
 std::string StringToBase64(const std::string& input);
 

src/google/protobuf/compiler/csharp/csharp_options.h

@@ -45,7 +45,8 @@ struct Options {
       file_extension(".cs"),
       base_namespace(""),
       base_namespace_specified(false),
-      internal_access(false) {
+      internal_access(false),
+      legacy_enum_values(false) {
   }
   // Extension of the generated file. Defaults to ".cs"
   string file_extension;
@@ -68,6 +69,12 @@ struct Options {
   // Whether the generated classes should have accessibility level of "internal".
   // Defaults to false that generates "public" classes.
   bool internal_access;
+  // By default, C# codegen now uses PascalCased enum values names, after
+  // removing the enum type name as a prefix (if it *is* a prefix of the value).
+  // Setting this option reverts to the previous behavior of just copying the
+  // value name specified in the .proto file, allowing gradual migration.
+  // This option will be removed before final release.
+  bool legacy_enum_values;
 };
 
 }  // namespace csharp