Merge remote-tracking branch 'refs/remotes/google/master'

18 files changed, 452 insertions, 331 deletions

diff --git a/csharp/src/Google.Protobuf/Google.Protobuf.csproj b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
index ef524baf..5557612a 100644
--- a/csharp/src/Google.Protobuf/Google.Protobuf.csproj
+++ b/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" />

diff --git a/csharp/src/Google.Protobuf/Google.Protobuf.nuspec b/csharp/src/Google.Protobuf/Google.Protobuf.nuspec
index d5302544..2892b8bf 100644
--- a/csharp/src/Google.Protobuf/Google.Protobuf.nuspec
+++ b/csharp/src/Google.Protobuf/Google.Protobuf.nuspec
@@ -23,7 +23,6 @@
       <group targetFramework="xamarin.ios" />
       <group targetFramework="monotouch" />
       <group targetFramework="monoandroid" />
-
       <!-- Dependencies for newer, more granular platforms (.NET Core etc) -->
       <group targetFramework="dotnet">
         <dependency id="System.Collections" version="4.0.0" />
@@ -34,10 +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>
@@ -49,18 +50,5 @@
     <file src="bin/ReleaseSigned/Google.Protobuf.pdb" target="lib/dotnet" />
     <file src="bin/ReleaseSigned/Google.Protobuf.xml" target="lib/dotnet" />
     <file src="**\*.cs" target="src" />
-    <file src="..\..\..\cmake\Release\protoc.exe" target="tools" />
-    <file src="..\..\..\src\google\protobuf\any.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\api.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\descriptor.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\duration.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\empty.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\field_mask.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\source_context.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\struct.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\timestamp.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\any.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\type.proto" target="tools\google\protobuf" />
-    <file src="..\..\..\src\google\protobuf\wrappers.proto" target="tools\google\protobuf" />
   </files>
 </package>
\ No newline at end of file
diff --git a/csharp/src/Google.Protobuf/JsonFormatter.cs b/csharp/src/Google.Protobuf/JsonFormatter.cs
index eb959c9f..83772473 100644
--- a/csharp/src/Google.Protobuf/JsonFormatter.cs
+++ b/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
 {
@@ -237,11 +238,13 @@ namespace Google.Protobuf
                 {
                     writer.Write(PropertySeparator);
                 }
-                WriteString(writer, ToCamelCase(accessor.Descriptor.Name));
+
+                WriteString(writer, accessor.Descriptor.JsonName);
                 writer.Write(NameValueSeparator);
                 WriteValue(writer, value);
+
                 first = false;
-            }            
+            }
             return !first;
         }
 
@@ -418,9 +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
                 {
@@ -563,7 +567,7 @@ namespace Google.Protobuf
 
             string typeUrl = (string) value.Descriptor.Fields[Any.TypeUrlFieldNumber].Accessor.GetValue(value);
             ByteString data = (ByteString) value.Descriptor.Fields[Any.ValueFieldNumber].Accessor.GetValue(value);
-            string typeName = GetTypeName(typeUrl);
+            string typeName = Any.GetTypeName(typeUrl);
             MessageDescriptor descriptor = settings.TypeRegistry.Find(typeName);
             if (descriptor == null)
             {
@@ -604,17 +608,7 @@ namespace Google.Protobuf
             writer.Write(data.ToBase64());
             writer.Write('"');
             writer.Write(" }");
-        }
-
-        internal static string GetTypeName(String typeUrl)
-        {
-            string[] parts = typeUrl.Split('/');
-            if (parts.Length != 2 || parts[0] != TypeUrlPrefix)
-            {
-                throw new InvalidProtocolBufferException($"Invalid type url: {typeUrl}");
-            }
-            return parts[1];
-        }
+        }        
 
         private void WriteStruct(TextWriter writer, IMessage message)
         {
@@ -875,5 +869,44 @@ 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);
+        }
     }
 }
diff --git a/csharp/src/Google.Protobuf/JsonParser.cs b/csharp/src/Google.Protobuf/JsonParser.cs
index 80d3013d..d738ebb0 100644
--- a/csharp/src/Google.Protobuf/JsonParser.cs
+++ b/csharp/src/Google.Protobuf/JsonParser.cs
@@ -513,7 +513,7 @@ namespace Google.Protobuf
                 throw new InvalidProtocolBufferException("Expected string value for Any.@type");
             }
             string typeUrl = token.StringValue;
-            string typeName = JsonFormatter.GetTypeName(typeUrl);
+            string typeName = Any.GetTypeName(typeUrl);
 
             MessageDescriptor descriptor = settings.TypeRegistry.Find(typeName);
             if (descriptor == null)
diff --git a/csharp/src/Google.Protobuf/Reflection/Descriptor.cs b/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
index 7de7b5fc..fa138dfe 100644
--- a/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
@@ -80,7 +80,7 @@ namespace Google.Protobuf.Reflection {
             "EhMKC291dHB1dF90eXBlGAMgASgJEi8KB29wdGlvbnMYBCABKAsyHi5nb29n",
             "bGUucHJvdG9idWYuTWV0aG9kT3B0aW9ucxIfChBjbGllbnRfc3RyZWFtaW5n",
             "GAUgASgIOgVmYWxzZRIfChBzZXJ2ZXJfc3RyZWFtaW5nGAYgASgIOgVmYWxz",
-            "ZSKuBQoLRmlsZU9wdGlvbnMSFAoMamF2YV9wYWNrYWdlGAEgASgJEhwKFGph",
+            "ZSKHBQoLRmlsZU9wdGlvbnMSFAoMamF2YV9wYWNrYWdlGAEgASgJEhwKFGph",
             "dmFfb3V0ZXJfY2xhc3NuYW1lGAggASgJEiIKE2phdmFfbXVsdGlwbGVfZmls",
             "ZXMYCiABKAg6BWZhbHNlEiwKHWphdmFfZ2VuZXJhdGVfZXF1YWxzX2FuZF9o",
             "YXNoGBQgASgIOgVmYWxzZRIlChZqYXZhX3N0cmluZ19jaGVja191dGY4GBsg",
@@ -91,54 +91,53 @@ namespace Google.Protobuf.Reflection {
             "cHlfZ2VuZXJpY19zZXJ2aWNlcxgSIAEoCDoFZmFsc2USGQoKZGVwcmVjYXRl",
             "ZBgXIAEoCDoFZmFsc2USHwoQY2NfZW5hYmxlX2FyZW5hcxgfIAEoCDoFZmFs",
             "c2USGQoRb2JqY19jbGFzc19wcmVmaXgYJCABKAkSGAoQY3NoYXJwX25hbWVz",
-            "cGFjZRglIAEoCRIrCh9qYXZhbmFub191c2VfZGVwcmVjYXRlZF9wYWNrYWdl",
-            "GCYgASgIQgIYARJDChR1bmludGVycHJldGVkX29wdGlvbhjnByADKAsyJC5n",
+            "cGFjZRglIAEoCRJDChR1bmludGVycHJldGVkX29wdGlvbhjnByADKAsyJC5n",
             "b29nbGUucHJvdG9idWYuVW5pbnRlcnByZXRlZE9wdGlvbiI6CgxPcHRpbWl6",
             "ZU1vZGUSCQoFU1BFRUQQARINCglDT0RFX1NJWkUQAhIQCgxMSVRFX1JVTlRJ",
-            "TUUQAyoJCOgHEICAgIACIuYBCg5NZXNzYWdlT3B0aW9ucxImChdtZXNzYWdl",
-            "X3NldF93aXJlX2Zvcm1hdBgBIAEoCDoFZmFsc2USLgofbm9fc3RhbmRhcmRf",
-            "ZGVzY3JpcHRvcl9hY2Nlc3NvchgCIAEoCDoFZmFsc2USGQoKZGVwcmVjYXRl",
-            "ZBgDIAEoCDoFZmFsc2USEQoJbWFwX2VudHJ5GAcgASgIEkMKFHVuaW50ZXJw",
-            "cmV0ZWRfb3B0aW9uGOcHIAMoCzIkLmdvb2dsZS5wcm90b2J1Zi5VbmludGVy",
-            "cHJldGVkT3B0aW9uKgkI6AcQgICAgAIimAMKDEZpZWxkT3B0aW9ucxI6CgVj",
-            "dHlwZRgBIAEoDjIjLmdvb2dsZS5wcm90b2J1Zi5GaWVsZE9wdGlvbnMuQ1R5",
-            "cGU6BlNUUklORxIOCgZwYWNrZWQYAiABKAgSPwoGanN0eXBlGAYgASgOMiQu",
-            "Z29vZ2xlLnByb3RvYnVmLkZpZWxkT3B0aW9ucy5KU1R5cGU6CUpTX05PUk1B",
-            "TBITCgRsYXp5GAUgASgIOgVmYWxzZRIZCgpkZXByZWNhdGVkGAMgASgIOgVm",
-            "YWxzZRITCgR3ZWFrGAogASgIOgVmYWxzZRJDChR1bmludGVycHJldGVkX29w",
+            "TUUQAyoJCOgHEICAgIACSgQIJhAnIuYBCg5NZXNzYWdlT3B0aW9ucxImChdt",
+            "ZXNzYWdlX3NldF93aXJlX2Zvcm1hdBgBIAEoCDoFZmFsc2USLgofbm9fc3Rh",
+            "bmRhcmRfZGVzY3JpcHRvcl9hY2Nlc3NvchgCIAEoCDoFZmFsc2USGQoKZGVw",
+            "cmVjYXRlZBgDIAEoCDoFZmFsc2USEQoJbWFwX2VudHJ5GAcgASgIEkMKFHVu",
+            "aW50ZXJwcmV0ZWRfb3B0aW9uGOcHIAMoCzIkLmdvb2dsZS5wcm90b2J1Zi5V",
+            "bmludGVycHJldGVkT3B0aW9uKgkI6AcQgICAgAIimAMKDEZpZWxkT3B0aW9u",
+            "cxI6CgVjdHlwZRgBIAEoDjIjLmdvb2dsZS5wcm90b2J1Zi5GaWVsZE9wdGlv",
+            "bnMuQ1R5cGU6BlNUUklORxIOCgZwYWNrZWQYAiABKAgSPwoGanN0eXBlGAYg",
+            "ASgOMiQuZ29vZ2xlLnByb3RvYnVmLkZpZWxkT3B0aW9ucy5KU1R5cGU6CUpT",
+            "X05PUk1BTBITCgRsYXp5GAUgASgIOgVmYWxzZRIZCgpkZXByZWNhdGVkGAMg",
+            "ASgIOgVmYWxzZRITCgR3ZWFrGAogASgIOgVmYWxzZRJDChR1bmludGVycHJl",
+            "dGVkX29wdGlvbhjnByADKAsyJC5nb29nbGUucHJvdG9idWYuVW5pbnRlcnBy",
+            "ZXRlZE9wdGlvbiIvCgVDVHlwZRIKCgZTVFJJTkcQABIICgRDT1JEEAESEAoM",
+            "U1RSSU5HX1BJRUNFEAIiNQoGSlNUeXBlEg0KCUpTX05PUk1BTBAAEg0KCUpT",
+            "X1NUUklORxABEg0KCUpTX05VTUJFUhACKgkI6AcQgICAgAIijQEKC0VudW1P",
+            "cHRpb25zEhMKC2FsbG93X2FsaWFzGAIgASgIEhkKCmRlcHJlY2F0ZWQYAyAB",
+            "KAg6BWZhbHNlEkMKFHVuaW50ZXJwcmV0ZWRfb3B0aW9uGOcHIAMoCzIkLmdv",
+            "b2dsZS5wcm90b2J1Zi5VbmludGVycHJldGVkT3B0aW9uKgkI6AcQgICAgAIi",
+            "fQoQRW51bVZhbHVlT3B0aW9ucxIZCgpkZXByZWNhdGVkGAEgASgIOgVmYWxz",
+            "ZRJDChR1bmludGVycHJldGVkX29wdGlvbhjnByADKAsyJC5nb29nbGUucHJv",
+            "dG9idWYuVW5pbnRlcnByZXRlZE9wdGlvbioJCOgHEICAgIACInsKDlNlcnZp",
+            "Y2VPcHRpb25zEhkKCmRlcHJlY2F0ZWQYISABKAg6BWZhbHNlEkMKFHVuaW50",
+            "ZXJwcmV0ZWRfb3B0aW9uGOcHIAMoCzIkLmdvb2dsZS5wcm90b2J1Zi5Vbmlu",
+            "dGVycHJldGVkT3B0aW9uKgkI6AcQgICAgAIiegoNTWV0aG9kT3B0aW9ucxIZ",
+            "CgpkZXByZWNhdGVkGCEgASgIOgVmYWxzZRJDChR1bmludGVycHJldGVkX29w",
             "dGlvbhjnByADKAsyJC5nb29nbGUucHJvdG9idWYuVW5pbnRlcnByZXRlZE9w",
-            "dGlvbiIvCgVDVHlwZRIKCgZTVFJJTkcQABIICgRDT1JEEAESEAoMU1RSSU5H",
-            "X1BJRUNFEAIiNQoGSlNUeXBlEg0KCUpTX05PUk1BTBAAEg0KCUpTX1NUUklO",
-            "RxABEg0KCUpTX05VTUJFUhACKgkI6AcQgICAgAIijQEKC0VudW1PcHRpb25z",
-            "EhMKC2FsbG93X2FsaWFzGAIgASgIEhkKCmRlcHJlY2F0ZWQYAyABKAg6BWZh",
-            "bHNlEkMKFHVuaW50ZXJwcmV0ZWRfb3B0aW9uGOcHIAMoCzIkLmdvb2dsZS5w",
-            "cm90b2J1Zi5VbmludGVycHJldGVkT3B0aW9uKgkI6AcQgICAgAIifQoQRW51",
-            "bVZhbHVlT3B0aW9ucxIZCgpkZXByZWNhdGVkGAEgASgIOgVmYWxzZRJDChR1",
-            "bmludGVycHJldGVkX29wdGlvbhjnByADKAsyJC5nb29nbGUucHJvdG9idWYu",
-            "VW5pbnRlcnByZXRlZE9wdGlvbioJCOgHEICAgIACInsKDlNlcnZpY2VPcHRp",
-            "b25zEhkKCmRlcHJlY2F0ZWQYISABKAg6BWZhbHNlEkMKFHVuaW50ZXJwcmV0",
-            "ZWRfb3B0aW9uGOcHIAMoCzIkLmdvb2dsZS5wcm90b2J1Zi5VbmludGVycHJl",
-            "dGVkT3B0aW9uKgkI6AcQgICAgAIiegoNTWV0aG9kT3B0aW9ucxIZCgpkZXBy",
-            "ZWNhdGVkGCEgASgIOgVmYWxzZRJDChR1bmludGVycHJldGVkX29wdGlvbhjn",
-            "ByADKAsyJC5nb29nbGUucHJvdG9idWYuVW5pbnRlcnByZXRlZE9wdGlvbioJ",
-            "COgHEICAgIACIp4CChNVbmludGVycHJldGVkT3B0aW9uEjsKBG5hbWUYAiAD",
-            "KAsyLS5nb29nbGUucHJvdG9idWYuVW5pbnRlcnByZXRlZE9wdGlvbi5OYW1l",
-            "UGFydBIYChBpZGVudGlmaWVyX3ZhbHVlGAMgASgJEhoKEnBvc2l0aXZlX2lu",
-            "dF92YWx1ZRgEIAEoBBIaChJuZWdhdGl2ZV9pbnRfdmFsdWUYBSABKAMSFAoM",
-            "ZG91YmxlX3ZhbHVlGAYgASgBEhQKDHN0cmluZ192YWx1ZRgHIAEoDBIXCg9h",
-            "Z2dyZWdhdGVfdmFsdWUYCCABKAkaMwoITmFtZVBhcnQSEQoJbmFtZV9wYXJ0",
-            "GAEgAigJEhQKDGlzX2V4dGVuc2lvbhgCIAIoCCLVAQoOU291cmNlQ29kZUlu",
-            "Zm8SOgoIbG9jYXRpb24YASADKAsyKC5nb29nbGUucHJvdG9idWYuU291cmNl",
-            "Q29kZUluZm8uTG9jYXRpb24ahgEKCExvY2F0aW9uEhAKBHBhdGgYASADKAVC",
-            "AhABEhAKBHNwYW4YAiADKAVCAhABEhgKEGxlYWRpbmdfY29tbWVudHMYAyAB",
-            "KAkSGQoRdHJhaWxpbmdfY29tbWVudHMYBCABKAkSIQoZbGVhZGluZ19kZXRh",
-            "Y2hlZF9jb21tZW50cxgGIAMoCSKnAQoRR2VuZXJhdGVkQ29kZUluZm8SQQoK",
-            "YW5ub3RhdGlvbhgBIAMoCzItLmdvb2dsZS5wcm90b2J1Zi5HZW5lcmF0ZWRD",
-            "b2RlSW5mby5Bbm5vdGF0aW9uGk8KCkFubm90YXRpb24SEAoEcGF0aBgBIAMo",
-            "BUICEAESEwoLc291cmNlX2ZpbGUYAiABKAkSDQoFYmVnaW4YAyABKAUSCwoD",
-            "ZW5kGAQgASgFQlgKE2NvbS5nb29nbGUucHJvdG9idWZCEERlc2NyaXB0b3JQ",
-            "cm90b3NIAVoKZGVzY3JpcHRvcqICA0dQQqoCGkdvb2dsZS5Qcm90b2J1Zi5S",
-            "ZWZsZWN0aW9u"));
+            "dGlvbioJCOgHEICAgIACIp4CChNVbmludGVycHJldGVkT3B0aW9uEjsKBG5h",
+            "bWUYAiADKAsyLS5nb29nbGUucHJvdG9idWYuVW5pbnRlcnByZXRlZE9wdGlv",
+            "bi5OYW1lUGFydBIYChBpZGVudGlmaWVyX3ZhbHVlGAMgASgJEhoKEnBvc2l0",
+            "aXZlX2ludF92YWx1ZRgEIAEoBBIaChJuZWdhdGl2ZV9pbnRfdmFsdWUYBSAB",
+            "KAMSFAoMZG91YmxlX3ZhbHVlGAYgASgBEhQKDHN0cmluZ192YWx1ZRgHIAEo",
+            "DBIXCg9hZ2dyZWdhdGVfdmFsdWUYCCABKAkaMwoITmFtZVBhcnQSEQoJbmFt",
+            "ZV9wYXJ0GAEgAigJEhQKDGlzX2V4dGVuc2lvbhgCIAIoCCLVAQoOU291cmNl",
+            "Q29kZUluZm8SOgoIbG9jYXRpb24YASADKAsyKC5nb29nbGUucHJvdG9idWYu",
+            "U291cmNlQ29kZUluZm8uTG9jYXRpb24ahgEKCExvY2F0aW9uEhAKBHBhdGgY",
+            "ASADKAVCAhABEhAKBHNwYW4YAiADKAVCAhABEhgKEGxlYWRpbmdfY29tbWVu",
+            "dHMYAyABKAkSGQoRdHJhaWxpbmdfY29tbWVudHMYBCABKAkSIQoZbGVhZGlu",
+            "Z19kZXRhY2hlZF9jb21tZW50cxgGIAMoCSKnAQoRR2VuZXJhdGVkQ29kZUlu",
+            "Zm8SQQoKYW5ub3RhdGlvbhgBIAMoCzItLmdvb2dsZS5wcm90b2J1Zi5HZW5l",
+            "cmF0ZWRDb2RlSW5mby5Bbm5vdGF0aW9uGk8KCkFubm90YXRpb24SEAoEcGF0",
+            "aBgBIAMoBUICEAESEwoLc291cmNlX2ZpbGUYAiABKAkSDQoFYmVnaW4YAyAB",
+            "KAUSCwoDZW5kGAQgASgFQlgKE2NvbS5nb29nbGUucHJvdG9idWZCEERlc2Ny",
+            "aXB0b3JQcm90b3NIAVoKZGVzY3JpcHRvcqICA0dQQqoCGkdvb2dsZS5Qcm90",
+            "b2J1Zi5SZWZsZWN0aW9u"));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
@@ -152,7 +151,7 @@ namespace Google.Protobuf.Reflection {
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.EnumValueDescriptorProto), global::Google.Protobuf.Reflection.EnumValueDescriptorProto.Parser, new[]{ "Name", "Number", "Options" }, null, null, null),
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.ServiceDescriptorProto), global::Google.Protobuf.Reflection.ServiceDescriptorProto.Parser, new[]{ "Name", "Method", "Options" }, null, null, null),
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.MethodDescriptorProto), global::Google.Protobuf.Reflection.MethodDescriptorProto.Parser, new[]{ "Name", "InputType", "OutputType", "Options", "ClientStreaming", "ServerStreaming" }, null, null, null),
-            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.FileOptions), global::Google.Protobuf.Reflection.FileOptions.Parser, new[]{ "JavaPackage", "JavaOuterClassname", "JavaMultipleFiles", "JavaGenerateEqualsAndHash", "JavaStringCheckUtf8", "OptimizeFor", "GoPackage", "CcGenericServices", "JavaGenericServices", "PyGenericServices", "Deprecated", "CcEnableArenas", "ObjcClassPrefix", "CsharpNamespace", "JavananoUseDeprecatedPackage", "UninterpretedOption" }, null, new[]{ typeof(global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode) }, null),
+            new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.FileOptions), global::Google.Protobuf.Reflection.FileOptions.Parser, new[]{ "JavaPackage", "JavaOuterClassname", "JavaMultipleFiles", "JavaGenerateEqualsAndHash", "JavaStringCheckUtf8", "OptimizeFor", "GoPackage", "CcGenericServices", "JavaGenericServices", "PyGenericServices", "Deprecated", "CcEnableArenas", "ObjcClassPrefix", "CsharpNamespace", "UninterpretedOption" }, null, new[]{ typeof(global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode) }, null),
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.MessageOptions), global::Google.Protobuf.Reflection.MessageOptions.Parser, new[]{ "MessageSetWireFormat", "NoStandardDescriptorAccessor", "Deprecated", "MapEntry", "UninterpretedOption" }, null, null, null),
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.FieldOptions), global::Google.Protobuf.Reflection.FieldOptions.Parser, new[]{ "Ctype", "Packed", "Jstype", "Lazy", "Deprecated", "Weak", "UninterpretedOption" }, null, new[]{ typeof(global::Google.Protobuf.Reflection.FieldOptions.Types.CType), typeof(global::Google.Protobuf.Reflection.FieldOptions.Types.JSType) }, null),
             new pbr::GeneratedClrTypeInfo(typeof(global::Google.Protobuf.Reflection.EnumOptions), global::Google.Protobuf.Reflection.EnumOptions.Parser, new[]{ "AllowAlias", "Deprecated", "UninterpretedOption" }, null, null, null),
@@ -1291,7 +1290,7 @@ namespace Google.Protobuf.Reflection {
 
     /// <summary>Field number for the "label" field.</summary>
     public const int LabelFieldNumber = 4;
-    private global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label label_ = global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL;
+    private global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label label_ = 0;
     public global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label Label {
       get { return label_; }
       set {
@@ -1301,7 +1300,7 @@ namespace Google.Protobuf.Reflection {
 
     /// <summary>Field number for the "type" field.</summary>
     public const int TypeFieldNumber = 5;
-    private global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type type_ = global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type.TYPE_DOUBLE;
+    private global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type type_ = 0;
     /// <summary>
     ///  If type_name is set, this need not be set.  If both this and type_name
     ///  are set, this must be one of TYPE_ENUM, TYPE_MESSAGE or TYPE_GROUP.
@@ -1429,8 +1428,8 @@ namespace Google.Protobuf.Reflection {
       int hash = 1;
       if (Name.Length != 0) hash ^= Name.GetHashCode();
       if (Number != 0) hash ^= Number.GetHashCode();
-      if (Label != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) hash ^= Label.GetHashCode();
-      if (Type != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) hash ^= Type.GetHashCode();
+      if (Label != 0) hash ^= Label.GetHashCode();
+      if (Type != 0) hash ^= Type.GetHashCode();
       if (TypeName.Length != 0) hash ^= TypeName.GetHashCode();
       if (Extendee.Length != 0) hash ^= Extendee.GetHashCode();
       if (DefaultValue.Length != 0) hash ^= DefaultValue.GetHashCode();
@@ -1457,11 +1456,11 @@ namespace Google.Protobuf.Reflection {
         output.WriteRawTag(24);
         output.WriteInt32(Number);
       }
-      if (Label != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) {
+      if (Label != 0) {
         output.WriteRawTag(32);
         output.WriteEnum((int) Label);
       }
-      if (Type != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) {
+      if (Type != 0) {
         output.WriteRawTag(40);
         output.WriteEnum((int) Type);
       }
@@ -1495,10 +1494,10 @@ namespace Google.Protobuf.Reflection {
       if (Number != 0) {
         size += 1 + pb::CodedOutputStream.ComputeInt32Size(Number);
       }
-      if (Label != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) {
+      if (Label != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Label);
       }
-      if (Type != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) {
+      if (Type != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Type);
       }
       if (TypeName.Length != 0) {
@@ -1532,10 +1531,10 @@ namespace Google.Protobuf.Reflection {
       if (other.Number != 0) {
         Number = other.Number;
       }
-      if (other.Label != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Label.LABEL_OPTIONAL) {
+      if (other.Label != 0) {
         Label = other.Label;
       }
-      if (other.Type != global::Google.Protobuf.Reflection.FieldDescriptorProto.Types.Type.TYPE_DOUBLE) {
+      if (other.Type != 0) {
         Type = other.Type;
       }
       if (other.TypeName.Length != 0) {
@@ -1624,59 +1623,59 @@ namespace Google.Protobuf.Reflection {
         ///  0 is reserved for errors.
         ///  Order is weird for historical reasons.
         /// </summary>
-        TYPE_DOUBLE = 1,
-        TYPE_FLOAT = 2,
+        [pbr::OriginalName("TYPE_DOUBLE")] Double = 1,
+        [pbr::OriginalName("TYPE_FLOAT")] Float = 2,
         /// <summary>
         ///  Not ZigZag encoded.  Negative numbers take 10 bytes.  Use TYPE_SINT64 if
         ///  negative values are likely.
         /// </summary>
-        TYPE_INT64 = 3,
-        TYPE_UINT64 = 4,
+        [pbr::OriginalName("TYPE_INT64")] Int64 = 3,
+        [pbr::OriginalName("TYPE_UINT64")] Uint64 = 4,
         /// <summary>
         ///  Not ZigZag encoded.  Negative numbers take 10 bytes.  Use TYPE_SINT32 if
         ///  negative values are likely.
         /// </summary>
-        TYPE_INT32 = 5,
-        TYPE_FIXED64 = 6,
-        TYPE_FIXED32 = 7,
-        TYPE_BOOL = 8,
-        TYPE_STRING = 9,
+        [pbr::OriginalName("TYPE_INT32")] Int32 = 5,
+        [pbr::OriginalName("TYPE_FIXED64")] Fixed64 = 6,
+        [pbr::OriginalName("TYPE_FIXED32")] Fixed32 = 7,
+        [pbr::OriginalName("TYPE_BOOL")] Bool = 8,
+        [pbr::OriginalName("TYPE_STRING")] String = 9,
         /// <summary>
         ///  Tag-delimited aggregate.
         /// </summary>
-        TYPE_GROUP = 10,
+        [pbr::OriginalName("TYPE_GROUP")] Group = 10,
         /// <summary>
         ///  Length-delimited aggregate.
         /// </summary>
-        TYPE_MESSAGE = 11,
+        [pbr::OriginalName("TYPE_MESSAGE")] Message = 11,
         /// <summary>
         ///  New in version 2.
         /// </summary>
-        TYPE_BYTES = 12,
-        TYPE_UINT32 = 13,
-        TYPE_ENUM = 14,
-        TYPE_SFIXED32 = 15,
-        TYPE_SFIXED64 = 16,
+        [pbr::OriginalName("TYPE_BYTES")] Bytes = 12,
+        [pbr::OriginalName("TYPE_UINT32")] Uint32 = 13,
+        [pbr::OriginalName("TYPE_ENUM")] Enum = 14,
+        [pbr::OriginalName("TYPE_SFIXED32")] Sfixed32 = 15,
+        [pbr::OriginalName("TYPE_SFIXED64")] Sfixed64 = 16,
         /// <summary>
         ///  Uses ZigZag encoding.
         /// </summary>
-        TYPE_SINT32 = 17,
+        [pbr::OriginalName("TYPE_SINT32")] Sint32 = 17,
         /// <summary>
         ///  Uses ZigZag encoding.
         /// </summary>
-        TYPE_SINT64 = 18,
+        [pbr::OriginalName("TYPE_SINT64")] Sint64 = 18,
       }
 
       internal enum Label {
         /// <summary>
         ///  0 is reserved for errors
         /// </summary>
-        LABEL_OPTIONAL = 1,
-        LABEL_REQUIRED = 2,
+        [pbr::OriginalName("LABEL_OPTIONAL")] Optional = 1,
+        [pbr::OriginalName("LABEL_REQUIRED")] Required = 2,
         /// <summary>
         ///  TODO(sanjay): Should we add LABEL_MAP?
         /// </summary>
-        LABEL_REPEATED = 3,
+        [pbr::OriginalName("LABEL_REPEATED")] Repeated = 3,
       }
 
     }
@@ -2563,7 +2562,6 @@ namespace Google.Protobuf.Reflection {
       ccEnableArenas_ = other.ccEnableArenas_;
       objcClassPrefix_ = other.objcClassPrefix_;
       csharpNamespace_ = other.csharpNamespace_;
-      javananoUseDeprecatedPackage_ = other.javananoUseDeprecatedPackage_;
       uninterpretedOption_ = other.uninterpretedOption_.Clone();
     }
 
@@ -2666,7 +2664,7 @@ namespace Google.Protobuf.Reflection {
 
     /// <summary>Field number for the "optimize_for" field.</summary>
     public const int OptimizeForFieldNumber = 9;
-    private global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode optimizeFor_ = global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode.SPEED;
+    private global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode optimizeFor_ = 0;
     public global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode OptimizeFor {
       get { return optimizeFor_; }
       set {
@@ -2790,21 +2788,6 @@ namespace Google.Protobuf.Reflection {
       }
     }
 
-    /// <summary>Field number for the "javanano_use_deprecated_package" field.</summary>
-    public const int JavananoUseDeprecatedPackageFieldNumber = 38;
-    private bool javananoUseDeprecatedPackage_;
-    /// <summary>
-    ///  Whether the nano proto compiler should generate in the deprecated non-nano
-    ///  suffixed package.
-    /// </summary>
-    [global::System.ObsoleteAttribute()]
-    public bool JavananoUseDeprecatedPackage {
-      get { return javananoUseDeprecatedPackage_; }
-      set {
-        javananoUseDeprecatedPackage_ = value;
-      }
-    }
-
     /// <summary>Field number for the "uninterpreted_option" field.</summary>
     public const int UninterpretedOptionFieldNumber = 999;
     private static readonly pb::FieldCodec<global::Google.Protobuf.Reflection.UninterpretedOption> _repeated_uninterpretedOption_codec
@@ -2842,7 +2825,6 @@ namespace Google.Protobuf.Reflection {
       if (CcEnableArenas != other.CcEnableArenas) return false;
       if (ObjcClassPrefix != other.ObjcClassPrefix) return false;
       if (CsharpNamespace != other.CsharpNamespace) return false;
-      if (JavananoUseDeprecatedPackage != other.JavananoUseDeprecatedPackage) return false;
       if(!uninterpretedOption_.Equals(other.uninterpretedOption_)) return false;
       return true;
     }
@@ -2854,7 +2836,7 @@ namespace Google.Protobuf.Reflection {
       if (JavaMultipleFiles != false) hash ^= JavaMultipleFiles.GetHashCode();
       if (JavaGenerateEqualsAndHash != false) hash ^= JavaGenerateEqualsAndHash.GetHashCode();
       if (JavaStringCheckUtf8 != false) hash ^= JavaStringCheckUtf8.GetHashCode();
-      if (OptimizeFor != global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode.SPEED) hash ^= OptimizeFor.GetHashCode();
+      if (OptimizeFor != 0) hash ^= OptimizeFor.GetHashCode();
       if (GoPackage.Length != 0) hash ^= GoPackage.GetHashCode();
       if (CcGenericServices != false) hash ^= CcGenericServices.GetHashCode();
       if (JavaGenericServices != false) hash ^= JavaGenericServices.GetHashCode();
@@ -2863,7 +2845,6 @@ namespace Google.Protobuf.Reflection {
       if (CcEnableArenas != false) hash ^= CcEnableArenas.GetHashCode();
       if (ObjcClassPrefix.Length != 0) hash ^= ObjcClassPrefix.GetHashCode();
       if (CsharpNamespace.Length != 0) hash ^= CsharpNamespace.GetHashCode();
-      if (JavananoUseDeprecatedPackage != false) hash ^= JavananoUseDeprecatedPackage.GetHashCode();
       hash ^= uninterpretedOption_.GetHashCode();
       return hash;
     }
@@ -2881,7 +2862,7 @@ namespace Google.Protobuf.Reflection {
         output.WriteRawTag(66);
         output.WriteString(JavaOuterClassname);
       }
-      if (OptimizeFor != global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode.SPEED) {
+      if (OptimizeFor != 0) {
         output.WriteRawTag(72);
         output.WriteEnum((int) OptimizeFor);
       }
@@ -2929,10 +2910,6 @@ namespace Google.Protobuf.Reflection {
         output.WriteRawTag(170, 2);
         output.WriteString(CsharpNamespace);
       }
-      if (JavananoUseDeprecatedPackage != false) {
-        output.WriteRawTag(176, 2);
-        output.WriteBool(JavananoUseDeprecatedPackage);
-      }
       uninterpretedOption_.WriteTo(output, _repeated_uninterpretedOption_codec);
     }
 
@@ -2953,7 +2930,7 @@ namespace Google.Protobuf.Reflection {
       if (JavaStringCheckUtf8 != false) {
         size += 2 + 1;
       }
-      if (OptimizeFor != global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode.SPEED) {
+      if (OptimizeFor != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) OptimizeFor);
       }
       if (GoPackage.Length != 0) {
@@ -2980,9 +2957,6 @@ namespace Google.Protobuf.Reflection {
       if (CsharpNamespace.Length != 0) {
         size += 2 + pb::CodedOutputStream.ComputeStringSize(CsharpNamespace);
       }
-      if (JavananoUseDeprecatedPackage != false) {
-        size += 2 + 1;
-      }
       size += uninterpretedOption_.CalculateSize(_repeated_uninterpretedOption_codec);
       return size;
     }
@@ -3006,7 +2980,7 @@ namespace Google.Protobuf.Reflection {
       if (other.JavaStringCheckUtf8 != false) {
         JavaStringCheckUtf8 = other.JavaStringCheckUtf8;
       }
-      if (other.OptimizeFor != global::Google.Protobuf.Reflection.FileOptions.Types.OptimizeMode.SPEED) {
+      if (other.OptimizeFor != 0) {
         OptimizeFor = other.OptimizeFor;
       }
       if (other.GoPackage.Length != 0) {
@@ -3033,9 +3007,6 @@ namespace Google.Protobuf.Reflection {
       if (other.CsharpNamespace.Length != 0) {
         CsharpNamespace = other.CsharpNamespace;
       }
-      if (other.JavananoUseDeprecatedPackage != false) {
-        JavananoUseDeprecatedPackage = other.JavananoUseDeprecatedPackage;
-      }
       uninterpretedOption_.Add(other.uninterpretedOption_);
     }
 
@@ -3102,10 +3073,6 @@ namespace Google.Protobuf.Reflection {
             CsharpNamespace = input.ReadString();
             break;
           }
-          case 304: {
-            JavananoUseDeprecatedPackage = input.ReadBool();
-            break;
-          }
           case 7994: {
             uninterpretedOption_.AddEntriesFrom(input, _repeated_uninterpretedOption_codec);
             break;
@@ -3125,15 +3092,15 @@ namespace Google.Protobuf.Reflection {
         /// <summary>
         ///  Generate complete code for parsing, serialization,
         /// </summary>
-        SPEED = 1,
+        [pbr::OriginalName("SPEED")] Speed = 1,
         /// <summary>
         ///  etc.
         /// </summary>
-        CODE_SIZE = 2,
+        [pbr::OriginalName("CODE_SIZE")] CodeSize = 2,
         /// <summary>
         ///  Generate code using MessageLite and the lite runtime.
         /// </summary>
-        LITE_RUNTIME = 3,
+        [pbr::OriginalName("LITE_RUNTIME")] LiteRuntime = 3,
       }
 
     }
@@ -3436,7 +3403,7 @@ namespace Google.Protobuf.Reflection {
 
     /// <summary>Field number for the "ctype" field.</summary>
     public const int CtypeFieldNumber = 1;
-    private global::Google.Protobuf.Reflection.FieldOptions.Types.CType ctype_ = global::Google.Protobuf.Reflection.FieldOptions.Types.CType.STRING;
+    private global::Google.Protobuf.Reflection.FieldOptions.Types.CType ctype_ = 0;
     /// <summary>
     ///  The ctype option instructs the C++ code generator to use a different
     ///  representation of the field than it normally would.  See the specific
@@ -3469,7 +3436,7 @@ namespace Google.Protobuf.Reflection {
 
     /// <summary>Field number for the "jstype" field.</summary>
     public const int JstypeFieldNumber = 6;
-    private global::Google.Protobuf.Reflection.FieldOptions.Types.JSType jstype_ = global::Google.Protobuf.Reflection.FieldOptions.Types.JSType.JS_NORMAL;
+    private global::Google.Protobuf.Reflection.FieldOptions.Types.JSType jstype_ = 0;
     /// <summary>
     ///  The jstype option determines the JavaScript type used for values of the
     ///  field.  The option is permitted only for 64 bit integral and fixed types
@@ -3591,9 +3558,9 @@ namespace Google.Protobuf.Reflection {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (Ctype != global::Google.Protobuf.Reflection.FieldOptions.Types.CType.STRING) hash ^= Ctype.GetHashCode();
+      if (Ctype != 0) hash ^= Ctype.GetHashCode();
       if (Packed != false) hash ^= Packed.GetHashCode();
-      if (Jstype != global::Google.Protobuf.Reflection.FieldOptions.Types.JSType.JS_NORMAL) hash ^= Jstype.GetHashCode();
+      if (Jstype != 0) hash ^= Jstype.GetHashCode();
       if (Lazy != false) hash ^= Lazy.GetHashCode();
       if (Deprecated != false) hash ^= Deprecated.GetHashCode();
       if (Weak != false) hash ^= Weak.GetHashCode();
@@ -3606,7 +3573,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (Ctype != global::Google.Protobuf.Reflection.FieldOptions.Types.CType.STRING) {
+      if (Ctype != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) Ctype);
       }
@@ -3622,7 +3589,7 @@ namespace Google.Protobuf.Reflection {
         output.WriteRawTag(40);
         output.WriteBool(Lazy);
       }
-      if (Jstype != global::Google.Protobuf.Reflection.FieldOptions.Types.JSType.JS_NORMAL) {
+      if (Jstype != 0) {
         output.WriteRawTag(48);
         output.WriteEnum((int) Jstype);
       }
@@ -3635,13 +3602,13 @@ namespace Google.Protobuf.Reflection {
 
     public int CalculateSize() {
       int size = 0;
-      if (Ctype != global::Google.Protobuf.Reflection.FieldOptions.Types.CType.STRING) {
+      if (Ctype != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Ctype);
       }
       if (Packed != false) {
         size += 1 + 1;
       }
-      if (Jstype != global::Google.Protobuf.Reflection.FieldOptions.Types.JSType.JS_NORMAL) {
+      if (Jstype != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Jstype);
       }
       if (Lazy != false) {
@@ -3661,13 +3628,13 @@ namespace Google.Protobuf.Reflection {
       if (other == null) {
         return;
       }
-      if (other.Ctype != global::Google.Protobuf.Reflection.FieldOptions.Types.CType.STRING) {
+      if (other.Ctype != 0) {
         Ctype = other.Ctype;
       }
       if (other.Packed != false) {
         Packed = other.Packed;
       }
-      if (other.Jstype != global::Google.Protobuf.Reflection.FieldOptions.Types.JSType.JS_NORMAL) {
+      if (other.Jstype != 0) {
         Jstype = other.Jstype;
       }
       if (other.Lazy != false) {
@@ -3729,24 +3696,24 @@ namespace Google.Protobuf.Reflection {
         /// <summary>
         ///  Default mode.
         /// </summary>
-        STRING = 0,
-        CORD = 1,
-        STRING_PIECE = 2,
+        [pbr::OriginalName("STRING")] String = 0,
+        [pbr::OriginalName("CORD")] Cord = 1,
+        [pbr::OriginalName("STRING_PIECE")] StringPiece = 2,
       }
 
       internal enum JSType {
         /// <summary>
         ///  Use the default type.
         /// </summary>
-        JS_NORMAL = 0,
+        [pbr::OriginalName("JS_NORMAL")] JsNormal = 0,
         /// <summary>
         ///  Use JavaScript strings.
         /// </summary>
-        JS_STRING = 1,
+        [pbr::OriginalName("JS_STRING")] JsString = 1,
         /// <summary>
         ///  Use JavaScript numbers.
         /// </summary>
-        JS_NUMBER = 2,
+        [pbr::OriginalName("JS_NUMBER")] JsNumber = 2,
       }
 
     }
diff --git a/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs b/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
index c6caaec6..6c6f6ee0 100644
--- a/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
@@ -30,9 +30,8 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endregion
 
-using System;
-using System.Linq;
 using Google.Protobuf.Compatibility;
+using System;
 
 namespace Google.Protobuf.Reflection
 {
@@ -41,20 +40,35 @@ namespace Google.Protobuf.Reflection
     /// </summary>
     public sealed class FieldDescriptor : DescriptorBase, IComparable<FieldDescriptor>
     {
-        private readonly FieldDescriptorProto proto;
         private EnumDescriptor enumType;
         private MessageDescriptor messageType;
-        private readonly MessageDescriptor containingType;
-        private readonly OneofDescriptor containingOneof;
         private FieldType fieldType;
         private readonly string propertyName; // Annoyingly, needed in Crosslink.
         private IFieldAccessor accessor;
 
+        /// <summary>
+        /// Get the field's containing message type.
+        /// </summary>
+        public MessageDescriptor ContainingType { get; }
+
+        /// <summary>
+        /// Returns the oneof containing this field, or <c>null</c> if it is not part of a oneof.
+        /// </summary>
+        public OneofDescriptor ContainingOneof { get; }
+
+        /// <summary>
+        /// The effective JSON name for this field. This is usually the lower-camel-cased form of the field name,
+        /// but can be overridden using the <c>json_name</c> option in the .proto file.
+        /// </summary>
+        public string JsonName { get; }
+
+        internal FieldDescriptorProto Proto { get; }
+
         internal FieldDescriptor(FieldDescriptorProto proto, FileDescriptor file,
                                  MessageDescriptor parent, int index, string propertyName)
             : base(file, file.ComputeFullName(parent, proto.Name), index)
         {
-            this.proto = proto;
+            Proto = proto;
             if (proto.Type != 0)
             {
                 fieldType = GetFieldTypeFromProtoType(proto.Type);
@@ -64,7 +78,7 @@ namespace Google.Protobuf.Reflection
             {
                 throw new DescriptorValidationException(this, "Field numbers must be positive integers.");
             }
-            containingType = parent;
+            ContainingType = parent;
             // OneofIndex "defaults" to -1 due to a hack in FieldDescriptor.OnConstruction.
             if (proto.OneofIndex != -1)
             {
@@ -73,7 +87,7 @@ namespace Google.Protobuf.Reflection
                     throw new DescriptorValidationException(this,
                         $"FieldDescriptorProto.oneof_index is out of range for type {parent.Name}");
                 }
-                containingOneof = parent.Oneofs[proto.OneofIndex];
+                ContainingOneof = parent.Oneofs[proto.OneofIndex];
             }
 
             file.DescriptorPool.AddSymbol(this);
@@ -83,14 +97,14 @@ namespace Google.Protobuf.Reflection
             // We could trust the generated code and check whether the type of the property is
             // a MapField, but that feels a tad nasty.
             this.propertyName = propertyName;
+            JsonName =  Proto.JsonName == "" ? JsonFormatter.ToCamelCase(Proto.Name) : Proto.JsonName;
         }
+    
 
         /// <summary>
         /// The brief name of the descriptor's target.
         /// </summary>
-        public override string Name { get { return proto.Name; } }
-
-        internal FieldDescriptorProto Proto { get { return proto; } }
+        public override string Name => Proto.Name;
 
         /// <summary>
         /// Returns the accessor for this field.
@@ -110,7 +124,7 @@ namespace Google.Protobuf.Reflection
         /// and this property will return null.
         /// </para>
         /// </remarks>
-        public IFieldAccessor Accessor { get { return accessor; } }
+        public IFieldAccessor Accessor => accessor;
         
         /// <summary>
         /// Maps a field type as included in the .proto file to a FieldType.
@@ -119,41 +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");
@@ -163,62 +177,32 @@ namespace Google.Protobuf.Reflection
         /// <summary>
         /// Returns <c>true</c> if this field is a repeated field; <c>false</c> otherwise.
         /// </summary>
-        public bool IsRepeated
-        {
-            get { return 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.
         /// </summary>
-        public bool IsMap
-        {
-            get { return fieldType == FieldType.Message && messageType.Proto.Options != null && messageType.Proto.Options.MapEntry; }
-        }
+        public bool IsMap => fieldType == FieldType.Message && messageType.Proto.Options != null && messageType.Proto.Options.MapEntry;
 
         /// <summary>
         /// Returns <c>true</c> if this field is a packed, repeated field; <c>false</c> otherwise.
         /// </summary>
-        public bool IsPacked
-        {
+        public bool IsPacked => 
             // Note the || rather than && here - we're effectively defaulting to packed, because that *is*
             // the default in proto3, which is all we support. We may give the wrong result for the protos
             // within descriptor.proto, but that's okay, as they're never exposed and we don't use IsPacked
             // within the runtime.
-            get { return Proto.Options == null || Proto.Options.Packed; }
-        }        
-
-        /// <summary>
-        /// Get the field's containing message type.
-        /// </summary>
-        public MessageDescriptor ContainingType
-        {
-            get { return containingType; }
-        }
-
-        /// <summary>
-        /// Returns the oneof containing this field, or <c>null</c> if it is not part of a oneof.
-        /// </summary>
-        public OneofDescriptor ContainingOneof
-        {
-            get { return containingOneof; }
-        }
-
+            Proto.Options == null || Proto.Options.Packed;
+        
         /// <summary>
         /// Returns the type of the field.
         /// </summary>
-        public FieldType FieldType
-        {
-            get { return fieldType; }
-        }
+        public FieldType FieldType => fieldType;
 
         /// <summary>
         /// Returns the field number declared in the proto file.
         /// </summary>
-        public int FieldNumber
-        {
-            get { return Proto.Number; }
-        }
+        public int FieldNumber => Proto.Number;
 
         /// <summary>
         /// Compares this descriptor with another one, ordering in "canonical" order
@@ -228,7 +212,7 @@ namespace Google.Protobuf.Reflection
         /// </summary>
         public int CompareTo(FieldDescriptor other)
         {
-            if (other.containingType != containingType)
+            if (other.ContainingType != ContainingType)
             {
                 throw new ArgumentException("FieldDescriptors can only be compared to other FieldDescriptors " +
                                             "for fields of the same message type.");
@@ -331,14 +315,14 @@ namespace Google.Protobuf.Reflection
 
             File.DescriptorPool.AddFieldByNumber(this);
 
-            if (containingType != null && containingType.Proto.Options != null && containingType.Proto.Options.MessageSetWireFormat)
+            if (ContainingType != null && ContainingType.Proto.Options != null && ContainingType.Proto.Options.MessageSetWireFormat)
             {
                 throw new DescriptorValidationException(this, "MessageSet format is not supported.");
             }
-            accessor = CreateAccessor(propertyName);
+            accessor = CreateAccessor();
         }
 
-        private IFieldAccessor CreateAccessor(string propertyName)
+        private IFieldAccessor CreateAccessor()
         {
             // If we're given no property name, that's because we really don't want an accessor.
             // (At the moment, that means it's a map entry message...)
@@ -346,10 +330,10 @@ namespace Google.Protobuf.Reflection
             {
                 return null;
             }
-            var property = containingType.ClrType.GetProperty(propertyName);
+            var property = ContainingType.ClrType.GetProperty(propertyName);
             if (property == null)
             {
-                throw new DescriptorValidationException(this, $"Property {propertyName} not found in {containingType.ClrType}");
+                throw new DescriptorValidationException(this, $"Property {propertyName} not found in {ContainingType.ClrType}");
             }
             return IsMap ? new MapFieldAccessor(property, this)
                 : IsRepeated ? new RepeatedFieldAccessor(property, this)
diff --git a/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs b/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
index f5798d1e..f5a835e5 100644
--- a/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
@@ -102,8 +102,8 @@ namespace Google.Protobuf.Reflection
             var map = new Dictionary<string, FieldDescriptor>();
             foreach (var field in fields)
             {
-                map[JsonFormatter.ToCamelCase(field.Name)] = field;
                 map[field.Name] = field;
+                map[field.JsonName] = field;
             }
             return new ReadOnlyDictionary<string, FieldDescriptor>(map);
         }
diff --git a/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs b/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs
new file mode 100644
index 00000000..27f9ab98
--- /dev/null
+++ b/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs
@@ -0,0 +1,58 @@
+#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
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
index 48cd99a1..871a383f 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
@@ -24,9 +24,10 @@ namespace Google.Protobuf.WellKnownTypes {
       byte[] descriptorData = global::System.Convert.FromBase64String(
           string.Concat(
             "Chlnb29nbGUvcHJvdG9idWYvYW55LnByb3RvEg9nb29nbGUucHJvdG9idWYi",
-            "JgoDQW55EhAKCHR5cGVfdXJsGAEgASgJEg0KBXZhbHVlGAIgASgMQksKE2Nv",
-            "bS5nb29nbGUucHJvdG9idWZCCEFueVByb3RvUAGgAQGiAgNHUEKqAh5Hb29n",
-            "bGUuUHJvdG9idWYuV2VsbEtub3duVHlwZXNiBnByb3RvMw=="));
+            "JgoDQW55EhAKCHR5cGVfdXJsGAEgASgJEg0KBXZhbHVlGAIgASgMQnIKE2Nv",
+            "bS5nb29nbGUucHJvdG9idWZCCEFueVByb3RvUAFaJWdpdGh1Yi5jb20vZ29s",
+            "YW5nL3Byb3RvYnVmL3B0eXBlcy9hbnmgAQGiAgNHUEKqAh5Hb29nbGUuUHJv",
+            "dG9idWYuV2VsbEtub3duVHlwZXNiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
@@ -38,8 +39,36 @@ namespace Google.Protobuf.WellKnownTypes {
   }
   #region Messages
   /// <summary>
-  ///  `Any` contains an arbitrary serialized message along with a URL
-  ///  that describes the type of the serialized message.
+  ///  `Any` contains an arbitrary serialized protocol buffer message along with a
+  ///  URL that describes the type of the serialized message.
+  ///
+  ///  Protobuf library provides support to pack/unpack Any values in the form
+  ///  of utility functions or additional generated methods of the Any type.
+  ///
+  ///  Example 1: Pack and unpack a message in C++.
+  ///
+  ///      Foo foo = ...;
+  ///      Any any;
+  ///      any.PackFrom(foo);
+  ///      ...
+  ///      if (any.UnpackTo(&amp;foo)) {
+  ///        ...
+  ///      }
+  ///
+  ///  Example 2: Pack and unpack a message in Java.
+  ///
+  ///      Foo foo = ...;
+  ///      Any any = Any.pack(foo);
+  ///      ...
+  ///      if (any.is(Foo.class)) {
+  ///        foo = any.unpack(Foo.class);
+  ///      }
+  ///
+  ///  The pack methods provided by protobuf library will by default use
+  ///  'type.googleapis.com/full.type.name' as the type URL and the unpack
+  ///  methods only use the fully qualified type name after the last '/'
+  ///  in the type URL, for example "foo.bar.com/x/y.z" will yield type
+  ///  name "y.z".
   ///
   ///  JSON
   ///  ====
@@ -102,7 +131,7 @@ namespace Google.Protobuf.WellKnownTypes {
     private string typeUrl_ = "";
     /// <summary>
     ///  A URL/resource name whose content describes the type of the
-    ///  serialized message.
+    ///  serialized protocol buffer message.
     ///
     ///  For URLs which use the schema `http`, `https`, or no schema, the
     ///  following restrictions and interpretations apply:
@@ -110,6 +139,8 @@ namespace Google.Protobuf.WellKnownTypes {
     ///  * If no schema is provided, `https` is assumed.
     ///  * The last segment of the URL's path must represent the fully
     ///    qualified name of the type (as in `path/google.protobuf.Duration`).
+    ///    The name should be in a canonical form (e.g., leading "." is
+    ///    not accepted).
     ///  * An HTTP GET on the URL must yield a [google.protobuf.Type][]
     ///    value in binary format, or produce an error.
     ///  * Applications are allowed to cache lookup results based on the
@@ -132,7 +163,7 @@ namespace Google.Protobuf.WellKnownTypes {
     public const int ValueFieldNumber = 2;
     private pb::ByteString value_ = pb::ByteString.Empty;
     /// <summary>
-    ///  Must be valid serialized data of the above specified type.
+    ///  Must be a valid serialized protocol buffer of the above specified type.
     /// </summary>
     public pb::ByteString Value {
       get { return value_; }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/AnyPartial.cs b/csharp/src/Google.Protobuf/WellKnownTypes/AnyPartial.cs
index 9d43856e..f4fac738 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/AnyPartial.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/AnyPartial.cs
@@ -36,11 +36,27 @@ namespace Google.Protobuf.WellKnownTypes
 {
     public partial class Any
     {
+        private const string DefaultPrefix = "type.googleapis.com";
+
         // This could be moved to MessageDescriptor if we wanted to, but keeping it here means
         // all the Any-specific code is in the same place.
-        private static string GetTypeUrl(MessageDescriptor descriptor)
+        private static string GetTypeUrl(MessageDescriptor descriptor, string prefix) =>
+            prefix.EndsWith("/") ? prefix + descriptor.FullName : prefix + "/" + descriptor.FullName;
+
+        /// <summary>
+        /// Retrieves the type name for a type URL. This is always just the last part of the URL,
+        /// after the trailing slash. No validation of anything before the trailing slash is performed.
+        /// If the type URL does not include a slash, an empty string is returned rather than an exception
+        /// being thrown; this won't match any types, and the calling code is probably in a better position
+        /// to give a meaningful error.
+        /// There is no handling of fragments or queries  at the moment.
+        /// </summary>
+        /// <param name="typeUrl">The URL to extract the type name from</param>
+        /// <returns>The type name</returns>
+        internal static string GetTypeName(string typeUrl)
         {
-            return "type.googleapis.com/" + descriptor.FullName;
+            int lastSlash = typeUrl.LastIndexOf('/');
+            return lastSlash == -1 ? "" : typeUrl.Substring(lastSlash + 1);
         }
 
         /// <summary>
@@ -55,25 +71,37 @@ namespace Google.Protobuf.WellKnownTypes
             // Note: this doesn't perform as well is it might. We could take a MessageParser<T> in an alternative overload,
             // which would be expected to perform slightly better... although the difference is likely to be negligible.
             T target = new T();
-            string targetTypeUrl = GetTypeUrl(target.Descriptor);
-            if (TypeUrl != targetTypeUrl)
+            if (GetTypeName(TypeUrl) != target.Descriptor.FullName)
             {
-                throw new InvalidProtocolBufferException(string.Format("Type url for {0} is {1}; Any message's type url is {2}",
-                    target.Descriptor.Name, targetTypeUrl, TypeUrl));
+                throw new InvalidProtocolBufferException(
+                    $"Full type name for {target.Descriptor.Name} is {target.Descriptor.FullName}; Any message's type url is {TypeUrl}");
             }
             target.MergeFrom(Value);
             return target;
         }
 
         /// <summary>
-        /// Packs the specified message into an Any message.
+        /// Packs the specified message into an Any message using a type URL prefix of "type.googleapis.com".
+        /// </summary>
+        /// <param name="message">The message to pack.</param>
+        /// <returns>An Any message with the content and type URL of <paramref name="message"/>.</returns>
+        public static Any Pack(IMessage message) => Pack(message, DefaultPrefix);
+
+        /// <summary>
+        /// Packs the specified message into an Any message using the specified type URL prefix.
         /// </summary>
         /// <param name="message">The message to pack.</param>
+        /// <param name="typeUrlPrefix">The prefix for the type URL.</param>
         /// <returns>An Any message with the content and type URL of <paramref name="message"/>.</returns>
-        public static Any Pack(IMessage message)
+        public static Any Pack(IMessage message, string typeUrlPrefix)
         {
-            ProtoPreconditions.CheckNotNull(message, "message");
-            return new Any { TypeUrl = GetTypeUrl(message.Descriptor), Value = message.ToByteString() };
+            ProtoPreconditions.CheckNotNull(message, nameof(message));
+            ProtoPreconditions.CheckNotNull(typeUrlPrefix, nameof(typeUrlPrefix));
+            return new Any
+            {
+                TypeUrl = GetTypeUrl(message.Descriptor, typeUrlPrefix),
+                Value = message.ToByteString()
+            };
         }
     }
 }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
index de7aea3a..e568a2c9 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
+++ b/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;
       }
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
index 73e221d4..f17358f4 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
@@ -25,9 +25,10 @@ namespace Google.Protobuf.WellKnownTypes {
           string.Concat(
             "Ch5nb29nbGUvcHJvdG9idWYvZHVyYXRpb24ucHJvdG8SD2dvb2dsZS5wcm90",
             "b2J1ZiIqCghEdXJhdGlvbhIPCgdzZWNvbmRzGAEgASgDEg0KBW5hbm9zGAIg",
-            "ASgFQlAKE2NvbS5nb29nbGUucHJvdG9idWZCDUR1cmF0aW9uUHJvdG9QAaAB",
-            "AaICA0dQQqoCHkdvb2dsZS5Qcm90b2J1Zi5XZWxsS25vd25UeXBlc2IGcHJv",
-            "dG8z"));
+            "ASgFQnwKE2NvbS5nb29nbGUucHJvdG9idWZCDUR1cmF0aW9uUHJvdG9QAVoq",
+            "Z2l0aHViLmNvbS9nb2xhbmcvcHJvdG9idWYvcHR5cGVzL2R1cmF0aW9uoAEB",
+            "ogIDR1BCqgIeR29vZ2xlLlByb3RvYnVmLldlbGxLbm93blR5cGVzYgZwcm90",
+            "bzM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
index 6cad4124..e08ea240 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
@@ -24,9 +24,10 @@ namespace Google.Protobuf.WellKnownTypes {
       byte[] descriptorData = global::System.Convert.FromBase64String(
           string.Concat(
             "Chtnb29nbGUvcHJvdG9idWYvZW1wdHkucHJvdG8SD2dvb2dsZS5wcm90b2J1",
-            "ZiIHCgVFbXB0eUJQChNjb20uZ29vZ2xlLnByb3RvYnVmQgpFbXB0eVByb3Rv",
-            "UAGgAQH4AQGiAgNHUEKqAh5Hb29nbGUuUHJvdG9idWYuV2VsbEtub3duVHlw",
-            "ZXNiBnByb3RvMw=="));
+            "ZiIHCgVFbXB0eUJ5ChNjb20uZ29vZ2xlLnByb3RvYnVmQgpFbXB0eVByb3Rv",
+            "UAFaJ2dpdGh1Yi5jb20vZ29sYW5nL3Byb3RvYnVmL3B0eXBlcy9lbXB0eaAB",
+            "AfgBAaICA0dQQqoCHkdvb2dsZS5Qcm90b2J1Zi5XZWxsS25vd25UeXBlc2IG",
+            "cHJvdG8z"));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
index 2ba2b96f..6f0a64d6 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
@@ -86,7 +86,7 @@ namespace Google.Protobuf.WellKnownTypes {
   ///  operation applies to all fields (as if a FieldMask of all fields
   ///  had been specified).
   ///
-  ///  Note that a field mask does not necessarily applies to the
+  ///  Note that a field mask does not necessarily apply to the
   ///  top-level response message. In case of a REST get operation, the
   ///  field mask applies directly to the response, but in case of a REST
   ///  list operation, the mask instead applies to each individual message
@@ -159,6 +159,33 @@ namespace Google.Protobuf.WellKnownTypes {
   ///      {
   ///        mask: "user.displayName,photo"
   ///      }
+  ///
+  ///  # Field Masks and Oneof Fields
+  ///
+  ///  Field masks treat fields in oneofs just as regular fields. Consider the
+  ///  following message:
+  ///
+  ///      message SampleMessage {
+  ///        oneof test_oneof {
+  ///          string name = 4;
+  ///          SubMessage sub_message = 9;
+  ///        }
+  ///      }
+  ///
+  ///  The field mask can be:
+  ///
+  ///      mask {
+  ///        paths: "name"
+  ///      }
+  ///
+  ///  Or:
+  ///
+  ///      mask {
+  ///        paths: "sub_message"
+  ///      }
+  ///
+  ///  Note that oneof type names ("test_oneof" in this case) cannot be used in
+  ///  paths.
   /// </summary>
   [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
   public sealed partial class FieldMask : pb::IMessage<FieldMask> {
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
index 8e2ce8cf..edc8940d 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
@@ -34,9 +34,10 @@ namespace Google.Protobuf.WellKnownTypes {
             "ABIwCgpsaXN0X3ZhbHVlGAYgASgLMhouZ29vZ2xlLnByb3RvYnVmLkxpc3RW",
             "YWx1ZUgAQgYKBGtpbmQiMwoJTGlzdFZhbHVlEiYKBnZhbHVlcxgBIAMoCzIW",
             "Lmdvb2dsZS5wcm90b2J1Zi5WYWx1ZSobCglOdWxsVmFsdWUSDgoKTlVMTF9W",
-            "QUxVRRAAQk4KE2NvbS5nb29nbGUucHJvdG9idWZCC1N0cnVjdFByb3RvUAGg",
-            "AQGiAgNHUEKqAh5Hb29nbGUuUHJvdG9idWYuV2VsbEtub3duVHlwZXNiBnBy",
-            "b3RvMw=="));
+            "QUxVRRAAQoEBChNjb20uZ29vZ2xlLnByb3RvYnVmQgtTdHJ1Y3RQcm90b1AB",
+            "WjFnaXRodWIuY29tL2dvbGFuZy9wcm90b2J1Zi9wdHlwZXMvc3RydWN0O3N0",
+            "cnVjdHBioAEBogIDR1BCqgIeR29vZ2xlLlByb3RvYnVmLldlbGxLbm93blR5",
+            "cGVzYgZwcm90bzM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(new[] {typeof(global::Google.Protobuf.WellKnownTypes.NullValue), }, new pbr::GeneratedClrTypeInfo[] {
@@ -59,7 +60,7 @@ namespace Google.Protobuf.WellKnownTypes {
     /// <summary>
     ///  Null value.
     /// </summary>
-    NULL_VALUE = 0,
+    [pbr::OriginalName("NULL_VALUE")] NullValue = 0,
   }
 
   #endregion
@@ -108,7 +109,7 @@ namespace Google.Protobuf.WellKnownTypes {
         = new pbc::MapField<string, global::Google.Protobuf.WellKnownTypes.Value>.Codec(pb::FieldCodec.ForString(10), pb::FieldCodec.ForMessage(18, global::Google.Protobuf.WellKnownTypes.Value.Parser), 10);
     private readonly pbc::MapField<string, global::Google.Protobuf.WellKnownTypes.Value> fields_ = new pbc::MapField<string, global::Google.Protobuf.WellKnownTypes.Value>();
     /// <summary>
-    ///  Map of dynamically typed values.
+    ///  Unordered map of dynamically typed values.
     /// </summary>
     public pbc::MapField<string, global::Google.Protobuf.WellKnownTypes.Value> Fields {
       get { return fields_; }
@@ -234,7 +235,7 @@ 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;
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
index 318b0f61..053b88bd 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
@@ -25,9 +25,10 @@ namespace Google.Protobuf.WellKnownTypes {
           string.Concat(
             "Ch9nb29nbGUvcHJvdG9idWYvdGltZXN0YW1wLnByb3RvEg9nb29nbGUucHJv",
             "dG9idWYiKwoJVGltZXN0YW1wEg8KB3NlY29uZHMYASABKAMSDQoFbmFub3MY",
-            "AiABKAVCVAoTY29tLmdvb2dsZS5wcm90b2J1ZkIOVGltZXN0YW1wUHJvdG9Q",
-            "AaABAfgBAaICA0dQQqoCHkdvb2dsZS5Qcm90b2J1Zi5XZWxsS25vd25UeXBl",
-            "c2IGcHJvdG8z"));
+            "AiABKAVCgQEKE2NvbS5nb29nbGUucHJvdG9idWZCDlRpbWVzdGFtcFByb3Rv",
+            "UAFaK2dpdGh1Yi5jb20vZ29sYW5nL3Byb3RvYnVmL3B0eXBlcy90aW1lc3Rh",
+            "bXCgAQH4AQGiAgNHUEKqAh5Hb29nbGUuUHJvdG9idWYuV2VsbEtub3duVHlw",
+            "ZXNiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
index 8faa1d1c..657c2464 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
@@ -79,11 +79,11 @@ namespace Google.Protobuf.WellKnownTypes {
     /// <summary>
     ///  Syntax `proto2`.
     /// </summary>
-    SYNTAX_PROTO2 = 0,
+    [pbr::OriginalName("SYNTAX_PROTO2")] Proto2 = 0,
     /// <summary>
     ///  Syntax `proto3`.
     /// </summary>
-    SYNTAX_PROTO3 = 1,
+    [pbr::OriginalName("SYNTAX_PROTO3")] Proto3 = 1,
   }
 
   #endregion
@@ -188,7 +188,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "syntax" field.</summary>
     public const int SyntaxFieldNumber = 6;
-    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.
     /// </summary>
@@ -226,7 +226,7 @@ namespace Google.Protobuf.WellKnownTypes {
       hash ^= oneofs_.GetHashCode();
       hash ^= options_.GetHashCode();
       if (sourceContext_ != null) hash ^= SourceContext.GetHashCode();
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) hash ^= Syntax.GetHashCode();
+      if (Syntax != 0) hash ^= Syntax.GetHashCode();
       return hash;
     }
 
@@ -246,7 +246,7 @@ namespace Google.Protobuf.WellKnownTypes {
         output.WriteRawTag(42);
         output.WriteMessage(SourceContext);
       }
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         output.WriteRawTag(48);
         output.WriteEnum((int) Syntax);
       }
@@ -263,7 +263,7 @@ namespace Google.Protobuf.WellKnownTypes {
       if (sourceContext_ != null) {
         size += 1 + pb::CodedOutputStream.ComputeMessageSize(SourceContext);
       }
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Syntax);
       }
       return size;
@@ -285,7 +285,7 @@ namespace Google.Protobuf.WellKnownTypes {
         }
         SourceContext.MergeFrom(other.SourceContext);
       }
-      if (other.Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (other.Syntax != 0) {
         Syntax = other.Syntax;
       }
     }
@@ -371,7 +371,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "kind" field.</summary>
     public const int KindFieldNumber = 1;
-    private global::Google.Protobuf.WellKnownTypes.Field.Types.Kind kind_ = global::Google.Protobuf.WellKnownTypes.Field.Types.Kind.TYPE_UNKNOWN;
+    private global::Google.Protobuf.WellKnownTypes.Field.Types.Kind kind_ = 0;
     /// <summary>
     ///  The field type.
     /// </summary>
@@ -384,7 +384,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "cardinality" field.</summary>
     public const int CardinalityFieldNumber = 2;
-    private global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality cardinality_ = global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality.CARDINALITY_UNKNOWN;
+    private global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality cardinality_ = 0;
     /// <summary>
     ///  The field cardinality.
     /// </summary>
@@ -526,8 +526,8 @@ namespace Google.Protobuf.WellKnownTypes {
 
     public override int GetHashCode() {
       int hash = 1;
-      if (Kind != global::Google.Protobuf.WellKnownTypes.Field.Types.Kind.TYPE_UNKNOWN) hash ^= Kind.GetHashCode();
-      if (Cardinality != global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality.CARDINALITY_UNKNOWN) hash ^= Cardinality.GetHashCode();
+      if (Kind != 0) hash ^= Kind.GetHashCode();
+      if (Cardinality != 0) hash ^= Cardinality.GetHashCode();
       if (Number != 0) hash ^= Number.GetHashCode();
       if (Name.Length != 0) hash ^= Name.GetHashCode();
       if (TypeUrl.Length != 0) hash ^= TypeUrl.GetHashCode();
@@ -544,11 +544,11 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
-      if (Kind != global::Google.Protobuf.WellKnownTypes.Field.Types.Kind.TYPE_UNKNOWN) {
+      if (Kind != 0) {
         output.WriteRawTag(8);
         output.WriteEnum((int) Kind);
       }
-      if (Cardinality != global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality.CARDINALITY_UNKNOWN) {
+      if (Cardinality != 0) {
         output.WriteRawTag(16);
         output.WriteEnum((int) Cardinality);
       }
@@ -585,10 +585,10 @@ namespace Google.Protobuf.WellKnownTypes {
 
     public int CalculateSize() {
       int size = 0;
-      if (Kind != global::Google.Protobuf.WellKnownTypes.Field.Types.Kind.TYPE_UNKNOWN) {
+      if (Kind != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Kind);
       }
-      if (Cardinality != global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality.CARDINALITY_UNKNOWN) {
+      if (Cardinality != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Cardinality);
       }
       if (Number != 0) {
@@ -620,10 +620,10 @@ namespace Google.Protobuf.WellKnownTypes {
       if (other == null) {
         return;
       }
-      if (other.Kind != global::Google.Protobuf.WellKnownTypes.Field.Types.Kind.TYPE_UNKNOWN) {
+      if (other.Kind != 0) {
         Kind = other.Kind;
       }
-      if (other.Cardinality != global::Google.Protobuf.WellKnownTypes.Field.Types.Cardinality.CARDINALITY_UNKNOWN) {
+      if (other.Cardinality != 0) {
         Cardinality = other.Cardinality;
       }
       if (other.Number != 0) {
@@ -712,79 +712,79 @@ namespace Google.Protobuf.WellKnownTypes {
         /// <summary>
         ///  Field type unknown.
         /// </summary>
-        TYPE_UNKNOWN = 0,
+        [pbr::OriginalName("TYPE_UNKNOWN")] TypeUnknown = 0,
         /// <summary>
         ///  Field type double.
         /// </summary>
-        TYPE_DOUBLE = 1,
+        [pbr::OriginalName("TYPE_DOUBLE")] TypeDouble = 1,
         /// <summary>
         ///  Field type float.
         /// </summary>
-        TYPE_FLOAT = 2,
+        [pbr::OriginalName("TYPE_FLOAT")] TypeFloat = 2,
         /// <summary>
         ///  Field type int64.
         /// </summary>
-        TYPE_INT64 = 3,
+        [pbr::OriginalName("TYPE_INT64")] TypeInt64 = 3,
         /// <summary>
         ///  Field type uint64.
         /// </summary>
-        TYPE_UINT64 = 4,
+        [pbr::OriginalName("TYPE_UINT64")] TypeUint64 = 4,
         /// <summary>
         ///  Field type int32.
         /// </summary>
-        TYPE_INT32 = 5,
+        [pbr::OriginalName("TYPE_INT32")] TypeInt32 = 5,
         /// <summary>
         ///  Field type fixed64.
         /// </summary>
-        TYPE_FIXED64 = 6,
+        [pbr::OriginalName("TYPE_FIXED64")] TypeFixed64 = 6,
         /// <summary>
         ///  Field type fixed32.
         /// </summary>
-        TYPE_FIXED32 = 7,
+        [pbr::OriginalName("TYPE_FIXED32")] TypeFixed32 = 7,
         /// <summary>
         ///  Field type bool.
         /// </summary>
-        TYPE_BOOL = 8,
+        [pbr::OriginalName("TYPE_BOOL")] TypeBool = 8,
         /// <summary>
         ///  Field type string.
         /// </summary>
-        TYPE_STRING = 9,
+        [pbr::OriginalName("TYPE_STRING")] TypeString = 9,
         /// <summary>
         ///  Field type group. Proto2 syntax only, and deprecated.
         /// </summary>
-        TYPE_GROUP = 10,
+        [pbr::OriginalName("TYPE_GROUP")] TypeGroup = 10,
         /// <summary>
         ///  Field type message.
         /// </summary>
-        TYPE_MESSAGE = 11,
+        [pbr::OriginalName("TYPE_MESSAGE")] TypeMessage = 11,
         /// <summary>
         ///  Field type bytes.
         /// </summary>
-        TYPE_BYTES = 12,
+        [pbr::OriginalName("TYPE_BYTES")] TypeBytes = 12,
         /// <summary>
         ///  Field type uint32.
         /// </summary>
-        TYPE_UINT32 = 13,
+        [pbr::OriginalName("TYPE_UINT32")] TypeUint32 = 13,
         /// <summary>
         ///  Field type enum.
         /// </summary>
-        TYPE_ENUM = 14,
+        [pbr::OriginalName("TYPE_ENUM")] TypeEnum = 14,
         /// <summary>
         ///  Field type sfixed32.
         /// </summary>
-        TYPE_SFIXED32 = 15,
+        [pbr::OriginalName("TYPE_SFIXED32")] TypeSfixed32 = 15,
         /// <summary>
         ///  Field type sfixed64.
         /// </summary>
-        TYPE_SFIXED64 = 16,
+        [pbr::OriginalName("TYPE_SFIXED64")] TypeSfixed64 = 16,
         /// <summary>
         ///  Field type sint32.
         /// </summary>
-        TYPE_SINT32 = 17,
+        [pbr::OriginalName("TYPE_SINT32")] TypeSint32 = 17,
         /// <summary>
         ///  Field type sint64.
         /// </summary>
-        TYPE_SINT64 = 18,
+        [pbr::OriginalName("TYPE_SINT64")] TypeSint64 = 18,
       }
 
       /// <summary>
@@ -794,19 +794,19 @@ namespace Google.Protobuf.WellKnownTypes {
         /// <summary>
         ///  For fields with unknown cardinality.
         /// </summary>
-        CARDINALITY_UNKNOWN = 0,
+        [pbr::OriginalName("CARDINALITY_UNKNOWN")] Unknown = 0,
         /// <summary>
         ///  For optional fields.
         /// </summary>
-        CARDINALITY_OPTIONAL = 1,
+        [pbr::OriginalName("CARDINALITY_OPTIONAL")] Optional = 1,
         /// <summary>
         ///  For required fields. Proto2 syntax only.
         /// </summary>
-        CARDINALITY_REQUIRED = 2,
+        [pbr::OriginalName("CARDINALITY_REQUIRED")] Required = 2,
         /// <summary>
         ///  For repeated fields.
         /// </summary>
-        CARDINALITY_REPEATED = 3,
+        [pbr::OriginalName("CARDINALITY_REPEATED")] Repeated = 3,
       }
 
     }
@@ -900,7 +900,7 @@ namespace Google.Protobuf.WellKnownTypes {
 
     /// <summary>Field number for the "syntax" field.</summary>
     public const int SyntaxFieldNumber = 5;
-    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.
     /// </summary>
@@ -936,7 +936,7 @@ namespace Google.Protobuf.WellKnownTypes {
       hash ^= enumvalue_.GetHashCode();
       hash ^= options_.GetHashCode();
       if (sourceContext_ != null) hash ^= SourceContext.GetHashCode();
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) hash ^= Syntax.GetHashCode();
+      if (Syntax != 0) hash ^= Syntax.GetHashCode();
       return hash;
     }
 
@@ -955,7 +955,7 @@ namespace Google.Protobuf.WellKnownTypes {
         output.WriteRawTag(34);
         output.WriteMessage(SourceContext);
       }
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         output.WriteRawTag(40);
         output.WriteEnum((int) Syntax);
       }
@@ -971,7 +971,7 @@ namespace Google.Protobuf.WellKnownTypes {
       if (sourceContext_ != null) {
         size += 1 + pb::CodedOutputStream.ComputeMessageSize(SourceContext);
       }
-      if (Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (Syntax != 0) {
         size += 1 + pb::CodedOutputStream.ComputeEnumSize((int) Syntax);
       }
       return size;
@@ -992,7 +992,7 @@ namespace Google.Protobuf.WellKnownTypes {
         }
         SourceContext.MergeFrom(other.SourceContext);
       }
-      if (other.Syntax != global::Google.Protobuf.WellKnownTypes.Syntax.SYNTAX_PROTO2) {
+      if (other.Syntax != 0) {
         Syntax = other.Syntax;
       }
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
index d6796d1a..c8867d0e 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
@@ -29,10 +29,10 @@ namespace Google.Protobuf.WellKnownTypes {
             "KAMiHAoLVUludDY0VmFsdWUSDQoFdmFsdWUYASABKAQiGwoKSW50MzJWYWx1",
             "ZRINCgV2YWx1ZRgBIAEoBSIcCgtVSW50MzJWYWx1ZRINCgV2YWx1ZRgBIAEo",
             "DSIaCglCb29sVmFsdWUSDQoFdmFsdWUYASABKAgiHAoLU3RyaW5nVmFsdWUS",
-            "DQoFdmFsdWUYASABKAkiGwoKQnl0ZXNWYWx1ZRINCgV2YWx1ZRgBIAEoDEJT",
-            "ChNjb20uZ29vZ2xlLnByb3RvYnVmQg1XcmFwcGVyc1Byb3RvUAGgAQH4AQGi",
-            "AgNHUEKqAh5Hb29nbGUuUHJvdG9idWYuV2VsbEtub3duVHlwZXNiBnByb3Rv",
-            "Mw=="));
+            "DQoFdmFsdWUYASABKAkiGwoKQnl0ZXNWYWx1ZRINCgV2YWx1ZRgBIAEoDEJ/",
+            "ChNjb20uZ29vZ2xlLnByb3RvYnVmQg1XcmFwcGVyc1Byb3RvUAFaKmdpdGh1",
+            "Yi5jb20vZ29sYW5nL3Byb3RvYnVmL3B0eXBlcy93cmFwcGVyc6ABAfgBAaIC",
+            "A0dQQqoCHkdvb2dsZS5Qcm90b2J1Zi5XZWxsS25vd25UeXBlc2IGcHJvdG8z"));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {