From dbf77c65c45d338bd57814d7261d748e9db8e1eb Mon Sep 17 00:00:00 2001
From: Sydney Acksman <ObsidianMinor@users.noreply.github.com>
Date: Mon, 11 Feb 2019 17:12:40 -0600
Subject: [PATCH] Refactor how group endings are detected in generated C# code
 (#5686)

* Modify how end tags are encounted in merge code (compiler)

* Modify how end tags are encounted in merge code (generated)

* Modify how end tags are encounted in merge code (library)

* Regenerate generated code through generate_descriptor_proto.sh
---
 csharp/src/AddressBook/Addressbook.cs         |  12 +-
 .../Conformance.cs                            |  16 +-
 .../TestProtos/MapUnittestProto3.cs           |  28 +---
 .../TestProtos/TestMessagesProto3.cs          |  12 +-
 .../TestProtos/UnittestCustomOptionsProto3.cs |  84 +++-------
 .../TestProtos/UnittestImportProto3.cs        |   4 +-
 .../TestProtos/UnittestImportPublicProto3.cs  |   4 +-
 .../TestProtos/UnittestIssues.cs              |  52 ++----
 .../TestProtos/UnittestProto3.cs              | 156 +++++-------------
 .../TestProtos/UnittestWellKnownTypes.cs      |  16 +-
 .../Google.Protobuf/Reflection/Descriptor.cs  |  76 +++------
 csharp/src/Google.Protobuf/UnknownFieldSet.cs |  23 ---
 .../src/Google.Protobuf/WellKnownTypes/Any.cs |   4 +-
 .../src/Google.Protobuf/WellKnownTypes/Api.cs |  12 +-
 .../WellKnownTypes/Duration.cs                |   4 +-
 .../Google.Protobuf/WellKnownTypes/Empty.cs   |   4 +-
 .../WellKnownTypes/FieldMask.cs               |   4 +-
 .../WellKnownTypes/SourceContext.cs           |   4 +-
 .../Google.Protobuf/WellKnownTypes/Struct.cs  |  12 +-
 .../WellKnownTypes/Timestamp.cs               |   4 +-
 .../Google.Protobuf/WellKnownTypes/Type.cs    |  20 +--
 .../WellKnownTypes/Wrappers.cs                |  36 +---
 .../compiler/csharp/csharp_helpers.cc         |  13 ++
 .../protobuf/compiler/csharp/csharp_helpers.h |   3 +
 .../compiler/csharp/csharp_message.cc         |  13 +-
 .../protobuf/compiler/csharp/csharp_message.h |   1 +
 26 files changed, 167 insertions(+), 450 deletions(-)

diff --git a/csharp/src/AddressBook/Addressbook.cs b/csharp/src/AddressBook/Addressbook.cs
index c05125c629..d3e1ea9534 100644
--- a/csharp/src/AddressBook/Addressbook.cs
+++ b/csharp/src/AddressBook/Addressbook.cs
@@ -260,9 +260,7 @@ namespace Google.Protobuf.Examples.AddressBook {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -442,9 +440,7 @@ namespace Google.Protobuf.Examples.AddressBook {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 10: {
                 Number = input.ReadString();
@@ -577,9 +573,7 @@ namespace Google.Protobuf.Examples.AddressBook {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             people_.AddEntriesFrom(input, _repeated_people_codec);
diff --git a/csharp/src/Google.Protobuf.Conformance/Conformance.cs b/csharp/src/Google.Protobuf.Conformance/Conformance.cs
index 73a140d3d1..0a5106280e 100644
--- a/csharp/src/Google.Protobuf.Conformance/Conformance.cs
+++ b/csharp/src/Google.Protobuf.Conformance/Conformance.cs
@@ -216,9 +216,7 @@ namespace Conformance {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             failure_.AddEntriesFrom(input, _repeated_failure_codec);
@@ -581,9 +579,7 @@ namespace Conformance {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             ProtobufPayload = input.ReadBytes();
@@ -1001,9 +997,7 @@ namespace Conformance {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             ParseError = input.ReadString();
@@ -1166,9 +1160,7 @@ namespace Conformance {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             UseJspbArrayAnyFormat = input.ReadBool();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
index 2844ca62ce..6d3cd026d1 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
@@ -541,9 +541,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             mapInt32Int32_.AddEntriesFrom(input, _map_mapInt32Int32_codec);
@@ -739,9 +737,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (testMap_ == null) {
@@ -865,9 +861,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             mapInt32Message_.AddEntriesFrom(input, _map_mapInt32Message_codec);
@@ -1007,9 +1001,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             map1_.AddEntriesFrom(input, _map_map1_codec);
@@ -1358,9 +1350,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             mapInt32Int32_.AddEntriesFrom(input, _map_mapInt32Int32_codec);
@@ -1541,9 +1531,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             type_.AddEntriesFrom(input, _map_type_codec);
@@ -1678,9 +1666,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             entry_.AddEntriesFrom(input, _map_entry_codec);
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/TestMessagesProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/TestMessagesProto3.cs
index b59075bc10..b14ee6caee 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/TestMessagesProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/TestMessagesProto3.cs
@@ -2895,9 +2895,7 @@ namespace ProtobufTestMessages.Proto3 {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             OptionalInt32 = input.ReadInt32();
@@ -3625,9 +3623,7 @@ namespace ProtobufTestMessages.Proto3 {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 A = input.ReadInt32();
@@ -3768,9 +3764,7 @@ namespace ProtobufTestMessages.Proto3 {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             C = input.ReadInt32();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestCustomOptionsProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestCustomOptionsProto3.cs
index 9b9ffe2560..2a9efe55ff 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestCustomOptionsProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestCustomOptionsProto3.cs
@@ -352,9 +352,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Field1 = input.ReadString();
@@ -480,9 +478,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -583,9 +579,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -686,9 +680,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -789,9 +781,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -892,9 +882,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1008,9 +996,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1111,9 +1097,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1214,9 +1198,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1317,9 +1299,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1420,9 +1400,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1523,9 +1501,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -1714,9 +1690,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Foo = input.ReadInt32();
@@ -1928,9 +1902,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (bar_ == null) {
@@ -2079,9 +2051,7 @@ namespace UnitTest.Issues.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Waldo = input.ReadInt32();
@@ -2215,9 +2185,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Qux = input.ReadInt32();
@@ -2325,9 +2293,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -2509,9 +2475,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             I = input.ReadInt32();
@@ -2651,9 +2615,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Fieldname = input.ReadInt32();
@@ -2761,9 +2723,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -2895,9 +2855,7 @@ namespace UnitTest.Issues.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 NestedField = input.ReadInt32();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
index 931dc2eb03..6bf9715171 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
@@ -167,9 +167,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             D = input.ReadInt32();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
index fee0120b42..97d181aff4 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
@@ -155,9 +155,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             E = input.ReadInt32();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
index f8296b0fab..f27ab64074 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
@@ -181,9 +181,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -286,9 +284,7 @@ namespace UnitTest.Issues.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
             }
           }
@@ -391,9 +387,7 @@ namespace UnitTest.Issues.TestProtos {
               while ((tag = input.ReadTag()) != 0) {
                 switch(tag) {
                   default:
-                    if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                      return;
-                    }
+                    _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                     break;
                 }
               }
@@ -560,9 +554,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = (global::UnitTest.Issues.TestProtos.NegativeEnum) input.ReadEnum();
@@ -677,9 +669,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -909,9 +899,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             PrimitiveValue = input.ReadInt32();
@@ -1068,9 +1056,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Item = input.ReadInt32();
@@ -1223,9 +1209,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Types_ = input.ReadInt32();
@@ -1339,9 +1323,7 @@ namespace UnitTest.Issues.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
             }
           }
@@ -1665,9 +1647,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             PlainString = input.ReadString();
@@ -1867,9 +1847,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -2069,9 +2047,7 @@ namespace UnitTest.Issues.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Text = input.ReadString();
@@ -2235,9 +2211,7 @@ namespace UnitTest.Issues.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 X = input.ReadInt32();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
index 1d4367b781..bbbee22c7b 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
@@ -1387,9 +1387,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             SingleInt32 = input.ReadInt32();
@@ -1757,9 +1755,7 @@ namespace Google.Protobuf.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Bb = input.ReadInt32();
@@ -1942,9 +1938,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (child_ == null) {
@@ -2088,9 +2082,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             DeprecatedInt32 = input.ReadInt32();
@@ -2223,9 +2215,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             C = input.ReadInt32();
@@ -2330,9 +2320,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -2463,9 +2451,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (foreignNested_ == null) {
@@ -2628,9 +2614,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             A = input.ReadInt32();
@@ -2790,9 +2774,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (a_ == null) {
@@ -2934,9 +2916,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (bb_ == null) {
@@ -3095,9 +3075,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (a_ == null) {
@@ -3233,9 +3211,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = (global::Google.Protobuf.TestProtos.TestEnumWithDupValue) input.ReadEnum();
@@ -3507,9 +3483,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             PrimitiveField = input.ReadInt32();
@@ -3750,9 +3724,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             MyInt = input.ReadInt64();
@@ -3927,9 +3899,7 @@ namespace Google.Protobuf.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Bb = input.ReadInt32();
@@ -4067,9 +4037,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             SparseEnum = (global::Google.Protobuf.TestProtos.TestSparseEnum) input.ReadEnum();
@@ -4201,9 +4169,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Data = input.ReadString();
@@ -4324,9 +4290,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             data_.AddEntriesFrom(input, _repeated_data_codec);
@@ -4455,9 +4419,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Data = input.ReadBytes();
@@ -4586,9 +4548,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Data = input.ReadBytes();
@@ -4720,9 +4680,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Data = input.ReadInt32();
@@ -4851,9 +4809,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Data = input.ReadUInt32();
@@ -4982,9 +4938,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Data = input.ReadInt64();
@@ -5113,9 +5067,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Data = input.ReadUInt64();
@@ -5244,9 +5196,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Data = input.ReadBool();
@@ -5463,9 +5413,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             FooInt = input.ReadInt32();
@@ -5807,9 +5755,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 722:
           case 720: {
@@ -6208,9 +6154,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 722:
           case 720: {
@@ -6491,9 +6435,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 98:
           case 101: {
@@ -6651,9 +6593,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             A = input.ReadString();
@@ -6761,9 +6701,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -6864,9 +6802,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -6967,9 +6903,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -7070,9 +7004,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -7173,9 +7105,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -7276,9 +7206,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -7379,9 +7307,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
@@ -7512,9 +7438,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Text = input.ReadString();
@@ -7661,9 +7585,7 @@ namespace Google.Protobuf.TestProtos {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 10: {
                 NestedText = input.ReadString();
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
index a36825dc32..45f8ece646 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
@@ -788,9 +788,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             if (anyField_ == null) {
@@ -1318,9 +1316,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             anyField_.AddEntriesFrom(input, _repeated_anyField_codec);
@@ -2031,9 +2027,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             global::Google.Protobuf.WellKnownTypes.Any subBuilder = new global::Google.Protobuf.WellKnownTypes.Any();
@@ -2544,9 +2538,7 @@ namespace Google.Protobuf.TestProtos {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             anyField_.AddEntriesFrom(input, _map_anyField_codec);
diff --git a/csharp/src/Google.Protobuf/Reflection/Descriptor.cs b/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
index f101cd3526..0c33e63df4 100644
--- a/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/Descriptor.cs
@@ -302,9 +302,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             file_.AddEntriesFrom(input, _repeated_file_codec);
@@ -735,9 +733,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -1102,9 +1098,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -1363,9 +1357,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Start = input.ReadInt32();
@@ -1568,9 +1560,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Start = input.ReadInt32();
@@ -1703,9 +1693,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 7994: {
             uninterpretedOption_.AddEntriesFrom(input, _repeated_uninterpretedOption_codec);
@@ -2212,9 +2200,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -2501,9 +2487,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -2748,9 +2732,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -2966,9 +2948,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 8: {
                 Start = input.ReadInt32();
@@ -3197,9 +3177,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -3407,9 +3385,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -3759,9 +3735,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -6949,9 +6923,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 18: {
             name_.AddEntriesFrom(input, _repeated_name_codec);
@@ -7164,9 +7136,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 10: {
                 NamePart_ = input.ReadString();
@@ -7345,9 +7315,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             location_.AddEntriesFrom(input, _repeated_location_codec);
@@ -7655,9 +7623,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 10:
               case 8: {
@@ -7810,9 +7776,7 @@ namespace Google.Protobuf.Reflection {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             annotation_.AddEntriesFrom(input, _repeated_annotation_codec);
@@ -8063,9 +8027,7 @@ namespace Google.Protobuf.Reflection {
           while ((tag = input.ReadTag()) != 0) {
             switch(tag) {
               default:
-                if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-                  return;
-                }
+                _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
                 break;
               case 10:
               case 8: {
diff --git a/csharp/src/Google.Protobuf/UnknownFieldSet.cs b/csharp/src/Google.Protobuf/UnknownFieldSet.cs
index 9121567621..21ec13bf84 100644
--- a/csharp/src/Google.Protobuf/UnknownFieldSet.cs
+++ b/csharp/src/Google.Protobuf/UnknownFieldSet.cs
@@ -260,29 +260,6 @@ namespace Google.Protobuf
             }
             return unknownFields;
         }
-
-        /// <summary>
-        /// Create a new UnknownFieldSet if unknownFields is null.
-        /// Parse a single field from <paramref name="input"/> and merge it
-        /// into unknownFields. If <paramref name="input"/> is configured to discard unknown fields,
-        /// <paramref name="unknownFields"/> will be returned as-is and the field will be skipped.
-        /// </summary>
-        /// <param name="unknownFields">The UnknownFieldSet which need to be merged</param>
-        /// <param name="input">The coded input stream containing the field</param>
-        /// <returns>The merged UnknownFieldSet</returns>
-        public static bool MergeFieldFrom(ref UnknownFieldSet unknownFields, CodedInputStream input)
-        {
-            if (input.DiscardUnknownFields)
-            {
-                input.SkipLastField();
-                return true;
-            }
-            if (unknownFields == null)
-            {
-                unknownFields = new UnknownFieldSet();
-            }
-            return unknownFields.MergeFieldFrom(input);
-        }
 
         /// <summary>
         /// Merges the fields from <paramref name="other"/> into this set.
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
index b1ed0bc307..dd9911067e 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
@@ -292,9 +292,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             TypeUrl = input.ReadString();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
index a566e40640..438e1db8da 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
@@ -345,9 +345,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -663,9 +661,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -929,9 +925,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
index 691ca334ea..2858b532b6 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
@@ -254,9 +254,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Seconds = input.ReadInt64();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
index 03ffc4a057..2113add9bc 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
@@ -143,9 +143,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
         }
       }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
index 8114aa3924..6ad31a50ea 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
@@ -352,9 +352,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             paths_.AddEntriesFrom(input, _repeated_paths_codec);
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
index 2cae68631d..124ddaa712 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
@@ -165,9 +165,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             FileName = input.ReadString();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
index 9667472522..194b81e965 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
@@ -189,9 +189,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             fields_.AddEntriesFrom(input, _map_fields_codec);
@@ -515,9 +513,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             kind_ = input.ReadEnum();
@@ -677,9 +673,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             values_.AddEntriesFrom(input, _repeated_values_codec);
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
index 524ac06e3d..2e5809f2fa 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
@@ -273,9 +273,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Seconds = input.ReadInt64();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
index adea910634..52bd343ba8 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
@@ -328,9 +328,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -725,9 +723,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Kind = (global::Google.Protobuf.WellKnownTypes.Field.Types.Kind) input.ReadEnum();
@@ -1104,9 +1100,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -1306,9 +1300,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
@@ -1488,9 +1480,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Name = input.ReadString();
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
index 679eb0f234..25a65aa72c 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
@@ -177,9 +177,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 9: {
             Value = input.ReadDouble();
@@ -316,9 +314,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 13: {
             Value = input.ReadFloat();
@@ -455,9 +451,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = input.ReadInt64();
@@ -594,9 +588,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = input.ReadUInt64();
@@ -733,9 +725,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = input.ReadInt32();
@@ -872,9 +862,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = input.ReadUInt32();
@@ -1011,9 +999,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 8: {
             Value = input.ReadBool();
@@ -1150,9 +1136,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Value = input.ReadString();
@@ -1289,9 +1273,7 @@ namespace Google.Protobuf.WellKnownTypes {
       while ((tag = input.ReadTag()) != 0) {
         switch(tag) {
           default:
-            if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {
-              return;
-            }
+            _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);
             break;
           case 10: {
             Value = input.ReadBytes();
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.cc b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
index dace41006a..b11e40da5c 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
@@ -278,6 +278,19 @@ std::string GetEnumValueName(const std::string& enum_name, const std::string& en
   return result;
 }
 
+uint GetGroupEndTag(const Descriptor* descriptor) {
+  const Descriptor* containing_type = descriptor->containing_type();
+  if (containing_type == NULL) {
+    return 0;
+  }
+  const FieldDescriptor* field = containing_type->FindFieldByName(descriptor->name());
+  if (field != NULL && field->type() == FieldDescriptor::Type::TYPE_GROUP) {
+    return internal::WireFormatLite::MakeTag(field->number(), internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+  } else {
+    return 0;
+  }
+}
+
 std::string ToCSharpName(const std::string& name, const FileDescriptor* file) {
   std::string result = GetFileNamespace(file);
   if (result != "") {
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.h b/src/google/protobuf/compiler/csharp/csharp_helpers.h
index 5b9f90e0ef..d351a1c9b7 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.h
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.h
@@ -118,6 +118,9 @@ inline bool IsMapEntryMessage(const Descriptor* descriptor) {
   return descriptor->options().map_entry();
 }
 
+// Checks if this descriptor is for a group and gets its end tag or 0 if it's not a group
+uint GetGroupEndTag(const Descriptor* descriptor);
+
 // Determines whether we're generating code for the proto representation of
 // descriptors etc, for use in the runtime. This is the only type which is
 // allowed to use proto2 syntax, and it generates internal classes.
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.cc b/src/google/protobuf/compiler/csharp/csharp_message.cc
index be1cd115a5..6a79979f77 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message.cc
@@ -63,7 +63,8 @@ MessageGenerator::MessageGenerator(const Descriptor* descriptor,
                                    const Options* options)
     : SourceGeneratorBase(descriptor->file(), options),
       descriptor_(descriptor),
-      has_bit_field_count_(0) {
+      has_bit_field_count_(0),
+      end_tag_(GetGroupEndTag(descriptor)) {
   // fields by number
   for (int i = 0; i < descriptor_->field_count(); i++) {
     fields_by_number_.push_back(descriptor_->field(i));
@@ -539,10 +540,14 @@ void MessageGenerator::GenerateMergingMethods(io::Printer* printer) {
   } else {
     printer->Print(
       "default:\n"
-      "  if (!pb::UnknownFieldSet.MergeFieldFrom(ref _unknownFields, input)) {\n"
-      "    return;\n"
-      "  }\n"
+      "  _unknownFields = pb::UnknownFieldSet.MergeFieldFrom(_unknownFields, input);\n"
       "  break;\n");
+    if (end_tag_ != 0) {
+      printer->Print(
+        "$end_tag$:\n"
+        "  return;\n",
+        "end_tag", SimpleItoa(end_tag_));
+    }
   }
   for (int i = 0; i < fields_by_number().size(); i++) {
     const FieldDescriptor* field = fields_by_number()[i];
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.h b/src/google/protobuf/compiler/csharp/csharp_message.h
index 5e0ac960d8..d2ffe66a4e 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.h
+++ b/src/google/protobuf/compiler/csharp/csharp_message.h
@@ -59,6 +59,7 @@ class MessageGenerator : public SourceGeneratorBase {
   const Descriptor* descriptor_;
   std::vector<const FieldDescriptor*> fields_by_number_;
   int has_bit_field_count_;
+  uint end_tag_;
 
   void GenerateMessageSerializationMethods(io::Printer* printer);
   void GenerateMergingMethods(io::Printer* printer);