regenerate C# protos
diff --git a/csharp/src/Google.Protobuf.Benchmarks/BenchmarkMessage1Proto3.cs b/csharp/src/Google.Protobuf.Benchmarks/BenchmarkMessage1Proto3.cs
index 6a21334..027da02 100644
--- a/csharp/src/Google.Protobuf.Benchmarks/BenchmarkMessage1Proto3.cs
+++ b/csharp/src/Google.Protobuf.Benchmarks/BenchmarkMessage1Proto3.cs
@@ -706,6 +706,9 @@
 
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
       if (Field1.Length != 0) {
         output.WriteRawTag(10);
         output.WriteString(Field1);
@@ -870,8 +873,179 @@
       if (_unknownFields != null) {
         _unknownFields.WriteTo(output);
       }
+    #endif
     }
 
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (Field1.Length != 0) {
+        output.WriteRawTag(10);
+        output.WriteString(Field1);
+      }
+      if (Field2 != 0) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Field2);
+      }
+      if (Field3 != 0) {
+        output.WriteRawTag(24);
+        output.WriteInt32(Field3);
+      }
+      if (Field4.Length != 0) {
+        output.WriteRawTag(34);
+        output.WriteString(Field4);
+      }
+      field5_.WriteTo(ref output, _repeated_field5_codec);
+      if (Field6 != 0) {
+        output.WriteRawTag(48);
+        output.WriteInt32(Field6);
+      }
+      if (Field7.Length != 0) {
+        output.WriteRawTag(58);
+        output.WriteString(Field7);
+      }
+      if (Field9.Length != 0) {
+        output.WriteRawTag(74);
+        output.WriteString(Field9);
+      }
+      if (Field12 != false) {
+        output.WriteRawTag(96);
+        output.WriteBool(Field12);
+      }
+      if (Field13 != false) {
+        output.WriteRawTag(104);
+        output.WriteBool(Field13);
+      }
+      if (Field14 != false) {
+        output.WriteRawTag(112);
+        output.WriteBool(Field14);
+      }
+      if (field15_ != null) {
+        output.WriteRawTag(122);
+        output.WriteMessage(Field15);
+      }
+      if (Field16 != 0) {
+        output.WriteRawTag(128, 1);
+        output.WriteInt32(Field16);
+      }
+      if (Field17 != false) {
+        output.WriteRawTag(136, 1);
+        output.WriteBool(Field17);
+      }
+      if (Field18.Length != 0) {
+        output.WriteRawTag(146, 1);
+        output.WriteString(Field18);
+      }
+      if (Field22 != 0L) {
+        output.WriteRawTag(176, 1);
+        output.WriteInt64(Field22);
+      }
+      if (Field23 != 0) {
+        output.WriteRawTag(184, 1);
+        output.WriteInt32(Field23);
+      }
+      if (Field24 != false) {
+        output.WriteRawTag(192, 1);
+        output.WriteBool(Field24);
+      }
+      if (Field25 != 0) {
+        output.WriteRawTag(200, 1);
+        output.WriteInt32(Field25);
+      }
+      if (Field29 != 0) {
+        output.WriteRawTag(232, 1);
+        output.WriteInt32(Field29);
+      }
+      if (Field30 != false) {
+        output.WriteRawTag(240, 1);
+        output.WriteBool(Field30);
+      }
+      if (Field59 != false) {
+        output.WriteRawTag(216, 3);
+        output.WriteBool(Field59);
+      }
+      if (Field60 != 0) {
+        output.WriteRawTag(224, 3);
+        output.WriteInt32(Field60);
+      }
+      if (Field67 != 0) {
+        output.WriteRawTag(152, 4);
+        output.WriteInt32(Field67);
+      }
+      if (Field68 != 0) {
+        output.WriteRawTag(160, 4);
+        output.WriteInt32(Field68);
+      }
+      if (Field78 != false) {
+        output.WriteRawTag(240, 4);
+        output.WriteBool(Field78);
+      }
+      if (Field80 != false) {
+        output.WriteRawTag(128, 5);
+        output.WriteBool(Field80);
+      }
+      if (Field81 != false) {
+        output.WriteRawTag(136, 5);
+        output.WriteBool(Field81);
+      }
+      if (Field100 != 0) {
+        output.WriteRawTag(160, 6);
+        output.WriteInt32(Field100);
+      }
+      if (Field101 != 0) {
+        output.WriteRawTag(168, 6);
+        output.WriteInt32(Field101);
+      }
+      if (Field102.Length != 0) {
+        output.WriteRawTag(178, 6);
+        output.WriteString(Field102);
+      }
+      if (Field103.Length != 0) {
+        output.WriteRawTag(186, 6);
+        output.WriteString(Field103);
+      }
+      if (Field104 != 0) {
+        output.WriteRawTag(192, 6);
+        output.WriteInt32(Field104);
+      }
+      if (Field128 != 0) {
+        output.WriteRawTag(128, 8);
+        output.WriteInt32(Field128);
+      }
+      if (Field129.Length != 0) {
+        output.WriteRawTag(138, 8);
+        output.WriteString(Field129);
+      }
+      if (Field130 != 0) {
+        output.WriteRawTag(144, 8);
+        output.WriteInt32(Field130);
+      }
+      if (Field131 != 0) {
+        output.WriteRawTag(152, 8);
+        output.WriteInt32(Field131);
+      }
+      if (Field150 != 0) {
+        output.WriteRawTag(176, 9);
+        output.WriteInt32(Field150);
+      }
+      if (Field271 != 0) {
+        output.WriteRawTag(248, 16);
+        output.WriteInt32(Field271);
+      }
+      if (Field272 != 0) {
+        output.WriteRawTag(128, 17);
+        output.WriteInt32(Field272);
+      }
+      if (Field280 != 0) {
+        output.WriteRawTag(192, 17);
+        output.WriteInt32(Field280);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     public int CalculateSize() {
       int size = 0;
@@ -1851,6 +2025,9 @@
 
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     public void WriteTo(pb::CodedOutputStream output) {
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+      output.WriteRawMessage(this);
+    #else
       if (Field1 != 0) {
         output.WriteRawTag(8);
         output.WriteInt32(Field1);
@@ -1934,8 +2111,98 @@
       if (_unknownFields != null) {
         _unknownFields.WriteTo(output);
       }
+    #endif
     }
 
+    #if !GOOGLE_PROTOBUF_REFSTRUCT_COMPATIBILITY_MODE
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
+    void pb::IBufferMessage.InternalWriteTo(ref pb::WriteContext output) {
+      if (Field1 != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(Field1);
+      }
+      if (Field2 != 0) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Field2);
+      }
+      if (Field3 != 0) {
+        output.WriteRawTag(24);
+        output.WriteInt32(Field3);
+      }
+      if (Field12 != false) {
+        output.WriteRawTag(96);
+        output.WriteBool(Field12);
+      }
+      if (Field13 != 0L) {
+        output.WriteRawTag(104);
+        output.WriteInt64(Field13);
+      }
+      if (Field14 != 0L) {
+        output.WriteRawTag(112);
+        output.WriteInt64(Field14);
+      }
+      if (Field15.Length != 0) {
+        output.WriteRawTag(122);
+        output.WriteString(Field15);
+      }
+      if (Field16 != 0) {
+        output.WriteRawTag(128, 1);
+        output.WriteInt32(Field16);
+      }
+      if (Field19 != 0) {
+        output.WriteRawTag(152, 1);
+        output.WriteInt32(Field19);
+      }
+      if (Field20 != false) {
+        output.WriteRawTag(160, 1);
+        output.WriteBool(Field20);
+      }
+      if (Field21 != 0UL) {
+        output.WriteRawTag(169, 1);
+        output.WriteFixed64(Field21);
+      }
+      if (Field22 != 0) {
+        output.WriteRawTag(176, 1);
+        output.WriteInt32(Field22);
+      }
+      if (Field23 != false) {
+        output.WriteRawTag(184, 1);
+        output.WriteBool(Field23);
+      }
+      if (Field28 != false) {
+        output.WriteRawTag(224, 1);
+        output.WriteBool(Field28);
+      }
+      if (Field203 != 0) {
+        output.WriteRawTag(221, 12);
+        output.WriteFixed32(Field203);
+      }
+      if (Field204 != 0) {
+        output.WriteRawTag(224, 12);
+        output.WriteInt32(Field204);
+      }
+      if (Field205.Length != 0) {
+        output.WriteRawTag(234, 12);
+        output.WriteString(Field205);
+      }
+      if (Field206 != false) {
+        output.WriteRawTag(240, 12);
+        output.WriteBool(Field206);
+      }
+      if (Field207 != 0UL) {
+        output.WriteRawTag(248, 12);
+        output.WriteUInt64(Field207);
+      }
+      if (Field300 != 0UL) {
+        output.WriteRawTag(224, 18);
+        output.WriteUInt64(Field300);
+      }
+      if (_unknownFields != null) {
+        _unknownFields.WriteTo(ref output);
+      }
+    }
+    #endif
+
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     public int CalculateSize() {
       int size = 0;