Canged CodedInputStream.ReadTag to use boolean result with out params to

support reading a field name rather than a field tag.

src/AddressBook/AddressBookProtos.cs

@@ -287,14 +287,12 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -327,6 +325,11 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -582,14 +585,12 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -624,6 +625,11 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -899,14 +905,12 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -929,6 +933,11 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtoGen/MessageGenerator.cs

@@ -615,19 +615,21 @@ namespace Google.ProtocolBuffers.ProtoGen
             {
                 writer.WriteLine("pb::UnknownFieldSet.Builder unknownFields = null;");
             }
-            writer.WriteLine("while (true) {");
+            writer.WriteLine("uint tag;");
+            writer.WriteLine("string field_name;");
+            writer.WriteLine("while (input.ReadTag(out tag, out field_name)) {");
             writer.Indent();
-            writer.WriteLine("uint tag = input.ReadTag();");
             writer.WriteLine("switch (tag) {");
             writer.Indent();
             writer.WriteLine("case 0: {"); // 0 signals EOF / limit reached
-            if (!UseLiteRuntime)
-            {
-                writer.WriteLine("  if (unknownFields != null) {");
-                writer.WriteLine("    this.UnknownFields = unknownFields.Build();");
-                writer.WriteLine("  }");
-            }
-            writer.WriteLine("  return this;");
+            //if (!UseLiteRuntime)
+            //{
+            //    writer.WriteLine("  if (unknownFields != null) {");
+            //    writer.WriteLine("    this.UnknownFields = unknownFields.Build();");
+            //    writer.WriteLine("  }");
+            //}
+            //writer.WriteLine("  return this;");
+            writer.WriteLine("  throw InvalidProtocolBufferException.InvalidTag();");
             writer.WriteLine("}");
             writer.WriteLine("default: {");
             writer.WriteLine("  if (pb::WireFormat.IsEndGroupTag(tag)) {");
@@ -663,6 +665,14 @@ namespace Google.ProtocolBuffers.ProtoGen
             writer.WriteLine("}");
             writer.Outdent();
             writer.WriteLine("}");
+            writer.WriteLine();
+            if (!UseLiteRuntime)
+            {
+                writer.WriteLine("if (unknownFields != null) {");
+                writer.WriteLine("  this.UnknownFields = unknownFields.Build();");
+                writer.WriteLine("}");
+            }
+            writer.WriteLine("return this;");
             writer.Outdent();
             writer.WriteLine("}");
             writer.WriteLine();

src/ProtocolBuffers.Test/CodedInputStreamTest.cs

@@ -283,16 +283,16 @@ namespace Google.ProtocolBuffers
             CodedInputStream input2 = CodedInputStream.CreateInstance(rawBytes);
             UnknownFieldSet.Builder unknownFields = UnknownFieldSet.CreateBuilder();
 
-            while (true)
+            uint tag;
+            string name;
+            while (input1.ReadTag(out tag, out name))
             {
-                uint tag = input1.ReadTag();
-                Assert.AreEqual(tag, input2.ReadTag());
-                if (tag == 0)
-                {
-                    break;
-                }
+                uint tag2;
+                Assert.IsTrue(input2.ReadTag(out tag2, out name));
+                Assert.AreEqual(tag, tag2);
+
                 unknownFields.MergeFieldFrom(tag, input1);
-                input2.SkipField(tag);
+                input2.SkipField();
             }
         }
 
@@ -355,7 +355,10 @@ namespace Google.ProtocolBuffers
             ms.Position = 0;
 
             CodedInputStream input = CodedInputStream.CreateInstance(ms);
-            Assert.AreEqual(tag, input.ReadTag());
+            uint testtag;
+            string ignore;
+            Assert.IsTrue(input.ReadTag(out testtag, out ignore));
+            Assert.AreEqual(tag, testtag);
 
             try
             {
@@ -497,7 +500,12 @@ namespace Google.ProtocolBuffers
             ms.Position = 0;
 
             CodedInputStream input = CodedInputStream.CreateInstance(ms);
-            Assert.AreEqual(tag, input.ReadTag());
+
+            uint testtag;
+            string ignored;
+
+            Assert.IsTrue(input.ReadTag(out testtag, out ignored));
+            Assert.AreEqual(tag, testtag);
             string text = input.ReadString();
             Assert.AreEqual('\ufffd', text[0]);
         }

src/ProtocolBuffers.Test/TestProtos/UnitTestCSharpOptionsProtoFile.cs

@@ -259,14 +259,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -295,6 +293,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs

@@ -576,14 +576,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -604,6 +602,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -779,14 +782,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -803,6 +804,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -959,14 +965,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -983,6 +987,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -1154,14 +1163,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1178,6 +1185,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -1334,14 +1346,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1358,6 +1368,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -1514,14 +1529,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1538,6 +1551,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -1694,14 +1712,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1718,6 +1734,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -1874,14 +1895,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1898,6 +1917,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -2054,14 +2078,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2078,6 +2100,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -2234,14 +2261,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2258,6 +2283,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -2476,14 +2506,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2512,6 +2540,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -2773,14 +2806,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2801,6 +2832,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -3018,14 +3054,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3064,6 +3098,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3359,14 +3398,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3387,6 +3424,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -3577,14 +3619,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3614,6 +3654,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3843,14 +3888,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3871,6 +3914,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -4045,14 +4093,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -4069,6 +4115,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }

src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs

@@ -253,14 +253,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -292,6 +290,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestGoogleSpeedProtoFile.cs

@@ -1069,14 +1069,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1262,6 +1260,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -2579,14 +2582,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2683,6 +2684,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3570,14 +3576,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3663,6 +3667,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -4736,14 +4745,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -4882,6 +4889,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -5838,14 +5850,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -5906,6 +5916,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestImportLiteProtoFile.cs

@@ -207,11 +207,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -226,6 +227,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestImportProtoFile.cs

@@ -232,14 +232,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -260,6 +258,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs

@@ -250,14 +250,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -274,6 +272,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -449,14 +452,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -482,6 +483,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -695,14 +701,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -723,6 +727,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -918,14 +927,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -946,6 +953,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1191,14 +1203,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1223,6 +1233,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -1416,14 +1431,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1446,6 +1459,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestNoGenericServicesProtoFile.cs

@@ -247,14 +247,12 @@ namespace Google.ProtocolBuffers.TestProtos.NoGenericService {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -275,6 +273,11 @@ namespace Google.ProtocolBuffers.TestProtos.NoGenericService {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestRpcInterop.cs

@@ -252,14 +252,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -280,6 +278,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -533,14 +536,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -565,6 +566,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -762,14 +768,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -792,6 +796,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1034,14 +1043,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1071,6 +1078,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/TestProtos/UnitTestXmlSerializerTestProtoFile.cs

@@ -320,14 +320,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -360,6 +358,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -561,14 +564,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -585,6 +586,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
     }
@@ -819,14 +825,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -859,6 +863,11 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -1195,14 +1204,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1254,6 +1261,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1613,14 +1625,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1641,6 +1651,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers.Test/WireFormatTest.cs

@@ -173,17 +173,13 @@ namespace Google.ProtocolBuffers
             CodedInputStream input = data.CreateCodedInput();
             uint previousTag = 0;
 
-            while (true)
+            uint tag;
+            string name;
+            while (input.ReadTag(out tag, out name))
             {
-                uint tag = input.ReadTag();
-                if (tag == 0)
-                {
-                    break;
-                }
-
                 Assert.IsTrue(tag > previousTag);
                 previousTag = tag;
-                input.SkipField(tag);
+                input.SkipField();
             }
         }
 

src/ProtocolBuffers/CodedInputStream.cs

@@ -162,29 +162,40 @@ namespace Google.ProtocolBuffers
         #endregion
 
         #region Reading of tags etc
-
+        
         /// <summary>
-        /// Attempt to read a field tag, returning 0 if we have reached the end
-        /// of the input data. Protocol message parsers use this to read tags,
-        /// since a protocol message may legally end wherever a tag occurs, and
-        /// zero is not a valid tag number.
+        /// Attempt to read a field tag, returning false if we have reached the end
+        /// of the input data.
         /// </summary>
+        /// <remarks>
+        /// <para>
+        /// If fieldTag is non-zero and ReadTag returns true then the value in fieldName
+        /// may or may not be populated.  However, if fieldTag is zero and ReadTag returns
+        /// true, then fieldName should be populated with a non-null field name.
+        /// </para><para>
+        /// In other words if ReadTag returns true then either fieldTag will be non-zero OR
+        /// fieldName will be non-zero.  In some cases both may be populated, however the
+        /// builders will always prefer the fieldTag over fieldName.
+        /// </para>
+        /// </remarks>
         [CLSCompliant(false)]
-        public uint ReadTag()
+        public bool ReadTag(out uint fieldTag, out string fieldName)
         {
+            fieldName = null;
+
             if (IsAtEnd)
             {
-                lastTag = 0;
-                return 0;
+                lastTag = fieldTag = 0;
+                return false;
             }
 
-            lastTag = ReadRawVarint32();
+            lastTag = fieldTag = ReadRawVarint32();
             if (lastTag == 0)
             {
                 // If we actually read zero, that's not a valid tag.
                 throw InvalidProtocolBufferException.InvalidTag();
             }
-            return lastTag;
+            return true;
         }
 
         /// <summary>
@@ -1030,8 +1041,9 @@ namespace Google.ProtocolBuffers
         /// <returns>false if the tag is an end-group tag, in which case
         /// nothing is skipped. Otherwise, returns true.</returns>
         [CLSCompliant(false)]
-        public bool SkipField(uint tag)
+        public bool SkipField()
         {
+            uint tag = lastTag;
             switch (WireFormat.GetTagWireType(tag))
             {
                 case WireFormat.WireType.Varint:
@@ -1065,10 +1077,11 @@ namespace Google.ProtocolBuffers
         /// </summary>
         public void SkipMessage()
         {
-            while (true)
+            uint tag;
+            string name;
+            while (ReadTag(out tag, out name))
             {
-                uint tag = ReadTag();
-                if (tag == 0 || !SkipField(tag))
+                if (!SkipField())
                 {
                     return;
                 }

src/ProtocolBuffers/DescriptorProtos/CSharpOptions.cs

@@ -514,14 +514,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -598,6 +596,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1012,14 +1015,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1040,6 +1041,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1234,14 +1240,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1262,6 +1266,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1456,14 +1465,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1484,6 +1491,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs

@@ -400,14 +400,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -430,6 +428,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -811,14 +814,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -880,6 +881,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -1358,14 +1364,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1390,6 +1394,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -1723,14 +1732,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1790,6 +1797,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -2385,14 +2397,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2462,6 +2472,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -2850,14 +2865,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -2893,6 +2906,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3202,14 +3220,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3243,6 +3259,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3538,14 +3559,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3581,6 +3600,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -3909,14 +3933,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3954,6 +3976,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -4382,14 +4409,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -4448,6 +4473,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -4838,14 +4868,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -4876,6 +4904,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -5228,14 +5261,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -5282,6 +5313,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -5579,14 +5615,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -5609,6 +5643,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -5833,14 +5872,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -5863,6 +5900,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -6087,14 +6129,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -6117,6 +6157,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -6341,14 +6386,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -6371,6 +6414,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       
@@ -6635,14 +6683,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
             pb::UnknownFieldSet.Builder unknownFields = null;
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  if (unknownFields != null) {
-                    this.UnknownFields = unknownFields.Build();
-                  }
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -6667,6 +6713,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
                 }
               }
             }
+            
+            if (unknownFields != null) {
+              this.UnknownFields = unknownFields.Build();
+            }
+            return this;
           }
           
           
@@ -6959,14 +7010,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7009,6 +7058,11 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffers/ExtendableBuilderLite.cs

@@ -168,7 +168,7 @@ namespace Google.ProtocolBuffers
             if (unknown)
             {
                 // Unknown field or wrong wire type.  Skip.
-                return input.SkipField(tag);
+                return input.SkipField();
             }
 
             if (packed)

src/ProtocolBuffers/GeneratedBuilderLite.cs

@@ -101,7 +101,7 @@ namespace Google.ProtocolBuffers
         protected virtual bool ParseUnknownField(CodedInputStream input,
                                                  ExtensionRegistry extensionRegistry, uint tag)
         {
-            return input.SkipField(tag);
+            return input.SkipField();
         }
 
         /// <summary>

src/ProtocolBuffers/InvalidProtocolBufferException.cs

@@ -71,7 +71,7 @@ namespace Google.ProtocolBuffers
                 "CodedInputStream encountered a malformed varint.");
         }
 
-        internal static InvalidProtocolBufferException InvalidTag()
+        public static InvalidProtocolBufferException InvalidTag()
         {
             return new InvalidProtocolBufferException(
                 "Protocol message contained an invalid tag (zero).");

src/ProtocolBuffers/MessageStreamIterator.cs

@@ -219,13 +219,14 @@ namespace Google.ProtocolBuffers
                 CodedInputStream input = CodedInputStream.CreateInstance(stream);
                 input.SetSizeLimit(sizeLimit);
                 uint tag;
-                while ((tag = input.ReadTag()) != 0)
+                string name;
+                while (input.ReadTag(out tag, out name))
                 {
-                    if (tag != ExpectedTag)
-                    {
+                    if ((tag == 0 && name == "item") || (tag == ExpectedTag))
+                        yield return messageReader(input, extensionRegistry);
+                    else
                         throw InvalidProtocolBufferException.InvalidMessageStreamTag();
-                    }
-                    yield return messageReader(input, extensionRegistry);
+
                     input.ResetSizeCounter();
                 }
             }

src/ProtocolBuffers/UnknownFieldSet.cs

@@ -419,13 +419,19 @@ namespace Google.ProtocolBuffers
             /// </summary>
             public Builder MergeFrom(CodedInputStream input)
             {
-                while (true)
+                uint tag;
+                string name;
+                while (input.ReadTag(out tag, out name))
                 {
-                    uint tag = input.ReadTag();
-                    if (tag == 0 || !MergeFieldFrom(tag, input))
+                    if (tag == 0)
                     {
+                        if (input.SkipField())
+                            continue; //can't merge unknown without field tag
                         break;
                     }
+
+                    if(!MergeFieldFrom(tag, input))
+                        break;
                 }
                 return this;
             }
@@ -581,11 +587,14 @@ namespace Google.ProtocolBuffers
 
             internal void MergeFrom(CodedInputStream input, ExtensionRegistry extensionRegistry, IBuilder builder)
             {
-                while (true)
+                uint tag;
+                string name;
+                while (input.ReadTag(out tag, out name))
                 {
-                    uint tag = input.ReadTag();
                     if (tag == 0)
                     {
+                        if (input.SkipField())
+                            continue; //can't merge unknown without field tag
                         break;
                     }
 
@@ -765,11 +774,14 @@ namespace Google.ProtocolBuffers
                 IBuilderLite subBuilder = null;
                 FieldDescriptor field = null;
 
-                while (true)
+                uint tag;
+                string name;
+                while (input.ReadTag(out tag, out name))
                 {
-                    uint tag = input.ReadTag();
                     if (tag == 0)
                     {
+                        if (input.SkipField())
+                            continue; //can't merge unknown without field tag
                         break;
                     }
 
@@ -833,7 +845,7 @@ namespace Google.ProtocolBuffers
                     else
                     {
                         // Unknown tag.  Skip it.
-                        if (!input.SkipField(tag))
+                        if (!input.SkipField())
                         {
                             break; // end of group
                         }

src/ProtocolBuffersLite.Test/TestProtos/UnitTestExtrasLiteProtoFile.cs

@@ -247,11 +247,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -274,6 +275,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -541,11 +544,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           }
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -568,6 +572,8 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            return this;
           }
           
           
@@ -876,11 +882,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           }
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -911,6 +918,8 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            return this;
           }
           
           
@@ -1321,11 +1330,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1369,6 +1379,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -1706,11 +1718,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1725,6 +1738,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       

src/ProtocolBuffersLite.Test/TestProtos/UnitTestImportLiteProtoFile.cs

@@ -207,11 +207,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -226,6 +227,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       

src/ProtocolBuffersLite.Test/TestProtos/UnitTestImportProtoFile.cs

@@ -232,14 +232,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
         pb::UnknownFieldSet.Builder unknownFields = null;
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              if (unknownFields != null) {
-                this.UnknownFields = unknownFields.Build();
-              }
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -260,6 +258,11 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        if (unknownFields != null) {
+          this.UnknownFields = unknownFields.Build();
+        }
+        return this;
       }
       
       

src/ProtocolBuffersLite.Test/TestProtos/UnitTestLiteImportNonLiteProtoFile.cs

@@ -196,11 +196,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -220,6 +221,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       

src/ProtocolBuffersLite.Test/TestProtos/UnitTestLiteProtoFile.cs

@@ -1250,11 +1250,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           }
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1269,6 +1270,8 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            return this;
           }
           
           
@@ -1465,11 +1468,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           }
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1484,6 +1488,8 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            return this;
           }
           
           
@@ -1680,11 +1686,12 @@ namespace Google.ProtocolBuffers.TestProtos {
           }
           
           public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-            while (true) {
-              uint tag = input.ReadTag();
+            uint tag;
+            string field_name;
+            while (input.ReadTag(out tag, out field_name)) {
               switch (tag) {
                 case 0: {
-                  return this;
+                  throw InvalidProtocolBufferException.InvalidTag();
                 }
                 default: {
                   if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -1699,6 +1706,8 @@ namespace Google.ProtocolBuffers.TestProtos {
                 }
               }
             }
+            
+            return this;
           }
           
           
@@ -3607,11 +3616,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -3958,6 +3968,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -5724,11 +5736,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -5743,6 +5756,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -6430,11 +6445,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -6575,6 +6591,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -7123,11 +7141,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7138,6 +7157,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
     }
@@ -7316,11 +7337,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7335,6 +7357,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -7531,11 +7555,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7550,6 +7575,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
       
@@ -7732,11 +7759,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7747,6 +7775,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
     }
@@ -7905,11 +7935,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -7920,6 +7951,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }
       
     }
@@ -8098,11 +8131,12 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       public override Builder MergeFrom(pb::CodedInputStream input, pb::ExtensionRegistry extensionRegistry) {
-        while (true) {
-          uint tag = input.ReadTag();
+        uint tag;
+        string field_name;
+        while (input.ReadTag(out tag, out field_name)) {
           switch (tag) {
             case 0: {
-              return this;
+              throw InvalidProtocolBufferException.InvalidTag();
             }
             default: {
               if (pb::WireFormat.IsEndGroupTag(tag)) {
@@ -8117,6 +8151,8 @@ namespace Google.ProtocolBuffers.TestProtos {
             }
           }
         }
+        
+        return this;
       }