Canged CodedInputStream.ReadTag to use boolean result with out params to
support reading a field name rather than a field tag.
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
index 53a076e..c300e20 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
@@ -576,14 +576,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

       

@@ -779,14 +782,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -959,14 +965,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -1154,14 +1163,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -1334,14 +1346,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -1514,14 +1529,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -1694,14 +1712,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -1874,14 +1895,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -2054,14 +2078,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -2234,14 +2261,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }

@@ -2476,14 +2506,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

       

@@ -2773,14 +2806,12 @@
           

           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 @@
                 }

               }

             }

+            

+            if (unknownFields != null) {

+              this.UnknownFields = unknownFields.Build();

+            }

+            return this;

           }

           

           

@@ -3018,14 +3054,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

       

@@ -3359,14 +3398,12 @@
           

           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 @@
                 }

               }

             }

+            

+            if (unknownFields != null) {

+              this.UnknownFields = unknownFields.Build();

+            }

+            return this;

           }

           

           

@@ -3577,14 +3619,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

       

@@ -3843,14 +3888,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

       

@@ -4045,14 +4093,12 @@
       

       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 @@
             }

           }

         }

+        

+        if (unknownFields != null) {

+          this.UnknownFields = unknownFields.Build();

+        }

+        return this;

       }

       

     }