fix bug for Field Presence

src/google/protobuf/compiler/csharp/csharp_enum_field.cc

@@ -170,7 +170,7 @@ void EnumFieldGenerator::WriteHash(Writer* writer) {
   } else {
     writer->WriteLine("if ($0$ != $1$) {", property_name(), default_value());
   }
-  writer->WriteLine("  hash ^= $1$_.GetHashCode();", name());
+  writer->WriteLine("  hash ^= $0$_.GetHashCode();", name());
   writer->WriteLine("}");
 }
 void EnumFieldGenerator::WriteEquals(Writer* writer) {

src/google/protobuf/compiler/csharp/csharp_primitive_field.cc

@@ -161,7 +161,7 @@ void PrimitiveFieldGenerator::WriteHash(Writer* writer) {
   } else {
     writer->WriteLine("if ($0$ != $1$) {", property_name(), default_value());
   }
-  writer->WriteLine("  hash ^= $1$_.GetHashCode();", name());
+  writer->WriteLine("  hash ^= $0$_.GetHashCode();", name());
   writer->WriteLine("}");
 }
 void PrimitiveFieldGenerator::WriteEquals(Writer* writer) {