title: Facing undefined reference error after upgrading Protobuf
body: <p>I had upgraded the protoc version from <strong>3.0.0</strong> to <strong>3.15.2</strong> . Now I am unable to compile the program that uses protoc output files(*.pb.cpp , *.pb.h). I am getting the error as shown below:</p>
  <pre><code>In function `google::protobuf::io::EpsCopyOutputStream::EnsureSpace(unsigned char*)':
  /usr/local/include/google/protobuf/io/coded_stream.h:694: undefined reference to `google::protobuf::io::EpsCopyOutputStream::EnsureSpaceFallback(unsigned char*)'
  
   In function `google::protobuf::internal::TaggedPtr&lt;std::string&gt;::Set(std::string*)':
  /usr/local/include/google/protobuf/arenastring.h:101: undefined reference to `google::protobuf::internal::fixed_address_empty_string'
  
   In function `google::protobuf::Arena::AllocateAlignedWithHook(unsigned long, unsigned long, std::type_info const*)':
  /usr/local/include/google/protobuf/arena.h:700: undefined reference to `google::protobuf::Arena::AllocateAlignedWithHook(unsigned long, std::type_info const*)'
  
   In function `google::protobuf::internal::ReadTag(char const*, unsigned int*, unsigned int)':
  /usr/local/include/google/protobuf/parse_context.h:544: undefined reference to `google::protobuf::internal::ReadTagFallback(char const*, unsigned int)'
  
   In function `google::protobuf::Arena::SpaceAllocated() const':
  /usr/local/include/google/protobuf/arena.h:349: undefined reference to `google::protobuf::internal::ThreadSafeArena::SpaceAllocated() const'
  
   In function `google::protobuf::UnknownFieldSet::Clear()':
  /usr/local/include/google/protobuf/unknown_field_set.h:312: undefined reference to `google::protobuf::UnknownFieldSet::ClearFallback()'
  
  </code></pre>
  <p>I am facing this <strong>undefined reference</strong> error in <strong>google::protobuf</strong> path . There are so many lines of same errors of the kind show above.
  <strong>Do I have to include any other additional library for the upgraded version ?</strong>
  or
  <strong>Do I have to change path of any library ?</strong> as here <a href="https://stackoverflow.com/questions/48911254/undefined-reference-to-google-protobuf">undefined reference to google protobuf</a></p>
  <p>Any kind of help with respect to this is appreciated .</p>
  <p><strong>Thank you</strong></p>