anchor.diff:       f("~p([], Bin) ->~n", [PackedFnName]),
        f("    Bin.~n~n")].
   
  -format_unknowsize_packed_field_encoder2(MsgName, #field{name=FName,
  -                                                        fnum=FNum}=FDef) ->
  +format_unknownsize_packed_field_encoder2(MsgName, #field{name=FName,
  +                                                         fnum=FNum}=FDef) ->
       FnName = mk_field_encode_fn_name(MsgName, FDef),
       ElemEncoderFn = mk_field_encode_fn_name(MsgName,
                                               FDef#field{occurrence=required}),
  
positive.code: format_packed_field_encoder2(MsgName, #field{type=Type}=FDef) ->
      case packed_byte_size_can_be_computed(Type) of
          {yes, BitLen, BitType} ->
              format_knowsize_packed_field_encoder2(MsgName, FDef,
                                                    BitLen, BitType);
          no ->
              format_unknowsize_packed_field_encoder2(MsgName, FDef)
      end.
  
  packed_byte_size_can_be_computed(fixed32)  -> {yes, 32, 'little'};
  
negative.code: packed_byte_size_can_be_computed(double)   -> {yes, 64, 'little-float'};
  packed_byte_size_can_be_computed(_)        -> no.
  
  format_knownsize_packed_field_encoder2(MsgName, #field{name=FName,
                                                         fnum=FNum}=FDef,
                                        BitLen, BitType) ->
      FnName = mk_field_encode_fn_name(MsgName, FDef),
      KeyTxt = mk_key_txt(FNum, bytes),
  