Re: [Boost-bugs] [Boost C++ Libraries] #9843: binary serializer wrong behaviour treating enums

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9843: binary serializer wrong behaviour treating enums
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-04-10 07:09:22

#9843: binary serializer wrong behaviour treating enums
-------------------------------+-----------------------------------------
  Reporter:  jpjps@…           |      Owner:  ramey
      Type:  Bugs              |     Status:  reopened
 Milestone:  To Be Determined  |  Component:  serialization
   Version:  Boost 1.55.0      |   Severity:  Problem
Resolution:                    |   Keywords:  enum seriliazation typesize
-------------------------------+-----------------------------------------
Changes (by jpjps@…):

 * status:  closed => reopened
 * resolution:  invalid =>

Comment:

 simple snippet:

 {{{
         enum class SyncCode : unsigned char
         {
                 ProcessId,
                 ModuleFileName,
         };
         std::ostringstream stream;
         binary_oarchive archive(stream, boost::archive::no_header);
         archive << SyncCode::ProcessId;
         auto firstSize = stream.str().size();
         stream = std::ostringstream();
         archive << (unsigned char)SyncCode::ProcessId;
         auto secondarySize = stream.str().size();
 }}}

 firstSize results 4, secondarySize 1.
 on vs2013 / windows8.1 x64, targeted x86.

 simple trick works on this case:
 {{{
 //oserializer.hpp
 template<class Archive>
 struct save_enum_type
 {
         template<unsigned char TypeSize>
         struct same_sized_integral_type; // undefined
         template<>
         struct same_sized_integral_type<1>
         {
                 typedef unsigned char type;
         };
         template<>
         struct same_sized_integral_type<2>
         {
                 typedef unsigned short type;
         };
         template<>
         struct same_sized_integral_type<4>
         {
                 typedef unsigned int type;
         };
         template<>
         struct same_sized_integral_type<8>
         {
                 typedef unsigned long long type;
         };

     template<class T>
     static void invoke(Archive &ar, const T &t){
         // convert enum to integers on save
                 const same_sized_integral_type<sizeof(T)>::type i =
 static_cast<same_sized_integral_type<sizeof(T)>::type>(t);
         ar << boost::serialization::make_nvp(NULL, i);
     }
 };
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9843#comment:2>
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