Re: [Boost-bugs] [Boost C++ Libraries] #11423: Serialization with versioning not working with (pure virtual) base classes

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11423: Serialization with versioning not working with (pure virtual) base classes
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-06-30 10:37:55

#11423: Serialization with versioning not working with (pure virtual) base classes
-------------------------------+---------------------------
  Reporter:  anonymous         |      Owner:  ramey
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  serialization
   Version:  Boost 1.58.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+---------------------------

Comment (by anonymous):

 Replying to [comment:1 ramey]:
 > I can't imagine why this would be a problem.
 >
 > In order to help with this, I'd really have to see a small example
 demonstrating the problem.

 I stepped through the code and found that what I'm observing (version
 number ignored) is due to a different reason, though serializing an
 inheritance hierarchy may be heavily affected by this issue.

 Here is what I found:
 Consider the following class structure that are contained in two different
 modules (compilation units).

 ===========
 ModuleA.dll
 ===========

 class ClassA
 {
     template<class Archive>
     void serialize(Archive &ar, const unsigned int uiVersion);
 };

 BOOST_CLASS_VERSION(ClassA, 1)

 ===========
 ModuleA.dll
 ===========
 [[BR]]
 [[BR]]
 ===========
 ModuleB.dll
 ===========

 class ClassB : public ClassA
 {
     template<class Archive>
     void serialize(Archive &ar, const unsigned int uiVersion)
     {
       ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(ClassA);
     }
 }

 BOOST_CLASS_VERSION(ClassB, 1)

 ===========
 ModuleB.dll
 ===========


 Now consider the following call stack:

 [...][[BR]]
 ModuleB.dll!ClassB::serialize(...) <- this triggers
 BOOST_SERIALIZATION_BASE_OBJECT_NVP(ClassA); [[BR]]
 [...][[BR]]
 ModuleB.dll!oserializer<Archive, ClassA>::save_object_data(...) <- this
 call uses ::boost::serialization::version<ClassA>::value [[BR]]


 The problem now is that ::boost::serialization::version<ClassA>::value
 evaluates to 0 as the specialization (version #1) is only known inside
 ModuleA.

 I think this should be a new ticket if this is indeed the issue...

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11423#comment:2>
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