Re: [Boost-users] Serialization: C4308 warning with MSVC9

19 May 2010

      --- On Tue, 5/18/10, Robert Ramey  wrote:
...
From: Robert Ramey 
Subject: Re: [Boost-users] Serialization: C4308 warning with MSVC9
To: boost-users@lists.boost.org
Date: Tuesday, May 18, 2010, 10:35 PM
Political Confusion wrote:
...
Political Confusion  writes:
...
I'm using Boost 1.43 with MSVC9 SP1 and Windows
...
I've
created a class like the "A Very
Simple Case" example (i.e. added 'access' as
friend and a templated
serialize function).  In serialize, I just
archive 10 ints (signed
and unsigned).  It compiles fine, but when I
add
SDK v7 on Windows 7.
program code to save my class to
...
a text_oarchive, I get a warning:
c:\third-party\boost_1_43_0\boost\mpl\print.hpp(51) :
warning C4308:
...
negative integral constant converted to unsigned
type
Line 51 of print.hpp is: enum { n = sizeof(T) + -1
};
Calling sizeof() on my class gives a 44.  I
do not get any warning
when I load
my class with text_iarchive.  And
both save and load appear to work fine.
I had to add the following to make this warning go
away:
BOOST_CLASS_TRACKING( my_class,
boost::serialization::track_never )
This warning should precede a long call chain.  If you
go to the the
call BEFORE this, you should find a comment which indicates
why this
warning is invoked.
Robert Ramey
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Hello Robert,

That's what I did.  The lines above the warning (boost/archive/detail/check.hpp(98)):

    // saving an non-const object of a type not marked "track_never)

    // may be an indicator of an error usage of the
    // serialization library and should be double checked.  
    // See documentation on object tracking.  Also, see the 
    // "rationale" section of the documenation
    // for motivation for this checking.

    BOOST_STATIC_WARNING(typex::value);

So I added the BOOST_CLASS_TRACKING() line.  I get the same warning if I modify save_schedule() in demo.cpp to instantiate a gps_position and save it to oa.  gps_position was the example I used for my class.

Thanks for the reply and thanks for your work.