[boost] RE: const_string + recursive_variant = boom

From: Maxim Yegorushkin (e-maxim_at_[hidden])
Date: 2004-11-04 14:18:29

I striped the sample down to:

    typedef make_recursive_variant<int, std::pair<int,
recursive_variant_> >::type value;
    value v;

Which compiles fine with MS VC 7.1 and fails to compile on Intel C++ 8.

Here is Intel output:

C:\Program Files\Microsoft Visual Studio .NET
2003\Vc7/include/utility(51): error: incomplete type is not allowed
          _Ty2 second;	// the second stored value
               ^
          detected during:
            instantiation of class "std::pair<_Ty1, _Ty2> [with
_Ty1=int, _Ty2=boost::recursive_variant_]" at line 252 of
"D:\lib\boost\boost/variant/detail/visitation_impl.hpp"
            instantiation of "Visitor::result_type
boost::detail::variant::visitation_impl(const int, const int, Visitor &,
VoidPtrCV, boost::mpl::false_, NoBackupFlag, Which *, step0 *) [with
Which=boost::mpl::int_<0>,
step0=boost::detail::variant::visitation_impl_step<boost::mpl::begin<boo
st::variant<boost::detail::variant::recursive_flag<int>, std::pair<int,
boost::recursive_variant_>, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
                      boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_,
 
boost::detail::variant::void_>::recursive_enabled_types>::type,
boost::mpl::end<boost::variant<boost::detail::variant::recursive_flag<in
t>, std::pair<int, boost::recursive_variant_>,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_,
                      boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_,
boost::detail::variant::void_>::recursive_enabled_types>::type>,
Visitor=boost::detail::variant::destroyer, VoidPtrCV=void *,
NoBackupFlag=boost::variant<boost::detail::variant::recursive_flag<int>,
std::pair<int,
                      boost::recursive_variant_>,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
                      boost::detail::variant::void_,
boost::detail::variant::void_, boost::detail::variant::void_,
boost::detail::variant::void_>::has_fallback_type_]" at line 1738 of
"D:\lib\boost\boost/variant/variant.hpp"
            instantiation of "Visitor::result_type boost::variant<T0_,
T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16,
T17, T18, T19>::internal_apply_visitor_impl(int, int, Visitor &,
VoidPtrCV) [with T0_=boost::detail::variant::recursive_flag<int>,
T1=std::pair<int, boost::recursive_variant_>,
T2=boost::detail::variant::void_, T3=boost::detail::variant::void_,
T4=boost::detail::variant::void_, T5=boost::detail::variant::void_,
T6=boost::detail::variant::void_,
                      T7=boost::detail::variant::void_,
T8=boost::detail::variant::void_, T9=boost::detail::variant::void_,
T10=boost::detail::variant::void_, T11=boost::detail::variant::void_,
T12=boost::detail::variant::void_, T13=boost::detail::variant::void_,
T14=boost::detail::variant::void_, T15=boost::detail::variant::void_,
T16=boost::detail::variant::void_, T17=boost::detail::variant::void_,
T18=boost::detail::variant::void_, T19=boost::detail::variant::void_,
                      Visitor=boost::detail::variant::destroyer,
VoidPtrCV=void *]" at line 1749 of
"D:\lib\boost\boost/variant/variant.hpp"
            instantiation of "Visitor::result_type boost::variant<T0_,
T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16,
T17, T18, T19>::internal_apply_visitor(Visitor &) [with
T0_=boost::detail::variant::recursive_flag<int>, T1=std::pair<int,
boost::recursive_variant_>, T2=boost::detail::variant::void_,
T3=boost::detail::variant::void_, T4=boost::detail::variant::void_,
T5=boost::detail::variant::void_, T6=boost::detail::variant::void_,
T7=boost::detail::variant::void_,
                      T8=boost::detail::variant::void_,
T9=boost::detail::variant::void_, T10=boost::detail::variant::void_,
T11=boost::detail::variant::void_, T12=boost::detail::variant::void_,
T13=boost::detail::variant::void_, T14=boost::detail::variant::void_,
T15=boost::detail::variant::void_, T16=boost::detail::variant::void_,
T17=boost::detail::variant::void_, T18=boost::detail::variant::void_,
T19=boost::detail::variant::void_,
Visitor=boost::detail::variant::destroyer]" at line 1157 of
                      "D:\lib\boost\boost/variant/variant.hpp"
            instantiation of "void boost::variant<T0_, T1, T2, T3, T4,
T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18,
T19>::destroy_content() [with
T0_=boost::detail::variant::recursive_flag<int>, T1=std::pair<int,
boost::recursive_variant_>, T2=boost::detail::variant::void_,
T3=boost::detail::variant::void_, T4=boost::detail::variant::void_,
T5=boost::detail::variant::void_, T6=boost::detail::variant::void_,
T7=boost::detail::variant::void_, T8=boost::detail::variant::void_,
                      T9=boost::detail::variant::void_,
T10=boost::detail::variant::void_, T11=boost::detail::variant::void_,
T12=boost::detail::variant::void_, T13=boost::detail::variant::void_,
T14=boost::detail::variant::void_, T15=boost::detail::variant::void_,
T16=boost::detail::variant::void_, T17=boost::detail::variant::void_,
T18=boost::detail::variant::void_, T19=boost::detail::variant::void_]"
at line 1164 of "D:\lib\boost\boost/variant/variant.hpp"
            instantiation of "boost::variant<T0_, T1, T2, T3, T4, T5,
T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18,
T19>::~variant() [with T0_=boost::detail::variant::recursive_flag<int>,
T1=std::pair<int, boost::recursive_variant_>,
T2=boost::detail::variant::void_, T3=boost::detail::variant::void_,
T4=boost::detail::variant::void_, T5=boost::detail::variant::void_,
T6=boost::detail::variant::void_, T7=boost::detail::variant::void_,
T8=boost::detail::variant::void_,
                      T9=boost::detail::variant::void_,
T10=boost::detail::variant::void_, T11=boost::detail::variant::void_,
T12=boost::detail::variant::void_, T13=boost::detail::variant::void_,
T14=boost::detail::variant::void_, T15=boost::detail::variant::void_,
T16=boost::detail::variant::void_, T17=boost::detail::variant::void_,
T18=boost::detail::variant::void_, T19=boost::detail::variant::void_]"

> -----Original Message-----
> From: Caleb Epstein [mailto:caleb.epstein_at_[hidden]]
> Sent: Thursday, November 04, 2004 9:00 PM
> To: boost_at_[hidden]; Maxim Yegorushkin
> Subject: const_string + recursive_variant = boom
> 
> I've been trying to build a generic "message" type class using
> boost.variant and have just run across a problem when trying to
> convert it from using std::string to using the proposed
> boost::const_string.
> 
> Attached is a small test case and the output from gcc 3.3.2 (the
> latter gzipped due to its hugeness).  All is well if the mystring type
> is std::string.
> 
> Any thoughts on how to fix this?
> 
> --
> Caleb Epstein
> caleb.epstein_at_[hidden]