[boost] [concept_check] fails with types declared in anonymous namespace (gcc 4.2.3)

From: Stephan Diederich (stephan.diederich_at_[hidden])
Date: 2008-06-17 09:39:53

Hi,

after upgrading to gcc 4.2.3 the following snippet fails to compile

#include <boost/concept_check.hpp>
struct MyVisitor{};
namespace test{ struct MyVisitor{};}
namespace{ struct MyVisitorAnon{};}

int main(){
   using namespace boost;
   function_requires<CopyConstructible<MyVisitor> >();
   function_requires<CopyConstructible<test::MyVisitor> >();
   function_requires<CopyConstructible<MyVisitorAnon> >(); //this line
breaks the build
   return 0;
}

with the error message:
/usr/include/boost/concept_check.hpp: In instantiation of
'boost::CopyConstructible<<unnamed>::MyVisitorAnon>':
/usr/include/boost/concept/detail/has_constraints.hpp:40:
instantiated from 'const bool
boost::concept::not_satisfied<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>::value'
/usr/include/boost/concept/detail/has_constraints.hpp:43:
instantiated from
'boost::concept::not_satisfied<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>'
/usr/include/boost/mpl/if.hpp:67:   instantiated from
'boost::mpl::if_<boost::concept::not_satisfied<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>, boost::concept::constraint<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>, boost::concept::requirement<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
> >'
/usr/include/boost/concept/detail/general.hpp:19:   instantiated from
'boost::concept::requirement_<void
(*)(boost::CopyConstructible<<unnamed>::MyVisitorAnon>)>'
/usr/include/boost/concept_check.hpp:43:   instantiated from 'void
boost::function_requires(Model*) [with Model =
boost::CopyConstructible<<unnamed>::MyVisitorAnon>]'
/home/diederich/projects/tests/make/graph_concept.cpp:11:
instantiated from here
/usr/include/boost/concept_check.hpp:156: error:
'boost::concept::requirement<Model>::failed [with Model =
boost::concept::usage_requirements<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>]' is not a valid template argument for type 'void (*)()' because
function 'static void boost::concept::requirement<Model>::failed()
[with Model = boost::concept::usage_requirements<boost::CopyConstructible<<unnamed>::MyVisitorAnon>
>]' has not external linkage
/usr/include/boost/concept_check.hpp: In function 'void
boost::function_requires(Model*) [with Model =
boost::CopyConstructible<<unnamed>::MyVisitorAnon>]':
/home/diederich/projects/tests/make/graph_concept.cpp:11:
instantiated from here
/usr/include/boost/concept_check.hpp:43: error:
'boost::concept::requirement<Model>::failed [with Model =
boost::CopyConstructible<<unnamed>::MyVisitorAnon>]' is not a valid
template argument for type 'void (*)()' because function 'static void
boost::concept::requirement<Model>::failed() [with Model =
boost::CopyConstructible<<unnamed>::MyVisitorAnon>]' has not external
linkage

I found the error while compiling a module which uses
depth_first_search where a visitor is declared in an unnamed
namespace.
Can someone help me with that?

Thanks in advance,
Stephan