[Boost-users] question about BOOST_CONCEPT_REQUIRES

Subject: [Boost-users] question about BOOST_CONCEPT_REQUIRES
From: Robert Ramey (ramey_at_[hidden])
Date: 2013-08-18 15:56:32

#include "boost/concept/requires.hpp"
#include "boost/concept_check.hpp"
#include <iterator>
template <typename T>
BOOST_CONCEPT_REQUIRES((
    ((boost::ForwardIterator<T>))
    ((boost::LessThanComparable<
        typename std::iterator_traits<T>::value_type
    >))
    ),
    (void)
)
bubble_sort(T begin, T end);

if I compile this with gcc 4.5.3 I get some error messages which I don't 
expect to see:

z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: * cannot 
appear in a constant-expression
z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: a call 
to a constructor cannot appear in a constant-expression
z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: template 
argument 1 is invalid
z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: template 
argument 1 is invalid
z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:14:28: error: invalid 
type in declaration before ; token

Note this occurs even before the template declaration is invoked.

Any insight would be appreciated.

Robert Ramey