Steven Watanabe — Wed, 16 Jun 2010 03:37:17 GMT

Hmmm. The fact that this even compiles is an artifact of the way mpl::na is implemented. and_ is only intended to take two or more arguments.

owner, version, severity, milestone changed; cc set

Bryce Adelstein Lelbach — Thu, 30 Dec 2010 14:39:41 GMT

cc admin@… added
owner changed from Aleksey Gurtovoy to Joel Falcou
version Boost 1.44.0 → Boost Development Trunk
severity Cosmetic → Problem
milestone Boost 1.43.0 → Boost 1.46.0

Confirmed, this is still a problem, possibly a problem with other binary logical operations too. I think we need to prohibit an unary and_ entirely. This reproduces the problem:

#include <boost/mpl/assert.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/and.hpp>
int main (void) {
  using boost::mpl::and_;
  using boost::mpl::true_;
  BOOST_MPL_ASSERT((and_<true_>));
}

Boost C++ Libraries: Ticket #4301: and_::type is false_

owner, version, severity, milestone changed; cc set