Re: [Boost-bugs] [Boost C++ Libraries] #9647: BOOST_MPL_ASSERT_RELATION fails to properly handle unsigned types

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9647: BOOST_MPL_ASSERT_RELATION fails to properly handle unsigned types
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-03-23 18:23:55

#9647: BOOST_MPL_ASSERT_RELATION fails to properly handle unsigned types
-------------------------------+----------------------
  Reporter:  ramey             |      Owner:  viboes
      Type:  Bugs              |     Status:  assigned
 Milestone:  To Be Determined  |  Component:  integer
   Version:  Boost 1.54.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+----------------------

Comment (by ramey):

 I looked into this a little bit more.

 First of all, my original guess about problematic type promotions was
 wrong - I don't think there is any issue with libc++ or anything else in
 the standard library.

 The following test program illustrates my

 {{{
 #include <boost/integer_traits.hpp>
 #include <boost/mpl/assert.hpp>

 BOOST_MPL_ASSERT_RELATION(
     (boost::integer_traits<unsigned long>::const_max),
     >,
     (boost::integer_traits<unsigned char>::const_max)
 ); // compile error under clang

 enum { x  = (
     (boost::integer_traits<unsigned long>::const_max)
     >
     (boost::integer_traits<unsigned char>::const_max)
     )
 }; // compiles OK - can't figure out why

 constexpr bool result = (
     (boost::integer_traits<unsigned long>::const_max)
     >
     (boost::integer_traits<unsigned char>::const_max)
     ); // compiles fine

 static_assert(result, "compilation error");

 int main(int argc, char * argv[]){
     return ! (boost::integer_traits<unsigned long>::const_max >
 boost::integer_traits<unsigned char>::const_max);
 }
 }}}

 So I believe this is an issue with MPL_ASSERT_RELATION.  I've believe the
 problem is found in boost/mpl/assert.hpp at the line #329:  It's probably
 deeper than this but I didn't trace it further

 Robert Ramey

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9647#comment:4>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.