id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
9944	Regression test relies on undefined compiler behavior	chris.cooper@…	No-Maintainer	"libs/utility/numeric_traits_test.cpp generates values complement_traits<Number>::min using a clever recursive template, but that template relies on left-shifting a negative value, and according to the C++11 standard that’s a no-no (“the behavior is undefined”) which means it’s not a constant expression, which means it can’t be calculated at compile time, which means the BOOST_STATIC_ASSERT in line 332 won’t compile, saying “static_assert expression is not an integral constant expression” (I’m using clang++). 

The only use for the clever templates, as the comment in the file says, is for ""platforms without <limits> support"" so my proposed fix is:

#ifndef BOOST_NO_LIMITS 
template <class Number> struct complement_traits
{
    BOOST_STATIC_CONSTANT(Number, min = std::numeric_limits<Number>::min());
    BOOST_STATIC_CONSTANT(Number, max = std::numeric_limits<Number>::max());
};
#else
[SNIP] All of the other template definitions for complement_traits, complement_traits_aux, etc.
#endif
"	Bugs	new	To Be Determined	utility	Boost 1.54.0	Problem