Round up to the next highest power of 2 using C++11 compile-time templates

nextpow2.hpp

#include <type_traits>
#include <limits>

template <typename UIntType, UIntType v, unsigned int n>
struct set_lower_bits : public std::integral_constant<UIntType, v | (v >> n) | set_lower_bits<UIntType, v | (v >> n), (n >> 1)>::value> {};

template <typename UIntType, UIntType v>
struct set_lower_bits<UIntType, v, 1> : public std::integral_constant<UIntType, v | (v >> 1)> {};

template <typename UIntType, UIntType v>
struct nextpow2 : public std::integral_constant<UIntType, set_lower_bits<UIntType, v - 1, (std::numeric_limits<UIntType>::digits >> 1)>::value + 1> {};