This constexpr code does not compiled in Visual Studio 2013 version 12.0.21005.1 REL
Is there a newer Visual Studio compiler that works with constexpr?
Microsoft publishes a C++11 compatibility table, under which constexpr is clearly marked as not being available in Visual Studio 2013.
constexpr
The November 2013 CTP has it, though.
Source: Google visual studio constexpr
visual studio constexpr