message: Enable CONSTCD14 for VS2017
diff: @@ -57,15 +57,22 @@ namespace date
  // Configuration |
  //---------------+
  -// MSVC's constexpr support is still a WIP, even in VS2015.
  -// Fall back to a lesser mode to support it.
  -// TODO: Remove this or retest later once MSVC's constexpr improves.
  -#if defined(_MSC_VER) && _MSC_VER <= 1900 && ! defined(__clang__)
  -// MS cl compiler pre VS2017
  +#if defined(_MSC_VER) && !defined(__clang__)
  +// MSVC
  +# if _MSC_VER < 1910
  +// before VS2017
  # define CONSTDATA const
  # define CONSTCD11
  # define CONSTCD14
  # define NOEXCEPT _NOEXCEPT
  +# else
  +// VS2017 and later
  +# define CONSTDATA constexpr const
  +# define CONSTCD11 constexpr
  +# define CONSTCD14 constexpr
  +# define NOEXCEPT noexcept
  +# endif
  +
  #elif __cplusplus >= 201402
  // C++14
  # define CONSTDATA constexpr const
  