It's horrible when you use a "std::uint16_t" only to find that it
promotes to a signed 32-Bit integer. Believe it or not, I recently
wrote the following code:

        using std::uint_fast32_t;
        // We can't use uint_fast32_t if it undergoes promotion,
        // so instead use long unsigned (which might be 64-Bit)
        typedef typename std::conditional<
            std::is_same< uint_fast32_t, decltype(uint_fast32_t() +
uint_fast32_t()) >::value,
            uint_fast32_t,
            long unsigned >::type UIntType;

So how about if we could tell the compiler that we want to use a
specific integer type, and that we don't want it to promote. Perhaps
here's how we'd define such an integer:

    short unsigned _NoPromo n = 0xFFFF;

And similarly, if we already have a variable, and we want to do some
calculations without it promoting at some point, then we make a
_NoPromo reference to it:

    short unsigned original_variable = 0xFFFF;

    short unsigned _NoPromo &safe_variable = original_variable;

    safe_variable = ~safe_variable; // no promotion takes place here