enums used with boost::mpl::integral_c may need to be extended.

[dabrahams]

This issue suggests that the enums being used with mpl::integral_c need two additional cases. The problem was detected by the newest Clang in trunk.

[dabrahams]

Actually the easiest workaround is to add an underlying type (e.g. int) for each of these enums.

enum example : int { zero };
constexpr example x{static_cast<example>(-1)};

[pdimov]

Can't add : int in C++03 libraries though.

[pdimov]

Something like this

enum int_float_mixture_enum
{
    // for mpl::integral_c<int_float_mixture_enum, integral_to_integral>
    int_float_mixture_enum_unused_first = -1,

    integral_to_integral,
    integral_to_float,
    float_to_integral,
    float_to_float,

    // for mpl::integral_c<int_float_mixture_enum, float_to_float>
    int_float_mixture_enum_unused_last
};

works, but then switch statements start generating "not all enumeration values handled in a switch" warnings. :-/

[pdimov]

Switching to boost::integral_constant seems to work and is the least intrusive fix.

[pdimov]

Applied 50a1eae to develop.