The char type is supposed to be like either signed char or unsigned
char, which one is implementation defined. Similarly, the wchar_t type
is supposed to be like one of the other integral types, which one is
implementation defined. Could we have some sort of structure indicating
those types' base types? I guess it would be something like:

//==========================================================================
template <typename T>  struct underlying_type;

template <> 
struct underlying_type<char> 
{
typedef something base_type;
};

// The following should be macro-blocked for compilers that don't have
// a separate wchar_t type.

template <> 
struct underlying_type<wchar_t> 
{
typedef something base_type;
};

// Should there be a general version of this template? If so, I guess that
// the those T types should map to themselves.

// We don't have to do class templates, maybe macro magic will do:
#if SOMETHING
typedef signed char char_underlying_type
#else
typedef unsigned char char_underlying_type
#endif

#if HAVE_INTRINSIC_WCHAR_T
#if SOMETHING
typedef signed char wchar_t_underlying_type
#elif SOMETHING_ELSE
typedef unsigned char wchar_t_underlying_type
//...
#else
typedef unsigned long long wchar_t_underlying_type
#endif
#endif
//==========================================================================

How would we figure out the types? I guess something using <climits>  macros
and/or comparisons from <limits>  values would be used. What header would
this go under, type_traits.hpp or a new one?

--
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT mac DOT com