G++ enums 'underlying type'

[Gabriel Dos Reis]

Paul Schlie <schlie@comcast.net> writes:

| > From: Paolo Carlini <pcarlini at suse dot de>
| > assuming something specific about g++ 'underlying type' (7.2/5) will alow me
| > to remarkably simplifiy the implementation of tr1/type_traits/is_enum: is it
| > signed or not? Basing on some simple experiments on x86, seems always wide
| > either like an int or a long: is this correct in general?
| 
| To my understanding, C enums need only be represented as the smallest rank
| signed or unsigned integer type capable of representing it's value range
| (although GCC tends to first unnecessarily promote enums to int, which I
| believe is officially the largest enum equivalent type, and then back them
| down opportunistically; keeping their converted form as small as possible is
| significant to small machine targets, so they should not be unnecessarily
| represented as being any larger than necessary, just as bool/char/short
| types should not be needlessly promoted).

In C, enumerator are ints -- even though the associated enumeration
type is considered a distinct types.  Only C++ allows for the smallest
integer type as the underlying type; and C++ enumerators are not ints. 


-- 
                                                       Gabriel Dos Reis 
                                           gdr@integrable-solutions.net