On Fri, 1 Dec 2006, Linus Torvalds wrote:
>
> But at times, some of the gcc extensions aren't necessarily that well
> defined or thought out, or simply not worth it. The extended type system
> for enums in gcc is just basically messy, and it doesn't really offer you
> anything important.
Btw, try this stupid program, to see just how _strange_ gcc enums are.. A
sizeof of the enum is not the same as the size of the individual entries.
Notice also how the size of the enum entry is _not_ tied to the type of
the expression it had, but literally to its _value_. The size of "one"
ends up being 4, even though it was initialized with a "1ll" value.
So with gcc-enums, you CANNOT get a sane type result.
In contrast, if you want sane types, you could easily do
#define one (1ull)
#define other (0x10000ull)
#define strange (0x100000000ull)
and they'd all have the same type (and having the same type means that
they act the same in expressions - you get the same expression type in
mixing these values, _unlike_ the insane gcc enum cases)
Linus
---
enum hello {
one = 1ll,
other = 0x10000,
bigval = 0x1000000000000ll,
};
int main(int argc, char **argv)
{
printf("%zu %zu %zu %zu\n",
sizeof(enum hello),
sizeof(one),
sizeof(other),
sizeof(bigval));
return 0;
}
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