Re: Proposal: immediate strings

[Dmitry Antipov <dmantipov@yandex.ru>]

On 06/06/2012 10:41 AM, Paul Eggert wrote:

> OK, but can't we then simply say 'unsigned int foo : N' where N is the
> proper width?

struct foo {
   unsigned int x : BITS_PER_PTRDIFF_T - 1;
   unsigned y : 1;
};

will work only if sizeof (ptrdiff_t) == sizeof (int); if
sizeof (ptrdiff_t) == sizeof (long) and sizeof (long) > sizeof (int),
(the most of 64-bit environments), compilers will complain about
an invalid bitfield size. For the particular case of gcc, it's
'width of ‘x’ exceeds its type' error.

Note 'unsigned long' bitfield type:

struct foo {
   unsigned long x : BITS_PER_PTRDIFF_T - 1;
   unsigned y : 1;
}

works even if BITS_PER_PTRDIFF_T < BITS_PER_LONG.

Dmitry