On 03.10.2012 15:59, Thorsten Glaser wrote: > Hi, > > https://bugs.launchpad.net/ubuntu/+source/mksh/+bug/1058035 > was just the beginning, as gcc-snapshot in Debian had it (I > wrote that in the bugreport already), but, now, gcc-4.{6,7} > in sid also have it. > > I’ve just tracked it down for gcc-4.6 to have been introdu‐ > ced between 4.6.3-9 and 4.6.3-10; gcc-4.7 as currently sits > in wheezy (4.7.1-7) doesn’t have the problem, 4.7.2-2 does. > > tg@zigo:~/b $ cat t.c > #include <stdint.h> > typedef int32_t mksh_ari_t; > char ari_sign_32_bit_and_wrap[( > > (mksh_ari_t)(((((mksh_ari_t)1 << 15) << 15) - 1) * 2 + 1) > > (mksh_ari_t)(((((mksh_ari_t)1 << 15) << 15) - 1) * 2 + 2) > > ) ? 1 : -1]; > > int main(void) { return (sizeof(ari_sign_32_bit_and_wrap)); } > tg@zigo:~/b $ gcc-4.6 -O -Wextra t.c > t.c:6:62: warning: integer overflow in expression [-Woverflow] > t.c:3:6: error: variably modified ‘ari_sign_32_bit_and_wrap’ at file scope > > My question now is, how am I supposed to deal with that? Will > the affected gcc versions transition into wheezy? In that case > I’ll need to apply the hotfix I made for Ubuntu into Debian as > well, so I’d like an answer. > > More generally, why does GCC suddenly break such compile-time > check constructs? (mksh guarantees to scripts it runs that all > arithmetic operations are 32-bit and that both signed and un‐ > signed operations wrap around, so it *must* know whether the > system does that correctly. And its build script is cross-com‐ > pile agnostic, so it doesn’t do run-time checks.)
how does gcc-snapshot behave? If you think it's a regression, please could you forward it upstream? thanks, Matthias -- To UNSUBSCRIBE, email to debian-gcc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/506d9c1a.9070...@debian.org
