On Sun, Apr 14, 2013 at 10:05 AM, Eric Botcazou <ebotca...@adacore.com> wrote: > Hi, > > this is a regression present on the mainline and 4.8 branch and introduced by > the latest series of sizetype changes. Associated adjustments were made in > the various front-ends for it, most notably Ada which was the most affected, > but this issue slipped through the cracks in the form of a bogus overflow > detection for 0-based arrays with variable upper bound included in a record > with discriminant. > > The proposed fix is to disable overflow detection in sizetype for one special > case (0 - 1) in size_binop_loc. An equivalent kludge was added to layout_type > to disable overflow detection for the size expression of [0, -1] arrays. > > Tested on x86_64-suse-linux, OK for the mainline and 4.8 branch?
I think I already rejected this and asked you to fix the users (like layout_type is a user). Clearly 0 - 1 in unsigned arithmetic overflows. Not indicating this may cause bugs elsewhere as easily as it fixes code not dealing with this fact. Richard. > > 2013-04-14 Eric Botcazou <ebotca...@adacore.com> > > PR middle-end/56474 > * fold-const.c (size_binop_loc): Disable overflow detection for 0 - 1. > > > 2013-04-14 Eric Botcazou <ebotca...@adacore.com> > > * gnat.dg/specs/array3.ads: New test. > > > -- > Eric Botcazou
