Hi Andreas, On Thu, 23 Aug 2018 at 08:58 Andreas Tille <andr...@fam-tille.de> wrote:
> > On Wed, Aug 22, 2018 at 09:42:13PM +0200, Liubov Chuprikova wrote: > > An autopkgtest fails with segfault in testing and unstable [1]. > > > > ``` > > /usr/bin/../lib/atac/bin/statsGenerator -a > /tmp/autopkgtest-lxc.epng5fx9/downtmp/autopkgtest_tmp/results/EcolivsSent.atac > > -p > /tmp/autopkgtest-lxc.epng5fx9/downtmp/autopkgtest_tmp/results/stats/EcolivsSent > > -g A > > /tmp/autopkgtest-lxc.epng5fx9/downtmp/autopkgtest_tmp/results/stats/EcolivsSent.stats > > > > Segmentation fault > > Failed to ganerate statistics. > > ``` > > > > Notably, that building and testing in stable were successful (I tested > > it in clean chroot). JFI, I tried installing an older version of gcc on > > testing, the one that is used in stable (4:6.3.0-4), and this eliminated > > the segfault. > > Thanks for this good catch which proves how important your Outreachy > project is for providing stable and working packages in Debian Med. > Now I see! > Thanks also for verifying that older compilers seem to produce working > code while newer don't. > This seemed just something to go on. I wonder whether you feel able to do some debugging what position of > code causes the issue. My first shout would be to grep for > "Failed to ganerate statistics" > which is probably in a wrapper around some code and than use some > debugging techniques (either you are comfortable with gdb / want to > become comfortable with gdb or simply use some > printf("DEBUG %s(%i): ...", __FILE__, __LINE__, ...); > statements in the code to watch what's happening. > It might be helpful to lower / switch off optimisation options to see > whether some optimisation feature of some later gcc will deal > differently with some not properly specified code part. > Thanks a lot for your advise! I tried debugging with grep when I had just caught the error for the first time, but it was without result at that moment. Turning off optimization flags, as you recommended, also did not help. After that I made one more attemp to debug with grep and printing some statements and finally found what it is called classical non-bug in gcc [1]. I have just uploaded a patch. Could you please sponsor an upload? With regards, Liubov [1] https://gcc.gnu.org/bugs/#nonbugs_c