Package segfaults when built with -O2 but not with -O0

[Paul Howarth]

On Fri, 18 Nov 2011 15:28:27 +0000
Andrew Haley <aph at redhat.com> wrote:

> On 11/18/2011 11:31 AM, Paul Howarth wrote:
> > One of my packages, pptp, suffers occasional segfaults as reported
> > in http://bugzilla.redhat.com/749455. However, whilst investigating
> > this, it seems to be the case that simply rebuilding the package
> > using no optimization (-O0) as opposed to the default -O2 is enough
> > to stop this happening.
> > 
> > This raises two questions (at least!):
> > 
> > 1. Is it reasonable for me to flout the packaging guidelines by
> > rebuilding with -O0 until this is resolved?
> > 
> > 2. How to determine what the actual problem is, e.g. a problem with
> > the way the code is written leading to unsafe optimizations, or a
> > gcc bug?
> 
> You're just going to have to debug it.
> 
> To start with, build with warnings, and look at them all.  If none of
> that works and you're stuck, I'll have a look.

It already builds with -Wall and there are no warnings:

http://koji.fedoraproject.org/koji/getfile?taskID=3507432&name=build.log

> This is unlikely to be a gcc bug.
> 
> Does the upstream package segfault?

Upstream's Makefile uses -O0 and doesn't appear to segfault (probably
as a result).

Paul.