[pkg-boost-devel] Bug#506939: Bug#506939: boost: setting CFLAGS in debian/rules clobbers environment

[Steve Langasek]

On Wed, Nov 26, 2008 at 08:43:18PM -0600, Steve M. Robbins wrote:
> On Wed, Nov 26, 2008 at 11:34:31AM -0800, Steve Langasek wrote:
> > On Wed, Nov 26, 2008 at 02:01:53AM -0600, Steve M. Robbins wrote:

> > > The patch bjam-no-strict-aliasing only applies to the second build
> > > (using the bootstrap bjam).  We need to supply
> > > CFLAGS=-fno-strict-aliasing on the first bjam build because otherwise
> > > the first bjam segfaults on some architectures, e.g. alpha [1].

> > That's true if not specifying the gcc profile when building; if you do (as
> > in the Ubuntu patch), then it applies equally well to both builds.

> Examining build.sh, I don't see any evidence of that.

Hmm, you're right; it turns out that this approach works only because the
gcc profile is not using -O2 by default, and the aliasing bug only manifests
under -O2.  So this proposed patch isn't actually any more correct than the
current behavior, sorry about that; I'll drop that change out of the Ubuntu
package in the next upload.

> > I know
> > this to be true because the Ubuntu patch was added to address the exact same
> > issue, but I've also tested that the Ubuntu package builds exactly as
> > intended on alpha, too.

> The crashes appear to happen at unpredictable times.  I suspect you
> merely got lucky.

Hrm, no, it's not very unpredictable at all - if you build with -O2 and
without -fno-strict-aliasing on alpha, it segfaults 100% of the time.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org