Show-stopper samba-4.7.0rc3 on AIX when using xlc

[Andrew Bartlett]

On Tue, 2017-08-08 at 20:28 +0200, Michael Felt via samba-technical
wrote:
> On 05/08/2017 10:46, Andrew Bartlett via samba-technical wrote:
> > On Sat, 2017-08-05 at 09:45 +0200, Michael Felt via samba-technical
> > wrote:
> > > On 01/08/2017 11:55, Michael Felt via samba-technical wrote:
> > > > Been working on packaging SAMBA for AIX the last 24 hours. Via
> > > > the bug
> > > > reports I saw some patches that have been applied to SAMBA-4.7
> > > > (but
> > > > not in the 4.4.15.+ I guess) - so started a test of the rc as
> > > > well.
> > > > 
> > > > It stops almost immediately - with a bad compiler flag -
> > > 
> > > Just curious - is there no interest in the RC3 release, or did I
> > > post
> > > this to the wrong list (as I see nothing about samba4.7rc3
> > > testing at all).
> > 
> > This is the right place, it is just really hard to get folks to
> > test
> > our release candidate releases.
> > 
> > I'm sorry I missed your mail earlier this week.
> > 
> > The issue is in lib/replace/wscript
> > 
> > The code tests for -Wno-format-truncation and then if that exists
> > but
> > unconditionally sets -Wno-format-zero-length.
> > 
> > > Q2: as I have been reading a bit - if I was going to try and
> > > 'fix' this,
> > > would that be in the wafsamba directory (of buildtools)?
> > 
> > Fixing it shouldn't be hard, just make that test -Wno-format-
> > truncation
> > also conditional.
> > 
> > If you look over the git log, you can see us trying hard to keep
> > too
> > many different compiler versions happy.  It all started with:
> > 
> > commit b02d636e0b1c43821a83297f51599bb03b5858b3
> > Author: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>
> > Date:   Tue Nov 1 13:26:11 2016 +1300
> > 
> >      lib/replace tests: prevent GCC fretting over snprintf sizes
> >      
> >      These tests deliberately use snprintf for truncating strings,
> > which
> > is
> >      fine for tests. This has the effect of leaving the warning in
> > place
> >      but preventing it from becoming a fatal error.
> >      
> >      Signed-off-by: Douglas Bagnall <douglas.bagnall at catalyst.net.n
> > z>
> >      Reviewed-by: Andrew Bartlett <abartlet at samba.org>
> > 
> > Thanks so much for chasing this down, I'm sure you can get a patch
> > knocked up pretty quickly with that info.
> 
> Well, you chased it down - I only fell over it.
> 
> Learning more about python, looking (for) how things such as 
> HAVE_WNO_FORMAT_TRUNCATIONis determined.
> 
> p.s. - a simple change would be:
> From:
> replace_test_cflags="-Wno-format-zero-length"
> if bld.CONFIG_SET('HAVE_WNO_FORMAT_TRUNCATION'):
> replace_test_cflags += "-Wno-format-truncation"
> TO:
> if bld.CONFIG_SET('HAVE_WNO_FORMAT_TRUNCATION'):
> replace_test_cflags="-Wno-format-zero-length -Wno-format-truncation"
> else:
>      replace_test_cflags=""
> 
> This changes the assumption that all compilers know about 
> -Wno-format-zero-length to:
> ALL compilers that know -Wno-format-truncation ALSO know 
> -Wno-format-zero-length
> 
> I'll work this into a PATCH email (aka bug report) tomorrow. But (as
> I 
> am also learning git) I do not think I will be able to get it into a
> PR.

There are lots of very good tutorials on the web.  Please make it a
signed-off git commit, sent here as git-format-patch -1, it makes it
much, much more likely to be picked up in a timely manner, which in
turn makes a 4.7 backport much more practical. 

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba