Re: ofono build error on ARM

[=?unknown-8bit?q?R=C3=A9mi?= Denis-Courmont <remi@remlab.net>]

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Le samedi 1 août 2009 18:06:49 Marcel Holtmann, vous avez écrit :
> > > cc1: warnings being treated as errors
> > > netlink.c: In function ‘g_pn_nl_process’:
> > > netlink.c:75: error: cast increases required alignment of target type
> > > netlink.c:107: error: cast increases required alignment of target type
> > > netlink.c:109: error: cast increases required alignment of target type
> > > make[2]: *** [netlink.lo] Error 1
> >
> > I think there is no way to fix this. It comes from the Netlink packet
> > format and macros, which are confusing gcc. That's why I hate to enfore
> > -Werror.
>
> we only enforce -Werror for the developers and it is important to have
> gcc help us catch mistakes that might be easily overlooked.

If I recall correctly, `-Werror' is enforced when maintainer mode is enabled. 
Really, turning off maintainer mode is primilarly useful to binary package 
maintainers who *might* not want to trigger autotools updates. Then again, 
some might waht to have them anyway... I find the underlying assumption to be 
a bit restrictive if not flawed.

> I would have to look into these one and how we can fix them properly.

As far as I understand, those warnings come from casting receive buffers into 
structure with higher-order alignment requirement  - with some of your 
competitors' CPU architectures anyway ;) Arguably, those are caused by 
kernel/libc headers, not Ofono. I will check on Monday if we can fix them by 
promoting the receive buffers to larger integer types, but it might make the 
code worse.

But generally, there remain a problem that some warnings might simply be 
bogus, or not under our control. For instance -outside of Ofono- I'm yet to 
find a way around dummy variable "clobber warnings" when using POSIX thread 
cancellation cleanup handlers. Sure, I could make all variables volatile, but 
I refuse to damage optimizations for the sake of bogus warnings...

The real shame is that -Werror-* is dysfunctional in GCC :(

-- 
Rémi Denis-Courmont
http://www.remlab.net/