Re: [Xen-devel] [PATCH 11 of 18] tools/libxl: fix build errors caused by Werror in disk_eject_xswatch_callback

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-04-03 at 10:11 +0100, Olaf Hering wrote:
> On Tue, Apr 03, Ian Campbell wrote:
> 
> > [0] Even gcc(1) says:
> >        -Wno-format-zero-length (C and Objective-C only)
> >            If -Wformat is specified, do not warn about zero-length formats.
> >            The C standard specifies that zero-length formats are allowed.
> > So quite why it appears that Wall is enabling Wformat-zero-length I have
> > no idea, this is a clear gcc bug in my opinion.
> 
> Thats what they say:
> 
> "<jakub> olaf_: warnings aren't just about things that aren't allowed in
> the standard, but about things considered bad by significant amount of
> users"

I find it hard to believe that a significant amount of users think this
particular warning is worthwhile, since there are clearly legitimate
uses of an empty format string (our use in libxl__xs_write being the
obvious example!), and as far as I can tell the only argument for it is
that it might waste a few precious cycles, but I've not got the energy
to argue with the gcc developers about it.

> So gcc wont be changed.

Then we should disable this warning, after our own Wall.

If something else (like RPM_OPTS) is also adding Wall then it had better
do the same.

Ian.


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