[Spice-devel] [PATCH xf86-video-qxl 04/13] qxl_driver: cleanup: fix const cast warnings

[Christophe Fergeau]

On Wed, Apr 11, 2012 at 03:04:37PM +0300, Alon Levy wrote:
> On Wed, Apr 11, 2012 at 01:37:49PM +0200, Christophe Fergeau wrote:
> > On Wed, Apr 11, 2012 at 02:05:17PM +0300, Alon Levy wrote:
> > > On Wed, Apr 11, 2012 at 12:46:18PM +0200, Christophe Fergeau wrote:
> > > > On Tue, Apr 10, 2012 at 04:02:56PM +0300, Alon Levy wrote:
> > > > > My bad for not putting it in. It's warning on a const attribute removal
> > > > > cast, since a static string "bla" is (const char*).
> > > > 
> > > > For the record, the warning is -Wcast-qual. While this patch is okayish,
> > > > the 2 other similar patches are a bit ugly imo. Maybe we could use a pragma
> > > > to disable this warning around the initialisation of X structures?
> > > > 
> > > > Christophe
> > > 
> > > Which pragma does that?
> > 
> > Dunno, but actually I was wrong about the flag that causes these warnings,
> > it's -Wwrite-strings actually.
> > gcc documentation says:
> > -Wwrite-strings:
> >            When compiling C, give string constants the type "const
> > char[length]" so that copying the address of one into a non-"const" "char
> > *" pointer will get a warning.  These warnings will help you find at
> > compile time code that can try to write into a string constant, but only if
> > you have been very careful about using "const" in declarations and
> > prototypes.  Otherwise, it will just be a nuisance. This is why we did not
> > make -Wall request these warnings.
> > 
> > Given that we are definitely dealing with code not using "const"
> > consistently in declarations and prototypes, I'd tend to just drop that
> > warning.
> 
> My problem with carying on this seamingly simple suggestion is that I
> haven't found the source of the warnings yet, I think it's via
> xorg-macros, if I could disable this I'd also disable -Winline at the
> same time.

They come from the XORG_COMPILER_FLAGS macro from
/usr/share/aclocal/xorg-macros.m4 which is called by XORG_DEFAULT_OPTIONS
in configure.ac. Since xorg is using this flag too, it would be interesting
to see if they got similar errors, and how they fixed them. We can just
append -Wno-inline -Wno-write-strings to CWARNFLAGS to disable these
warnings in qxl I think.
However, I won't ACK such a change, I'd prefer to know how ssp feels about
it first.

Christophe
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