Re: [Qemu-devel] [PATCH repost] gtk: avoid redefining _WIN32_WINNT macro

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Sep 08, 2015 at 11:35:15AM +0200, Paolo Bonzini wrote:
> 
> 
> On 08/09/2015 11:28, Daniel P. Berrange wrote:
> > In file included from ui/gtk.c:40:0:
> > include/ui/gtk.h:5:0: warning: "_WIN32_WINNT" redefined
> >  # define _WIN32_WINNT 0x0601 /* needed to get definition of MAPVK_VK_TO_VSC */
> >   ^
> > In file included from /usr/i686-w64-mingw32/sys-root/mingw/include/crtdefs.h:10:0,
> >                  from /usr/i686-w64-mingw32/sys-root/mingw/include/stdio.h:9,
> >                  from /home/berrange/src/virt/qemu/include/qemu/fprintf-fn.h:12,
> >                  from /home/berrange/src/virt/qemu/include/qemu-common.h:18,
> >                  from ui/gtk.c:37:
> > /usr/i686-w64-mingw32/sys-root/mingw/include/_mingw.h:225:0: note: this is the location of the previous definition
> >  #define _WIN32_WINNT 0x502
> >  ^
> > 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >  include/ui/gtk.h | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/ui/gtk.h b/include/ui/gtk.h
> > index ee6dffd..7796231 100644
> > --- a/include/ui/gtk.h
> > +++ b/include/ui/gtk.h
> > @@ -2,7 +2,9 @@
> >  #define UI_GTK_H
> >  
> >  #ifdef _WIN32
> > -# define _WIN32_WINNT 0x0601 /* needed to get definition of MAPVK_VK_TO_VSC */
> > +# ifndef _WIN32_WINNT
> > +#  define _WIN32_WINNT 0x0601 /* needed to get definition of MAPVK_VK_TO_VSC */
> > +# endif
> >  #endif
> 
> Your error message shows that _WIN32_WINNT was 0x0502, do you get
> MAPVK_VK_TO_VSC with this patch?

Yes, it still sees that constant just fine and compiles without error.

Interestingly, looking at the header files in mingw64 for Fedora 18
and Fedora 22, I see

#define MAPVK_VK_TO_VSC    0
#define MAPVK_VSC_TO_VK    1
#define MAPVK_VK_TO_CHAR   2
#define MAPVK_VSC_TO_VK_EX 3
#if (_WIN32_WINNT >= 0x0600)
#define MAPVK_VK_TO_VSC_EX 4
#endif

IOW, the constant we use is made available unconditionally, only
the _EX variant needs the _WIN32_WINNT definition.

I wonder if there are some very old mingw versions which lack it
though ?

> Perhaps #undef the macro first, or do something like:
> 
> #if !defined _WIN32_WINNT || _WIN32_WINNT < 0x0601
> # undef _WIN32_WINNT
> # define _WIN32_WINNT 0x0601
> #endif

Perhaps a better way is to avoid the WINNT stuff entirely and instead
directly define the constant we actually care about. eg

 #ifnef MAPVK_VK_TO_VSC
 # define MAPVK_VK_TO_VSC 0
 #endif

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|