Re: [Qemu-devel] [PATCH v2] configure: sanity check the glib library that pkg-config finds

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

On Mon, Jan 25, 2016 at 02:42:10PM +0000, Peter Maydell wrote:
> On 13 November 2015 at 11:31, Daniel P. Berrange <berrange@redhat.com> wrote:
> > Developers on 64-bit machines will often try to perform a
> > 32-bit build of QEMU by running
> >
> >   ./configure --extra-cflags="-m32"
> >
> > Unfortunately if PKG_CONFIG_LIBDIR is not set to point to
> > the location of the 32-bit pkg-config files, then configure
> > will silently pick up the 64-bit pkg-config files and still
> > succeed.
> >
> > This causes a problem for glib because it means QEMU will
> > be pulling in /usr/lib64/glib-2.0/include/glibconfig.h
> > instead of /usr/lib/glib-2.0/include/glibconfig.h
> >
> > This causes problems because the 'gsize' type (defined as
> > 'unsigned long') will no longer be fully compatible with
> > the 'size_t' type (defined as 'unsigned int'). Although
> > both are the same size, the compiler refuses to allow
> > casts from 'unsigned long *' to 'unsigned int *' as they
> > are different pointer types. This results in non-obvious
> > compiler errors when building QEMU eg
> >
> > qga/commands-posix.c: In function ‘qmp_guest_set_user_password’:
> > qga/commands-posix.c:1912:55: error: passing argument 2 of ‘g_base64_decode’ from incompatible pointer type [-Werror=incompatible-pointer-types]
> >      rawpasswddata = (char *)g_base64_decode(password, &rawpasswdlen);
> >                                                             ^
> > In file included from /usr/include/glib-2.0/glib.h:35:0,
> >                  from qga/commands-posix.c:14:
> > /usr/include/glib-2.0/glib/gbase64.h:52:9: note: expected ‘gsize * {aka long unsigned int *}’ but argument is of type ‘size_t * {aka unsigned int *}’
> >  guchar *g_base64_decode         (const gchar  *text,
> >          ^
> > cc1: all warnings being treated as errors
> >
> > To detect this problem, add a check to configure that
> > verifies that GLIB_SIZEOF_SIZE_T matches sizeof(size_t).
> > If this fails print a warning suggesting that the dev
> > probably needs to set PKG_CONFIG_LIBDIR.
> >
> > On Fedora x86_64 it passes with any of:
> >
> >  # ./configure
> >  # PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig ./configure --extra-cflags="-m32"
> >  # PKG_CONFIG_LIBDIR=/usr/lib64/pkgconfig ./configure --extra-cflags="-m64"
> >
> > And fails with a mis-match
> >
> >  # PKG_CONFIG_LIBDIR=/usr/lib64/pkgconfig ./configure --extra-cflags="-m32"
> >  # PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig ./configure --extra-cflags="-m64"
> >
> > ERROR: sizeof(size_t) doesn't match GLIB_SIZEOF_SIZE_T.
> >        You probably need to set PKG_CONFIG_LIBDIR
> >        to point to the right pkg-config files for your
> >        build target
> >
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> 
> I just noticed this never got applied to master -- did it just fall through
> the cracks, or is there an issue with it?

AFAIK, no one raised a blocking issue with it.

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 :|