[Qemu-devel] glib-compat tales of woe

[Cornelia Huck]

After some updates were applied on our SLES11SP3 development server,
current qemu fails to build:

In file included from /home/cohuck/git/qemu/include/qemu-common.h:43,
                 from /home/cohuck/git/qemu/qapi/qapi-visit-core.c:14:
/home/cohuck/git/qemu/include/glib-compat.h:35: error: static declaration of 
‘g_get_monotonic_time’ follows non-static declaration
/usr/include/glib-2.0/glib/gmain.h:236: error: previous declaration of 
‘g_get_monotonic_time’ was here


and so on.

pkg-config reports a glib-2.0 version of 2.22.5 - but the SLES
development package contains a helpfully backported version of
g_get_monotonic_time, which you wouldn't know from the reported version.

Question: How do we deal with problems like this?

I don't think it's unlikely that distributors will do similar backports
in the future, and each of them may break the glib-version dependant
compat code.

- Drop support for ancient distros doing weird stuff?
- Try to figure out if we have a version that does not quite provide
  what we think it does, and differentiate accordingly?
- Check if a function exists before trying to provide a compat version?

I'll only do builds on my (non-SLES11SP3) test systems for now, but I
think we need a generic solution.