Bug#678324: glib2.0-dev: changes from 2.30.2 to 2.32.3 cause undeclared compatibility breakage for Qt

[Yann Dirson <ydirson@free.fr>]

Package: libglib2.0-dev
Version: 2.32.3-1
X-Debbugs-Cc: qt4-x11@packages.debian.org

For various reason I have for now postponned upgrading glib on my
wheezy box, and it is still at 2.30.2-6.  In this situation, the
"qbuild" program fails to work (it is built and tested by the
./configure script from qtmoko, most easily found via
git://github.com/radekp/qtmoko.git).

Now for the details:

* qbuild uses QtCore.  With the 4.8.0-1 Qt packages from experimental,
  things were fine, but with the 4.8.1 and 4.8.2 packages things break
  - in fact, the test run does nearly work, but the program stays
  stuck waiting for a QWaitCondition, while the GLib main loop is
  polling.

* if I use a set of Qt 4.8.2 packages, rebuilt on the samemachine, or
  if I run this test with QT_NO_GLIB=1, it does work fine.  If I
  rebuild Qt in a sid chroot, the resulting packages do show the
  qbuild test lockup.  If I just downgrade glib2.0-dev and the handful
  of packages that must be downgraded with it, in this chroot, the
  resulting packages DO NOT show the qbuild test lockup.

The conclusion seems to be that something in libglib2.0-dev changed
between 2.30.2 and 2.32.3, likely in header files, and related to
g_main_loop, which is causing this breakage, and that somehow packages
built against newer versions of glib (Qt in this case) should have
inherited tighter versionned dependencies against glib in one way or
another.  But this may also come from an unwanted change in glib or
another component, glib is just the "most likely culprit" at this
point...

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (101, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: armel

Kernel: Linux 3.2.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=C, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages libglib2.0-dev depends on:
ii  libc6           2.13-33
ii  libglib2.0-0    2.30.2-6
ii  libglib2.0-bin  2.30.2-6
ii  pkg-config      0.26-1
ii  zlib1g-dev      1:1.2.7.dfsg-11

Versions of packages libglib2.0-dev recommends:
ii  python  2.7.3~rc2-1

Versions of packages libglib2.0-dev suggests:
pn  libglib2.0-doc  <none>

-- no debconf information