We had separate checks for glib-2.0, gobject-2.0, gmodule-2.0, and
gio-unix-2.0. It doesn't make sense to link a binary against all 4
because gio-unix-2.0 depends on glib-2.0 and gobject-2.0. Doing this
actually breaks things in unusual circumstances.
Generally, few bits of NM actually just use glib, and not gio. We
might as well coalesce those requirements together, even if it means
in some cases we "overlink". Additionally, I chose for now to fold
gmodule-2.0 in as well, even though many fewer programs need it. The
cost of overlinking is quite small.
The benefit of this is less repeated junk in Makefile.am, as well as
more centralized control over GLib. A followup patch will allow us to
set -DGLIB_VERSION_MIN_REQUIRED in just one place, rather than having
to replicate it 4 times.
The NM configure is still suboptimal - for example, libpolkit-1
depends on gio-2.0, so really we should determine the compiler flags
all in one pass. But it doesn't matter too much for now.
This functionality is (mostly) obsoleted by the newer
GLIB_VERSION_MIN_REQUIRED and GLIB_VERSION_MAX_ALLOWED defines. With
this, your build doesn't all of a sudden blow up if we deprecate
something in GLib - you have to explicitly opt-in to the newer
version.
G_DISABLE_DEPRECATED does still apply for macros and things that can't
take __attribute__((deprecated)), but it's not really worth the pain
and cargo culting around just for that.
