If one of these libraries breaks its GIR API in future, then upgrading
packages unrelated to gnome-shell might pull in the newer version,
causing gnome-shell to crash when it gets a newer GIR API that is
incompatible with its expectations. For example, this seems to be
happening in Debian testing at the moment, when GNOME Shell 41.4
imports GWeather and can get version 4.0 instead of the version 3.0 that
it expected.
Adding explicit API versions at the time the newer version is released
is too late, because that will still let the newer version of the GIR API
break pre-existing GNOME Shell packages. Prevent similar crashes in
future by making the desired versions explicit.
This is done for all third-party libraries except GLib, similar to the
common practice in Python code; if GLib breaks API, then that will be
a disruptive change to the whole GLib/GObject ecosystem, regardless.
Gvc, Meta, Shell, Shew, St are not included because they're private
(only exist in a non-default search path entry).
Clutter and Cogl *are* included, because we need to import the fork of
them that comes with Meta, as opposed to their deprecated standalone
versions.
Signed-off-by: Simon McVittie <smcv@debian.org>
Bug-Debian: https://bugs.debian.org/1008926
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2261>
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