Otherwise this test will succeed at build-time, but will fail when run
as an as-installed test via ginsttest-runner.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This can be used to mark entire types as deprecated,
and trigger a warning when they are instantiated
and `G_ENABLE_DIAGNOSTIC=1` is set in the environment.
There's currently no convenient macros for defining
types with the new flag, but you can do:
```c
_G_DEFINE_TYPE_EXTENDED_BEGIN (GtkAppChooserWidget,
gtk_app_chooser_widget,
GTK_TYPE_WIDGET,
G_TYPE_FLAG_DEPRECATED)
...
_G_DEFINE_TYPE_EXTENDED_END ()
```
Includes a unit test by Philip Withnall.
All of these warnings indicate programmer error, so critical is most
appropriate here.
Exceptions: deprecation warnings are just warnings. Also, warnings that
are worded with uncertainty can remain warnings rather than criticals.
