Shell is using these, which was revealed by
1bbb5c8107 breaking its build when
generating its introspection due to meta_startup_notification_get_type()
not being found.
We keep the class structs private, so in practice MetaStartupSequence
and MetaBackend can't be derived from (the are semi-private).
Make meson link libmutter using -fvisibility=hidden, and introduce META_EXPORT
and META_EXPORT_TEST defines to mark a symbols as visible.
The TEST version is meant to be used to flag symbols that are only used
internally by mutter tests, but that should not be considered public API.
This allows us to be more precise in selecting what is exported and what is
not, without the need of a version-script file that would be more complicated
to maintain.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/395
The order and way include macros were structured was chaotic, with no
real common thread between files. Try to tidy up the mess with some
common scheme, to make things look less messy.
This is kind of in a middle ground at the moment. Even though it
handles sequences not coming from libsn, they're added nowhere at
the moment, we'll rely on the app launch context being in the x11
side at the moment.
Also, even though we do create internal sequence objects, we keep
exposing SnStartupSequences to make gnome-shell happy, we could
consider making this object "public" (and the sequence objects with
it), things stay private at the moment.
https://bugzilla.gnome.org/show_bug.cgi?id=762268
