The executable depends only on the generated header file at compile
time, and on the library at link time. So meson can decide to compile
gdbus-peer.c before compiling the library and thus won't have generated
the header yet, causing the build error.
So declare_dependency() should only have the header file in its sources,
to force generating files before compiling gdbus-peer.c without
including objectmanager-gen.c into gdbus-peer's sources.
We use libgdbus_example_objectmanager_dep as dependency for various
tests, but this implies only a link dependency while it doesn't ensure
that the sources are generated.
Make this explicit
When using glib as a meson subproject on Windows the build currently fails
due to too long paths during the build process. See
https://github.com/mesonbuild/meson/issues/4226 for the upstream bug.
To work around the issue shorten the filenames of the generated gdbus files.
Properly define GLIB/GOBJECT_STATIC_COMPILATION when static build is enabled.
Use library() instead of shared_library() to allow selecting static builds.
https://bugzilla.gnome.org/show_bug.cgi?id=784995
