"libnm-core/" is rather complicated. It provides a static library that
is linked into libnm.so and NetworkManager. It also contains public
headers (like "nm-setting.h") which are part of public libnm API.
Then we have helper libraries ("libnm-core/nm-libnm-core-*/") which
only rely on public API of libnm-core, but are themself static
libraries that can be used by anybody who uses libnm-core. And
"libnm-core/nm-libnm-core-intern" is used by libnm-core itself.
Move "libnm-core/" to "src/". But also split it in different
directories so that they have a clearer purpose.
The goal is to have a flat directory hierarchy. The "src/libnm-core*/"
directories correspond to the different modules (static libraries and set
of headers that we have). We have different kinds of such modules because
of how we combine various code together. The directory layout now reflects
this.
Our cast macros (like NM_AUTH_SUBJECT()) are plain C pointer casts,
unless when building with more asserts enabled.
Still, they are unnecessary and even their ability to check the type
(with more asserts) is not needed, because we must trust glib's
g_object_new() to return reasonable objects. That is a basic
requirement, that we don't need to assert against.
Also, in the majority of cases we don't do this either.
Currently "src/" mostly contains the source code of the daemon.
I say mostly, because that is not true, there are also the device,
settings, wwan, ppp plugins, the initrd generator, the pppd and dhcp
helper, and probably more.
Also we have source code under libnm-core/, libnm/, clients/, and
shared/ directories. That is all confusing.
We should have one "src" directory, that contains subdirectories. Those
subdirectories should contain individual parts (libraries or
applications), that possibly have dependencies on other subdirectories.
There should be a flat hierarchy of directories under src/, which
contains individual modules.
As the name "src/" is already taken, that prevents any sensible
restructuring of the code.
As a first step, move "src/" to "src/core/". This gives space to
reorganize the code better by moving individual components into "src/".
For inspiration, look at systemd's "src/" directory.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/743
