[Bug analyzer/106390] Support gsl::owner<T> and/or [[gnu::owner]] attribute in -fanalyzer

["vultkayn at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106390

Benjamin Priour <vultkayn at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vultkayn at gcc dot gnu.org

--- Comment #3 from Benjamin Priour <vultkayn at gcc dot gnu.org> ---
I think gsl::owner might be insufficient and we should rather introduce
[[gnu::owner(unique)]] and [[gnu::owner(shared)]] 

Let's say we only had [[gnu::owner]] for ownership, whether unique or shared.
If so, annotating [[gnu::owner]] would mean "I am becoming A (not THE) owner of
the given resource", i.e. it would always mean "shared" ownership.

Yet doing so would make the attribute only useful to check spurious
deallocations of non-owned resource, as well as detect the resource has been
released in the destructor, but otherwise useless to check move operations, as
we cannot require a move upon acquiring a shared resource.

Thus an additional attribute will be necessary anyway, either to differentiate
"shared" and "unique" ownership, or to annotate a move operation. 

I believe [[gnu::owner(unique|shared)]] to be preferable, as we can use it to
deduce a move operation, whereas a flagged move does not induce the quality of
ownership.