Unfortunately, due to its removing the old header, Cartopy does not
support Proj 8, even in the development branch. It is unlikely to be
done before F34 (though I see from later emails you won't be updating
there), but I will try to push to get it done for F35 upstream.
I spent many hours trying to get it building with proj-8, but I gave up
(tests failing telling that coordinates are being transformed which do
not belong to the same celestial body etc...). Here is what I came up
with so far [1].
Since I'm starting to get desperate to land the proj-8 thing, I've opted
for the drastic solution of bundling/statically linking proj-7 into
cartopy, see [2]. If this looks reasonable, I'd fire off a build to
finally merge the side-tag.
Thanks
Sandro
[1]
https://github.com/SciTools/cartopy/pull/1752
[2]
https://src.fedoraproject.org/rpms/python-cartopy/pull-request/3