[icon4py,gt4py] How to interact with cmake to avoid full rebuilds?

[jonasjucker]

Problem

cmake of icon-dsl checks if files changed in icon4py/gt4py, and only those changed are rebuilt.
With Spack you end-up with an installation, that is completely rewritten if you reinstall one of the packages.
Then this mechanism is not working anymore.

Solution 1

Test if one could use rsync as install for both python packages. Rsync would only change files that were modified.
Downside is that we hack an established install-method from Spack, this will fail/cause problems at some point for sure.

Solution 2

Figure out a smart mechanism using pip. Maybe the fancy Python world offers something.

Solution 3

Come up with a second version of the packages (py-gt4py-dev, py-icon4py-dev) that implement solution 1.
For basic users (non-developpers) the current situation is perfect. And don't want to add more complexity for the
least experienced users.