Another issue is that doxygen is not installed on the CI runner hosts: https://gitlab.com/monomon/inkscape/-/jobs/40347524
The Dockerfile of the image needs to be changed too. I'll do this, but I've no clue how to coordinate it.
Should be fixed (I just added doxygen to the Dockerfile). I also just merged the doxygen MR now that I understood how to build it and could test it :)
Alternatively, I see that a merge request has the build run on it, but would the .gitlab-ci.yml be taken from the fork?
Yes, if it's in the MR diff.
The easiest thing to do would probably be to automatically get gitlab to upload stuff to http://inkscape.gitlab.io/inkscape/
Some time ago I put the scan-build result there, but it would make sense to have subfolders /doxygen/ and /scan-build/ to store different artifacts that are produced from the code. Would it be enough to rebuild the doc only every month (we can change the frequency) along with the scan-build report so that they are uploaded together ? (I put an attempt at https://gitlab.com/inkscape/inkscape/merge_requests/134 )