Thank you for moving the bug report to the correct source package. The changes made do not address the bug, I'm afraid. wireguard-dkms fails to install because kernel-image 4.19.0-9 includes a backported change that is not caught by the pragmas in compat.h. This backport might be a Debian-ism that perhaps should not need to be handled in upstream, I'll admit, but wireguard-dkms (and upstream wireguard-linux-compat, of course), fail to build with 4.19.0-9.
Let me know if you need anything else from me. -- Luca Filipozzi
