Hi,
I looked into this and fixed the issues so it compiles now on all platforms, see PR fix compile issues by qno · Pull Request #315 · surge-synthesizer/surge-rack · GitHub
I added also a Github workflow action for CI builds on native OS, which means the plugin is compiled on MacOS, Windows and Linux VMs which are available from Github. This can be checked under the Github Actions tab.
Using Github action is much simpler than Azure, because it doesn’t require any repo setup on a third party service for other participants.
At first I tried to cross compile the project with the rack-plugin-toolchain Docker container in CI, but it took way too much time and I had to add ugly workarounds to sort out toolchain issues.
My changes just make the plugin build working, but I think it is still far from an optimal solution to build the plugin at all.
The plugins for Windows, Mac and Linux versions can be downloaded from the related Github Action run.