Definitely needed. You already do things like push Github commit status updates on cancel. There must be some kind of internal on_cancel handling already?

C'mon this is a basic survival tool.. why this does not exist yet?

I was looking for this to be a thing already. Please bring it.

It is useful when you have a job running tests and you see the test have started to fail and you want to cancel right away to identify the failed test avoiding the job to keep running.

If we had a when for cancelled jobs we could add it to the store artifacts or store test results and be able to get the artifact data for the failed tests that run before we cancelled the build.

This would be really useful

Created a fresh issue to list the old threads: https://discuss.circleci.com/t/feature-add-option-to-when-attribute-for-on-cancel/31738

There are multiple dead threads on the forums: