i'm just now seeing this comment (https://github.com/pantsbuild/pants/blob/c82393964933cb94254d11f8bf2ea874a8f15137/src/python/pants/core_tasks/bash_completion.py#L55):

# We ignore advanced options, as they aren't intended to be used on the cmd line.

from benjy's comment here: https://github.com/pantsbuild/pants/pull/7637#issuecomment-488016327 and i wanted to note that i did not realize before that marking an option as

advanced=True

=> "likely not used on the command line", and am not sure if that could be better-documented for task developers