In general, I think it is useful to warn users about unused parameters, because they might actually be the result of undesired typos, for instance --resume instead of -resume. In this case, the warning would help them fix the CLI syntax.

Let me talk about both the traditional CLI and CLI v2 (#3600).

I see two main sub-cases so far:

• any non-dash-prefixed argument should give a warning (for CLI v2, also single-dash-prefixed - these would be first checked about -x styled runtime parameters)
• double-dash-prefixed arguments should be compared with a dictionary of params of the pipeline being run; if no match, they should give a warning (for CLI v2, there will be the additional early check around them being runtime parameters)