1714239 - allow for using `formatter_class` kwarg in @CommandArgument

Status: NEW

(Firefox Build System :: Mach Core, enhancement, P3)

Description

[Aki Sasaki (not active)]

argparse auto-wraps and auto-normalizes whitespace in help comments. This is generally helpful, but sometimes you want to specially format your help comments, and argparse allows for this via the formatter_class kwarg.

I tried using this with a @CommandArgument and that proceeded to die with TypeError: __init__() got an unexpected keyword argument 'formatter_class'.

So now, my help, which currently looks like

            "clobber": delete cloned repos.
            "prepurge": purge outgoing revisions from strings repo at beginning.
            ...

in code, gets output as

                        "clobber": delete cloned repos. "prepurge": purge
                        outgoing revisions from strings repo at beginning.

which is less readable.

I started digging into the @CommandArgument decorator to try to add formatter_class to this allowlist, but that seemed to push the error deeper into mach internals.