How is -Wconf supposed to work?

[som-snytt]

Questions are not bug reports

What if it's a documentation bug?

I realize that's another question.

Reproduction steps

Scala version: 2.13.13

scalameta/munit#461

to exercise -Wconf:cat=deprecation:s -Xlint and upgrading a project.

Problem

It still warns, even with -Wconf:any:s.

If I junkify the config, it tells me

[error] Failed to parse `-Wconf` configuration: List(cat=deprecation:w, junk:s, cat=unchecked:w, cat=feature:w, cat=deprecation:ws, cat=feature:ws, cat=optimizer:ws)
[error] unknown filter: junk

Ah, I thought a plugin was prepending to the config, but I just realized that Xlint sets deprecation which sets -Wconf.

But what if I only want to see some deprecations?

That is my third and final question.

Besides documenting the behavior, under -verbose it could echo settings or explain what's going on when a filter matches.