Flag: passes

[steveklabnik]

This issue is part of #125

--passes: add more rustdoc passes

Using this flag looks like this:

$ rustdoc --passes list
$ rustdoc src/lib.rs --passes strip-priv-imports

An argument of "list" will print a list of possible "rustdoc passes", and other
arguments will be the name of which passes to run in addition to the defaults.

For more details on passes, see the chapter on them.

See also --no-defaults.

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Should we keep this flag or not?

[steveklabnik]

We don't currently have the "passes" architecture, so I'm not sure this flag makes sense.

Existing usage, as far as I know, is mostly to use it in combination with --no-defaults in order to document private things, which we can instead support more directly.

[steveklabnik]

We talked about this at the tools team meeting today and the intention is to remove this flag. Passes don't make much sense in new rustdoc.

[steveklabnik]

rust-lang/rust#44136 is the issue tracking the deprecation; it may or may not be removed, but it means we don't need to support it.