Re: [RFC PATCH 0/2] drop the concept of 'known-but-ignored' attributes

[Josh Triplett <josh@joshtriplett.org>]

On Thu, Feb 15, 2018 at 09:33:14AM -0800, Linus Torvalds wrote:
> On Thu, Feb 15, 2018 at 7:57 AM, Josh Triplett <josh@joshtriplett.org> wrote:
> >
> > I absolutely agree that these have been annoying. However, they've also
> > been useful in the past to identify new flags used in the kernel and
> > other projects that we may need to actually act on, rather than just
> > ignore.
> 
> I think the issue is that the warning is useful for _sparse_
> developers, but not to actual users.

Unless they're debugging why Sparse doesn't fully understand their code,
yes.

> So I do think the warning itself should be off by default - but maybe
> the "known but ignored" table should exist so that sparse people can
> say "is there a new attribute that I need to look at"?

Agreed on both counts.

I also wonder if it might make sense to make "unknown attribute" a
warning that automatically gets displayed *if* displaying other warnings
at the same time, to help with debugging the other warnings. That way,
if you run Sparse on a file that would otherwise produce no warnings, an
unknown attribute doesn't create noise; however, if you run Sparse on a
file that would give warnings anyway, you get the unknown attribute
warning as well, which might make it obvious why the other warnings
arise.

For instance, if you see Sparse warn about an unknown attribute on a
type, followed by a pile of type mismatches involving that type, perhaps
you'd want to investigate that attribute and its use.