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Re: Unused macros warning?
- From: Zack Weinberg <zack at codesourcery dot com>
- To: Neil Booth <neil at daikokuya dot co dot uk>
- Cc: gcc at gcc dot gnu dot org
- Date: Mon, 22 Jul 2002 22:55:29 -0700
- Subject: Re: Unused macros warning?
- References: <20020722063352.GA22349@daikokuya.co.uk>
On Mon, Jul 22, 2002 at 07:33:52AM +0100, Neil Booth wrote:
> I made a local modification to cpplib so that, if -Wunused, it reports
> all macros defined in the main file that are unused, or unused before
> being #undef-ed.
>
> Might this be a useful addition to mainline? It shouldn't be in -Wall,
> as it involves a slightly expensive hashtable walk at the end of
> preprocessing which most users wouldn't want to pay for, but could
> be enabled with the front ends' -Wunused, say.
Yes, I think this would be useful, as long as it doesn't ding you for
macros in headers.
> Long-term, it would be nice if cpplib could tell you if any header you
> include is not used for any purpose. The kernel guys have wanted this
> feature for a long time.
Oooh, I want this.
> I think it's not too hard, once the front end uses logical lines
> internally; it then just becomes a matter of reporting a line as
> "used" when something from it (like a macro, struct, typedef etc.)
> is used, and letting cpplib use the line maps to convert that to
> file usage, and doing a quick pass over the linemap structures at
> the end of preprocessing.
Sounds plausible.
zw