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Date: Thu, 3 Oct 1996 18:16:22 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199610030816.SAA06864@godzilla.zeta.org.au>
To: peter@spinner.dialix.com, sos@FreeBSD.org
Subject: Re: cvs commit: src/sys/i386/isa syscons.c
Cc: cvs-all@freefall.freebsd.org, CVS-committers@freefall.freebsd.org,
        cvs-sys@freefall.freebsd.org, jkh@freefall.freebsd.org
Sender: owner-cvs-sys@FreeBSD.org
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>In theory, it can be written:
    practice

>void
>func(x, y)
>int x __unused;
>char *y __unused;
>{
>	return (1);
>}
>...
>That should be enough to shut up gcc.  Althought what to do about the
>SYSCTL macro for declaring functions where you don't get the chance to
>do this, I'm not sure about.

The macro cases are easier.  You just add __unused once to each arg
in the macro instead of to thousands of args in scattered functions.
This works because the `unused' attribute doesn't mean that the
thing that it is attached to is unused - it means that the thing
is possibly unused and so the -Wunused warning should be suppressed.

I don't want to add non-C to thousands of args in scattered functions.

The unused attribute doesn't work right in typedefs.  Otherwise we
could use

/* Args to switch functions are often unused, so don't warn about them. */
typedef int sy_call_t __P((struct proc *p __unused, void *uap __unused,
			   int *retval __unused));

The unused attribute is silently ignored here :-(.

Bruce