On Fri, Jul 05, 2024 at 10:03:05AM -0400, Mouse wrote:
> In...C++, I think it is?, you can do this by declaring the unused arg
> without a name, as in
>
> void fxn(int arg1, int)
> {
> ...
> }
>
> but as far as I know nobody's picked that up in C. (It strikes me as a
> very sensible approach.)
Then you need to update your knowledge: this is now standard C23.> (I suspect > use of compilers that handle (void)arg or __attribute__ is commoner > than the presence of __USE or whatever). Your suspicion is correct here: void casts are universal, unused-tagging will functionally work everywhere (or, at the very least, not not work), whereas __USE is a NetBSD macro: sys/sys/cdefs.h:#define __USE(a) (/*LINTED*/(void)(a)) and NetBSD uses it liberally (I also interrogated OpenBSD (no hits) and FreeBSD (four hits, all below a directory that said "netbsd-...")). If you want to ignore an argument and don't want to nominally target C23, use (void)arg; otherwise just don't name it. If you have a variable that's used compile-time-conditionally, tag it __attribute__((unused)) (<C23) or [[maybe_unused]] (≥C23). Best,
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