Date: Thu, 29 Sep 2011 05:44:29 +0000 From: Nali Toja <nalitoja@gmail.com> To: "Klaus T. Aehlig" <aehlig@linta.de> Cc: ports@freebsd.org, ehaupt@FreeBSD.org Subject: Re: clang and configure checking for equivalent simple type Message-ID: <86y5x7hphe.fsf@gmail.com> In-Reply-To: <20110929045818.GA3463@curry.linta.de> (Klaus T. Aehlig's message of "Thu, 29 Sep 2011 05:58:18 %2B0100") References: <20110929045818.GA3463@curry.linta.de>
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"Klaus T. Aehlig" <aehlig@linta.de> writes:
[...]
> #include <sys/types.h>
> #include <unistd.h>
> int
> main ()
> {
> off_t u; long v; &u==&v;
> ;
> return 0;
> }
>
> and check for compile errors. However, the above program is rejected
> by clang, as the value &u==&v is unused, which, of course, has nothing
> to do with the intended check whether off_t * and long * are compatible
> pointer.
>
> Adding
>
> CFLAGS+= -Wno-unused
>
> solves this problem.
Alternatively, you can turn off only a specific -Werror, e.g.
CFLAGS += -Wno-error=unused
it's ignored by gcc in base while gcc46 wants -Wno-error=unused-value
$ gcc -Wunused -Werror -Wno-error=unused test.c
cc1: warnings being treated as errors
test.c: In function 'main':
test.c:6: warning: statement with no effect
Exit 1
$ gcc46 -Wunused -Werror -Wno-error=unused-value test.c
test.c: In function 'main':
test.c:6:18: warning: statement with no effect [-Wunused-value]
$ clang -Wunused -Werror -Wno-error=unused test.c
test.c:6:20: warning: expression result unused [-Wunused-value]
off_t u; long v; &u==&v;
~~^ ~~
1 warning generated.
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