cc1: warning: unrecognized command line option "-Wno-narrowing"

cc1: warning: unrecognized command line option "-Wno-narrowing"

[Ralf Corsepius]

Hi,

Since recently, I am facing several of the warnings above when building 
GCC-trunk cross for RTEMS targets.

So far, not much clues about what is going on, except that I see 
-Wno-narrowing were recently added to
gcc/configure.ac and libcpp/configure.ac.

Ralf

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Michael Meissner]

On Sun, Nov 06, 2011 at 07:18:52AM +0100, Ralf Corsepius wrote:
> Hi,
> 
> Since recently, I am facing several of the warnings above when
> building GCC-trunk cross for RTEMS targets.
> 
> So far, not much clues about what is going on, except that I see
> -Wno-narrowing were recently added to
> gcc/configure.ac and libcpp/configure.ac.

FWIW, I'm seeing it also when I'm building on x86_64 RHEL 6.1 targeting
powerpc64-linux, so I suspect it is a cross compiler issue, but I haven't
checked it in detail.

-- 
Michael Meissner, IBM
5 Technology Place Drive, M/S 2757, Westford, MA 01886-3141, USA
meissner@linux.vnet.ibm.com	fax +1 (978) 399-6899

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Jonathan Wakely]

On 8 November 2011 19:29, Michael Meissner wrote:
> On Sun, Nov 06, 2011 at 07:18:52AM +0100, Ralf Corsepius wrote:
>> Hi,
>>
>> Since recently, I am facing several of the warnings above when
>> building GCC-trunk cross for RTEMS targets.
>>
>> So far, not much clues about what is going on, except that I see
>> -Wno-narrowing were recently added to
>> gcc/configure.ac and libcpp/configure.ac.
>
> FWIW, I'm seeing it also when I'm building on x86_64 RHEL 6.1 targeting
> powerpc64-linux, so I suspect it is a cross compiler issue, but I haven't
> checked it in detail.

I saw it on a native build, possibly netbsd, but I ignored it as I was
in the middle of something.  Will keep an eye out for it again.

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Jason Merrill]

On 11/08/2011 03:08 PM, Jonathan Wakely wrote:
> I saw it on a native build, possibly netbsd, but I ignored it as I was
> in the middle of something.  Will keep an eye out for it again.

I see it occasionally too, but haven't been able to reproduce it when 
calling the compiler directly.  Very odd.

Jason

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Paolo Carlini]

Hi,

> I saw it on a native build, possibly netbsd, but I ignored it as I was
> in the middle of something.  Will keep an eye out for it again.

I believe that the core issue is pretty clear: -Wno-narrowing disables a C++ only warning but somehow we are passing it also in a few C compiler invocations, thus the driver warns. We could suppress such warnings too ;) or special case those files?

Paolo

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Jason Merrill]

On 11/08/2011 03:22 PM, Paolo Carlini wrote:
> I believe that the core issue is pretty clear: -Wno-narrowing disables a C++ only warning but somehow we are passing it also in a few C compiler invocations, thus the driver warns.

No, it's accepted by the C front end too, it just has no effect.  It's 
listed as a C option in c.opt.  But during builds cc1 warns about it 
sometimes and not others.  It's very odd.

Jason

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Paolo Carlini]

Hi,

> On 11/08/2011 03:22 PM, Paolo Carlini wrote:
>> I believe that the core issue is pretty clear: -Wno-narrowing disables a C++ only warning but somehow we are passing it also in a few C compiler invocations, thus the driver warns.
> 
> No, it's accepted by the C front end too, it just has no effect.

I see. Actually I'm clear about the no effect thing and also that the warning isn't really worrisome. But I thought that  the front end in general warns for such no effects warnings. I didn't really study the relevant code, to be honest.

Paolo

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Andreas Schwab]

Jason Merrill <jason@redhat.com> writes:

> No, it's accepted by the C front end too, it just has no effect.  It's
> listed as a C option in c.opt.  But during builds cc1 warns about it
> sometimes and not others.  It's very odd.

$ gcc -Wno-narrowing -c hello.c 
$ gcc -Wno-narrowing -c hello.c -Wall
hello.c:14:1: warning: return type defaults to ‘int’
cc1: warning: unrecognized command line option "-Wno-narrowing"

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: cc1: warning: unrecognized command line option "-Wno-narrowing"

[Andreas Schwab]

Andreas Schwab <schwab@linux-m68k.org> writes:

> Jason Merrill <jason@redhat.com> writes:
>
>> No, it's accepted by the C front end too, it just has no effect.  It's
>> listed as a C option in c.opt.  But during builds cc1 warns about it
>> sometimes and not others.  It's very odd.
>
> $ gcc -Wno-narrowing -c hello.c 
> $ gcc -Wno-narrowing -c hello.c -Wall
> hello.c:14:1: warning: return type defaults to ‘int’
> cc1: warning: unrecognized command line option "-Wno-narrowing"

/* Buffer the unknown option described by the string OPT.  Currently,
   we only complain about unknown -Wno-* options if they may have
   prevented a diagnostic. Otherwise, we just ignore them.  Note that
   if we do complain, it is only as a warning, not an error; passing
   the compiler an unrecognised -Wno-* option should never change
   whether the compilation succeeds or fails.  */

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."