Re: [patch #8186] ax_pthread adds -pthread when it should not on OSX when compiling with clang

On Thu, 2013 Sep 26 8:47+1000, Peter Johansson wrote:
>
> > The problem appears to be that Clang blithely accepts options it
> > doesn't recognize, printing a warning at most. Without some
> > additional flag to disable this behavior, there's no good way to
> > implement a feature test.
>
> My understanding is that's exactly what gnulib folks are doing when
> they add
>
> '-Werror -Wunknown-warning-option' to CFLAGS.

Note that the gnulib macro addresses *warning options*, not
arbitrary compiler options.

Anyway, I figured it would be easier to actually try installing and
running the damn thing rather than talk about it endlessly, so here's
what I found:

$ cat hello.c
#include <stdio.h>
int main()
{
        return 0;
}
$ clang -c hello.c ; echo exit status $?
exit status 0
$ clang -pthread -c hello.c ; echo exit status $?
exit status 0
$ clang -foobaz -c hello.c ; echo exit status $?
clang: warning: argument unused during compilation: '-foobaz'
exit status 0
$ clang -Werror -pthread -c hello.c ; echo exit status $?
exit status 0
$ clang -Werror -foobaz -c hello.c ; echo exit status $?
clang: error: argument unused during compilation: '-foobaz'
exit status 1

That's basically what I needed, and I'll have a draft update of the
macro ready for testing soon.


--Daniel


-- 
Daniel Richard G. || [email protected]
My ASCII-art .sig got a bad case of Times New Roman.