Re: [Qemu-devel] [PATCH, RFC] ld flag --warn-common

["Blue Swirl" <blauwirbel@gmail.com>]

On 9/22/08, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> On Sat, Sep 20, 2008 at 10:49:36AM +0300, Blue Swirl wrote:
>  > On 9/19/08, Kirill A. Shutemov <kirill@shutemov.name> wrote:
>  > > On Sun, Sep 07, 2008 at 11:24:37AM +0300, Blue Swirl wrote:
>  > >  > Hi,
>  > >  >
>  > >  > These trivial patches enable linker flag --warn-common and fix the
>  > >  > warnings caused by enabling the flag.
>  > >
>  > >
>  > > This flag cause a lot of warning on my machine, even with trivial program.
>  > >
>  > >  $ cat 1.c
>  > >  #include <stdio.h>
>  > >
>  > >  int main()
>  > >  {
>  > >         printf("test\n");
>  > >         return 0;
>  > >  }
>  > >  $ gcc -Wl,--warn-common -static 1.c
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtoul.o): warning: multiple common of `_nl_category_name_idxs'
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): warning: previous common is here
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol_l.o): warning: multiple common of `_nl_category_name_idxs'
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): warning: previous common is here
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtoul_l.o): warning: multiple common of `_nl_category_name_idxs'
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): warning: previous common is here
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(vfprintf.o): warning: multiple common of `_nl_category_name_idxs'
>  > >  /usr/lib64/gcc/x86_64-alt-linux/4.1.2/../../../../lib64/libc.a(strtol.o): warning: previous common is here
>  > >
>  > >  ...and so on.
>  > >
>  > >
>  > >  Is it problem with my toolchain? What is your testing environment?
>  >
>  > I get no warnings for Qemu build on Debian i386, amd64
>  > (stable/unstable), Sparc32, Sparc64 or on OpenBSD/Sparc64. Your
>  > program produces one warning on Debian stable (all hosts except no
>  > warnings on arm), no warnings on Debian amd64 unstable or OpenBSD.
>
>
> I've got a lot of warnings on ALT Linux x86_64 and Ubuntu x86_64. Both
>  with gcc 4.1.2. Are you sure that you test static build?

$ gcc -Wl,--warn-common -static main.c
/usr/lib/gcc/x86_64-linux-gnu/4.1.2/../../../../lib64/libc.a(dl-open.o):
warning: definition of `_dl_tls_static_size' overriding common
/usr/lib/gcc/x86_64-linux-gnu/4.1.2/../../../../lib64/libc.a(libc-tls.o):
warning: common is here
$ cat main.c
#include <stdio.h>

int main()
{
       printf("test\n");
       return 0;
}