[Bug c/61476] New: GCC is not aware of glibc extensions for format strings

[doko at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61476

            Bug ID: 61476
           Summary: GCC is not aware of glibc extensions for format
                    strings
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at gcc dot gnu.org

Is this something which can and should be addressed, or should be closed as
won't fix?

$ cat foo.c 
#include <errno.h>
#include <stdio.h>

int main()
{
        fprintf(stderr, "error %d: %m\n", errno, errno);
        return 0;
}
$ gcc -Wall foo.c 
foo.c: In function 'main':
foo.c:6:2: warning: too many arguments for format [-Wformat-extra-args]
  fprintf(stderr, "error %d: %m\n", errno, errno);
  ^

fprintf(3):
       m      (Glibc  extension.)   Print output of strerror(errno).  No argu‐
              ment is required.