1  /*
       2     { dg-options "-D _GNU_SOURCE -fdiagnostics-show-caret" }
       3     { dg-do compile }
       4   */
       5  
       6  #define _GNU_SOURCE 	/* { dg-warning "-:redefined" } */
       7  
       8  /* { dg-message "" "#define _GNU_SOURCE" {target *-*-* } 0 } */