1  // { dg-do preprocess }
       2  // { dg-options "-std=gnu99 -fdiagnostics-show-option -Werror=comments" }
       3  /* { dg-message "some warnings being treated as errors" "" {target "*-*-*"} 0 } */
       4  /* /* */  // { dg-error "\"\.\*\" within comment .-Werror=comment." }
       5  
       6  // \
       7            // { dg-error "multi-line comment .-Werror=comment." "multi-line" { target *-*-* } .-1 }