1  // { dg-do preprocess }
       2  // { dg-options "-std=gnu99 -fdiagnostics-show-option -Werror=multichar" }
       3  /* { dg-message "some warnings being treated as errors" "" {target "*-*-*"} 0 } */
       4  #if 'ab'  // { dg-error "multi-character character constant .-Werror=multichar." }
       5  #endif