|    19 |   char *p = strdup (s); /* { dg-message "this call could return NULL" } */ | 
 |             ^~~~~~~~~~ | 
 |             | | 
 |             (1) this call could return NULL | 
|    20 |   requires_nonnull (p); /* { dg-warning "use of possibly-NULL 'p'" } */ | 
 |   ~~~~~~~~~~~~~~~~~~~~ | 
 |   | | 
 |   (2) argument 1 (‘p’) from (1) could be NULL where non-null expected |