Bug path

test_3
‘test_3’: events 1-2
19 char *p = strndup (s, 42); /* { dg-message "this call could return NULL" } */
^~~~~~~~~~~~~~~
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(1) this call could return NULL
20 requires_nonnull (p); /* { dg-warning "use of possibly-NULL 'p'" } */
~~~~~~~~~~~~~~~~~~~~
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(2) argument 1 (‘p’) from (1) could be NULL where non-null expected