https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86259
--- Comment #28 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- (In reply to Davin McCall from comment #27) > Again, there was no pointer arithmetic (other than the line containing > 'strlen', but that particular case the pointer has the address of the union > object, which has been cast to (char *), and the '+ 4' should be valid then, > surely, by 6.3.2.7 paragraph 7 (ignoring that it requires 'successive > increments' rather than arbitrary addition, or is that supposed to be > significant?). Can someone explain why the example in comment #21 works when pointer arithmentic instead of integer arithmetic is used? char *sp_ip = (char *)bp - offsetof(struct S,b); strcpy(u.xx, "abcdefghijk"); size_t len = strlen((char *)(union U*)sp_ip + 4); puts(len == 7 ? "YES" : "NO"); prints "YES"
