http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46196
--- Comment #10 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2010-10-30 11:52:46 UTC --- > Can we find any test case which is sensitive to this change? I di not find one in store!-( Am I correct to expect that such test will be of the "reject valid" kind? Clearly (dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived) && !(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived) is always false and the third test is the same. So these tests are just nops and the 'return 0' will never be reached. Then the if-else block reduces to if (!(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.u.derived) && gfc_compare_types (&dt1->ts, &dt2->ts) == 0) return 0; For this case we need a test with 'dt1->ts.type == BT_DERIVED' and 'dt1->ts.u.derived == derived1' and one of these conditions false for dt2. My understanding of the code is not good enough to reach a valid test from that (I don't know where derived* come from.