CCing the person who caused the regression is more appropriate. Assigning bugs to them detracts others from fixing the bug.
We already do that, and in lots of cases it doesn't work. CCing is not coercive enough, you only receive a few more mails (and some people don't even read their bugzilla mail). Take PR31095, for example. It's a 4.3 regression on x86 and x86_64 that is triggered on the GCC testsuite, it has been known for more than 2 months, Janis kindly did a reghunt a month ago to attribute it, the patch author was added in the CC list. Since then, nothing happened. I'm taking this example because I was remembered about it by a mail on the fortran list, but it has nothing specific, there are scores of these kind out there. I think assigning regressions to people who introduced them is only fair, after all, they are supposed to take care of it or find someone else to do it! FX
