[doomvox]

> no, there's been quite a few.

Yes, most of them relatively minor though, which is why the OP has never stumbled across one.

(I found one once-- it turned out one coder had invented his own hash slice syntax. It wasn't supposed to work, but it did, until a particular upgrade...).

In general, Perl has been traditionally committed to backwards compatibility, but not fanatically so-- there is a deprecation cycle that can be used to remove the more problematic things.