But what's wrong with what I suggested in my earlier post?
The regexes are in a DB. In the beginning, all of them where full regexes (no need for \Q...\E, etc...). But now, some of them are created by an user with a GUI. These "new" regexes are "plain text", and I want to ignore the metacharacters of *them* only, and not of all the regexes. If I "quotemeta" any regex i see, I can end up quoting real regexes :-(
Oh, and the interface is not in Perl, so I don't have quotemeta there. All I can do is surround with \Q...\E and hope it works, but as I found out (the bad way), it doesn't :-(