I've had to do this several times in the past. Honestly, my best advice would probably be make several backups, then to do as little as possible. If you need to

I've had to do this several times in the past. Honestly, my best advice would probably be make several backups, then to do as little as possible. If you need to make a small change, fine. Bigger changes? Consider if you can't do the bulk of the work in a technology or stack you understand and only make a small change to the legacy code base. Most of the time I spend with C++ code revolves around figuring out compile/link errors. Heaven forbid you need to deal with non-portable `make` files that for some reason work on the old box, but not yours... Oh, and I hope you have a ton of spare space because of some reason building a 500k exe takes 4GB. Keep in mind, this advice only applies to inherited C++ code bases. If you've written your own or are working on an actively maintained project these are non-issues. Sort-of.