On Thu, 5 Dec 2019 at 17:08, Michael Richardson wrote: > > Good morning! I’m assisting a client moving from/to the above-referenced versions. Any known issues with this specific upgrade? Apart from the fact you're moving from a very ancient release to an only slightly ancient release? There are hundreds of differences between those versions, including a stricter parser for C++ that will reject buggy code that used to be accepted. You haven't even said what language front ends you'll be using, so it's not really possible to be more specific about issues you might encounter. You can read the release notes for yourself: https://gcc.gnu.org/gcc-4.0/changes.html https://gcc.gnu.org/gcc-4.1/changes.html https://gcc.gnu.org/gcc-4.2/changes.html https://gcc.gnu.org/gcc-4.3/changes.html https://gcc.gnu.org/gcc-4.4/changes.html https://gcc.gnu.org/gcc-4.5/changes.html https://gcc.gnu.org/gcc-4.6/changes.html https://gcc.gnu.org/gcc-4.7/changes.html https://gcc.gnu.org/gcc-4.8/changes.html