[benreesman]

That definitely ups the stakes on the "modern" approach a lot (like, in the limit case `#ifdef`-hell to get part way there).

There are firms that will sell you a suite of frontends supporting every C compiler back to the early 80s and integrate them into a modern toolchain, I used to work with an alum of such a firm and I gather it's great stuff. I also gather it costs whatever you can afford, so there's that. I forget the name of the company but I could ping my friend if that's interesting to you.

Worst case, you could not have to chase memory corruptions on the subset of your target platforms that LLVM targets.