We are using Nix to do this. It’s only a few lines of code. We build a gcc 14 stdenv that uses an old glibc.
But I agree that this should just be a simple target SDK flag.
I think the issue is that the Linux community is generally hostile towards proprietary software and it’s less of an issue for FLOSS because they can always be compiled against the latest.
Because Linux userland is an unmitigated clusterfuck of bad design that makes this really really really hard.
GCC/Clang and Glibc make it effectively impossible almost impossible to do this on their own. The only way you can actually do this is:
1. create a userland container from the past 2. use Zig which moved oceans and mountains to make it somewhat tractable
It's awful.