Earlier quoted context omitted.
It'll only rebuild the packages that depended on that particular openssl. This is an area where Nix shines, because all packages are explicitly bound to their dependencies, it means it's no longer relevant what one file happens to be occupying `/usr/lib/libssl.so`, or even `/lib/x86_64-linux-gnu/libc.so.6`, so you can be running different apps that rely on totally different glibc versions alongside each other with no…
Oh, that sounds like it could solve my issue. E.g. I compiled my program against my glibc which is 2.24, but target was running 2.23. I didn't even use any "new" 2.24 features, but it was missing a symbol, so it wouldn't run. But then to compile against 2.23 locally, I had to get an older version of GCC (not sure why, but), and everything needed to build the older GCC, and so on. But then I got some old versions of l…
So I just built gcc myself which I found very easy.