Libc version mismatch between system and flatpak sandbox compiler

[Simon]

Hello,

I compiled a a basic command line tool (ddrescue) from within the sandbox, but when running it from outside the sandbox the libc version is incompatible.

1. from an other post I start a sandbox in a terminal
   flatpak run --command=bash -d --filesystem=home org.gnome.Sdk

2. I compile the tool with ./configure then Make.
   I get an executable that runs, but I want to use it outside the sanbox.

3. I exit the sanbox, run the tool and get libc incompatibility error:
   ddrescue: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.33’ not found (required by ddrescue)

4. outside the sandbox ls -l /lib/x86_64-linux-gnu/libc.so.6 shows v2.31
   lrwxrwxrwx 5 root root 12 Nov 28 2020 /lib/x86_64-linux-gnu/libc.so.6 -> libc-2.31.so

inside the sandbox libc is v2.33:
lrwxrwxrwx 1 nfsnobody nfsnobody 12 Mar 17 15:25 /lib/x86_64-linux-gnu/libc.so.6 -> libc-2.33.so

so, not working…
It would be nice to solve this in general.
In my particular case I need to be able to reach the CDdrive /dev/sr0, which I see oustide the sandbox, but disappears inside. so either ddrescue runs, but I can’t reach the CD or ddrescue does not run, but I can reach the drive. Sad.