Unfortunately a project I'm working on doesn't work on some platforms. It crashes with an error like

/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.34' not found
/lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.29' not found

I followed this hivemind advice to check which GLIBC versions the binary compatible with:

$ objdump -T libmylib_rs.so | grep -Eo 'GLIBC_\S+' | sort -u
GLIBC_2.10)
GLIBC_2.14)
GLIBC_2.17)
GLIBC_2.18)
GLIBC_2.2.5)
GLIBC_2.25)
GLIBC_2.28)
GLIBC_2.29)
GLIBC_2.3)
GLIBC_2.3.2)
GLIBC_2.3.4)
GLIBC_2.33)
GLIBC_2.34)
GLIBC_2.4)
GLIBC_2.7)
GLIBC_2.9)

Unfortunately, GLIBC 2.31 isn't in this list. That's pretty weird, because GLIBC 2.29 and 2.33 are supported. How that could be?

The lib uses clock_gettime which was removed in 2.26 according to that report, but it wasn't re-added back. It also uses pthread_attr_destroy and pthread_attr_init that were removed in 2.31. How it works on later versions? Any "hello world" app which uses Rust's tokio lib uses these symbols from libc.

Furthermore, I can build my code on a system with GLIBC 2.31 and run it there or on systems with newer GLIBC, but not vice versa.

I cannot fix that issue until I understand it.