rlibc is used at run time in 87 crates (of which 70 optionally). It is a direct run-time dependency in 14 crates. It's used only as a dev dependency in 8 crates (of which 1 directly).

Depender (with downloads and own rev deps) rlibc version
6.5K 36 ink_env ^1
2 sel4-sys ^1.0.0
1 enclave ^1.0.0
amber ^1
libsel4-sys ^1.0
lambdaOS ^1.0
processortrace ^1.0.0
1 ruspiro-allocator ~1.0.0
owasm-libc ^1.0
rustboot ^1
efi ^1.0.0
130 12 mech-core optional =1.0
5 mech-syntax optional =1.0
waveform optional ^1.0.0
ntrumls-plus dev ^1.0.0