The Rust people have removed C routines as "unsafe". C is not unsafe, lazy programmers are unsafe.
Anyhow, they have screwed the python cryptography module and everyone's CI pipelines are breaking.
The solution is to recompile the Rust toolchain.
I notice Funtoo did a mini update to 5.10.26_p1 and that should compile whatever broke. When I am compiling toolchain stuff, I emerge @system first and then @world, which is redundant but ensures the toolchain is complete.
ex: emerge -uDN --with-bdeps=y --emptytree @system
Note: this takes almost two days on my iCore 5.