* installing *source* package ‘fdars’ ...
** package ‘fdars’ successfully unpacked and MD5 sums checked
** using staged installation
-----------------------------------------------------
ERROR: Rust toolchain not found.

This package requires the Rust programming language.
Please install Rust from: https://rustup.rs/

On most systems, you can install Rust with:
  curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

After installation, restart your terminal and try again.
-----------------------------------------------------
ERROR: configuration failed for package ‘fdars’
* removing ‘/Volumes/Builds/packages/big-sur-arm64/results/4.4/fdars.Rcheck/fdars’