> How to tell "use older parts in toolchain"? > Yeah, probably a Rust newbie question, still a sincere question. > Was a older version installed? How to tell `rustup` to keep old > versions? Was done with a cargo.toml entry? Or with file > `rust-toolchain`? Please tell (Please spoon feed me ;-)
Using `rust-toolchain.toml` should work. Another option would be to override the default version for the given directory with `rustup override set nightly-2021-02-20`. You could also set the global default `rustc` to a specific nightly release: `rustup default nightly-2021-02-20`. More info here: https://rust-lang.github.io/rustup/overrides.html