Is it possible to have multiple coexisting Rust installations?

Question

Would it be possible to have a nightly build Rust compiler for convenience (faster build cycle, auto-update) and a dev version of Rust cloned from GitHub for experimentation

Answer 1

Usually when dealing with rustup, you're dealing with toolchains–a single installation of the Rust compiler. There are 3 major release channels:

• stable
• beta
• nightly

The channel can be appended with optional date and host names: channel[-date][-host].

You can install multiple toolchains using rustup:

rustup toolchain install nightly
rustup toolchain install stable-x86_64-pc-windows-msvc

Be careful when nightly is installed as any updates using rustup update will also update stable.

You can have different level of overrides:

# command level
rustc +beta 
cargo +beta 

# environment level
export RUSTUP_TOOLCHAIN=nightly-2019-05-22

# directory level
rustup override set stable

The toolchain configuration can also be version controlled using a rust-toolchain file, which contains just the toolchain name.

$ cat rust-toolchain
nightly-2019-05-22

No host name can be configured in the rust-toolchain file.

The override precedence is:

• An explicit toolchain, e.g. cargo +beta
• The RUSTUP_TOOLCHAIN environment variable
• A directory override, ala rustup override set beta
• The rust-toolchain file
• The default toolchain

Reference: https://github.com/rust-lang/rustup.rs#toolchain-specification