Toolchain override for specific cargo subcommand

[dzamlo]

The idea is that you can override the toolchain used to run a specific cargo sub-command.

My use case is running cargo clippy while using the stable toolchain for everything else. There is a workaround: rustup run nightly cargo clippy, but its pretty annoying. With this functionality I could override the toolchain for the clippy sub-command while still using the stable toolchain for the everything else..

[Luthaf]

A thing I recently found in the code, and I do not think is documented, is that you can add +<toolchain> in the command line to select a toolchain for a specific command:

cargo +nightly clippy
cargo +beta test --lib

As it is not documented, it might not be something we can rely on, but this is a less verbose way to use an alternative toolchain.

[vitiral]

can the cargo +<toolchain> be documented somewhere? I love it!

[pnkfelix]

@vitiral I think it is documented here in the rustup.rs README?

[jedahan]

Hmm this is no longer working for me

 ▲ ~ cargo +nightly bench
error: no such subcommand: `+nightly`

[dzamlo]

It still works for me. Are you sure you are using the rustup version of cargo and the normal one?

[jedahan]

I think I am using the one installed via homebrew (brew info rust shows rust: stable 1.25.0 (bottled), HEAD)

~ cargo version
cargo 0.25.0

[vitiral]

I'm not on mac, but if you are a dev it is recommended to install rustup instead of cargo/rust directly.

[tmplt]

This is certainly not the correct issue, but if anyone else using NixOS also stumbles upon this issue:

I had both rustup and cargo in my system packages, which yielded

$ cargo expand
error: no such subcommand: `+nightly`

Removing cargo (and effectively using the binary shipped with rustup instead) fixed the issue.