Configuration setting to select toolchain (nightly)

[binkley]

Describe the problem you are trying to solve

I feel my issue might already be covered in another issue, or be a non-issue, however I was not able to find the right issue in GitHub. Apologies if this is a duplicate.

I would like local per-project configuration on which toolchain to use (stable, beta, nightly). I am making use of the feature macro in a particular project, and when I cd to that project, I would like to type just cargo build rather than cargo +nightly build.

Describe the solution you'd like

I am looking for a setting in ./.cargo/config for my local directory which sets the toolchain to "nightly". This may exist! However, reading https://doc.rust-lang.org/cargo/reference/config.html I did not spot a setting to configure.

Notes

My project is here: https://github.com/binkley/spikes/tree/master/rust-green-threads

[ehuss]

rustup has several override features. You can either add a rust-toolchain file or use per-directory overrides.

[Eh2406]

So that is a rustup feature, not strictly a Cargo thing. You are looking for rustup override set nightly or the .toolchain file. ... and Eric beat me to it.

[binkley]

@ehuss Fantastic, thank you! Now cargo build works just fine.

Two requests/questions:

• git status does not show any changes. How would one cloning a repository needing nightly builds pick this up automatically?
• The documentation on this (https://doc.rust-lang.org/cargo/reference/config.html) does reference what you describe, but only obliquely. Could the documentation improve here? How would I improve the documentation?

[ehuss]

git status does not show any changes. How would one cloning a repository needing nightly builds pick this up automatically?

I'm not sure I understand the question. If you add and commit a rust-toolchain file to your repository, anyone checking it out should pick it up and start using that toolchain.

Could the documentation improve here?

Yea, we have an open issue (#8058) to improve it. It is a little awkward because rustup is a completely separate tool, and not everyone uses it, so it is not directly related to cargo per se. But I'd definitely like to make the documentation clearer and more discoverable.

[binkley]

@ehuss I'm looking for something like a .cargo/config which I can commit to a repository. The goal would be that when one clones a git repository needing the nightly toolchain, no more effort from them is required than just cargo build.

(See #8058 on documentation)

[sfackler]

I'm looking for something like a .cargo/config which I can commit to a repository. The goal would be that when one clones a git repository needing the nightly toolchain, no more effort from them is required than just cargo build.

If you add and commit a rust-toolchain file to your repository, anyone checking it out should pick it up and start using that toolchain.

[binkley]

@sfackler Fantastic, just what I was looking for! Thank you

[brandonros]

I'm looking for something like a .cargo/config which I can commit to a repository. The goal would be that when one clones a git repository needing the nightly toolchain, no more effort from them is required than just cargo build.

If you add and commit a rust-toolchain file to your repository, anyone checking it out should pick it up and start using that toolchain.

@sfackler am I doing something wrong here? #10743