doc: update GitHub developers setup guide

[opeolluwa]

What is in this PR?

• Update GitHub developers setup guide to resolve error

error: the 'cargo' binary, normally provided by the 'cargo' component, is not applicable to the 'nightly-2025-02-16-aarch64-apple-darwin' toolchain

[ndmitchell]

Thanks for the patch. If you are in the pyrefly directory (e.g. C:/Neil/pyrefly/pyrefly if you clone from C:/Neil) then cargo build is meant to pick up https://github.com/facebook/pyrefly/blob/main/pyrefly/rust-toolchain which is meant to automatically install the right nightly. Because nightlies sometimes have bugs we tend to develop pinned to a specific nightly (currently 2025-02-16, but we upgrade every 4 months or so).

If you try that, what fails? I just tried it on my windows machine with a fresh rustup (rustup 1.28.1) and the first time I ran cargo build it transparently installed the necessary nightly and selected it.

[opeolluwa]

@ndmitchell Thank you for the swift follow up<

Here's a copy of my command run for Mac,

error: the 'cargo' binary, normally provided by the 'cargo' component, is not applicable to the 'nightly-2025-02-16-aarch64-apple-darwin' toolchain

[ndmitchell]

Moving to my Mac, I removed all toolchains from rustup, then did:

ndmitchell@ndmitchell-mbp pyrefly % cargo build
info: syncing channel updates for 'nightly-2025-02-16-aarch64-apple-darwin'
info: latest update on 2025-02-16, rust version 1.86.0-nightly (9cd60bd2c 2025-02-15)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: downloading component 'rustc'
info: downloading component 'rustfmt'
info: installing component 'cargo'
info: installing component 'clippy'
info: installing component 'rust-docs'
info: installing component 'rust-std'
info: installing component 'rustc'
info: installing component 'rustfmt'
    Updating crates.io index
    Updating git repository `https://github.com/astral-sh/ruff/`
     Locking 359 packages to latest compatible versions
      Adding argfile v0.1.6 (available: v0.2.1)
      Adding blake3 v1.5.5 (available: v1.8.2)
      Adding const-str v0.4.3 (available: v0.6.2)
      Adding convert_case v0.6.0 (available: v0.8.0)
      Adding enum-iterator v1.5.0 (available: v2.1.0)
      Adding lsp-types v0.94.1 (available: v0.97.0)
      Adding notify v5.2.0 (available: v8.0.0)
      Adding parse-display v0.8.2 (available: v0.10.0)
      Adding regex-syntax v0.7.5 (available: v0.8.5)
      Adding serde_with v1.14.0 (available: v3.12.0)
      Adding which v4.4.2 (available: v7.0.3)
  Downloaded synstructure v0.13.2
  Downloaded cc v1.2.21
  Downloaded winnow v0.7.9
  Downloaded hashbrown v0.15.3
  Downloaded rustix v1.0.7
  Downloaded 5 crates (854.7 KB) in 2.85s
   Compiling unicode-ident v1.0.18
   Compiling proc-macro2 v1.0.95
   Compiling cfg-if v1.0.0
   ... many lines resulting in a compiled binary ...

In a different directory, in order to not be effected by the rust-toolchain file, I ran:

ndmitchell@ndmitchell-mbp pyrefly % cargo --version
cargo 1.86.0 (adf9b6ad1 2025-02-28)
ndmitchell@ndmitchell-mbp pyrefly % rustup --version
rustup 1.28.1 (f9edccde0 2025-03-05)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.86.0 (05f9846f8 2025-03-31)`

Showing that it does change cargo and my versions. Can you try the --version for both rustup and cargo. Then do rustup update. Then try and see if it works after?

[ndmitchell]

I think the issue here might be that if you get cargo from your distribution rather than for rustup then it ignores the rust_toolchain file we have.

[opeolluwa]

Not at all, it was from rustup.

[opeolluwa]

I uninstalled the entire Rust toolchain the other day, and I haven't re-run the project since.

I'll check back when I do