rustup allows `rustup toolchain link none`

[jyn514]

Problem

This is not necessarily a bug, but it seems very confusing.

; rustup default none
info: default toolchain unset
; rustup toolchain link none build/aarch64-unknown-linux-gnu/stage0
; cargo
error: rustup could not choose a version of cargo to run, because one wasn't specified explicitly, and no default is configured.
help: run 'rustup default stable' to download the latest stable release of Rust and set it as your default toolchain.
; cargo +none --version
cargo 1.67.0-beta.3 (f6e737b1e 2022-12-02)

Steps

1. Clone rust-lang/rust and run `./x.py --help
2. Run rustup toolchain link none build/aarch64-unknown-linux-gnu/stage0 (as appropriate for your host triple)
3. Run cargo +none --version

Possible Solution(s)

I think disallowing none for a custom toolchain name would be easier to understand, something like the existing error for reserved channel names:

; rustup toolchain link stable build/aarch64-unknown-linux-gnu/stage0
error: invalid custom toolchain name: 'stable-aarch64-unknown-linux-gnu'

Notes

No response

Rustup version

rustup 1.25.1 (bb60b1e89 2022-07-12)

Installed toolchains

> rustup show -v
Default host: aarch64-unknown-linux-gnu
rustup home:  /home/gh-jyn514/.local/lib/rustup

installed toolchains
--------------------

error: no default toolchain configured

(this seems like a second bug: I definitely have at least nightly installed.)

[ashutoshvarma]

@rustbot claim
@jyn514 If I understand right, setting none should not be allowed as custom toolchain name and should just simply throw an error?

[jyn514]

That's what I would expect, yes.