`rustup component list` shows rust-std components it won't accept

[jyn514]

Problem

; rustup component list | grep rust-std | head
rust-std-aarch64-apple-darwin
rust-std-aarch64-apple-ios
rust-std-aarch64-apple-ios-sim
rust-std-aarch64-linux-android
rust-std-aarch64-pc-windows-msvc
rust-std-aarch64-unknown-fuchsia
rust-std-aarch64-unknown-linux-gnu
rust-std-aarch64-unknown-linux-musl
rust-std-aarch64-unknown-none
rust-std-aarch64-unknown-none-softfloat
; rustup component add rust-std-aarch64-apple-darwin
error: toolchain 'nightly-x86_64-unknown-linux-gnu' does not contain component 'rust-std-aarch64-apple-darwin' for target 'x86_64-unknown-linux-gnu'
note: not all platforms have the standard library pre-compiled: https://doc.rust-lang.org/nightly/rustc/platform-support.html
help: consider using `cargo build -Z build-std` instead

This second error message is confusing and somewhat misleading. nightly does support aarch64-apple-darwin, but component doesn't know how to handle it, you need to use rustup target add instead.

Steps

1. rustup component list

Possible Solution(s)

One or more of the following:

1. Don't show components starting with rust-std in rustup target list
2. Give a better error message when trying rustup component add rust-std-*, ideally suggesting rustup target add.

Notes

No response

Rustup version

rustup 1.26.0 (5af9b9484 2023-04-05)

Installed toolchains

; rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /home/jyn/.local/lib/rustup

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

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)
r2-stage1
r3-stage1
stage1

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.70.0-nightly (9df3a39fb 2023-04-11)

[jyn514]

Ah, I see that rustup component add rust-std --target x86_64-apple-darwin does work. Maybe rustup component list should just format its output differently? Something like rust-std (target: aarch64-apple-darwin).

Note that this also applies for the rustc-dev component, which can't be installed with target add and has to use component add --target.

[rami3l]

Closing this as a duplicate of #3166, fixed in #3601:

> rustup --version
rustup 1.27.1+198 (81a71647f 2024-06-09)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.78.0 (9b00956e5 2024-04-29)`
> rustup component add rust-std-aarch64-apple-darwin
info: component 'rust-std' for target 'aarch64-apple-darwin' is up to date
> rustup component add rust-std-x86_64-apple-darwin
info: downloading component 'rust-std' for 'x86_64-apple-darwin'
info: installing component 'rust-std' for 'x86_64-apple-darwin'
 23.4 MiB /  23.4 MiB (100 %)  20.7 MiB/s in  1s
> rustup component remove rust-std-x86_64-apple-darwin
info: removing component 'rust-std' for 'x86_64-apple-darwin'