rustup is an installer, but install is not discoverable from rustup --help

[alexanderkjeldaas]

Verification

• I searched for recent similar issues at https://github.com/rust-lang/rustup/issues?q=is%3Aissue+is%3Aopen%2Cclosed and found no duplicates.
• I am on the latest version of Rustup according to https://github.com/rust-lang/rustup/tags and am still able to reproduce my issue.

Problem

The issue is about discoverability of rustup.

rustup is a "toolchain INSTALLER". However:

$ rustup --help 2>&1 | grep install                                                                                                          127
The Rust toolchain installer
  show         Show the active and installed toolchains or profiles
  toolchain    Modify or query the installed toolchains
  component    Modify a toolchain's installed components
  self         Modify the rustup installation
    Rustup installs The Rust Programming Language from the official

There is no command to install anything. There are commands to modify and show and query toolchains, and modify a toolchain, and modify rustup itself.

But no command to INSTALL a toolchain! There should be something in --help that indicate which command is used to install a toolchain.

Steps

rustup --help

Possible Solution(s)

Show an example installing the latest toolchain in the help.

Notes

No response

Rustup version

1.27.1

Installed toolchains

there is nothing installed

OS version

Nixos

[rami3l]

@alexanderkjeldaas Thanks for your report. You seem to be looking for the rustup toolchain install command.

Indeed the subcommand description might not be absolutely clear to a fresh pair of eyes, and we will try to fix that.

[djc]

Honestly "Modify or query the installed toolchains" doesn't seem that bad, and at least includes the "install" keyword.

[alexanderkjeldaas]

I think if the toolchain command included the "install" word, then it would be better, like "Install, modify, or query toolchains" or something similar.

[rami3l]

I think if the toolchain command included the "install" word, then it would be better, like "Install, modify, or query toolchains" or something similar.

@djc That's what I'm thinking about as well. I guess "modify" implies installed toolchains so the current help message can be optimized after all...

[djc]

Proposed some tweaks in #4272.