Fish completions for rustup suggest files alongside subcommands #5172

Verification

• I searched for recent similar issues at https://github.com/rust-lang/rustup/issues?q=is%3Aissue 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

In fish shell, when you use an autocomple using tab you're getting directories and files alongside rustup subcommands.

As i know, rustup doesn't use any directories or files as arguments, so i recognize it as a bug

Steps

1. Setup fish autocomplete. If you are on linux you can run rustup completions fish rustup > ~/.config/fish/completions/rustup.fish
2. In fish write 'rustup '(leave one space char) and press tab. It should display subcommands and files and dirs

Possible Solution(s)

You can add 'complete -c rustup -f' in the beginning of fish autocomplete output. It will prevent display of files and directories.
I also tried to fix this in source code. I haven't find better solution than this:

I tried to find out how to make it a bit more beautiful with clap but no result.

Notes

No response

Rustup version

rustup 1.29.2 (2026-10-22)

Installed toolchains

Default host: x86_64-unknown-linux-gnu
rustup home:  /home/nikolai/.local/share/rustup

installed toolchains
--------------------
stable-x86_64-unknown-linux-gnu (active, default)
nightly-x86_64-unknown-linux-gnu
1.93-x86_64-unknown-linux-gnu
1.93.0-x86_64-unknown-linux-gnu
1.95.0-x86_64-unknown-linux-gnu
1.96.0-x86_64-unknown-linux-gnu

active toolchain
----------------
name: stable-x86_64-unknown-linux-gnu
active because: it's the default toolchain
installed targets:
  wasm32-unknown-unknown
  x86_64-unknown-linux-gnu

OS version

OS: CachyOS
Kernel: Linux 7.3.0-4-cachyos