Calling mise use ruby@--version overwrites a mise.toml ruby value with --version

[schneems]

Expected

If you try to run mise use ruby@--version or some other invalid identifier, it will exit non-zero and not write any value to mise.toml.

Actual

$ mise use ruby@--version
ruby@--version                                                                                                                                                                         ◜
mise <directory>/mise.toml tools: ruby@--version
$ echo $?
0

Analysis

If you try to call it with a different input, it fails as you would expect:

$ mise use ruby@lol
ruby-build: definition not found: lol
mise ERROR ~/Library/Caches/mise/ruby/ruby-build/bin/ruby-build failed
ruby@lol        ruby-build                                                                                                                                                             ◟
mise ERROR Failed to install core:ruby@lol: ~/Library/Caches/mise/ruby/ruby-build/bin/ruby-build exited with non-zero status: exit code 2
mise ERROR Run with --verbose or MISE_VERBOSE=1 for more information

However, if you put dashes in front of the command the behavior starts to make sense:

$ mise use ruby@--lol
mise WARN  Failed to parse netrc file /Users/rschneeman/.netrc: Illegal format in 5:71 token: sso-keyblaster.herokai.com
ruby-build: invalid flag 'lol'
Usage: ruby-build [-dvpk] <definition> <prefix> [-- <configure-args...>]
       ruby-build {--list|--definitions}
       ruby-build --resolve <version>
       ruby-build --version
  -l, --list      List latest stable rel
  ...

It is passing the value directly to the underlying ruby-build tool. So any value you pass it like --list or --version will exit non-zero from ruby-build, and write that value to the mise.toml

$ mise use ruby@--list
ruby@--list                                                                                                                                                                            ◜
mise <directory>/mise.toml tools: ruby@--list
$ cat mise.toml | grep ruby
cat mise.toml | grep ruby
ruby = "--list"

Suggested

A simple-ish fix would be to reject inputs that start with a hyphen -. I don't know if other language build tools use it as a valid prefix or not, but it seems like it would be unusual at least.

Alternatively, have some post-install validation such as checking that the directory mise expects on disk was actually generated (instead of just assuming that a non-zero tool exit means it was) and exit non-zero if it's not found.

Why

Not important to the bug report at all, but I found it amusing (the bug still exists regardless of why I was calling mise use ruby@--version).

When I try a new tool, I like to alias for muscle memory, for example:

$ which pip
pip () {
	echo "use pip3 instead"
}

I did this with mise:

$ which chruby
chruby () {
	if [ -z "$1" ]
	then
		echo "Running $ mise ls ruby"
		mise ls ruby
	else
		echo "Running $ mise use ruby@$1"
		mise use "ruby@$1"
	fi
}

Unfortunately, the Ruby LSP calls chruby --version which my alias translates to mise use "ruby@--version" oops. It's fixable on my end, but it took quite a while of random "why does this keep happening?" since the LSP executes that command quietly and since none of the underlying machinery exits non-zero everyone assumes everything worked fine. This is not a common use case, but I still think it's worth making mise use ruby@--<anything> fail hard and loud.

[jdx]

Thanks for the detailed report. I opened #10113 to reject leading-dash tool versions during request validation, so mise use ruby@--version fails before reaching ruby-build and does not write the invalid version to mise.toml.

The PR includes a regression test that verifies the failed mise use ...@--version call leaves the existing config value unchanged.

This comment was generated by an AI coding assistant.

[schneems]

Thanks!