fix(cli/rustup_mode)!: skip auto-installation in some rustup commands

[rami3l]

Closes #4836 by making it possible to skip should_auto_install 's dynamic detection entirely.

Whether the skip should be applied can be predetermined during clap dispatch (at least for rustup_mode.rs), so the only remaining question seems to be where we would want to apply the skip.

[rami3l]

@djc At the moment of writing, this PR only covers rustup component and rustup target subcommands. As your previous comment (#4836 (comment)) has given a clear criterion for whether auto-installation is accepted, I'll propose the following classification to be implemented here:

Commands that should respect auto-installation:
  rustup-init  No, because the notion of toolchain doesn't exist yet in that stage
  install      No, because `rustup install` installs the active toolchain by default
  uninstall    No, similarly to `rustup install`
  toolchain    No
  default      No, because `rustup default foo` installs `foo`
  show         No, because it's query-only
  update       No, similarly to `rustup toolchain`
  check        No, because it's query-only
  target       No, because it operates on an installed toolchain
  component    No, similarly to `rustup target`
  override     No
  run          Yes, because the said toolchain is invoked
  which        No, because it's query-only
  doc          Yes, because the said toolchain is relied upon
  man          Yes, similarly to `rustup doc`
  self         No, similarly to `rustup-init`
  set          No
  completions  No

What do you think?

[djc]

I like it! Should we review toolchain by subcommand?

[rami3l]

I like it! Should we review toolchain by subcommand?

@djc We have four subcommands here: install and uninstall are already discussed above; list is query-only and link operates on an existing toolchain, so the conclusion would be a hard NO in all cases.

[djc]

Sounds good. Are there other commands with subcommands? target?

[rami3l]

Sounds good. Are there other commands with subcommands? target?

@djc I wrote all the above analysis with all subcommands in mind already. Please feel free to tell me if you think there are any cases you don't agree with.

PS: The best way to enumerate all dispatch points is to go to the code itself:

rustup/src/cli/rustup_mode.rs

Lines 643 to 770 in 6e68164

	match subcmd {
	RustupSubcmd::DumpTestament => common::dump_testament(process),
	RustupSubcmd::Install { opts } => update(cfg, opts, true).await,
	RustupSubcmd::Uninstall { opts } => toolchain_remove(cfg, opts).await,
	RustupSubcmd::Show { verbose, subcmd } => handle_epipe(match subcmd {
	None => show(cfg, verbose).await,
	Some(ShowSubcmd::ActiveToolchain { verbose }) => {
	show_active_toolchain(cfg, verbose).await
	}
	Some(ShowSubcmd::Home) => show_rustup_home(cfg),
	Some(ShowSubcmd::Profile) => {
	writeln!(process.stdout().lock(), "{}", cfg.get_profile()?)?;
	Ok(ExitCode::SUCCESS)
	}
	}),
	RustupSubcmd::Update {
	toolchain,
	no_self_update,
	force,
	force_non_host,
	} => {
	update(
	cfg,
	UpdateOpts {
	toolchain,
	no_self_update,
	force,
	force_non_host,
	..UpdateOpts::default()
	},
	false,
	)
	.await
	}
	RustupSubcmd::Toolchain { subcmd } => match subcmd {
	ToolchainSubcmd::Install { opts } => update(cfg, opts, true).await,
	ToolchainSubcmd::List { verbose, quiet } => {
	handle_epipe(common::list_toolchains(cfg, verbose, quiet).await)
	}
	ToolchainSubcmd::Link { toolchain, path } => {
	toolchain_link(cfg, &toolchain, &path).await
	}
	ToolchainSubcmd::Uninstall { opts } => toolchain_remove(cfg, opts).await,
	},
	RustupSubcmd::Check { opts } => check_updates(cfg, opts).await,
	RustupSubcmd::Default {
	toolchain,
	force_non_host,
	} => default_(cfg, toolchain, force_non_host).await,
	RustupSubcmd::Target { subcmd } => match subcmd {
	TargetSubcmd::List {
	toolchain,
	installed,
	quiet,
	} => handle_epipe(target_list(cfg, toolchain, installed, quiet).await),
	TargetSubcmd::Add { target, toolchain } => target_add(cfg, target, toolchain).await,
	TargetSubcmd::Remove { target, toolchain } => {
	target_remove(cfg, target, toolchain).await
	}
	},
	RustupSubcmd::Component { subcmd } => match subcmd {
	ComponentSubcmd::List {
	toolchain,
	installed,
	quiet,
	} => handle_epipe(component_list(cfg, toolchain, installed, quiet).await),
	ComponentSubcmd::Add {
	component,
	toolchain,
	target,
	} => component_add(cfg, component, toolchain, target).await,
	ComponentSubcmd::Remove {
	component,
	toolchain,
	target,
	} => component_remove(cfg, component, toolchain, target).await,
	},
	RustupSubcmd::Override { subcmd } => match subcmd {
	OverrideSubcmd::List => handle_epipe(common::list_overrides(cfg)),
	OverrideSubcmd::Set { toolchain, path } => {
	override_add(cfg, toolchain, path.as_deref()).await
	}
	OverrideSubcmd::Unset { path, nonexistent } => {
	override_remove(cfg, path.as_deref(), nonexistent)
	}
	},
	RustupSubcmd::Run {
	toolchain,
	command,
	install,
	} => run(cfg, toolchain, command, install)
	.await
	.map(ExitCode::from),
	RustupSubcmd::Which { command, toolchain } => which(cfg, &command, toolchain).await,
	RustupSubcmd::Doc {
	path,
	toolchain,
	topic,
	page,
	} => doc(cfg, path, toolchain, topic.as_deref(), &page).await,
	#[cfg(not(windows))]
	RustupSubcmd::Man { command, toolchain } => man(cfg, &command, toolchain).await,
	RustupSubcmd::Self_ { subcmd } => match subcmd {
	SelfSubcmd::Update => self_update::update(cfg).await,
	SelfSubcmd::Uninstall {
	no_prompt,
	no_modify_path,
	} => self_update::uninstall(no_prompt, no_modify_path, process),
	SelfSubcmd::UpgradeData => cfg.upgrade_data().map(|_| ExitCode::SUCCESS),
	},
	RustupSubcmd::Set { subcmd } => match subcmd {
	SetSubcmd::DefaultHost { host_triple } => cfg
	.set_default_host_triple(host_triple)
	.map(|_| ExitCode::SUCCESS),
	SetSubcmd::Profile { profile_name } => {
	cfg.set_profile(profile_name).map(|_| ExitCode::SUCCESS)
	}
	SetSubcmd::AutoSelfUpdate {
	auto_self_update_mode,
	} => set_auto_self_update(cfg, auto_self_update_mode),
	SetSubcmd::AutoInstall { auto_install_mode } => cfg
	.set_auto_install(auto_install_mode)
	.map(|_| ExitCode::SUCCESS),
	},
	RustupSubcmd::Completions { shell, command } => {
	output_completion_script(shell, command, process)
	}
	}

[djc]

@djc I wrote all the above analysis with all subcommands in mind already. Please feel free to tell me if you think there are any cases you don't agree with.

Okay, just checking!

[rami3l]

Almost done. The only concern would be that rustup show bails out too early when auto-installation is disabled (pre-existing issue).

I'll try to fix it here soon...

[rami3l]

PS: It's very fun in that I'll just need to search for .await to see where we can possibly trigger auto-installation in a subcommand XD

[rami3l]

Oh, the CI passes now, so I'm marking this first PR as ready. Please feel free to let me know if there are any improvements/clarifications to be made :)

[Copilot]

Pull request overview

This PR addresses rustup auto-install being triggered too eagerly (notably under certain rustup subcommands) by adding a configuration-level switch to disable auto-install earlier during clap dispatch in rustup_mode.

Changes:

• Add Cfg::allow_auto_install and gate Cfg::should_auto_install() on it, so auto-install can be disabled without consulting env/settings.
• Decide allow_auto_install per RustupSubcmd in rustup_mode (enabling it only for subcommands that execute/rely on the active toolchain).
• Adjust rustup show / --version behavior and update CLI test snapshots accordingly.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/suite/cli_v2.rs	Updates auto-install disable tests to exercise proxy (cargo +nightly) instead of rustup target.
tests/suite/cli_rustup.rs	Updates rustup show expectations when the active toolchain is missing.
tests/suite/cli_misc.rs	Updates snapshots for version message and which behavior when toolchains are missing.
src/config.rs	Introduces allow_auto_install and makes should_auto_install() return false when disallowed.
src/cli/setup_mode.rs	Updates Cfg::from_env call to pass allow_auto_install for setup/init flow.
src/cli/self_update.rs	Updates test to match new Cfg::from_env signature.
src/cli/rustup_mode.rs	Computes allow_auto_install from the selected subcommand; adjusts show and version output behavior.
src/cli/proxy_mode.rs	Updates Cfg::from_env call to pass allow_auto_install for proxy execution.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

View changes since this review

[djc]

Nice work!

View changes since this review

[djc]

Nice work! That deeply nested code looks a lot better now...

View changes since this review