feat(rustup-mode): install the active toolchain by default on `rustup…

… toolchain install`

src/cli/rustup_mode.rs

@@ -100,7 +100,7 @@ fn plus_toolchain_value_parser(s: &str) -> clap::error::Result<ResolvableToolcha
 #[derive(Debug, Subcommand)]
 #[command(name = "rustup", bin_name = "rustup[EXE]")]
 enum RustupSubcmd {
-    /// Update Rust toolchains
+    /// Install or update the given toolchains, or by default the active toolchain
     #[command(hide = true, after_help = INSTALL_HELP)]
     Install {
         #[command(flatten)]
@@ -302,7 +302,7 @@ enum ToolchainSubcmd {
         quiet: bool,
     },
 
-    /// Install or update a given toolchain
+    /// Install or update the given toolchains, or by default the active toolchain
     #[command(aliases = ["update", "add"] )]
     Install {
         #[command(flatten)]
@@ -330,7 +330,6 @@ enum ToolchainSubcmd {
 #[derive(Debug, Default, Args)]
 struct UpdateOpts {
     #[arg(
-        required = true,
         help = OFFICIAL_TOOLCHAIN_ARG_HELP,
         num_args = 1..,
     )]
@@ -584,7 +583,7 @@ pub async fn main(current_dir: PathBuf, process: &Process) -> Result<utils::Exit
 
     match subcmd {
         RustupSubcmd::DumpTestament => common::dump_testament(process),
-        RustupSubcmd::Install { opts } => update(cfg, opts, false).await,
+        RustupSubcmd::Install { opts } => update(cfg, opts, true).await,
         RustupSubcmd::Uninstall { opts } => toolchain_remove(cfg, opts),
         RustupSubcmd::Show { verbose, subcmd } => handle_epipe(match subcmd {
             None => show(cfg, verbose),
@@ -615,7 +614,7 @@ pub async fn main(current_dir: PathBuf, process: &Process) -> Result<utils::Exit
             .await
         }
         RustupSubcmd::Toolchain { subcmd } => match subcmd {
-            ToolchainSubcmd::Install { opts } => update(cfg, opts, false).await,
+            ToolchainSubcmd::Install { opts } => update(cfg, opts, true).await,
             ToolchainSubcmd::List { verbose, quiet } => {
                 handle_epipe(common::list_toolchains(cfg, verbose, quiet))
             }

tests/suite/cli-ui/rustup/rustup_toolchain_cmd_help_flag_stdout.toml

@@ -8,7 +8,7 @@ Usage: rustup[EXE] toolchain <COMMAND>
 
 Commands:
   list       List installed toolchains
-  install    Install or update a given toolchain
+  install    Install or update the given toolchains, or by default the active toolchain
   uninstall  Uninstall the given toolchains
   link       Create a custom toolchain by symlinking to a directory
   help       Print this message or the help of the given subcommand(s)

tests/suite/cli-ui/rustup/rustup_toolchain_cmd_install_cmd_help_flag_stdout.toml

@@ -1,13 +1,12 @@
 bin.name = "rustup"
 args = ["toolchain", "install", "--help"]
 stdout = """
-...
-Install or update a given toolchain
+Install or update the given toolchains, or by default the active toolchain
 
-Usage: rustup[EXE] toolchain install [OPTIONS] <TOOLCHAIN>...
+Usage: rustup[EXE] toolchain install [OPTIONS] [TOOLCHAIN]...
 
 Arguments:
-  <TOOLCHAIN>...  Toolchain name, such as 'stable', 'nightly', or '1.8.0'. For more information see
+  [TOOLCHAIN]...  Toolchain name, such as 'stable', 'nightly', or '1.8.0'. For more information see
                   `rustup help toolchain`
 
 Options:

tests/suite/cli_rustup.rs

@@ -1460,6 +1460,38 @@ async fn toolchain_install_is_like_update_except_that_bare_install_is_an_error()
         .await;
 }
 
+#[tokio::test]
+async fn toolchain_install_without_args_installs_active() {
+    let cx = CliTestContext::new(Scenario::SimpleV2).await;
+
+    let cwd = cx.config.current_dir();
+    let toolchain_file = cwd.join("rust-toolchain");
+    raw::write_file(
+        &toolchain_file,
+        r#"
+[toolchain]
+profile = "minimal"
+channel = "nightly"
+"#,
+    )
+    .unwrap();
+
+    cx.config
+        .expect_stderr_ok(
+            &["rustup", "toolchain", "install"],
+            for_host!(
+                "\
+info: syncing channel updates for 'nightly-{0}'
+info: latest update on 2015-01-02, rust version 1.3.0 (hash-nightly-2)
+info: downloading component 'rustc'
+info: installing component 'rustc'
+info: the active toolchain `nightly-{0}` has been installed
+info: it's active because: overridden by '"
+            ),
+        )
+        .await;
+}
+
 #[tokio::test]
 async fn toolchain_update_is_like_update() {
     let mut cx = CliTestContext::new(Scenario::SimpleV2).await;