Warn when tools are missing and allow to override

src/rustup-cli/common.rs

@@ -189,9 +189,9 @@ fn show_channel_updates(cfg: &Cfg, toolchains: Vec<(String, rustup::Result<Updat
     Ok(())
 }
 
-pub fn update_all_channels(cfg: &Cfg, self_update: bool) -> Result<()> {
+pub fn update_all_channels(cfg: &Cfg, self_update: bool, force_update: bool) -> Result<()> {
 
-    let toolchains = try!(cfg.update_all_channels());
+    let toolchains = try!(cfg.update_all_channels(force_update));
 
     if toolchains.is_empty() {
         info!("no updatable toolchains installed");

src/rustup-cli/rustup_mode.rs

@@ -144,7 +144,11 @@ pub fn cli() -> App<'static, 'static> {
                 .help("Don't perform self update when running the `rustup` command")
                 .long("no-self-update")
                 .takes_value(false)
-                .hidden(true)))
+                .hidden(true))
+            .arg(Arg::with_name("force")
+                .help("Force an update, even if some components are missing")
+                .long("force")
+                .takes_value(false)))
         .subcommand(SubCommand::with_name("default")
             .about("Set the default toolchain")
             .after_help(DEFAULT_HELP)
@@ -462,7 +466,7 @@ fn update(cfg: &Cfg, m: &ArgMatches) -> Result<()> {
             let toolchain = try!(cfg.get_toolchain(name, false));
 
             let status = if !toolchain.is_custom() {
-                Some(try!(toolchain.install_from_dist()))
+                Some(try!(toolchain.install_from_dist(m.is_present("force"))))
             } else if !toolchain.exists() {
                 return Err(ErrorKind::ToolchainNotInstalled(toolchain.name().to_string()).into());
             } else {
@@ -475,7 +479,11 @@ fn update(cfg: &Cfg, m: &ArgMatches) -> Result<()> {
             }
         }
     } else {
-        try!(common::update_all_channels(cfg, !m.is_present("no-self-update") && !self_update::NEVER_SELF_UPDATE));
+        try!(common::update_all_channels(
+            cfg,
+            !m.is_present("no-self-update") && !self_update::NEVER_SELF_UPDATE,
+            m.is_present("force"),
+        ));
     }
 
     Ok(())

src/rustup-cli/self_update.rs

@@ -747,7 +747,7 @@ fn maybe_install_rust(toolchain_str: &str, default_host_triple: &str, verbose: b
         // Set host triple first as it will affect resolution of toolchain_str
         try!(cfg.set_default_host_triple(default_host_triple));
         let toolchain = try!(cfg.get_toolchain(toolchain_str, false));
-        let status = try!(toolchain.install_from_dist());
+        let status = try!(toolchain.install_from_dist(false));
         try!(cfg.set_default(toolchain_str));
         println!("");
         try!(common::show_channel_update(cfg, toolchain_str, Ok(status)));

src/rustup-dist/src/dist.rs

@@ -462,7 +462,8 @@ pub fn update_from_dist<'a>(download: DownloadCfg<'a>,
                             toolchain: &ToolchainDesc,
                             prefix: &InstallPrefix,
                             add: &[Component],
-                            remove: &[Component])
+                            remove: &[Component],
+                            force_update: bool)
                             -> Result<Option<String>> {
 
     let fresh_install = !prefix.path().exists();
@@ -472,7 +473,8 @@ pub fn update_from_dist<'a>(download: DownloadCfg<'a>,
                                 toolchain,
                                 prefix,
                                 add,
-                                remove);
+                                remove,
+                                force_update);
 
     // Don't leave behind an empty / broken installation directory
     if res.is_err() && fresh_install {
@@ -485,12 +487,13 @@ pub fn update_from_dist<'a>(download: DownloadCfg<'a>,
 }
 
 pub fn update_from_dist_<'a>(download: DownloadCfg<'a>,
-                            update_hash: Option<&Path>,
-                            toolchain: &ToolchainDesc,
-                            prefix: &InstallPrefix,
-                            add: &[Component],
-                            remove: &[Component])
-                            -> Result<Option<String>> {
+                             update_hash: Option<&Path>,
+                             toolchain: &ToolchainDesc,
+                             prefix: &InstallPrefix,
+                             add: &[Component],
+                             remove: &[Component],
+                             force_update: bool)
+                             -> Result<Option<String>> {
 
     let toolchain_str = toolchain.to_string();
     let manifestation = try!(Manifestation::open(prefix.clone(), toolchain.target.clone()));
@@ -507,6 +510,7 @@ pub fn update_from_dist_<'a>(download: DownloadCfg<'a>,
             (download.notify_handler)(Notification::DownloadedManifest(&m.date, m.get_rust_version().ok()));
             return match try!(manifestation.update(&m,
                                                    changes,
+                                                   force_update,
                                                    &download,
                                                    download.notify_handler.clone())) {
                 UpdateStatus::Unchanged => Ok(None),