Do not install toolchain on rustup show * and rustup --version

Author: kellda

src/cli/rustup_mode.rs

@@ -85,7 +85,7 @@ pub fn main() -> Result<utils::ExitCode> {
                     cfg.set_toolchain_override(&t[1..]);
                 }
 
-                let toolchain = cfg.find_or_install_override_toolchain_or_default(&cwd)?.0;
+                let toolchain = cfg.find_or_install_override_toolchain_or_default(&cwd, false)?.0;
 
                 Ok(toolchain.rustc_version())
             }
@@ -1051,7 +1051,7 @@ fn show(cfg: &Cfg) -> Result<utils::ExitCode> {
     let cwd = utils::current_dir()?;
     let installed_toolchains = cfg.list_toolchains()?;
     // XXX: we may want a find_without_install capability for show.
-    let active_toolchain = cfg.find_or_install_override_toolchain_or_default(&cwd);
+    let active_toolchain = cfg.find_or_install_override_toolchain_or_default(&cwd, false);
 
     // active_toolchain will carry the reason we don't have one in its detail.
     let active_targets = if let Ok(ref at) = active_toolchain {
@@ -1176,7 +1176,7 @@ fn show(cfg: &Cfg) -> Result<utils::ExitCode> {
 
 fn show_active_toolchain(cfg: &Cfg) -> Result<utils::ExitCode> {
     let cwd = utils::current_dir()?;
-    match cfg.find_or_install_override_toolchain_or_default(&cwd) {
+    match cfg.find_or_install_override_toolchain_or_default(&cwd, false) {
         Err(crate::Error(crate::ErrorKind::ToolchainNotSelected, _)) => {}
         Err(e) => return Err(e.into()),
         Ok((toolchain, reason)) => {
@@ -1337,7 +1337,7 @@ fn explicit_or_dir_toolchain<'a>(cfg: &'a Cfg, m: &ArgMatches<'_>) -> Result<Too
     }
 
     let cwd = utils::current_dir()?;
-    let (toolchain, _) = cfg.toolchain_for_dir(&cwd)?;
+    let (toolchain, _) = cfg.find_or_install_override_toolchain_or_default(&cwd, true)?;
 
     Ok(toolchain)
 }

src/config.rs

@@ -409,7 +409,7 @@ impl Cfg {
     }
 
     pub fn which_binary(&self, path: &Path, binary: &str) -> Result<Option<PathBuf>> {
-        let (toolchain, _) = self.find_or_install_override_toolchain_or_default(path)?;
+        let (toolchain, _) = self.find_or_install_override_toolchain_or_default(path, true)?;
         Ok(Some(toolchain.binary_file(binary)))
     }
 
@@ -620,6 +620,7 @@ impl Cfg {
     pub fn find_or_install_override_toolchain_or_default(
         &self,
         path: &Path,
+        install: bool,
     ) -> Result<(Toolchain<'_>, Option<OverrideReason>)> {
         fn components_exist(
             distributable: &DistributableToolchain<'_>,
@@ -699,7 +700,7 @@ impl Cfg {
                 let targets: Vec<_> = targets.iter().map(AsRef::as_ref).collect();
 
                 let distributable = DistributableToolchain::new(&toolchain)?;
-                if !toolchain.exists() || !components_exist(&distributable, &components, &targets)?
+                if install && (!toolchain.exists() || !components_exist(&distributable, &components, &targets)?)
                 {
                     distributable.install_from_dist(true, false, &components, &targets, profile)?;
                 }
@@ -789,15 +790,8 @@ impl Cfg {
         })
     }
 
-    pub fn toolchain_for_dir(
-        &self,
-        path: &Path,
-    ) -> Result<(Toolchain<'_>, Option<OverrideReason>)> {
-        self.find_or_install_override_toolchain_or_default(path)
-    }
-
     pub fn create_command_for_dir(&self, path: &Path, binary: &str) -> Result<Command> {
-        let (ref toolchain, _) = self.toolchain_for_dir(path)?;
+        let (ref toolchain, _) = self.find_or_install_override_toolchain_or_default(path, true)?;
 
         if let Some(cmd) = self.maybe_do_cargo_fallback(toolchain, binary)? {
             Ok(cmd)