feat(errors)!: suggest rustup toolchain install when active toolchain is not installed

Author: rami3l

src/cli/rustup_mode.rs

@@ -837,7 +837,7 @@ async fn update(
                     d.update_extra(&components, &targets, profile, force, allow_downgrade)
                         .await?
                 }
-                Err(RustupError::ToolchainNotInstalled(_)) => {
+                Err(RustupError::ToolchainNotInstalled { .. }) => {
                     DistributableToolchain::install(
                         cfg,
                         &desc,
@@ -1321,7 +1321,7 @@ async fn override_add(
     let toolchain_name = toolchain.resolve(&cfg.get_default_host_triple()?)?;
     match Toolchain::new(cfg, (&toolchain_name).into()) {
         Ok(_) => {}
-        Err(e @ RustupError::ToolchainNotInstalled(_)) => match &toolchain_name {
+        Err(e @ RustupError::ToolchainNotInstalled { .. }) => match &toolchain_name {
             ToolchainName::Custom(_) => Err(e)?,
             ToolchainName::Official(desc) => {
                 let status =

src/config.rs

@@ -640,7 +640,7 @@ impl<'a> Cfg<'a> {
                     // XXX: this awkwardness deals with settings file being locked already
                     let toolchain_name = toolchain_name.resolve(&default_host_triple)?;
                     match Toolchain::new(self, (&toolchain_name).into()) {
-                        Err(RustupError::ToolchainNotInstalled(_)) => {
+                        Err(RustupError::ToolchainNotInstalled { .. }) => {
                             if matches!(toolchain_name, ToolchainName::Custom(_)) {
                                 bail!(
                                     "Toolchain {toolchain_name} in {} is custom and not installed",
@@ -817,7 +817,7 @@ impl<'a> Cfg<'a> {
             None => self.get_profile()?,
         };
         let (status, toolchain) = match DistributableToolchain::new(self, toolchain.clone()) {
-            Err(RustupError::ToolchainNotInstalled(_)) => {
+            Err(RustupError::ToolchainNotInstalled { .. }) => {
                 DistributableToolchain::install(
                     self,
                     toolchain,

src/errors.rs

@@ -87,14 +87,19 @@ pub enum RustupError {
     #[error("toolchain '{0}' is not installable")]
     ToolchainNotInstallable(String),
     #[error(
-        "toolchain '{0}' is not installed{}",
-        if let ToolchainName::Official(t) = .0 {
-            format!("\nhelp: run `rustup toolchain install {t}` to install it")
+        "toolchain '{}' is not installed{}",
+        .toolchain,
+        if let ToolchainName::Official(t) = .toolchain {
+            let t = if *.is_active { String::new() } else { format!(" {t}") };
+            format!("\nhelp: run `rustup toolchain install{t}` to install it")
         } else {
             String::new()
         },
     )]
-    ToolchainNotInstalled(ToolchainName),
+    ToolchainNotInstalled {
+        toolchain: ToolchainName,
+        is_active: bool,
+    },
     #[error("path '{0}' not found")]
     PathToolchainNotInstalled(PathBasedToolchainName),
     #[error(

src/toolchain.rs

@@ -50,9 +50,10 @@ impl<'a> Toolchain<'a> {
     ) -> anyhow::Result<Toolchain<'a>> {
         match Self::new(cfg, name) {
             Ok(tc) => Ok(tc),
-            Err(RustupError::ToolchainNotInstalled(ToolchainName::Official(desc)))
-                if install_if_missing =>
-            {
+            Err(RustupError::ToolchainNotInstalled {
+                toolchain: ToolchainName::Official(desc),
+                ..
+            }) if install_if_missing => {
                 Ok(
                     DistributableToolchain::install(cfg, &desc, &[], &[], cfg.get_profile()?, true)
                         .await?
@@ -72,7 +73,7 @@ impl<'a> Toolchain<'a> {
         reason: &ActiveReason,
     ) -> anyhow::Result<Self> {
         match Self::new(cfg, name.clone()) {
-            Err(RustupError::ToolchainNotInstalled(_)) => (),
+            Err(RustupError::ToolchainNotInstalled { .. }) => (),
             result => {
                 return Ok(result?);
             }
@@ -106,7 +107,14 @@ impl<'a> Toolchain<'a> {
         let path = cfg.toolchain_path(&name);
         if !Toolchain::exists(cfg, &name)? {
             return Err(match name {
-                LocalToolchainName::Named(name) => RustupError::ToolchainNotInstalled(name),
+                LocalToolchainName::Named(name) => {
+                    let is_active =
+                        matches!(cfg.find_active_toolchain(), Ok(Some((tc, _))) if tc == name);
+                    RustupError::ToolchainNotInstalled {
+                        toolchain: name,
+                        is_active,
+                    }
+                }
                 LocalToolchainName::Path(name) => RustupError::PathToolchainNotInstalled(name),
             });
         }

tests/suite/cli_v1.rs

@@ -187,7 +187,7 @@ async fn remove_override_toolchain_err_handling() {
             "",
             for_host!(
                 r"error: toolchain 'beta-{0}' is not installed
-help: run `rustup toolchain install beta-{0}` to install it
+help: run `rustup toolchain install` to install it
 "
             ),
         )

tests/suite/cli_v2.rs

@@ -329,7 +329,7 @@ async fn remove_override_toolchain_err_handling() {
             "",
             for_host!(
                 r"error: toolchain 'beta-{0}' is not installed
-help: run `rustup toolchain install beta-{0}` to install it
+help: run `rustup toolchain install` to install it
 "
             ),
         )