feat(custom-toolchains): rustup show now reporting installed targets

Author: FranciscoTGouveia

src/cli/rustup_mode.rs

@@ -987,17 +987,24 @@ async fn show(cfg: &Cfg<'_>, verbose: bool) -> Result<utils::ExitCode> {
 
     let active_toolchain_targets: Vec<TargetTriple> = active_toolchain_name
         .and_then(|atn| match atn {
-            ToolchainName::Official(desc) => DistributableToolchain::new(cfg, desc.clone()).ok(),
-            // So far, it is not possible to list targets for a custom toolchain.
-            ToolchainName::Custom(_) => None,
-        })
-        .and_then(|distributable| distributable.components().ok())
-        .map(|cs_vec| {
-            cs_vec
-                .into_iter()
-                .filter(|c| c.installed && c.component.short_name_in_manifest() == "rust-std")
-                .map(|c| c.component.target.expect("rust-std should have a target"))
-                .collect()
+            ToolchainName::Official(desc) => DistributableToolchain::new(cfg, desc.clone())
+                .ok()
+                .and_then(|distributable| distributable.components().ok())
+                .map(|cs_vec| {
+                    cs_vec
+                        .into_iter()
+                        .filter(|c| {
+                            c.installed && c.component.short_name_in_manifest() == "rust-std"
+                        })
+                        .map(|c| c.component.target.expect("rust-std should have a target"))
+                        .collect()
+                }),
+            ToolchainName::Custom(name) => {
+                Toolchain::new(cfg, LocalToolchainName::Named(name.into()))
+                    .ok()?
+                    .list_targets()
+                    .ok()
+            }
         })
         .unwrap_or_default();
 

src/dist/component/mod.rs

@@ -10,7 +10,7 @@ mod transaction;
 // The representation of a package, its components, and installation
 mod package;
 // The representation of *installed* components, and uninstallation
-mod components;
+pub mod components;
 
 #[cfg(test)]
 mod tests;

src/toolchain.rs

@@ -22,7 +22,10 @@ use wait_timeout::ChildExt;
 use crate::{
     RustupError,
     config::{ActiveReason, Cfg, InstalledPath},
-    dist::PartialToolchainDesc,
+    dist::{
+        PartialToolchainDesc, TargetTriple, component::components::Components,
+        prefix::InstallPrefix,
+    },
     env_var, install,
     notifications::Notification,
     utils::{self, raw::open_dir_following_links},
@@ -575,4 +578,27 @@ impl<'a> Toolchain<'a> {
         }
         Ok(())
     }
+
+    /// Get the list of installed targets for any toolchain
+    ///
+    /// NB: An assumption is made that custom toolchains always have a `rustlib/components` file
+    pub fn list_targets(&self) -> anyhow::Result<Vec<TargetTriple>> {
+        let prefix = InstallPrefix::from(self.path.clone());
+        let components = Components::open(prefix)?;
+        let installed_components = components.list()?;
+
+        let targets = installed_components
+            .into_iter()
+            .filter_map(|c| {
+                if c.name().starts_with("rust-std-") {
+                    Some(TargetTriple::new(
+                        c.name().trim_start_matches("rust-std-").to_string(),
+                    ))
+                } else {
+                    None
+                }
+            })
+            .collect();
+        Ok(targets)
+    }
 }