WIP: Thoughts on #2458

Signed-off-by: Daniel Silverstone (WSL2) <dsilvers@digital-scurf.org>

Author: kinnison

src/config.rs

@@ -33,6 +33,7 @@ impl OverrideFile {
 #[derive(Debug, Default, Deserialize, PartialEq, Eq)]
 struct ToolchainSection {
     channel: Option<String>,
+    path: Option<String>,
     components: Option<Vec<String>>,
     targets: Option<Vec<String>>,
 }
@@ -45,11 +46,21 @@ impl ToolchainSection {
 
 impl<T: Into<String>> From<T> for OverrideFile {
     fn from(channel: T) -> Self {
-        Self {
-            toolchain: ToolchainSection {
-                channel: Some(channel.into()),
-                ..Default::default()
-            },
+        let channel = channel.into();
+        if channel.contains('/') || channel.contains('\\') {
+            Self {
+                toolchain: ToolchainSection {
+                    path: Some(channel),
+                    ..Default::default()
+                },
+            }
+        } else {
+            Self {
+                toolchain: ToolchainSection {
+                    channel: Some(channel),
+                    ..Default::default()
+                },
+            }
         }
     }
 }
@@ -73,7 +84,7 @@ impl Display for OverrideReason {
     }
 }
 
-#[derive(Default)]
+#[derive(Default, Debug)]
 struct OverrideCfg<'a> {
     toolchain: Option<Toolchain<'a>>,
     components: Vec<String>,
@@ -83,9 +94,13 @@ struct OverrideCfg<'a> {
 impl<'a> OverrideCfg<'a> {
     fn from_file(cfg: &'a Cfg, file: OverrideFile) -> Result<Self> {
         Ok(Self {
-            toolchain: match file.toolchain.channel {
-                Some(name) => Some(Toolchain::from(cfg, &name)?),
-                None => None,
+            toolchain: match (file.toolchain.channel, file.toolchain.path) {
+                (Some(name), None) => Some(Toolchain::from(cfg, &name)?),
+                (None, Some(path)) => Some(Toolchain::from_path(cfg, &path)?),
+                (Some(channel), Some(path)) => {
+                    return Err(ErrorKind::CannotSpecifyChannelAndPath(channel, path.into()).into())
+                }
+                (None, None) => None,
             },
             components: file.toolchain.components.unwrap_or_default(),
             targets: file.toolchain.targets.unwrap_or_default(),
@@ -514,7 +529,6 @@ impl Cfg {
                     path.display()
                 ),
             };
-
             let override_cfg = OverrideCfg::from_file(self, file)?;
             if let Some(toolchain) = &override_cfg.toolchain {
                 // Overridden toolchains can be literally any string, but only
@@ -882,6 +896,7 @@ mod tests {
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: Some(contents.into()),
+                    path: None,
                     components: None,
                     targets: None,
                 }
@@ -903,6 +918,7 @@ targets = [ "wasm32-unknown-unknown", "thumbv2-none-eabi" ]
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: Some("nightly-2020-07-10".into()),
+                    path: None,
                     components: Some(vec!["rustfmt".into(), "rustc-dev".into()]),
                     targets: Some(vec![
                         "wasm32-unknown-unknown".into(),
@@ -925,6 +941,7 @@ channel = "nightly-2020-07-10"
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: Some("nightly-2020-07-10".into()),
+                    path: None,
                     components: None,
                     targets: None,
                 }
@@ -945,6 +962,7 @@ components = []
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: Some("nightly-2020-07-10".into()),
+                    path: None,
                     components: Some(vec![]),
                     targets: None,
                 }
@@ -965,6 +983,7 @@ targets = []
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: Some("nightly-2020-07-10".into()),
+                    path: None,
                     components: None,
                     targets: Some(vec![]),
                 }
@@ -984,6 +1003,7 @@ components = [ "rustfmt" ]
             OverrideFile {
                 toolchain: ToolchainSection {
                     channel: None,
+                    path: None,
                     components: Some(vec!["rustfmt".into()]),
                     targets: None,
                 }

src/errors.rs

@@ -188,6 +188,14 @@ error_chain! {
             description("invalid toolchain name")
             display("invalid toolchain name: '{}'", t)
         }
+        InvalidToolchainPath(p: PathBuf) {
+            description("invalid toolchain path"),
+            display("invalid toolchain path: '{}'", p.display())
+        }
+        CannotSpecifyChannelAndPath(channel: String, path: PathBuf) {
+            description("cannot specify channel and path simultaneously"),
+            display("cannot specify both channel ({}) and path ({}) simultaneously", channel, path.display())
+        }
         InvalidProfile(t: String) {
             description("invalid profile name")
             display("invalid profile name: '{}'; valid names are: {}", t, valid_profile_names())

src/toolchain.rs

@@ -63,6 +63,9 @@ pub enum UpdateStatus {
 
 impl<'a> Toolchain<'a> {
     pub fn from(cfg: &'a Cfg, name: &str) -> Result<Self> {
+        if name.contains('/') || name.contains('\\') {
+            return Self::from_path(cfg, name);
+        }
         let resolved_name = cfg.resolve_toolchain(name)?;
         let path = cfg.toolchains_dir.join(&resolved_name);
         Ok(Toolchain {
@@ -73,6 +76,26 @@ impl<'a> Toolchain<'a> {
         })
     }
 
+    pub fn from_path(cfg: &'a Cfg, path: impl AsRef<Path>) -> Result<Self> {
+        let path = path.as_ref();
+        let base = path
+            .components()
+            .last()
+            .ok_or_else(|| ErrorKind::InvalidToolchainPath(path.into()))?
+            .as_os_str()
+            .to_string_lossy();
+        // Perform minimal validation - that there's a `bin/` which might contain things for us to run
+        if !path.join("bin").is_dir() {
+            return Err(ErrorKind::InvalidToolchainPath(path.into()).into());
+        }
+        Ok(Toolchain {
+            cfg,
+            name: base.into(),
+            path: path.to_path_buf(),
+            dist_handler: Box::new(move |n| (cfg.notify_handler)(n.into())),
+        })
+    }
+
     pub fn as_installed_common(&'a self) -> Result<InstalledCommonToolchain<'a>> {
         if !self.exists() {
             // Should be verify perhaps?
@@ -250,6 +273,15 @@ impl<'a> Toolchain<'a> {
     }
 }
 
+impl<'a> std::fmt::Debug for Toolchain<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Toolchain")
+            .field("name", &self.name)
+            .field("path", &self.path)
+            .finish()
+    }
+}
+
 /// Newtype hosting functions that apply to both custom and distributable toolchains that are installed.
 pub struct InstalledCommonToolchain<'a>(&'a Toolchain<'a>);