Allow and test path override through env/cmd

This is needed so that proxy commands (like `cargo` -> `rustc`) will
continue to use the path toolchain.

Author: Jon Gjengset

src/config.rs

@@ -50,11 +50,21 @@ 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 override_ = channel.into();
+        if Path::new(&override_).is_absolute() {
+            Self {
+                toolchain: ToolchainSection {
+                    channel: Some(override_),
+                    ..Default::default()
+                },
+            }
+        } else {
+            Self {
+                toolchain: ToolchainSection {
+                    path: Some(PathBuf::from(override_)),
+                    ..Default::default()
+                },
+            }
         }
     }
 }

src/toolchain.rs

@@ -91,15 +91,13 @@ impl<'a> Toolchain<'a> {
             return Err(ErrorKind::InvalidToolchainPath(path.into()).into());
         }
 
-        let base = path
-            .components()
-            .last()
-            .ok_or_else(|| ErrorKind::InvalidToolchainPath(path.clone()))?
-            .as_os_str()
-            .to_string_lossy();
         Ok(Toolchain {
             cfg,
-            name: base.into(),
+            name: path
+                .as_os_str()
+                .to_str()
+                .ok_or_else(|| ErrorKind::InvalidToolchainPath(path.clone().into()))?
+                .to_owned(),
             path,
             dist_handler: Box::new(move |n| (cfg.notify_handler)(n.into())),
         })

tests/cli-rustup.rs

@@ -1384,6 +1384,70 @@ fn file_override() {
     });
 }
 
+#[test]
+fn env_override_path() {
+    setup(&|config| {
+        expect_ok(config, &["rustup", "default", "stable"]);
+        expect_ok(
+            config,
+            &[
+                "rustup",
+                "toolchain",
+                "install",
+                "nightly",
+                "--no-self-update",
+            ],
+        );
+
+        let toolchain_path = config
+            .rustupdir
+            .join("toolchains")
+            .join(format!("nightly-{}", this_host_triple()));
+
+        let mut cmd = clitools::cmd(config, "rustc", &["--version"]);
+        clitools::env(config, &mut cmd);
+        cmd.env("RUSTUP_TOOLCHAIN", toolchain_path.to_str().unwrap());
+
+        let out = cmd.output().unwrap();
+        assert!(String::from_utf8(out.stdout)
+            .unwrap()
+            .contains("hash-nightly-2"));
+    });
+}
+
+#[test]
+fn plus_override_path() {
+    setup(&|config| {
+        expect_ok(config, &["rustup", "default", "stable"]);
+        expect_ok(
+            config,
+            &[
+                "rustup",
+                "toolchain",
+                "install",
+                "nightly",
+                "--no-self-update",
+            ],
+        );
+
+        let toolchain_path = config
+            .rustupdir
+            .join("toolchains")
+            .join(format!("nightly-{}", this_host_triple()));
+        expect_stdout_ok(
+            config,
+            &[
+                "rustup",
+                "run",
+                toolchain_path.to_str().unwrap(),
+                "rustc",
+                "--version",
+            ],
+            "hash-nightly-2",
+        );
+    });
+}
+
 #[test]
 fn file_override_path() {
     setup(&|config| {
@@ -1406,7 +1470,7 @@ fn file_override_path() {
         let toolchain_file = config.current_dir().join("rust-toolchain.toml");
         raw::write_file(
             &toolchain_file,
-            &format!("[toolchain]\npath=\"{}\"", toolchain_path.display()),
+            &format!("[toolchain]\npath=\"{}\"", toolchain_path.to_str().unwrap()),
         )
         .unwrap();
 
@@ -1421,6 +1485,36 @@ fn file_override_path() {
     });
 }
 
+#[test]
+fn proxy_override_path() {
+    setup(&|config| {
+        expect_ok(config, &["rustup", "default", "stable"]);
+        expect_ok(
+            config,
+            &[
+                "rustup",
+                "toolchain",
+                "install",
+                "nightly",
+                "--no-self-update",
+            ],
+        );
+
+        let toolchain_path = config
+            .rustupdir
+            .join("toolchains")
+            .join(format!("nightly-{}", this_host_triple()));
+        let toolchain_file = config.current_dir().join("rust-toolchain.toml");
+        raw::write_file(
+            &toolchain_file,
+            &format!("[toolchain]\npath=\"{}\"", toolchain_path.to_str().unwrap()),
+        )
+        .unwrap();
+
+        expect_stdout_ok(config, &["cargo", "--call-rustc"], "hash-nightly-2");
+    });
+}
+
 #[test]
 fn file_override_path_relative() {
     setup(&|config| {
@@ -1472,7 +1566,7 @@ fn file_override_path_relative() {
 
         raw::write_file(
             &toolchain_file,
-            &format!("[toolchain]\npath=\"{}\"", relative_path.display()),
+            &format!("[toolchain]\npath=\"{}\"", relative_path.to_str().unwrap()),
         )
         .unwrap();