#820 Supress confusing NotADirectory error and show override missing

src/rustup/config.rs

@@ -233,7 +233,18 @@ impl Cfg {
             Ok(s.find_override(path, self.notify_handler.as_ref()))
         }));
         if let Some((name, reason_path)) = result {
-            let toolchain = try!(self.verify_toolchain(&name).chain_err(|| ErrorKind::ToolchainNotInstalled(name.to_string())));
+            let toolchain = match self.verify_toolchain(&name) {
+                Ok(t) => { t },
+                Err(Error(ErrorKind::Utils(::rustup_utils::ErrorKind::NotADirectory { .. }), _)) => {
+                    // Strip the confusing NotADirectory error and only mention that the override
+                    // toolchain is not installed.
+                    return Err(ErrorKind::OverrideToolchainNotInstalled(name.to_string()).into())
+                },
+                Err(e) => return Err(e).chain_err(|| {
+                    ErrorKind::OverrideToolchainNotInstalled(name.to_string())
+                })
+
+            };
             return Ok(Some((toolchain, OverrideReason::OverrideDB(reason_path))));
         }
 

src/rustup/errors.rs

@@ -22,6 +22,10 @@ error_chain! {
             description("toolchain is not installed")
             display("toolchain '{}' is not installed", t)
         }
+        OverrideToolchainNotInstalled(t: String) {
+            description("override toolchain is not installed")
+            display("override toolchain '{}' is not installed", t)
+        }
         BinaryNotFound(t: String, bin: String) {
             description("toolchain does not contain binary")
             display("toolchain '{}' does not have the binary `{}`", t, bin)

tests/cli-rustup.rs

@@ -512,8 +512,14 @@ fn show_toolchain_override_not_installed() {
         expect_ok(config, &["rustup", "toolchain", "remove", "nightly"]);
         // I'm not sure this should really be erroring when the toolchain
         // is not installed; just capturing the behavior.
-        expect_err(config, &["rustup", "show"],
-                   for_host!(r"error: toolchain 'nightly-{0}' is not installed"));
+        let mut cmd = clitools::cmd(config, "rustup", &["show"]);
+        clitools::env(config, &mut cmd);
+        let out = cmd.output().unwrap();
+        assert!(!out.status.success());
+        let stderr = String::from_utf8(out.stderr).unwrap();
+        assert!(stderr.starts_with(
+                for_host!("error: override toolchain 'nightly-{0}' is not installed")));
+        assert!(!stderr.contains("info: caused by: not a directory: "));
     });
 }