Propagate build errors using window/showMessage

src/actions/post_build.rs

@@ -86,8 +86,10 @@ impl PostBuildHandler {
                 trace!("build - Error {} when running {:?}", cause, cmd);
                 self.notifier.notify_begin_diagnostics();
                 if !self.shown_cargo_error.swap(true, Ordering::SeqCst) {
-                    let msg = format!("There was an error trying to build, RLS features will be limited: {}", cause);
-                    self.notifier.notify_error_diagnostics(&msg);
+                    // It's not a good idea to make a long message here, the output in
+                    // VSCode is one single line, and it's important to capture the
+                    // root cause.
+                    self.notifier.notify_error_diagnostics(cause);
                 }
                 self.notifier.notify_end_diagnostics();
                 self.active_build_count.fetch_sub(1, Ordering::SeqCst);

src/actions/progress.rs

@@ -34,8 +34,8 @@ pub enum ProgressUpdate {
 pub trait DiagnosticsNotifier: Send {
     fn notify_begin_diagnostics(&self);
     fn notify_publish_diagnostics(&self, PublishDiagnosticsParams);
+    fn notify_error_diagnostics(&self, msg: String);
     fn notify_end_diagnostics(&self);
-    fn notify_error_diagnostics(&self, msg: &str);
 }
 
 /// Generate a new progress params with a unique ID and the given title.
@@ -121,15 +121,15 @@ impl<O: Output> DiagnosticsNotifier for BuildDiagnosticsNotifier<O> {
     fn notify_publish_diagnostics(&self, params: PublishDiagnosticsParams) {
         self.out.notify(Notification::<PublishDiagnostics>::new(params));
     }
+    fn notify_error_diagnostics(&self, message: String) {
+        self.out.notify(Notification::<ShowMessage>::new(ShowMessageParams {
+             typ: MessageType::Error,
+             message: message.to_owned(),
+         }));
+    }
     fn notify_end_diagnostics(&self) {
         let mut params = self.progress_params.clone();
         params.done = Some(true);
         self.out.notify(Notification::<Progress>::new(params));
     }
-    fn notify_error_diagnostics(&self, msg: &str) {
-        self.out.notify(Notification::<ShowMessage>::new(ShowMessageParams {
-            typ: MessageType::Error,
-            message: msg.to_owned(),
-        }));
-    }
 }

src/build/cargo.rs

@@ -85,9 +85,17 @@ pub(super) fn cargo(internals: &Internals, package_arg: PackageArg, progress_sen
         }
         Ok(cwd) => BuildResult::Success(cwd, vec![], vec![], true),
         Err(err) => {
+            // This message goes like this to the UI via showMessage. In VSCode
+            // this ends up on one single line, so it's important to keep it concise.
             let stdout = String::from_utf8(out_clone.lock().unwrap().to_owned()).unwrap();
-            debug!("cargo failed\ncause: {}\nstdout: {}", err, stdout);
-            BuildResult::Err(err.to_string(), None)
+            let stdout_msg = if stdout.is_empty() {
+                "".to_string()
+            } else {
+                format!("({})", stdout)
+            };
+            let msg = format!("Cargo failed: {}{}", err, stdout_msg);
+            debug!("{}", msg);
+            BuildResult::Err(msg, None)
         }
     }
 }