LS: Hide errors from github sources only when they're not associated with a real project (microsoft#2139)

Small fix to microsoft#1787 while staying true to the intention of that change.

We want to _hide_ errors from GitHub sources that are open in the
editor, but aren't associated with a project. They're essentially
orphans. For example, you may have closed the original project that
referenced those GitHub sources, but left the GitHub source open in the
editor.

But we want to _show_ errors from GitHub sources if they're part of a
normal project. Errors from dependencies are helpful.

Author: minestarks

language_service/src/state.rs

@@ -417,6 +417,16 @@ impl<'a> CompilationStateUpdater<'a> {
             for (compilation_uri, compilation) in &state.compilations {
                 trace!("publishing diagnostics for {compilation_uri}");
 
+                if compilation_uri.starts_with(qsc_project::GITHUB_SCHEME) {
+                    // If the compilation URI is a GitHub virtual document URI,
+                    // that's a signal that this is a source file from a GitHub package
+                    // that is open in the editor.
+                    // We can't discover the manifest and load the project for these files.
+                    // So they end up in their own single-file compilation.
+                    // Don't publish diagnostics for these, as they will contain spurious errors.
+                    continue;
+                }
+
                 for (uri, errors) in map_errors_to_docs(
                     compilation_uri,
                     &compilation.0.compile_errors,
@@ -430,12 +440,6 @@ impl<'a> CompilationStateUpdater<'a> {
                         // a less confusing user experience.
                         continue;
                     }
-                    if uri.starts_with(qsc_project::GITHUB_SCHEME) {
-                        // Don't publish diagnostics for GitHub URIs.
-                        // This is temporary workaround to avoid spurious errors when a document
-                        // is opened in single file mode that is part of a read-only GitHub project.
-                        continue;
-                    }
 
                     self.publish_diagnostics_for_doc(state, &uri, errors);
                 }

language_service/src/state/tests.rs

@@ -1591,6 +1591,57 @@ async fn error_from_dependency_reported() {
     );
 }
 
+#[tokio::test]
+async fn single_github_source_no_errors() {
+    let received_errors = RefCell::new(Vec::new());
+    let test_cases = RefCell::new(Vec::new());
+    let mut updater = new_updater(&received_errors, &test_cases);
+
+    updater
+        .update_document("qsharp-github-source:foo/bar/Main.qs", 1, "badsyntax")
+        .await;
+
+    updater
+        .update_document("/foo/bar/Main.qs", 1, "badsyntax")
+        .await;
+
+    // Same error exists in both files, but the github one should not be reported
+
+    check_state_and_errors(
+        &updater,
+        &received_errors,
+        &expect![[r#"
+            {
+                "qsharp-github-source:foo/bar/Main.qs": OpenDocument {
+                    version: 1,
+                    compilation: "qsharp-github-source:foo/bar/Main.qs",
+                    latest_str_content: "badsyntax",
+                },
+                "/foo/bar/Main.qs": OpenDocument {
+                    version: 1,
+                    compilation: "/foo/bar/Main.qs",
+                    latest_str_content: "badsyntax",
+                },
+            }
+        "#]],
+        &expect![[r#"
+            qsharp-github-source:foo/bar/Main.qs: [
+              "qsharp-github-source:foo/bar/Main.qs": "badsyntax",
+            ],
+            /foo/bar/Main.qs: [
+              "/foo/bar/Main.qs": "badsyntax",
+            ],
+        "#]],
+        &expect![[r#"
+            [
+              uri: "/foo/bar/Main.qs" version: Some(1) errors: [
+                syntax error
+                  [/foo/bar/Main.qs] [badsyntax]
+              ],
+            ]"#]],
+    );
+}
+
 #[tokio::test]
 async fn test_case_detected() {
     let fs = FsNode::Dir(