fix: load rust-analyzer.toml for virtual workspaces

Author: Madoshakalaka

crates/load-cargo/src/lib.rs

@@ -282,6 +282,19 @@ impl ProjectFolders {
             }
         }
 
+        // Collect workspace roots not already covered by a local PackageRoot
+        // (e.g. virtual workspaces where no package lives at the workspace root).
+        // We need these to load workspace-root rust-analyzer.toml into a local source root.
+        let uncovered_ws_roots: Vec<AbsPathBuf> = workspaces
+            .iter()
+            .filter_map(|ws| {
+                let ws_root = ws.workspace_root().to_path_buf();
+                let dominated =
+                    roots.iter().any(|root| root.is_local && root.include.contains(&ws_root));
+                (!dominated).then_some(ws_root)
+            })
+            .collect();
+
         for root in roots.into_iter().filter(|it| !it.include.is_empty()) {
             let file_set_roots: Vec<VfsPath> =
                 root.include.iter().cloned().map(VfsPath::from).collect();
@@ -334,6 +347,20 @@ impl ProjectFolders {
             }
         }
 
+        // For virtual workspaces, the workspace root has no local PackageRoot, so
+        // rust-analyzer.toml there would fall into a library source root and be
+        // ignored. Load it explicitly via Entry::Files and register the workspace
+        // root as a local file-set root so the file is classified as local.
+        for ws_root in &uncovered_ws_roots {
+            let ratoml_path = ws_root.join("rust-analyzer.toml");
+            let file_set_roots = vec![VfsPath::from(ws_root.clone())];
+            let entry = vfs::loader::Entry::Files(vec![ratoml_path]);
+            res.watch.push(res.load.len());
+            res.load.push(entry);
+            local_filesets.push(fsc.len() as u64);
+            fsc.add_file_set(file_set_roots);
+        }
+
         if let Some(user_config_path) = user_config_dir_path {
             let ratoml_path = {
                 let mut p = user_config_path.to_path_buf();

crates/rust-analyzer/tests/slow-tests/ratoml.rs

@@ -1008,3 +1008,45 @@ fn main() {
         InternalTestingFetchConfigResponse::CheckWorkspace(true),
     );
 }
+
+#[test]
+fn ratoml_virtual_workspace() {
+    if skip_slow_tests() {
+        return;
+    }
+
+    let server = RatomlTest::new(
+        vec![
+            r#"
+//- /p1/Cargo.toml
+[workspace]
+members = ["member"]
+"#,
+            r#"
+//- /p1/rust-analyzer.toml
+assist.emitMustUse = true
+"#,
+            r#"
+//- /p1/member/Cargo.toml
+[package]
+name = "member"
+version = "0.1.0"
+edition = "2021"
+"#,
+            r#"
+//- /p1/member/src/lib.rs
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+"#,
+        ],
+        vec!["p1"],
+        None,
+    );
+
+    server.query(
+        InternalTestingFetchConfigOption::AssistEmitMustUse,
+        3,
+        InternalTestingFetchConfigResponse::AssistEmitMustUse(true),
+    );
+}