fix: Incorrect flychecks with multiple workspaces

crates/rust-analyzer/src/flycheck.rs

@@ -1021,7 +1021,7 @@ impl JsonLinesParser<CheckMessage> for CheckParser {
     }
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug)]
 #[serde(untagged)]
 enum JsonMessage {
     Cargo(cargo_metadata::Message),

crates/rust-analyzer/src/handlers/notification.rs

@@ -296,7 +296,7 @@ pub(crate) fn handle_did_change_watched_files(
         if let Ok(path) = from_proto::abs_path(&change.uri) {
             if !trigger_flycheck {
                 trigger_flycheck =
-                    state.config.workspace_roots().iter().any(|root| !path.starts_with(root));
+                    state.config.workspace_roots().iter().all(|root| !path.starts_with(root));
             }
             state.loader.handle.invalidate(path);
         }

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

@@ -110,3 +110,50 @@ fn main() {}
         diagnostics.diagnostics,
     );
 }
+
+#[cfg(unix)] // We're using sh -c in this test, so skip windows.
+#[test]
+fn test_flycheck_multiple_workspaces() {
+    if skip_slow_tests() {
+        return;
+    }
+
+    let server = Project::with_fixture(
+        r#"
+//- /ws1/Cargo.toml
+[package]
+name = "foo"
+version = "0.0.0"
+
+//- /ws1/src/main.rs
+fn main() {}
+
+//- /ws2/Cargo.toml
+[package]
+name = "bar"
+version = "0.0.0"
+
+//- /ws2/src/main.rs
+fn main() {}
+"#,
+    )
+    .root("ws1")
+    .root("ws2")
+    .with_config(serde_json::json!({
+        "checkOnSave": true,
+        "check": {
+            "overrideCommand": ["sh", "-c", "sleep 1 && rustc --error-format=json {saved_file}"],
+        }
+    }))
+    .server()
+    .wait_until_workspace_is_loaded();
+
+    server.write_file_and_save("ws1/src/main.rs", "fn main() {\n    let x = 1;\n}\n".to_owned());
+
+    let diag1 = server.wait_for_diagnostics();
+    assert!(
+        diag1.diagnostics.iter().any(|d| d.message.contains("unused variable")),
+        "expected unused variable diagnostic from ws1, got: {:?}",
+        diag1.diagnostics,
+    );
+}

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

@@ -497,7 +497,22 @@ impl Server {
                 text_document: self.doc_id(path),
                 text: Some(text),
             },
-        )
+        );
+
+        // In a real LSP session, we receive DidChangeWatchedFiles
+        // shortly after DidSave, but there is a non-zero amount of
+        // time between the notifications. Add a brief sleep so we can
+        // start handling the DidSave event, mimicking a real session.
+        std::thread::sleep(std::time::Duration::from_millis(500));
+
+        self.notification::<lsp_types::notification::DidChangeWatchedFiles>(
+            lsp_types::DidChangeWatchedFilesParams {
+                changes: vec![lsp_types::FileEvent {
+                    uri: self.doc_id(path).uri,
+                    typ: lsp_types::FileChangeType::CHANGED,
+                }],
+            },
+        );
     }
 }