Fix type hierarchy registration and subtype expansion

Author: sidux

src/server.rs

@@ -397,11 +397,7 @@ impl LanguageServer for Backend {
             .supports_type_hierarchy_dynamic_registration
             .load(Ordering::Acquire)
         {
-            registrations.push(Registration {
-                id: "type-hierarchy".to_string(),
-                method: "textDocument/prepareTypeHierarchy".to_string(),
-                register_options: None,
-            });
+            registrations.push(type_hierarchy_registration());
         }
 
         // Register file watchers for staleness detection.  The client
@@ -1588,6 +1584,27 @@ impl LanguageServer for Backend {
     }
 }
 
+fn type_hierarchy_registration() -> Registration {
+    Registration {
+        id: "type-hierarchy".to_string(),
+        method: "textDocument/prepareTypeHierarchy".to_string(),
+        register_options: Some(
+            serde_json::to_value(TypeHierarchyRegistrationOptions {
+                text_document_registration_options: TextDocumentRegistrationOptions {
+                    document_selector: Some(vec![DocumentFilter {
+                        language: Some("php".to_string()),
+                        scheme: None,
+                        pattern: None,
+                    }]),
+                },
+                type_hierarchy_options: TypeHierarchyOptions::default(),
+                static_registration_options: StaticRegistrationOptions::default(),
+            })
+            .expect("type hierarchy registration options serialize"),
+        ),
+    }
+}
+
 /// Convert a `Vec<Location>` into a `GotoDefinitionResponse`.
 ///
 /// Returns `Scalar` for a single location, `Array` for multiple, and
@@ -1603,6 +1620,26 @@ fn wrap_locations(locations: Vec<Location>) -> Option<GotoDefinitionResponse> {
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn type_hierarchy_registration_includes_php_document_selector() {
+        let registration = type_hierarchy_registration();
+
+        assert_eq!(registration.id, "type-hierarchy");
+        assert_eq!(registration.method, "textDocument/prepareTypeHierarchy");
+
+        let options = registration
+            .register_options
+            .expect("type hierarchy registration should include options");
+        assert_eq!(options["documentSelector"][0]["language"], "php");
+        assert!(options["documentSelector"][0].get("scheme").is_none());
+        assert!(options["documentSelector"][0].get("pattern").is_none());
+    }
+}
+
 // ─── Self-scan helpers ──────────────────────────────────────────────────────
 
 impl Backend {

src/type_hierarchy.rs

@@ -137,9 +137,23 @@ impl Backend {
         let ctx = self.file_context(item_uri);
         let class_loader = self.class_loader(&ctx);
 
-        // direct_only = true so only immediate children are returned;
-        // the client walks the tree one level at a time.
-        let implementors = self.find_implementors(short, &fqn, &class_loader, true, true);
+        // Subtypes are walked one level at a time by the client. Prefer
+        // the reverse inheritance index for known children so expanding an
+        // already-discovered hierarchy node does not re-run the broad
+        // go-to-implementation scanner over the workspace.
+        let indexed_children = self.gti_index.read().get(&fqn).cloned();
+        let implementors: Vec<ClassInfo> = if let Some(children) = indexed_children {
+            children
+                .into_iter()
+                .filter_map(|child_fqn| {
+                    class_loader(&child_fqn).map(std::sync::Arc::unwrap_or_clone)
+                })
+                .collect()
+        } else {
+            // Fall back to the wider scan for first discovery of unopened
+            // files that are known only through the FQN index.
+            self.find_implementors(short, &fqn, &class_loader, true, true)
+        };
 
         let mut result = Vec::new();
         for imp in &implementors {