Use definition to indicate out-of-project files with server support

lib/auto-languageclient.ts

@@ -313,6 +313,12 @@ export default class AutoLanguageClient {
       connection,
       capabilities: initializeResponse.capabilities,
       disposable: new CompositeDisposable(),
+      additionalPaths: new Set(),
+      considerDefinitionPath: (defPath: string): void => {
+        if (!defPath.startsWith(projectPath)) {
+          newServer.additionalPaths.add(path.dirname(defPath));
+        }
+      },
     };
     this.postInitialization(newServer);
     connection.initialized();
@@ -523,13 +529,25 @@ export default class AutoLanguageClient {
     }
 
     this.definitions = this.definitions || new DefinitionAdapter();
-    return this.definitions.getDefinition(
+    const queryPromise = this.definitions.getDefinition(
       server.connection,
       server.capabilities,
       this.getLanguageName(),
       editor,
       point,
     );
+
+    if (this.serversSupportDefinitionDestinations()) {
+      queryPromise.then((query) => {
+        if (query) {
+          for (const def of query.definitions) {
+            server.considerDefinitionPath(def.path);
+          }
+        }
+      });
+    }
+
+    return queryPromise;
   }
 
   // Outline View via LS documentSymbol---------------------------------
@@ -786,6 +804,16 @@ export default class AutoLanguageClient {
     stderr.split('\n').filter((l) => l).forEach((line) => this.logger.warn(`stderr ${line}`));
   }
 
+  /**
+   * Indicates that the language server can support LSP functionality for
+   * out of project files indicated by `textDocument/definition` responses.
+   *
+   * Default: false
+   */
+  protected serversSupportDefinitionDestinations(): boolean {
+    return false;
+  }
+
   private getServerAdapter<T extends keyof ServerAdapters>(
     server: ActiveServer, adapter: T,
   ): ServerAdapters[T] | undefined {

lib/server-manager.ts

@@ -33,6 +33,10 @@ export interface ActiveServer {
   process: LanguageServerProcess;
   connection: ls.LanguageClientConnection;
   capabilities: ls.ServerCapabilities;
+  // Out of project directories that this server can also support.
+  additionalPaths: Set<string>;
+  // Considers a path from `textDocument/definition` for inclusion in `additionalPaths`.
+  considerDefinitionPath(path: string): void;
 }
 
 interface RestartCounter {
@@ -259,7 +263,15 @@ export class ServerManager {
     if (filePath == null) {
       return null;
     }
-    return this._normalizedProjectPaths.find((d) => filePath.startsWith(d)) || null;
+
+    const projectPath = this._normalizedProjectPaths.find((d) => filePath.startsWith(d));
+    if (projectPath) {
+      return projectPath;
+    }
+
+    const serverWithClaim = this._activeServers
+      .find((s) => s.additionalPaths.has(path.dirname(filePath)));
+    return serverWithClaim && this.normalizePath(serverWithClaim.projectPath) || null;
   }
 
   public updateNormalizedProjectPaths(): void {

test/adapters/autocomplete-adapter.test.ts

@@ -20,6 +20,8 @@ describe('AutoCompleteAdapter', () => {
       disposable: new CompositeDisposable(),
       process: undefined as any,
       projectPath: '/',
+      additionalPaths: new Set(),
+      considerDefinitionPath: (_: string): void => {},
     };
   }