attempt to fall back to chokidar file watcher if the lsp client doesn…

…'t support `capabilities.workspace.didChangeWatchedFiles.dynamicRegistration`

packages/pyright-internal/src/common/chokidarFileWatcherProvider.ts

@@ -9,15 +9,15 @@
 import * as chokidar from 'chokidar';
 
 import { ConsoleInterface } from './console';
-import { FileWatcher, FileWatcherEventHandler, FileWatcherProvider } from './fileWatcher';
+import { FileWatcherEventHandler, FileWatcherProvider } from './fileWatcher';
 
 const _isMacintosh = process.platform === 'darwin';
 const _isLinux = process.platform === 'linux';
 
 export class ChokidarFileWatcherProvider implements FileWatcherProvider {
     constructor(private _console?: ConsoleInterface) {}
 
-    createFileWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher {
+    createFileWatcher(paths: string[], listener: FileWatcherEventHandler): chokidar.FSWatcher {
         return this._createFileSystemWatcher(paths).on('all', listener);
     }
 
@@ -56,8 +56,8 @@ export class ChokidarFileWatcherProvider implements FileWatcherProvider {
         watcherOptions.ignored = excludes;
 
         const watcher = chokidar.watch(paths, watcherOptions);
-        watcher.on('error', (_) => {
-            this._console?.error('Error returned from file system watcher.');
+        watcher.on('error', (e) => {
+            this._console?.error(`Error returned from file system watcher: ${e}`);
         });
 
         // Detect if for some reason the native watcher library fails to load

packages/pyright-internal/src/common/realFileSystem.ts

@@ -26,6 +26,8 @@ import { FileUri, FileUriSchema } from './uri/fileUri';
 import { Uri } from './uri/uri';
 import { getRootUri } from './uri/uriUtils';
 import { isMainThread } from './workersHost';
+import { ChokidarFileWatcherProvider } from './chokidarFileWatcherProvider';
+import { FSWatcher } from 'chokidar';
 
 // Automatically remove files created by tmp at process exit.
 tmp.setGracefulCleanup();
@@ -466,10 +468,38 @@ interface WorkspaceFileWatcher extends FileWatcher {
     eventHandler: FileWatcherEventHandler;
 }
 
+/**
+ * file watcher provider for lsp clients that support `capabilities.workspace.didChangeWatchedFiles.dynamicRegistration`.
+ *
+ * this class also contains functionality to convert its file watchers to chokidar ones. this is a bit gross but necessary
+ * because this class is created before we know which kid of file watcher the lsp client requires.
+ */
 export class WorkspaceFileWatcherProvider implements FileWatcherProvider, FileWatcherHandler {
     private _fileWatchers: WorkspaceFileWatcher[] = [];
+    private _chokidarFileWatchers?: FSWatcher[];
+    private _chokidarFileWatcherProvider?: ChokidarFileWatcherProvider;
+
+    /**
+     * converts all file watchers created with {@link createFileWatcher} to chokidar file watchers.
+     */
+    convertToChokidar = (console: ConsoleInterface) => {
+        console.info(`existing file watchers: ${this._fileWatchers}`);
+        if (this._chokidarFileWatchers) {
+            return;
+        }
+        this._chokidarFileWatcherProvider = new ChokidarFileWatcherProvider(console);
+        this._chokidarFileWatchers = this._fileWatchers.map((fileWatcher) => {
+            return this._chokidarFileWatcherProvider!.createFileWatcher(
+                fileWatcher.workspacePaths,
+                fileWatcher.eventHandler
+            );
+        });
+    };
 
     createFileWatcher(workspacePaths: string[], listener: FileWatcherEventHandler): FileWatcher {
+        if (this._chokidarFileWatcherProvider) {
+            return this._chokidarFileWatcherProvider.createFileWatcher(workspacePaths, listener);
+        }
         const self = this;
         const fileWatcher: WorkspaceFileWatcher = {
             close() {
@@ -487,6 +517,10 @@ export class WorkspaceFileWatcherProvider implements FileWatcherProvider, FileWa
     }
 
     onFileChange(eventType: FileWatcherEventType, fileUri: Uri): void {
+        if (this._chokidarFileWatchers) {
+            this._chokidarFileWatchers.forEach((fileWatcher) => fileWatcher.emit(eventType, fileUri.getFilePath()));
+            return;
+        }
         // Since file watcher is a server wide service, we don't know which watcher is
         // for which workspace (for multi workspace case), also, we don't know which watcher
         // is for source or library. so we need to solely rely on paths that can cause us

packages/pyright-internal/src/languageServerBase.ts

@@ -146,6 +146,7 @@ import { SemanticTokensProvider, SemanticTokensProviderLegend } from './language
 import { RenameUsageFinder } from './analyzer/renameUsageFinder';
 import { BaselineHandler } from './baseline';
 import { assert } from './common/debug';
+import { WorkspaceFileWatcherProvider } from './common/realFileSystem';
 
 export abstract class LanguageServerBase implements LanguageServerInterface, Disposable {
     // We support running only one "find all reference" at a time.
@@ -594,6 +595,8 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
                     this.workspaceFactory
                 )
             );
+        } else if (this.serverOptions.fileWatcherHandler instanceof WorkspaceFileWatcherProvider) {
+            this.serverOptions.fileWatcherHandler.convertToChokidar(this.console);
         }
         const result: InitializeResult = {
             capabilities: {