fix(@angular-devkit/build-angular): improve file watching on Windows when using certain IDEs

packages/angular_devkit/build_angular/src/tools/esbuild/watcher.ts

@@ -7,6 +7,7 @@
  */
 
 import { FSWatcher } from 'chokidar';
+import { normalize } from 'node:path';
 
 export class ChangedFiles {
   readonly added = new Set<string>();
@@ -51,19 +52,65 @@ export function createWatcher(options?: {
   let currentChanges: ChangedFiles | undefined;
   let nextWaitTimeout: NodeJS.Timeout | undefined;
 
-  watcher.on('all', (event, path) => {
+  /**
+   * We group the current events in a map as on Windows with certain IDE a file contents change can trigger multiple events.
+   *
+   * Example:
+   * rename | 'C:/../src/app/app.component.css'
+   * rename | 'C:/../src/app/app.component.css'
+   * change | 'C:/../src/app/app.component.css'
+   *
+   */
+  let currentEvents: Map</* Event name */ string, /* File path */ string> | undefined;
+
+  /**
+   * Using `watcher.on('all')` does not capture some of events fired when using Visual studio and this does not happen all the time,
+   * but only after a file has been changed 3 or more times.
+   *
+   * Also, some IDEs such as Visual Studio (not VS Code) will fire a rename event instead of unlink when a file is renamed or changed.
+   *
+   * Example:
+   * ```
+   * watcher.on('raw')
+   * Change 1
+   * rename | 'C:/../src/app/app.component.css'
+   * rename | 'C:/../src/app/app.component.css'
+   * change | 'C:/../src/app/app.component.css'
+   *
+   * Change 2
+   * rename | 'C:/../src/app/app.component.css'
+   * rename | 'C:/../src/app/app.component.css'
+   * change | 'C:/../src/app/app.component.css'
+   *
+   * Change 3
+   * rename | 'C:/../src/app/app.component.css'
+   * rename | 'C:/../src/app/app.component.css'
+   * change | 'C:/../src/app/app.component.css'
+   *
+   * watcher.on('all')
+   * Change 1
+   * change | 'C:\\..\\src\\app\\app.component.css'
+   *
+   * Change 2
+   * unlink | 'C:\\..\\src\\app\\app.component.css'
+   *
+   * Change 3
+   * ... (Nothing)
+   * ```
+   */
+  watcher.on('raw', (event, path, { watchedPath }) => {
     switch (event) {
       case 'add':
-        currentChanges ??= new ChangedFiles();
-        currentChanges.added.add(path);
-        break;
       case 'change':
-        currentChanges ??= new ChangedFiles();
-        currentChanges.modified.add(path);
-        break;
+      // When using Visual Studio the rename event is fired before a change event when the contents of the file changed
+      // or instead of `unlink` when the file has been renamed.
       case 'unlink':
-        currentChanges ??= new ChangedFiles();
-        currentChanges.removed.add(path);
+      case 'rename':
+        // When polling is enabled `watchedPath` can be undefined.
+        // `path` is always normalized unlike `watchedPath`.
+        const changedPath = watchedPath ? normalize(watchedPath) : path;
+        currentEvents ??= new Map();
+        currentEvents.set(changedPath, event);
         break;
       default:
         return;
@@ -74,10 +121,27 @@ export function createWatcher(options?: {
       nextWaitTimeout = setTimeout(() => {
         nextWaitTimeout = undefined;
         const next = nextQueue.shift();
-        if (next) {
-          const value = currentChanges;
-          currentChanges = undefined;
-          next(value);
+        if (next && currentEvents) {
+          const events = currentEvents;
+          currentEvents = undefined;
+
+          const currentChanges = new ChangedFiles();
+          for (const [path, event] of events) {
+            switch (event) {
+              case 'add':
+                currentChanges.added.add(path);
+                break;
+              case 'change':
+                currentChanges.modified.add(path);
+                break;
+              case 'unlink':
+              case 'rename':
+                currentChanges.removed.add(path);
+                break;
+            }
+          }
+
+          next(currentChanges);
         }
       }, 250);
       nextWaitTimeout?.unref();

packages/angular_devkit/build_angular/src/utils/environment-options.ts

@@ -102,7 +102,4 @@ export const debugPerformance = isPresent(debugPerfVariable) && isEnabled(debugP
 
 // Default to true on Windows to workaround Visual Studio atomic file saving watch issues
 const watchRootVariable = process.env['NG_BUILD_WATCH_ROOT'];
-export const shouldWatchRoot =
-  process.platform === 'win32'
-    ? !isPresent(watchRootVariable) || !isDisabled(watchRootVariable)
-    : isPresent(watchRootVariable) && isEnabled(watchRootVariable);
+export const shouldWatchRoot = isPresent(watchRootVariable) && isEnabled(watchRootVariable);