From 85dc5946cf000227cc608a275355e3ad18abe58b Mon Sep 17 00:00:00 2001
From: Youri Tomassen <gretch552@gmail.com>
Date: Fri, 2 May 2025 15:54:37 +0200
Subject: [PATCH] perf(@angular/build): fix unnecessary esbuild rebuilds

When using esbuild, Angular sets up a custom file watcher using esbuilds metafile inputs. Esbuild will generate <define:KEY> entries see https://esbuild.github.io/try/#YgAwLjI1LjMALS1kZWZpbmU6Rk9PPSd7fScgLS1tZXRhZmlsZSAtLWJ1bmRsZQBlAGVudHJ5LmpzAGNvbnNvbGUubG9nKEZPTyk. After the build is finished, the file watcher will notice that the <define:KEY> entries no longer exist on the file system and trigger a rebuild even though no files have changed.
This change, fixes the above issue by filtering files starting with `<define:`.
---
 .../build/src/tools/esbuild/bundler-context.ts       | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/angular/build/src/tools/esbuild/bundler-context.ts b/packages/angular/build/src/tools/esbuild/bundler-context.ts
index a551ae4defba..0d6b3d59ceaf 100644
--- a/packages/angular/build/src/tools/esbuild/bundler-context.ts
+++ b/packages/angular/build/src/tools/esbuild/bundler-context.ts
@@ -245,7 +245,7 @@ export class BundlerContext {
         // When incremental always add any files from the load result cache
         if (this.#loadCache) {
           for (const file of this.#loadCache.watchFiles) {
-            if (!isInternalAngularFile(file)) {
+            if (!isInternalAngularFileOrEsBuildDefine(file)) {
               // watch files are fully resolved paths
               this.watchFiles.add(file);
             }
@@ -260,7 +260,7 @@ export class BundlerContext {
     if (this.incremental) {
       // Add input files except virtual angular files which do not exist on disk
       for (const input of Object.keys(result.metafile.inputs)) {
-        if (!isInternalAngularFile(input)) {
+        if (!isInternalAngularFileOrEsBuildDefine(input)) {
           // input file paths are always relative to the workspace root
           this.watchFiles.add(join(this.workspaceRoot, input));
         }
@@ -417,12 +417,12 @@ export class BundlerContext {
   #addErrorsToWatch(result: BuildFailure | BuildResult): void {
     for (const error of result.errors) {
       let file = error.location?.file;
-      if (file && !isInternalAngularFile(file)) {
+      if (file && !isInternalAngularFileOrEsBuildDefine(file)) {
         this.watchFiles.add(join(this.workspaceRoot, file));
       }
       for (const note of error.notes) {
         file = note.location?.file;
-        if (file && !isInternalAngularFile(file)) {
+        if (file && !isInternalAngularFileOrEsBuildDefine(file)) {
           this.watchFiles.add(join(this.workspaceRoot, file));
         }
       }
@@ -475,6 +475,6 @@ export class BundlerContext {
   }
 }
 
-function isInternalAngularFile(file: string) {
-  return file.startsWith('angular:');
+function isInternalAngularFileOrEsBuildDefine(file: string) {
+  return file.startsWith('angular:') || file.startsWith('<define:');
 }