From d4d4e8125ac786fdf6677bf0e59a2fe434e722fe Mon Sep 17 00:00:00 2001
From: Alan Agius <17563226+alan-agius4@users.noreply.github.com>
Date: Fri, 11 Jul 2025 09:28:22 +0000
Subject: [PATCH] fix(@angular/build): emit a warning when `outputHashing` is
 set to `all` or `bundles` when HMR is enabled

These values are incompatible with HMR.

Closes #30697
---
 .../build/src/builders/dev-server/vite-server.ts   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/packages/angular/build/src/builders/dev-server/vite-server.ts b/packages/angular/build/src/builders/dev-server/vite-server.ts
index 7dbafe80f8f4..6f68a37691c6 100644
--- a/packages/angular/build/src/builders/dev-server/vite-server.ts
+++ b/packages/angular/build/src/builders/dev-server/vite-server.ts
@@ -28,6 +28,7 @@ import { loadProxyConfiguration, normalizeSourceMaps } from '../../utils';
 import { useComponentStyleHmr, useComponentTemplateHmr } from '../../utils/environment-options';
 import { loadEsmModule } from '../../utils/load-esm';
 import { Result, ResultFile, ResultKind } from '../application/results';
+import { OutputHashing } from '../application/schema';
 import {
   type ApplicationBuilderInternalOptions,
   BuildOutputFileType,
@@ -158,6 +159,19 @@ export async function* serveWithVite(
     process.setSourceMapsEnabled(true);
   }
 
+  if (
+    serverOptions.hmr &&
+    (browserOptions.outputHashing === OutputHashing.All ||
+      browserOptions.outputHashing === OutputHashing.Bundles)
+  ) {
+    serverOptions.hmr = false;
+
+    context.logger.warn(
+      `Hot Module Replacement (HMR) is disabled because the 'outputHashing' option is set to '${browserOptions.outputHashing}'. ` +
+        'HMR is incompatible with this setting.',
+    );
+  }
+
   const componentsHmrCanBeUsed =
     browserOptions.aot && serverOptions.liveReload && serverOptions.hmr;