From 04f3914390a2cae7c9f1788c85b2ea5cd6f37630 Mon Sep 17 00:00:00 2001
From: Nitin Kumar <snitin315@gmail.com>
Date: Wed, 25 Aug 2021 17:30:03 +0530
Subject: [PATCH] fix: show warning when `hot` is enabled with HMR plugin in
 config

---
 lib/Server.js | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/lib/Server.js b/lib/Server.js
index 898646266a..0968f4cebb 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -1044,16 +1044,20 @@ class Server {
       // TODO remove after drop webpack v4 support
       compiler.options.plugins = compiler.options.plugins || [];
 
-      if (
-        this.options.hot &&
-        !compiler.options.plugins.find(
+      if (this.options.hot) {
+        const HMRPluginExists = compiler.options.plugins.find(
           (p) => p.constructor === webpack.HotModuleReplacementPlugin
-        )
-      ) {
-        // apply the HMR plugin, if it didn't exist before.
-        const plugin = new webpack.HotModuleReplacementPlugin();
+        );
 
-        plugin.apply(compiler);
+        if (HMRPluginExists) {
+          this.logger.warn(
+            `"hot: true" automatically applies HMR plugin, you don't have to add it manually to your webpack configuration.`
+          );
+        } else {
+          // apply the HMR plugin
+          const plugin = new webpack.HotModuleReplacementPlugin();
+          plugin.apply(compiler);
+        }
       }
     });