From f4e5f1ad096738c9d21812b2eabb0b1127e65f8c Mon Sep 17 00:00:00 2001
From: Gal Schlezinger <gal@spitfire.co.il>
Date: Thu, 24 Feb 2022 12:13:04 +0200
Subject: [PATCH] Make it under an experimental flag

---
 packages/next/build/webpack-config.ts                          | 1 +
 .../build/webpack/plugins/middleware-source-maps-plugin.ts     | 3 ++-
 packages/next/server/config-shared.ts                          | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/next/build/webpack-config.ts b/packages/next/build/webpack-config.ts
index c3378ec65636bd6..54904755d64c349 100644
--- a/packages/next/build/webpack-config.ts
+++ b/packages/next/build/webpack-config.ts
@@ -1274,6 +1274,7 @@ export default async function getBaseWebpackConfig(
     },
     plugins: [
       ...getMiddlewareSourceMapPlugins({
+        isConfigured: !!config.experimental.middlewareSourceMaps,
         isProductionBrowserSourceMapsOn: config.productionBrowserSourceMaps,
       }),
       hasReactRefresh && new ReactRefreshWebpackPlugin(webpack),
diff --git a/packages/next/build/webpack/plugins/middleware-source-maps-plugin.ts b/packages/next/build/webpack/plugins/middleware-source-maps-plugin.ts
index 13d9ef93eb7ba1d..72f6248a9ce33ce 100644
--- a/packages/next/build/webpack/plugins/middleware-source-maps-plugin.ts
+++ b/packages/next/build/webpack/plugins/middleware-source-maps-plugin.ts
@@ -8,9 +8,10 @@ import type { webpack5 } from 'next/dist/compiled/webpack/webpack'
  * are emitted.
  */
 export const getMiddlewareSourceMapPlugins = (params: {
+  isConfigured: boolean
   isProductionBrowserSourceMapsOn: boolean
 }) => {
-  if (params.isProductionBrowserSourceMapsOn) {
+  if (!params.isConfigured || params.isProductionBrowserSourceMapsOn) {
     return []
   }
 
diff --git a/packages/next/server/config-shared.ts b/packages/next/server/config-shared.ts
index a580ee537efbbee..b927e37ffdc8140 100644
--- a/packages/next/server/config-shared.ts
+++ b/packages/next/server/config-shared.ts
@@ -106,6 +106,7 @@ export interface ExperimentalConfig {
   urlImports?: NonNullable<webpack5.Configuration['experiments']>['buildHttp']
   outputFileTracingRoot?: string
   outputStandalone?: boolean
+  middlewareSourceMaps?: boolean
 }
 
 /**