Ensure mangling is disabled for dev runtime builds (#75297)

Just ensures we keep mangling behavior prior to
#75294

---------

Co-authored-by: Hendrik Liebau <[email protected]>

Author: ijjk

contributing/core/vscode-debugger.md

@@ -24,4 +24,4 @@ To see the changes you make to the Next.js codebase during development, you can
 
 When developing/debugging Next.js, you can set breakpoints anywhere in the `packages/next` source code that will stop the debugger at certain locations so you can examine the behavior. Read more about [breakpoints in the VS Code documentation](https://code.visualstudio.com/docs/nodejs/nodejs-debugging#_breakpoints).
 
-To ensure that the original names are displayed in the "Variables" section, build the Next.js source code with `NEXT_SERVER_EVAL_SOURCE_MAPS=1`. This is automatically applied when using `pnpm dev`.
+To ensure that the original names are displayed in the "Variables" section, build the Next.js source code with `NEXT_SERVER_NO_MANGLE=1`. This is automatically applied when using `pnpm dev`.

packages/next/next_runtime.config.js

@@ -1,4 +1,4 @@
-const webpack = require('@rspack/core')
+const rspack = require('@rspack/core')
 const path = require('path')
 const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer')
 const DevToolsIgnoreListPlugin = require('./webpack-plugins/devtools-ignore-list-plugin')
@@ -172,11 +172,17 @@ module.exports = ({ dev, turbo, bundleType, experimental }) => {
       moduleIds: 'named',
       minimize: true,
       concatenateModules: true,
-      minimizer: [new webpack.SwcJsMinimizerRspackPlugin()],
+      minimizer: [
+        new rspack.SwcJsMinimizerRspackPlugin({
+          minimizerOptions: {
+            mangle: dev || process.env.NEXT_SERVER_NO_MANGLE ? false : true,
+          },
+        }),
+      ],
     },
     plugins: [
       new DevToolsIgnoreListPlugin({ shouldIgnorePath }),
-      new webpack.DefinePlugin({
+      new rspack.DefinePlugin({
         'typeof window': JSON.stringify('undefined'),
         'process.env.NEXT_MINIMAL': JSON.stringify('true'),
         'this.serverOptions.experimentalTestProxy': JSON.stringify(false),

packages/next/package.json

@@ -80,7 +80,7 @@
     "next": "./dist/bin/next"
   },
   "scripts": {
-    "dev": "taskr",
+    "dev": "cross-env NEXT_SERVER_NO_MANGLE=1 taskr",
     "release": "taskr release",
     "build": "pnpm release",
     "prepublishOnly": "cd ../../ && turbo run build",

packages/next/src/build/webpack/plugins/eval-source-map-dev-tool-plugin.ts

@@ -3,7 +3,6 @@
 	Author Tobias Koppers @sokra
 
   Forked to add support for `ignoreList`.
-  Keep in sync with packages/next/webpack-plugins/eval-source-map-dev-tool-plugin.js
 */
 import {
   type webpack,