Repository: vercel/next.js
Pull request: fix(Rspack): use loaderContext.utils.contextify to replace ModuleFilenameHelpers.createFilename

After careful consideration, i believe implementing `ModuleFilenameHelpers.createFilename` isn't necessary for Rspack. We can achieve the same result through direct string interpolation:

`webpack://_N_E/${this.utils.contextify(this._compiler!.context, this.resourcePath)}/__nextjs-internal-proxy.mjs`

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Changed files:
filename: packages/next/src/build/webpack/loaders/next-flight-loader/index.ts
patch: @@ -1,8 +1,9 @@
-import type {
-  javascript,
-  LoaderContext,
-  NormalModule,
-  webpack,
+import {
+  ModuleFilenameHelpers,
+  type javascript,
+  type LoaderContext,
+  type NormalModule,
+  type webpack,
 } from 'next/dist/compiled/webpack/webpack'
 import { RSC_MOD_REF_PROXY_ALIAS } from '../../../../lib/constants'
 import {
@@ -13,7 +14,6 @@ import { warnOnce } from '../../../../shared/lib/utils/warn-once'
 import { getRSCModuleInformation } from '../../../analysis/get-page-static-info'
 import { formatBarrelOptimizedResource } from '../../utils'
 import { getModuleBuildInfo } from '../get-module-build-info'
-import { ModuleFilenameHelpers } from 'next/dist/compiled/webpack/webpack'
 
 type SourceType = javascript.JavascriptParser['sourceType'] | 'commonjs'
 
@@ -148,19 +148,21 @@ ${JSON.stringify(ref)},
       }
 
       const compilation = this._compilation!
-      const originalSourceURL = ModuleFilenameHelpers.createFilename(
-        module,
-        {
-          moduleFilenameTemplate:
-            'webpack://[namespace]/[resource-path]/__nextjs-internal-proxy.mjs',
-          namespace: '_N_E',
-        },
-        {
-          requestShortener: compilation.requestShortener,
-          chunkGraph: compilation.chunkGraph,
-          hashFunction: compilation.outputOptions.hashFunction,
-        }
-      )
+      const originalSourceURL = process.env.NEXT_RSPACK
+        ? `webpack://_N_E/${this.utils.contextify(this.context || this.rootContext, this.resourcePath)}/__nextjs-internal-proxy.mjs`
+        : ModuleFilenameHelpers.createFilename(
+            module,
+            {
+              moduleFilenameTemplate:
+                'webpack://[namespace]/[resource-path]/__nextjs-internal-proxy.mjs',
+              namespace: '_N_E',
+            },
+            {
+              requestShortener: compilation.requestShortener,
+              chunkGraph: compilation.chunkGraph,
+              hashFunction: compilation.outputOptions.hashFunction,
+            }
+          )
 
       return this.callback(null, esmSource, {
         version: 3,
@@ -179,19 +181,21 @@ module.exports = createProxy(${stringifiedResourceKey})
 `
 
       const compilation = this._compilation!
-      const originalSourceURL = ModuleFilenameHelpers.createFilename(
-        module,
-        {
-          moduleFilenameTemplate:
-            'webpack://[namespace]/[resource-path]/__nextjs-internal-proxy.cjs',
-          namespace: '_N_E',
-        },
-        {
-          requestShortener: compilation.requestShortener,
-          chunkGraph: compilation.chunkGraph,
-          hashFunction: compilation.outputOptions.hashFunction,
-        }
-      )
+      const originalSourceURL = process.env.NEXT_RSPACK
+        ? `webpack://_N_E/${this.utils.contextify(this.context || this.rootContext, this.resourcePath)}/__nextjs-internal-proxy.cjs`
+        : ModuleFilenameHelpers.createFilename(
+            module,
+            {
+              moduleFilenameTemplate:
+                'webpack://[namespace]/[resource-path]/__nextjs-internal-proxy.cjs',
+              namespace: '_N_E',
+            },
+            {
+              requestShortener: compilation.requestShortener,
+              chunkGraph: compilation.chunkGraph,
+              hashFunction: compilation.outputOptions.hashFunction,
+            }
+          )
 
       return this.callback(null, cjsSource, {
         version: 3,