Ensure undefined values end up being replaced (#63138)

## What?

Follow-up to #63128

`JSON.stringify(undefined)` ends up with the value `undefined`. However
for Webpack/Turbopack to correctly inject `undefined` into the code it
has to be the string `'undefined'`. This change ensures the
serialization takes into account that case.

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Closes NEXT-2773

packages/next/src/build/index.ts

@@ -1351,15 +1351,14 @@ export default async function build(
           env: process.env as Record<string, string>,
           defineEnv: createDefineEnv({
             isTurbopack: true,
-            allowedRevalidateHeaderKeys: undefined,
-            clientRouterFilters: undefined,
+            clientRouterFilters: NextBuildContext.clientRouterFilters,
             config,
             dev,
             distDir,
-            fetchCacheKeyPrefix: undefined,
+            fetchCacheKeyPrefix: config.experimental.fetchCacheKeyPrefix,
             hasRewrites,
+            // TODO: Implement
             middlewareMatchers: undefined,
-            previewModeId: undefined,
           }),
         })
 

packages/next/src/build/swc/index.ts

@@ -435,15 +435,13 @@ export interface DefineEnv {
 
 export function createDefineEnv({
   isTurbopack,
-  allowedRevalidateHeaderKeys,
   clientRouterFilters,
   config,
   dev,
   distDir,
   fetchCacheKeyPrefix,
   hasRewrites,
   middlewareMatchers,
-  previewModeId,
 }: Omit<
   DefineEnvPluginOptions,
   'isClient' | 'isNodeOrEdgeCompilation' | 'isEdgeServer' | 'isNodeServer'
@@ -458,7 +456,6 @@ export function createDefineEnv({
     defineEnv[variant] = rustifyEnv(
       getDefineEnv({
         isTurbopack,
-        allowedRevalidateHeaderKeys,
         clientRouterFilters,
         config,
         dev,
@@ -470,7 +467,6 @@ export function createDefineEnv({
         isNodeOrEdgeCompilation: variant === 'nodejs' || variant === 'edge',
         isNodeServer: variant === 'nodejs',
         middlewareMatchers,
-        previewModeId,
       })
     )
   }

packages/next/src/build/webpack-config.ts

@@ -318,9 +318,7 @@ export default async function getBaseWebpackConfig(
     resolvedBaseUrl,
     supportedBrowsers,
     clientRouterFilters,
-    previewModeId,
     fetchCacheKeyPrefix,
-    allowedRevalidateHeaderKeys,
   }: {
     buildId: string
     config: NextConfigComplete
@@ -348,9 +346,7 @@ export default async function getBaseWebpackConfig(
         import('../shared/lib/bloom-filter').BloomFilter['export']
       >
     }
-    previewModeId?: string
     fetchCacheKeyPrefix?: string
-    allowedRevalidateHeaderKeys?: string[]
   }
 ): Promise<webpack.Configuration> {
   const isClient = compilerType === COMPILER_NAMES.client
@@ -1741,7 +1737,6 @@ export default async function getBaseWebpackConfig(
         }),
       getDefineEnvPlugin({
         isTurbopack: false,
-        allowedRevalidateHeaderKeys,
         clientRouterFilters,
         config,
         dev,
@@ -1753,7 +1748,6 @@ export default async function getBaseWebpackConfig(
         isNodeOrEdgeCompilation,
         isNodeServer,
         middlewareMatchers,
-        previewModeId,
       }),
       isClient &&
         new ReactLoadablePlugin({

packages/next/src/build/webpack/plugins/define-env-plugin.ts

@@ -23,7 +23,6 @@ type BloomFilter = ReturnType<
 
 export interface DefineEnvPluginOptions {
   isTurbopack: boolean
-  allowedRevalidateHeaderKeys: string[] | undefined
   clientRouterFilters?: {
     staticFilter: BloomFilter
     dynamicFilter: BloomFilter
@@ -38,15 +37,13 @@ export interface DefineEnvPluginOptions {
   isNodeOrEdgeCompilation: boolean
   isNodeServer: boolean
   middlewareMatchers: MiddlewareMatcher[] | undefined
-  previewModeId: string | undefined
 }
 
 interface DefineEnv {
   [key: string]:
     | string
     | string[]
     | boolean
-    | undefined
     | MiddlewareMatcher[]
     | BloomFilter
     | Partial<NextConfigComplete['images']>
@@ -129,7 +126,6 @@ function getImageConfig(
 
 export function getDefineEnv({
   isTurbopack,
-  allowedRevalidateHeaderKeys,
   clientRouterFilters,
   config,
   dev,
@@ -141,7 +137,6 @@ export function getDefineEnv({
   isNodeOrEdgeCompilation,
   isNodeServer,
   middlewareMatchers,
-  previewModeId,
 }: DefineEnvPluginOptions): SerializedDefineEnv {
   const defineEnv: DefineEnv = {
     // internal field to identify the plugin config
@@ -158,7 +153,7 @@ export function getDefineEnv({
              * and library authors to have different implementations based on
              * the runtime they are running with, if it's not using `edge-runtime`
              */
-            process.env.NEXT_EDGE_RUNTIME_PROVIDER || 'edge-runtime',
+            process.env.NEXT_EDGE_RUNTIME_PROVIDER ?? 'edge-runtime',
         }),
     'process.turbopack': isTurbopack,
     'process.env.TURBOPACK': isTurbopack,
@@ -172,70 +167,71 @@ export function getDefineEnv({
     'process.env.NEXT_MINIMAL': '',
     'process.env.__NEXT_PPR': config.experimental.ppr === true,
     'process.env.__NEXT_ACTIONS_DEPLOYMENT_ID':
-      config.experimental.useDeploymentIdServerActions,
-    'process.env.NEXT_DEPLOYMENT_ID': config.experimental.deploymentId || false,
-    'process.env.__NEXT_FETCH_CACHE_KEY_PREFIX': fetchCacheKeyPrefix,
-    'process.env.__NEXT_PREVIEW_MODE_ID': previewModeId,
-    'process.env.__NEXT_ALLOWED_REVALIDATE_HEADERS':
-      allowedRevalidateHeaderKeys,
-    'process.env.__NEXT_MIDDLEWARE_MATCHERS': middlewareMatchers || [],
+      config.experimental.useDeploymentIdServerActions ?? false,
+    'process.env.NEXT_DEPLOYMENT_ID': config.experimental.deploymentId ?? false,
+    'process.env.__NEXT_FETCH_CACHE_KEY_PREFIX': fetchCacheKeyPrefix ?? '',
+    'process.env.__NEXT_MIDDLEWARE_MATCHERS': middlewareMatchers ?? [],
     'process.env.__NEXT_MANUAL_CLIENT_BASE_PATH':
-      config.experimental.manualClientBasePath,
+      config.experimental.manualClientBasePath ?? false,
     'process.env.__NEXT_CLIENT_ROUTER_FILTER_ENABLED':
-      config.experimental.clientRouterFilter,
+      config.experimental.clientRouterFilter ?? true,
     'process.env.__NEXT_CLIENT_ROUTER_S_FILTER':
-      clientRouterFilters?.staticFilter,
+      clientRouterFilters?.staticFilter ?? false,
     'process.env.__NEXT_CLIENT_ROUTER_D_FILTER':
-      clientRouterFilters?.dynamicFilter,
+      clientRouterFilters?.dynamicFilter ?? false,
     'process.env.__NEXT_OPTIMISTIC_CLIENT_CACHE':
-      config.experimental.optimisticClientCache,
+      config.experimental.optimisticClientCache ?? true,
     'process.env.__NEXT_MIDDLEWARE_PREFETCH':
-      config.experimental.middlewarePrefetch,
+      config.experimental.middlewarePrefetch ?? 'flexible',
     'process.env.__NEXT_CROSS_ORIGIN': config.crossOrigin,
     'process.browser': isClient,
-    'process.env.__NEXT_TEST_MODE': process.env.__NEXT_TEST_MODE,
+    'process.env.__NEXT_TEST_MODE': process.env.__NEXT_TEST_MODE ?? false,
     // This is used in client/dev-error-overlay/hot-dev-client.js to replace the dist directory
-    ...(dev && (isClient || isEdgeServer)
+    ...(dev && (isClient ?? isEdgeServer)
       ? {
           'process.env.__NEXT_DIST_DIR': distDir,
         }
       : {}),
     'process.env.__NEXT_TRAILING_SLASH': config.trailingSlash,
-    'process.env.__NEXT_BUILD_INDICATOR': config.devIndicators.buildActivity,
+    'process.env.__NEXT_BUILD_INDICATOR':
+      config.devIndicators.buildActivity ?? true,
     'process.env.__NEXT_BUILD_INDICATOR_POSITION':
-      config.devIndicators.buildActivityPosition,
+      config.devIndicators.buildActivityPosition ?? 'bottom-right',
     'process.env.__NEXT_STRICT_MODE':
       config.reactStrictMode === null ? false : config.reactStrictMode,
     'process.env.__NEXT_STRICT_MODE_APP':
       // When next.config.js does not have reactStrictMode it's enabled by default.
       config.reactStrictMode === null ? true : config.reactStrictMode,
     'process.env.__NEXT_OPTIMIZE_FONTS': !dev && config.optimizeFonts,
-    'process.env.__NEXT_OPTIMIZE_CSS': config.experimental.optimizeCss && !dev,
+    'process.env.__NEXT_OPTIMIZE_CSS':
+      (config.experimental.optimizeCss && !dev) ?? false,
     'process.env.__NEXT_SCRIPT_WORKERS':
-      config.experimental.nextScriptWorkers && !dev,
+      (config.experimental.nextScriptWorkers && !dev) ?? false,
     'process.env.__NEXT_SCROLL_RESTORATION':
-      config.experimental.scrollRestoration,
+      config.experimental.scrollRestoration ?? false,
     ...getImageConfig(config, dev),
     'process.env.__NEXT_ROUTER_BASEPATH': config.basePath,
-    'process.env.__NEXT_STRICT_NEXT_HEAD': config.experimental.strictNextHead,
+    'process.env.__NEXT_STRICT_NEXT_HEAD':
+      config.experimental.strictNextHead ?? false,
     'process.env.__NEXT_HAS_REWRITES': hasRewrites,
     'process.env.__NEXT_CONFIG_OUTPUT': config.output,
     'process.env.__NEXT_I18N_SUPPORT': !!config.i18n,
-    'process.env.__NEXT_I18N_DOMAINS': config.i18n?.domains,
+    'process.env.__NEXT_I18N_DOMAINS': config.i18n?.domains ?? false,
     'process.env.__NEXT_ANALYTICS_ID': config.analyticsId, // TODO: remove in the next major version
     'process.env.__NEXT_NO_MIDDLEWARE_URL_NORMALIZE':
       config.skipMiddlewareUrlNormalize,
     'process.env.__NEXT_EXTERNAL_MIDDLEWARE_REWRITE_RESOLVE':
-      config.experimental.externalMiddlewareRewritesResolve,
+      config.experimental.externalMiddlewareRewritesResolve ?? false,
     'process.env.__NEXT_MANUAL_TRAILING_SLASH':
       config.skipTrailingSlashRedirect,
     'process.env.__NEXT_HAS_WEB_VITALS_ATTRIBUTION':
-      config.experimental.webVitalsAttribution &&
-      config.experimental.webVitalsAttribution.length > 0,
+      (config.experimental.webVitalsAttribution &&
+        config.experimental.webVitalsAttribution.length > 0) ??
+      false,
     'process.env.__NEXT_WEB_VITALS_ATTRIBUTION':
-      config.experimental.webVitalsAttribution,
+      config.experimental.webVitalsAttribution ?? false,
     'process.env.__NEXT_LINK_NO_TOUCH_START':
-      config.experimental.linkNoTouchStart,
+      config.experimental.linkNoTouchStart ?? false,
     'process.env.__NEXT_ASSET_PREFIX': config.assetPrefix,
     ...(isNodeOrEdgeCompilation
       ? {

packages/next/src/server/dev/hot-reloader-turbopack.ts

@@ -129,15 +129,15 @@ export async function createHotReloaderTurbopack(
     env: process.env as Record<string, string>,
     defineEnv: createDefineEnv({
       isTurbopack: true,
-      allowedRevalidateHeaderKeys: undefined,
+      // TODO: Implement
       clientRouterFilters: undefined,
       config: nextConfig,
       dev: true,
       distDir,
-      fetchCacheKeyPrefix: undefined,
+      fetchCacheKeyPrefix: opts.nextConfig.experimental.fetchCacheKeyPrefix,
       hasRewrites,
+      // TODO: Implement
       middlewareMatchers: undefined,
-      previewModeId: undefined,
     }),
   })
   const entrypointsSubscription = project.entrypointsSubscribe()

packages/next/src/server/lib/router-utils/setup-dev-bundler.ts

@@ -553,15 +553,15 @@ async function startWatcher(opts: SetupOpts) {
           await hotReloader.turbopackProject.update({
             defineEnv: createDefineEnv({
               isTurbopack: true,
-              allowedRevalidateHeaderKeys: undefined,
               clientRouterFilters,
               config: nextConfig,
               dev: true,
               distDir,
-              fetchCacheKeyPrefix: undefined,
+              fetchCacheKeyPrefix:
+                opts.nextConfig.experimental.fetchCacheKeyPrefix,
               hasRewrites,
+              // TODO: Implement
               middlewareMatchers: undefined,
-              previewModeId: undefined,
             }),
           })
         }
@@ -625,19 +625,18 @@ async function startWatcher(opts: SetupOpts) {
               ) {
                 const newDefine = getDefineEnv({
                   isTurbopack: false,
-                  allowedRevalidateHeaderKeys: undefined,
                   clientRouterFilters,
                   config: nextConfig,
                   dev: true,
                   distDir,
-                  fetchCacheKeyPrefix: undefined,
+                  fetchCacheKeyPrefix:
+                    opts.nextConfig.experimental.fetchCacheKeyPrefix,
                   hasRewrites,
                   isClient,
                   isEdgeServer,
                   isNodeOrEdgeCompilation: isNodeServer || isEdgeServer,
                   isNodeServer,
                   middlewareMatchers: undefined,
-                  previewModeId: undefined,
                 })
 
                 Object.keys(plugin.definitions).forEach((key) => {

packages/next/src/shared/lib/router/router.ts

@@ -765,13 +765,24 @@ export default class Router implements BaseRouter {
       const { BloomFilter } =
         require('../../lib/bloom-filter') as typeof import('../../lib/bloom-filter')
 
-      const staticFilterData:
-        | ReturnType<import('../../lib/bloom-filter').BloomFilter['export']>
-        | undefined = process.env.__NEXT_CLIENT_ROUTER_S_FILTER as any
+      type Filter = ReturnType<
+        import('../../lib/bloom-filter').BloomFilter['export']
+      >
 
-      const dynamicFilterData: typeof staticFilterData = process.env
+      const routerFilterSValue: Filter | false = process.env
+        .__NEXT_CLIENT_ROUTER_S_FILTER as any
+
+      const staticFilterData: Filter | undefined = routerFilterSValue
+        ? routerFilterSValue
+        : undefined
+
+      const routerFilterDValue: Filter | false = process.env
         .__NEXT_CLIENT_ROUTER_D_FILTER as any
 
+      const dynamicFilterData: Filter | undefined = routerFilterDValue
+        ? routerFilterDValue
+        : undefined
+
       if (staticFilterData?.numHashes) {
         this._bfl_s = new BloomFilter(
           staticFilterData.numItems,

test/development/basic/next-rs-api.test.ts

@@ -205,7 +205,6 @@ describe('next.rs api', () => {
       dev: true,
       defineEnv: createDefineEnv({
         isTurbopack: true,
-        allowedRevalidateHeaderKeys: undefined,
         clientRouterFilters: undefined,
         config: nextConfig,
         dev: true,
@@ -218,7 +217,6 @@ describe('next.rs api', () => {
         fetchCacheKeyPrefix: undefined,
         hasRewrites: false,
         middlewareMatchers: undefined,
-        previewModeId: undefined,
       }),
     })
     projectUpdateSubscription = filterMapAsyncIterator(