[fix] only validate next config once

Author: huozhi

packages/next/src/build/index.ts

@@ -849,6 +849,7 @@ export default async function build(
               loadConfig(PHASE_PRODUCTION_BUILD, dir, {
                 // Log for next.config loading process
                 silent: false,
+                validateConfig: true,
                 reactProductionProfiling,
               }),
             turborepoAccessTraceResult

packages/next/src/cli/next-dev.ts

@@ -219,7 +219,10 @@ const nextDev = async (
   // some set-ups that rely on listening on other interfaces
   const host = options.hostname
 
-  config = await loadConfig(PHASE_DEVELOPMENT_SERVER, dir)
+  config = await loadConfig(PHASE_DEVELOPMENT_SERVER, dir, {
+    validateConfig: true,
+    silent: false,
+  })
 
   if (
     options.experimentalUploadTrace &&

packages/next/src/server/config.ts

@@ -1156,12 +1156,14 @@ export default async function loadConfig(
     customConfig,
     rawConfig,
     silent = true,
+    validateConfig,
     onLoadUserConfig,
     reactProductionProfiling,
   }: {
     customConfig?: object | null
     rawConfig?: boolean
     silent?: boolean
+    validateConfig?: boolean
     onLoadUserConfig?: (conf: NextConfig) => void
     reactProductionProfiling?: boolean
   } = {}
@@ -1272,13 +1274,16 @@ export default async function loadConfig(
       userConfigModule.default || userConfigModule
     )) as NextConfig
 
-    if (!process.env.NEXT_MINIMAL) {
+    // Only validate the config against schema in:
+    // * non minimal mode
+    // * when `loadConfig` result is not silent
+    if (!process.env.NEXT_MINIMAL && validateConfig) {
       // We only validate the config against schema in non minimal mode
       const { configSchema } =
         require('./config-schema') as typeof import('./config-schema')
       const state = configSchema.safeParse(userConfig)
 
-      if (state.success === false) {
+      if (!state.success) {
         // error message header
         const messages = [`Invalid ${configFileName} options detected: `]
 

packages/next/src/server/lib/router-server.ts

@@ -99,8 +99,7 @@ export async function initialize(opts: {
 
   const config = await loadConfig(
     opts.dev ? PHASE_DEVELOPMENT_SERVER : PHASE_PRODUCTION_SERVER,
-    opts.dir,
-    { silent: false }
+    opts.dir
   )
 
   let compress: ReturnType<typeof setupCompression> | undefined

test/e2e/app-dir/metadata-streaming/metadata-streaming-customized-rule.test.ts

@@ -1,7 +1,7 @@
 import { nextTestSetup } from 'e2e-utils'
 
 describe('app-dir - metadata-streaming-customized-rule', () => {
-  const { next } = nextTestSetup({
+  const { next, isNextDev } = nextTestSetup({
     files: __dirname,
     overrideFiles: {
       'next.config.js': `
@@ -39,4 +39,12 @@ describe('app-dir - metadata-streaming-customized-rule', () => {
     expect(await $('head title').length).toBe(0)
     expect(await $('body title').length).toBe(1)
   })
+
+  if (isNextDev) {
+    it('should not have schema issue', () => {
+      expect(next.cliOutput).not.toContain(
+        'Invalid next.config.js options detected'
+      )
+    })
+  }
 })