feat(nuxt): warn on external webpack/nitro/postcss config

packages/nuxt/src/core/builder.ts

@@ -6,9 +6,10 @@ import { isIgnored, tryResolveModule, useNuxt } from '@nuxt/kit'
 import { interopDefault } from 'mlly'
 import { debounce } from 'perfect-debounce'
 import { normalize, relative, resolve } from 'pathe'
-import type { Nuxt } from 'nuxt/schema'
+import type { Nuxt, NuxtBuilder } from 'nuxt/schema'
 
 import { generateApp as _generateApp, createApp } from './app'
+import { checkForExternalConfigurationFiles } from './external-config-files'
 
 export async function build (nuxt: Nuxt) {
   const app = createApp(nuxt)
@@ -43,7 +44,7 @@ export async function build (nuxt: Nuxt) {
 
   await nuxt.callHook('build:before')
   if (!nuxt.options._prepare) {
-    await bundle(nuxt)
+    await Promise.all([checkForExternalConfigurationFiles(), bundle(nuxt)])
     await nuxt.callHook('build:done')
   }
 
@@ -178,23 +179,23 @@ async function bundle (nuxt: Nuxt) {
       ? await loadBuilder(nuxt, nuxt.options.builder)
       : nuxt.options.builder
 
-    return bundle(nuxt)
+    await bundle(nuxt)
   } catch (error: any) {
     await nuxt.callHook('build:error', error)
 
     if (error.toString().includes('Cannot find module \'@nuxt/webpack-builder\'')) {
-      throw new Error([
-        'Could not load `@nuxt/webpack-builder`. You may need to add it to your project dependencies, following the steps in `https://github.com/nuxt/framework/pull/2812`.'
-      ].join('\n'))
+      throw new Error('Could not load `@nuxt/webpack-builder`. You may need to add it to your project dependencies, following the steps in `https://github.com/nuxt/framework/pull/2812`.')
     }
 
     throw error
   }
 }
 
-async function loadBuilder (nuxt: Nuxt, builder: string) {
+async function loadBuilder (nuxt: Nuxt, builder: string): Promise<NuxtBuilder> {
   const builderPath = await tryResolveModule(builder, [nuxt.options.rootDir, import.meta.url])
-  if (builderPath) {
-    return import(pathToFileURL(builderPath).href)
+
+  if (!builderPath) {
+    throw new Error(`Loading \`${builder}\` builder failed. You can read more about the nuxt \`builder\` option at: \`https://nuxt.com/docs/api/configuration/nuxt-config#builder\``)
   }
+  return import(pathToFileURL(builderPath).href)
 }

packages/nuxt/src/core/external-config-files.ts

@@ -0,0 +1,77 @@
+import { findPath } from '@nuxt/kit'
+import { basename } from 'pathe'
+import { generateApp as _generateApp } from './app'
+
+/**
+ * Check for those external configuration files that are not compatible with Nuxt,
+ * and warns the user about them.
+ *
+ * @see {@link https://nuxt.com/docs/getting-started/configuration#external-configuration-files}
+ */
+export async function checkForExternalConfigurationFiles () {
+  const checkResults = await Promise.all([checkViteConfig(), checkWebpackConfig(), checkNitroConfig(), checkPostCSSConfig()])
+  const warningMessages = checkResults.filter(Boolean) as string[]
+
+  if (!warningMessages.length) {
+    return
+  }
+
+  const foundOneExternalConfig = warningMessages.length === 1
+  if (foundOneExternalConfig) {
+    console.warn(warningMessages[0])
+  } else {
+    const warningsAsList = warningMessages.map(message => `- ${message}`).join('\n')
+    const warning = `Found multiple external configuration files: \n\n${warningsAsList}`
+    console.warn(warning)
+  }
+}
+
+async function checkViteConfig () {
+  // https://github.com/vitejs/vite/blob/8fe69524d25d45290179175ba9b9956cbce87a91/packages/vite/src/node/constants.ts#L38
+  return await checkAndWarnAboutConfigFileExistence({
+    fileName: 'vite.config',
+    extensions: ['.js', '.mjs', '.ts', '.cjs', '.mts', '.cts'],
+    createWarningMessage: foundFile => `Using \`${foundFile}\` is not supported together with Nuxt. Use \`options.vite\` instead. You can read more in \`https://nuxt.com/docs/api/configuration/nuxt-config#vite\`.`
+  })
+}
+
+async function checkWebpackConfig () {
+  // https://webpack.js.org/configuration/configuration-languages/
+  return await checkAndWarnAboutConfigFileExistence({
+    fileName: 'webpack.config',
+    extensions: ['.js', '.mjs', '.ts', '.cjs', '.mts', '.cts', 'coffee'],
+    createWarningMessage: foundFile => `Using \`${foundFile}\` is not supported together with Nuxt. Use \`options.webpack\` instead. You can read more in \`https://nuxt.com/docs/api/configuration/nuxt-config#webpack-1\`.`
+  })
+}
+
+async function checkNitroConfig () {
+  // https://nitro.unjs.io/config#configuration
+  return await checkAndWarnAboutConfigFileExistence({
+    fileName: 'nitro.config',
+    extensions: ['.ts', '.mts'],
+    createWarningMessage: foundFile => `Using \`${foundFile}\` is not supported together with Nuxt. Use \`options.nitro\` instead. You can read more in \`https://nuxt.com/docs/api/configuration/nuxt-config#nitro\`.`
+  })
+}
+
+async function checkPostCSSConfig () {
+  return await checkAndWarnAboutConfigFileExistence({
+    fileName: 'postcss.config',
+    extensions: ['.js', '.cjs'],
+    createWarningMessage: foundFile => `Using \`${foundFile}\` is not supported together with Nuxt. Use \`options.postcss\` instead. You can read more in \`https://nuxt.com/docs/api/configuration/nuxt-config#postcss\`.`
+  })
+}
+
+interface CheckAndWarnAboutConfigFileExistenceOptions {
+  fileName: string,
+  extensions: string[],
+  createWarningMessage: (foundFile: string) => string
+}
+
+async function checkAndWarnAboutConfigFileExistence (options: CheckAndWarnAboutConfigFileExistenceOptions) {
+  const { fileName, extensions, createWarningMessage } = options
+
+  const configFile = await findPath(fileName, { extensions }).catch(() => null)
+  if (configFile) {
+    return createWarningMessage(basename(configFile))
+  }
+}

packages/schema/src/types/config.ts

@@ -95,7 +95,7 @@ export type NuxtConfigLayer = ConfigLayer<NuxtConfig & {
 /** Normalized Nuxt options available as `nuxt.options.*` */
 export interface NuxtOptions extends Omit<ConfigSchema, 'builder' | 'webpack'> {
   sourcemap: Required<Exclude<ConfigSchema['sourcemap'], boolean>>
-  builder: '@nuxt/vite-builder' | '@nuxt/webpack-builder' | { bundle: (nuxt: Nuxt) => Promise<void> }
+  builder: '@nuxt/vite-builder' | '@nuxt/webpack-builder' | NuxtBuilder
   webpack: ConfigSchema['webpack'] & {
     $client: ConfigSchema['webpack']
     $server: ConfigSchema['webpack']
@@ -104,6 +104,10 @@ export interface NuxtOptions extends Omit<ConfigSchema, 'builder' | 'webpack'> {
   $schema: SchemaDefinition
 }
 
+export interface NuxtBuilder {
+  bundle: (nuxt: Nuxt) => Promise<void>
+}
+
 export interface ViteConfig extends Omit<ViteUserConfig, 'publicDir'> {
   /** The path to the entrypoint for the Vite build. */
   entry?: string

packages/vite/src/vite.ts

@@ -1,14 +1,14 @@
 import { existsSync } from 'node:fs'
 import * as vite from 'vite'
-import { basename, dirname, join, resolve } from 'pathe'
-import type { Nuxt, ViteConfig } from '@nuxt/schema'
+import { dirname, join, resolve } from 'pathe'
+import type { Nuxt, NuxtBuilder, ViteConfig } from '@nuxt/schema'
 import { addVitePlugin, isIgnored, logger, resolvePath } from '@nuxt/kit'
 import replace from '@rollup/plugin-replace'
 import { sanitizeFilePath } from 'mlly'
 import { withoutLeadingSlash } from 'ufo'
 import { filename } from 'pathe/utils'
 import { resolveTSConfig } from 'pkg-types'
-import { consola } from 'consola'
+
 import { buildClient } from './client'
 import { buildServer } from './server'
 import virtual from './plugins/virtual'
@@ -26,14 +26,7 @@ export interface ViteBuildContext {
   ssrServer?: vite.ViteDevServer
 }
 
-export async function bundle (nuxt: Nuxt) {
-  // https://github.com/vitejs/vite/blob/8fe69524d25d45290179175ba9b9956cbce87a91/packages/vite/src/node/constants.ts#L38
-  const viteConfigPrefix = resolve(nuxt.options.rootDir, 'vite.config')
-  const viteConfigFile = await resolvePath(viteConfigPrefix).catch(() => null)
-  if (viteConfigFile && viteConfigFile !== viteConfigPrefix) {
-    consola.warn(`Using \`${basename(viteConfigFile)}\` is not supported together with Nuxt. Use \`options.vite\` instead. You can read more in \`https://nuxt.com/docs/api/configuration/nuxt-config#vite\`.`)
-  }
-
+export const bundle: NuxtBuilder['bundle'] = async (nuxt) => {
   const useAsyncEntry = nuxt.options.experimental.asyncEntry ||
     (nuxt.options.vite.devBundler === 'vite-node' && nuxt.options.dev)
   const entry = await resolvePath(resolve(nuxt.options.appDir, useAsyncEntry ? 'entry.async' : 'entry'))

packages/webpack/src/webpack.ts

@@ -7,7 +7,7 @@ import webpackDevMiddleware from 'webpack-dev-middleware'
 import webpackHotMiddleware from 'webpack-hot-middleware'
 import type { Compiler, Watching } from 'webpack'
 import { defu } from 'defu'
-import type { Nuxt } from '@nuxt/schema'
+import type { NuxtBuilder } from '@nuxt/schema'
 import { joinURL } from 'ufo'
 import { logger, useNuxt } from '@nuxt/kit'
 
@@ -22,7 +22,7 @@ import { applyPresets, createWebpackConfigContext, getWebpackConfig } from './ut
 // TODO: Support plugins
 // const plugins: string[] = []
 
-export async function bundle (nuxt: Nuxt) {
+export const bundle: NuxtBuilder['bundle'] = async (nuxt) => {
   registerVirtualModules()
 
   const webpackConfigs = [client, ...nuxt.options.ssr ? [server] : []].map((preset) => {
@@ -75,7 +75,8 @@ export async function bundle (nuxt: Nuxt) {
 
   // Start Builds
   if (nuxt.options.dev) {
-    return Promise.all(compilers.map(c => compile(c)))
+    await Promise.all(compilers.map(c => compile(c)))
+    return
   }
 
   for (const c of compilers) {