fix(typescript): worker execution failed with custom next.config.js (#37125)

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

The PR fixes #37122, an issue introduced by #37105.

`next.config.js` might/will include functions (custom `webpack`, `generateBuildId`, `exportPathsMap`, etc.) that are not able to pass from the main thread to a worker. The PR fixes the issue by only passing primitive args to the worker.

Author: SukkaW

packages/next/build/index.ts

@@ -272,7 +272,8 @@ export default async function build(
             dir,
             [pagesDir, viewsDir].filter(Boolean) as string[],
             !ignoreTypeScriptErrors,
-            config,
+            config.typescript.tsconfigPath,
+            config.images.disableStaticImages,
             cacheDir,
             config.experimental.cpus,
             config.experimental.workerThreads
@@ -2353,7 +2354,8 @@ function verifyTypeScriptSetup(
   dir: string,
   intentDirs: string[],
   typeCheckPreflight: boolean,
-  config: NextConfigComplete,
+  tsconfigPath: string,
+  disableStaticImages: boolean,
   cacheDir: string | undefined,
   numWorkers: number | undefined,
   enableWorkerThreads: boolean | undefined
@@ -2376,7 +2378,8 @@ function verifyTypeScriptSetup(
       dir,
       intentDirs,
       typeCheckPreflight,
-      config,
+      tsconfigPath,
+      disableStaticImages,
       cacheDir
     )
     .then((result) => {

packages/next/lib/typescript/getTypeScriptIntent.ts

@@ -1,6 +1,5 @@
 import { promises as fs } from 'fs'
 import path from 'path'
-import { NextConfigComplete } from '../../server/config-shared'
 import { fileExists } from '../file-exists'
 import { recursiveReadDir } from '../recursive-readdir'
 
@@ -9,18 +8,20 @@ export type TypeScriptIntent = { firstTimeSetup: boolean }
 export async function getTypeScriptIntent(
   baseDir: string,
   intentDirs: string[],
-  config: NextConfigComplete
+  tsconfigPath: string
 ): Promise<TypeScriptIntent | false> {
-  const tsConfigPath = path.join(baseDir, config.typescript.tsconfigPath)
+  const resolvedTsConfigPath = path.join(baseDir, tsconfigPath)
 
   // The integration turns on if we find a `tsconfig.json` in the user's
   // project.
-  const hasTypeScriptConfiguration = await fileExists(tsConfigPath)
+  const hasTypeScriptConfiguration = await fileExists(resolvedTsConfigPath)
   if (hasTypeScriptConfiguration) {
-    const content = await fs.readFile(tsConfigPath, { encoding: 'utf8' }).then(
-      (txt) => txt.trim(),
-      () => null
-    )
+    const content = await fs
+      .readFile(resolvedTsConfigPath, { encoding: 'utf8' })
+      .then(
+        (txt) => txt.trim(),
+        () => null
+      )
     return { firstTimeSetup: content === '' || content === '{}' }
   }
 

packages/next/lib/verifyTypeScriptSetup.ts

@@ -14,7 +14,6 @@ import { TypeCheckResult } from './typescript/runTypeCheck'
 import { writeAppTypeDeclarations } from './typescript/writeAppTypeDeclarations'
 import { writeConfigurationDefaults } from './typescript/writeConfigurationDefaults'
 import { missingDepsError } from './typescript/missingDependencyError'
-import { NextConfigComplete } from '../server/config-shared'
 
 const requiredPackages = [
   { file: 'typescript', pkg: 'typescript', exportsRestrict: false },
@@ -34,14 +33,15 @@ export async function verifyTypeScriptSetup(
   dir: string,
   intentDirs: string[],
   typeCheckPreflight: boolean,
-  config: NextConfigComplete,
+  tsconfigPath: string,
+  disableStaticImages: boolean,
   cacheDir?: string
 ): Promise<{ result?: TypeCheckResult; version: string | null }> {
-  const tsConfigPath = path.join(dir, config.typescript.tsconfigPath)
+  const resolvedTsConfigPath = path.join(dir, tsconfigPath)
 
   try {
     // Check if the project uses TypeScript:
-    const intent = await getTypeScriptIntent(dir, intentDirs, config)
+    const intent = await getTypeScriptIntent(dir, intentDirs, tsconfigPath)
     if (!intent) {
       return { version: null }
     }
@@ -68,17 +68,21 @@ export async function verifyTypeScriptSetup(
     }
 
     // Reconfigure (or create) the user's `tsconfig.json` for them:
-    await writeConfigurationDefaults(ts, tsConfigPath, intent.firstTimeSetup)
+    await writeConfigurationDefaults(
+      ts,
+      resolvedTsConfigPath,
+      intent.firstTimeSetup
+    )
     // Write out the necessary `next-env.d.ts` file to correctly register
     // Next.js' types:
-    await writeAppTypeDeclarations(dir, !config.images.disableStaticImages)
+    await writeAppTypeDeclarations(dir, !disableStaticImages)
 
     let result
     if (typeCheckPreflight) {
       const { runTypeCheck } = require('./typescript/runTypeCheck')
 
       // Verify the project passes type-checking before we go to webpack phase:
-      result = await runTypeCheck(ts, dir, tsConfigPath, cacheDir)
+      result = await runTypeCheck(ts, dir, resolvedTsConfigPath, cacheDir)
     }
     return { result, version: ts.version }
   } catch (err) {

packages/next/server/dev/next-dev-server.ts

@@ -424,7 +424,8 @@ export default class DevServer extends Server {
       this.dir,
       [this.pagesDir!, this.viewsDir].filter(Boolean) as string[],
       false,
-      this.nextConfig
+      this.nextConfig.typescript.tsconfigPath,
+      this.nextConfig.images.disableStaticImages
     )
 
     this.customRoutes = await loadCustomRoutes(this.nextConfig)

test/integration/typescript/test/index.test.js

@@ -108,6 +108,29 @@ export default function EvilPage(): JSX.Element {
     expect(output.code).toBe(0)
   })
 
+  it('should build the app with functions in next.config.js', async () => {
+    const nextConfig = new File(join(appDir, 'next.config.js'))
+
+    nextConfig.write(`
+    module.exports = {
+      webpack(config) { return config },
+      onDemandEntries: {
+        // Make sure entries are not getting disposed.
+        maxInactiveAge: 1000 * 60 * 60,
+      },
+    }
+    `)
+
+    try {
+      const output = await nextBuild(appDir, [], { stdout: true })
+
+      expect(output.stdout).toMatch(/Compiled successfully/)
+      expect(output.code).toBe(0)
+    } finally {
+      nextConfig.restore()
+    }
+  })
+
   it('should not inform when using default tsconfig path', async () => {
     const output = await nextBuild(appDir, [], { stdout: true })
     expect(output.stdout).not.toMatch(/Using tsconfig file:/)