fix(next): respect extends in tsconfig with exclude and include

packages/next/lib/typescript/writeConfigurationDefaults.ts

@@ -95,16 +95,16 @@ export async function writeConfigurationDefaults(
   }
 
   const desiredCompilerOptions = getDesiredCompilerOptions(ts)
-  const effectiveConfiguration = await getTypeScriptConfiguration(
-    ts,
-    tsConfigPath
-  )
+  const {
+    options: tsOptions,
+    raw: rawConfig,
+  } = await getTypeScriptConfiguration(ts, tsConfigPath)
 
   const userTsConfigContent = await fs.readFile(tsConfigPath, {
     encoding: 'utf8',
   })
   const userTsConfig = CommentJson.parse(userTsConfigContent)
-  if (userTsConfig.compilerOptions == null) {
+  if (userTsConfig.compilerOptions == null && !('extends' in rawConfig)) {
     userTsConfig.compilerOptions = {}
     isFirstTimeSetup = true
   }
@@ -114,14 +114,14 @@ export async function writeConfigurationDefaults(
   for (const optionKey of Object.keys(desiredCompilerOptions)) {
     const check = desiredCompilerOptions[optionKey]
     if ('suggested' in check) {
-      if (!(optionKey in effectiveConfiguration.options)) {
+      if (!(optionKey in tsOptions)) {
         userTsConfig.compilerOptions[optionKey] = check.suggested
         suggestedActions.push(
           chalk.cyan(optionKey) + ' was set to ' + chalk.bold(check.suggested)
         )
       }
     } else if ('value' in check) {
-      const ev = effectiveConfiguration.options[optionKey]
+      const ev = tsOptions[optionKey]
       if (
         !('parsedValues' in check
           ? check.parsedValues?.includes(ev)
@@ -143,7 +143,7 @@ export async function writeConfigurationDefaults(
     }
   }
 
-  if (userTsConfig.include == null) {
+  if (!('include' in rawConfig)) {
     userTsConfig.include = ['next-env.d.ts', '**/*.ts', '**/*.tsx']
     suggestedActions.push(
       chalk.cyan('include') +
@@ -152,7 +152,7 @@ export async function writeConfigurationDefaults(
     )
   }
 
-  if (userTsConfig.exclude == null) {
+  if (!('exclude' in rawConfig)) {
     userTsConfig.exclude = ['node_modules']
     suggestedActions.push(
       chalk.cyan('exclude') + ' was set to ' + chalk.bold(`['node_modules']`)

test/integration/tsconfig-verifier/test/index.test.js

@@ -10,13 +10,16 @@ jest.setTimeout(1000 * 60 * 5)
 describe('tsconfig.json verifier', () => {
   const appDir = path.join(__dirname, '../')
   const tsConfig = path.join(appDir, 'tsconfig.json')
+  const tsConfigBase = path.join(appDir, 'tsconfig.base.json')
 
   beforeEach(async () => {
     await remove(tsConfig)
+    await remove(tsConfigBase)
   })
 
   afterEach(async () => {
     await remove(tsConfig)
+    await remove(tsConfigBase)
   })
 
   it('Creates a default tsconfig.json when one is missing', async () => {
@@ -258,4 +261,55 @@ describe('tsconfig.json verifier', () => {
       "
     `)
   })
+
+  it('allows you to extend another configuration file', async () => {
+    expect(await exists(tsConfig)).toBe(false)
+    expect(await exists(tsConfigBase)).toBe(false)
+
+    await writeFile(
+      tsConfigBase,
+      `
+      {
+        "compilerOptions": {
+          "target": "es5",
+          "lib": [
+            "dom",
+            "dom.iterable",
+            "esnext"
+          ],
+          "allowJs": true,
+          "skipLibCheck": true,
+          "strict": false,
+          "forceConsistentCasingInFileNames": true,
+          "noEmit": true,
+          "esModuleInterop": true,
+          "module": "esnext",
+          "moduleResolution": "node",
+          "resolveJsonModule": true,
+          "isolatedModules": true,
+          "jsx": "preserve"
+        },
+        "include": [
+          "next-env.d.ts",
+          "**/*.ts",
+          "**/*.tsx"
+        ],
+        "exclude": [
+          "node_modules"
+        ]
+      }
+      `
+    )
+    await new Promise((resolve) => setTimeout(resolve, 500))
+
+    await writeFile(tsConfig, `{ "extends": "./tsconfig.base.json" }`)
+    await new Promise((resolve) => setTimeout(resolve, 500))
+
+    const { code } = await nextBuild(appDir)
+    expect(code).toBe(0)
+
+    expect(await readFile(tsConfig, 'utf8')).toMatchInlineSnapshot(
+      `"{ \\"extends\\": \\"./tsconfig.base.json\\" }"`
+    )
+  })
 })