Enable App Router for all applications

packages/next/src/server/config-shared.ts

@@ -686,7 +686,7 @@ export const defaultConfig: NextConfig = {
     swcFileReading: true,
     craCompat: false,
     esmExternals: true,
-    appDir: false,
+    appDir: true,
     // default to 50MB limit
     isrMemoryCacheSize: 50 * 1024 * 1024,
     incrementalCacheHandlerPath: undefined,

packages/next/src/server/config.ts

@@ -45,11 +45,6 @@ const experimentalWarning = execOnce(
       `Experimental features are not covered by semver, and may cause unexpected or broken application behavior. ` +
         `Use at your own risk.`
     )
-    if (features.includes('appDir')) {
-      Log.info(
-        `Thank you for testing \`appDir\` please leave your feedback at https://nextjs.link/app-feedback`
-      )
-    }
 
     console.warn()
   }

test/e2e/app-dir/app-static/app-static.test.ts

@@ -1877,14 +1877,6 @@ createNextDescribe(
       })
     })
 
-    if (!(global as any).isNextDeploy) {
-      it('should show a message to leave feedback for `appDir`', async () => {
-        expect(next.cliOutput).toContain(
-          `Thank you for testing \`appDir\` please leave your feedback at https://nextjs.link/app-feedback`
-        )
-      })
-    }
-
     it('should keep querystring on static page', async () => {
       const browser = await next.browser('/blog/tim?message=hello-world')
       const checkUrl = async () =>

test/integration/app-tree/pages/_app.tsx

@@ -5,7 +5,7 @@ import { render } from 'react-dom'
 import App, { AppContext } from 'next/app'
 import { renderToString } from 'react-dom/server'
 
-export const DummyContext = createContext(null)
+export const DummyContext = createContext(null) as React.Context<string | null>
 
 export default class MyApp extends App<{ html: string }> {
   static async getInitialProps({ Component, AppTree, ctx }: AppContext) {
@@ -20,7 +20,7 @@ export default class MyApp extends App<{ html: string }> {
 
     if (typeof window !== 'undefined') {
       const el = document.createElement('div')
-      document.querySelector('body').appendChild(el)
+      document.querySelector('body')?.appendChild(el)
       render(toRender, el)
       html = el.innerHTML
       el.remove()

test/integration/app-tree/pages/hello.tsx

@@ -20,7 +20,7 @@ Page.getInitialProps = async ({ AppTree }) => {
 
   if (typeof window !== 'undefined') {
     const el = document.createElement('div')
-    document.querySelector('body').appendChild(el)
+    document.querySelector('body')?.appendChild(el)
     render(toRender, el)
     html = el.innerHTML
     el.remove()

test/integration/app-tree/tsconfig.json

@@ -13,8 +13,14 @@
     "moduleResolution": "node",
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "jsx": "preserve"
+    "jsx": "preserve",
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ],
+    "strictNullChecks": true
   },
   "exclude": ["node_modules"],
-  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx"]
+  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"]
 }