From 8bc587aa30099bdf3ee379fe0b1a2fe3387801cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20Orb=C3=A1n?= <info@balazsorban.com>
Date: Fri, 9 Sep 2022 22:32:58 +0200
Subject: [PATCH] feat(ts): expose `AppType` (#40391)

An alternative solution to #40371

Ref: #38867, https://github.com/t3-oss/create-t3-app/issues/412,
https://github.com/t3-oss/create-t3-app/pull/414

## Bug

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

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
---
 packages/next/pages/_app.tsx               |  3 ++-
 packages/next/shared/lib/utils.ts          |  6 +++---
 test/integration/typescript/pages/_app.tsx | 17 +++--------------
 3 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/packages/next/pages/_app.tsx b/packages/next/pages/_app.tsx
index 691555628145f5f..c646d0842fea09e 100644
--- a/packages/next/pages/_app.tsx
+++ b/packages/next/pages/_app.tsx
@@ -5,10 +5,11 @@ import {
   AppInitialProps,
   AppPropsType,
   NextWebVitalsMetric,
+  AppType,
 } from '../shared/lib/utils'
 import type { Router } from '../client/router'
 
-export { AppInitialProps }
+export { AppInitialProps, AppType }
 
 export { NextWebVitalsMetric }
 
diff --git a/packages/next/shared/lib/utils.ts b/packages/next/shared/lib/utils.ts
index ec5197e0c3b9a80..76b9eee3a5207d9 100644
--- a/packages/next/shared/lib/utils.ts
+++ b/packages/next/shared/lib/utils.ts
@@ -27,10 +27,10 @@ export type DocumentType = NextComponentType<
   DocumentProps
 >
 
-export type AppType = NextComponentType<
+export type AppType<P = {}> = NextComponentType<
   AppContextType,
-  AppInitialProps,
-  AppPropsType
+  P,
+  AppPropsType<any, P>
 >
 
 export type AppTreeType = ComponentType<
diff --git a/test/integration/typescript/pages/_app.tsx b/test/integration/typescript/pages/_app.tsx
index bc26412e55dae24..adc878fa93ecd44 100644
--- a/test/integration/typescript/pages/_app.tsx
+++ b/test/integration/typescript/pages/_app.tsx
@@ -1,20 +1,9 @@
-// import App from "next/app";
-import type { AppProps /*, AppContext */ } from 'next/app'
+import type { AppType } from 'next/app'
 
-function MyApp({ Component, pageProps }: AppProps) {
+const MyApp: AppType<{ foo: string }> = ({ Component, pageProps }) => {
   return <Component {...pageProps} />
 }
 
-// Only uncomment this method if you have blocking data requirements for
-// every single page in your application. This disables the ability to
-// perform automatic static optimization, causing every page in your app to
-// be server-side rendered.
-//
-// MyApp.getInitialProps = async (appContext: AppContext) => {
-//   // calls page's `getInitialProps` and fills `appProps.pageProps`
-//   const appProps = await App.getInitialProps(appContext);
-
-//   return { ...appProps }
-// }
+MyApp.getInitialProps = () => ({ foo: 'bar' })
 
 export default MyApp