Enable strict mode by default for app dir

vercel · Oct 27, 2022 · a58ba30 · a58ba30
1 parent 11a6fd7
commit a58ba30
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Showing 3 changed files with 14 additions and 4 deletions.
diff --git a/packages/next/build/webpack-config.ts b/packages/next/build/webpack-config.ts
@@ -244,7 +244,17 @@ export function getDefineEnv({
     'process.env.__NEXT_BUILD_INDICATOR_POSITION': JSON.stringify(
       config.devIndicators.buildActivityPosition
     ),
-    'process.env.__NEXT_STRICT_MODE': JSON.stringify(config.reactStrictMode),
+    'process.env.__NEXT_STRICT_MODE': JSON.stringify(
+      config.reactStrictMode === null ? false : config.reactStrictMode
+    ),
+    'process.env.__NEXT_STRICT_MODE_APP': JSON.stringify(
+      // When next.config.js does not have reactStrictMode enabling appDir will enable it.
+      config.reactStrictMode === null
+        ? config.experimental.appDir
+          ? true
+          : false
+        : config.reactStrictMode
+    ),
     'process.env.__NEXT_REACT_ROOT': JSON.stringify(hasReactRoot),
     'process.env.__NEXT_OPTIMIZE_FONTS': JSON.stringify(
       !dev && config.optimizeFonts

diff --git a/packages/next/client/app-index.tsx b/packages/next/client/app-index.tsx
@@ -149,7 +149,7 @@ function ServerRoot({ cacheKey }: { cacheKey: string }): JSX.Element {
   return root
 }
 
-const StrictModeIfEnabled = process.env.__NEXT_STRICT_MODE
+const StrictModeIfEnabled = process.env.__NEXT_STRICT_MODE_APP
   ? React.StrictMode
   : React.Fragment
 

diff --git a/packages/next/server/config-shared.ts b/packages/next/server/config-shared.ts
@@ -391,7 +391,7 @@ export interface NextConfig extends Record<string, any> {
    *
    * @see [React Strict Mode](https://nextjs.org/docs/api-reference/next.config.js/react-strict-mode)
    */
-  reactStrictMode?: boolean
+  reactStrictMode?: boolean | null
 
   /**
    * Add public (in browser) runtime configuration to your app
@@ -545,7 +545,7 @@ export const defaultConfig: NextConfig = {
   excludeDefaultMomentLocales: true,
   serverRuntimeConfig: {},
   publicRuntimeConfig: {},
-  reactStrictMode: false,
+  reactStrictMode: null,
   httpAgentOptions: {
     keepAlive: true,
   },