Disable "use cache" outside of dynamicIO (#70538)

Author: sebmarkbage

packages/next/src/build/webpack/plugins/define-env-plugin.ts

@@ -183,6 +183,7 @@ export function getDefineEnv({
       config.devIndicators.appIsrStatus
     ),
     'process.env.__NEXT_PPR': checkIsAppPPREnabled(config.experimental.ppr),
+    'process.env.__NEXT_DYNAMIC_IO': !!config.experimental.dynamicIO,
     'process.env.__NEXT_AFTER': config.experimental.after ?? false,
     'process.env.NEXT_DEPLOYMENT_ID': config.deploymentId || false,
     'process.env.__NEXT_FETCH_CACHE_KEY_PREFIX': fetchCacheKeyPrefix ?? '',

packages/next/src/server/use-cache/use-cache-wrapper.ts

@@ -160,6 +160,11 @@ async function generateCacheEntry(
 }
 
 export function cache(kind: string, id: string, fn: any) {
+  if (!process.env.__NEXT_DYNAMIC_IO) {
+    throw new Error(
+      '"use cache" is only available with the experimental.dynamicIO config.'
+    )
+  }
   const cacheHandler = cacheHandlerMap.get(kind)
   if (cacheHandler === undefined) {
     throw new Error('Unknown cache handler: ' + kind)