fix(nuxt): deprecate old (pre-rc) runtimeConfig (#20082)

packages/nuxt/src/app/nuxt.ts

@@ -255,17 +255,19 @@ export function createNuxtApp (options: CreateOptions) {
   }
 
   // Expose runtime config
-  const runtimeConfig = process.server
-    ? options.ssrContext!.runtimeConfig
-    : reactive(nuxtApp.payload.config)
+  const runtimeConfig = process.server ? options.ssrContext!.runtimeConfig : reactive(nuxtApp.payload.config)
 
+  // TODO: remove in v3.5
   // Backward compatibility following #4254
   const compatibilityConfig = new Proxy(runtimeConfig, {
-    get (target, prop) {
-      if (prop === 'public') {
-        return target.public
+    get (target, prop: string) {
+      if (prop in target) {
+        return target[prop]
       }
-      return target[prop] ?? target.public[prop]
+      if (process.dev && prop in target.public) {
+        console.warn(`[nuxt] [runtimeConfig] You are trying to access a public runtime config value (\`${prop}\`) directly from the top level. This currently works (for backward compatibility with Nuxt 2) but this compatibility layer will be removed in v3.5. Instead, you can update \`config['${prop}']\` to \`config.public['${prop}']\`.`)
+      }
+      return target.public[prop]
     },
     set (target, prop, value) {
       if (process.server || prop === 'public' || prop === 'app') {

test/fixtures/basic/pages/index.vue

@@ -4,7 +4,7 @@
       <Title>Basic fixture</Title>
     </Head>
     <h1>Hello Nuxt 3!</h1>
-    <div>RuntimeConfig | testConfig: {{ config.testConfig }}</div>
+    <div>RuntimeConfig | testConfig: {{ config.public.testConfig }}</div>
     <div>Composable | foo: {{ foo }}</div>
     <div>Composable | bar: {{ bar }}</div>
     <div>Composable | template: {{ templateAutoImport }}</div>

test/fixtures/basic/plugins/async-plugin.ts

@@ -6,7 +6,7 @@ export default defineNuxtPlugin(async (/* nuxtApp */) => {
   return {
     provide: {
       asyncPlugin: () => config1 && config1 === config2
-        ? 'Async plugin works! ' + config1.testConfig + (data.value?.baz ? 'useFetch works!' : 'useFetch does not work')
+        ? 'Async plugin works! ' + config1.public.testConfig + (data.value?.baz ? 'useFetch works!' : 'useFetch does not work')
         : 'Async plugin failed!'
     }
   }