feat: change createMessagesDeclaration to an array for monorepo support

docs/src/pages/docs/workflows/typescript.mdx

@@ -203,15 +203,15 @@ TypeScript currently has a [limitation](https://github.com/microsoft/TypeScript/
 }
 ```
 
-2. Configure the `createMessagesDeclaration` setting in your Next.js config:
+2. Configure the `createMessagesDeclarations` setting in your Next.js config:
 
 ```tsx filename="next.config.mjs"
 import {createNextIntlPlugin} from 'next-intl/plugin';
 
 const withNextIntl = createNextIntlPlugin({
   experimental: {
     // Provide the path to the messages that you're using in `AppConfig`
-    createMessagesDeclaration: './messages/en.json'
+    createMessagesDeclarations: ['./messages/en.json']
   }
   // ...
 });

packages/next-intl/src/plugin/createMessagesDeclaration.tsx → packages/next-intl/src/plugin/createMessagesDeclarations.tsx

@@ -11,31 +11,35 @@ function runOnce(fn: () => void) {
   fn();
 }
 
-export default function createMessagesDeclaration(messagesPath: string) {
-  const fullPath = path.resolve(messagesPath);
-
-  if (!fs.existsSync(fullPath)) {
-    throwError(
-      `\`createMessagesDeclaration\` points to a non-existent file: ${fullPath}`
-    );
-  }
-  if (!fullPath.endsWith('.json')) {
-    throwError(
-      `\`createMessagesDeclaration\` needs to point to a JSON file. Received: ${fullPath}`
-    );
-  }
-
-  // Keep this as a runtime check and don't replace
-  // this with a constant during the build process
-  const env = process.env['NODE_ENV'.trim()];
-
+export default function createMessagesDeclarations(
+  messagesPaths: Array<string>
+) {
   // Next.js can call the Next.js config multiple
   // times - ensure we only run once.
   runOnce(() => {
-    compileDeclaration(messagesPath);
+    for (const messagesPath of messagesPaths) {
+      const fullPath = path.resolve(messagesPath);
+
+      if (!fs.existsSync(fullPath)) {
+        throwError(
+          `\`createMessagesDeclaration\` points to a non-existent file: ${fullPath}`
+        );
+      }
+      if (!fullPath.endsWith('.json')) {
+        throwError(
+          `\`createMessagesDeclaration\` needs to point to a JSON file. Received: ${fullPath}`
+        );
+      }
+
+      // Keep this as a runtime check and don't replace
+      // this with a constant during the build process
+      const env = process.env['NODE_ENV'.trim()];
+
+      compileDeclaration(messagesPath);
 
-    if (env === 'development') {
-      startWatching(messagesPath);
+      if (env === 'development') {
+        startWatching(messagesPath);
+      }
     }
   });
 }

packages/next-intl/src/plugin/createNextIntlPlugin.tsx

@@ -1,5 +1,5 @@
 import type {NextConfig} from 'next';
-import createMessagesDeclaration from './createMessagesDeclaration.js';
+import createMessagesDeclarations from './createMessagesDeclarations.js';
 import getNextConfig from './getNextConfig.js';
 import type {PluginConfig} from './types.js';
 import {warn} from './utils.js';
@@ -14,9 +14,9 @@ function initPlugin(
     );
   }
 
-  if (pluginConfig.experimental?.createMessagesDeclaration) {
-    createMessagesDeclaration(
-      pluginConfig.experimental.createMessagesDeclaration
+  if (pluginConfig.experimental?.createMessagesDeclarations) {
+    createMessagesDeclarations(
+      pluginConfig.experimental.createMessagesDeclarations
     );
   }
 

packages/next-intl/src/plugin/types.tsx

@@ -1,6 +1,6 @@
 export type PluginConfig = {
   requestConfig?: string;
   experimental?: {
-    createMessagesDeclaration?: string;
+    createMessagesDeclarations?: Array<string>;
   };
 };