Preserve Expo-generated modulemap in replace-rncore-version.js

packages/react-native/scripts/replace-rncore-version.js

@@ -96,6 +96,18 @@ function replaceRNCoreConfiguration(
       );
     }
 
+    // Preserve Expo-generated modulemap before replacing directories
+    const useFrameworksModulemapName = 'React-use-frameworks.modulemap';
+    const useFrameworksModulemapPath = path.join(
+      finalLocation,
+      useFrameworksModulemapName,
+    );
+    let savedModulemap = null;
+    if (fs.existsSync(useFrameworksModulemapPath)) {
+      console.log('Preserving', useFrameworksModulemapName);
+      savedModulemap = fs.readFileSync(useFrameworksModulemapPath);
+    }
+
     // Delete all directories in finalLocation - not files, since we want to
     // keep the React-VFS.yaml file
     const dirs = fs
@@ -132,9 +144,21 @@ function replaceRNCoreConfiguration(
         }
       }
     }
+
   } finally {
     // Clean up temp directory
     fs.rmSync(tmpDir, {force: true, recursive: true});
+
+    // Restore Expo-generated modulemap after directory replacement.
+    // Runs in finally so it is not skipped if mv/cp partially fails.
+    if (savedModulemap != null) {
+      const restoredPath = path.join(
+        finalLocation,
+        useFrameworksModulemapName,
+      );
+      fs.writeFileSync(restoredPath, savedModulemap);
+      console.log('Restored', useFrameworksModulemapName);
+    }
   }
 }