Jakub Grzywacz 864833fca9 Generate keep.xml to prevent resource shrinking on Android (#50620)
Summary:
On Android, when resource shrinking is enabled, all resources added by Metro may be removed as react-native is accessing resources based on strings rather than references, so AGP can't see its usage.

Example output of `android/app/build/outputs/mapping/release/resources.txt `when `shrinkResources` is enabled.
```
raw/__node_modules_expo_vectoricons_build_vendor_reactnativevectoricons_fonts_materialcommunityicons : reachable=false
drawable/__common_assets_haptics_icon : reachable=false
```

It’s a coincidence that most of the resources are currently working, as many file names begin with strings that already exist in the String Pool. For example, `node_modules...` is flagged as used because 'node' is present in the String Pool, causing it to be whitelisted. However, this does not guarantee that the same will apply to all files - especially in a monorepo setup, where paths are significantly different. For example
* `__node_modules_expo_vectoricons_build_vendor_reactnativevectoricons_fonts_materialcommunityicons`
* `__common_assets_haptics_icon`

To prevent that behavior, metro during assets export should create `keep.xml` listing all resources generated by metro.
https://developer.android.com/build/shrink-code#keep-resources

We have already made a similar change in expo cli: https://github.com/expo/expo/pull/35465

## Changelog:

[ANDROID][ADDED] - Generate keep.xml to prevent resource shrinking

Pull Request resolved: https://github.com/facebook/react-native/pull/50620

Test Plan:
1. Enable resource shrinking in RNTester by adding this to `android.buildTypes.release` to `packages/rn-tester/android/app/build.gradle.kts`
```gradle
isMinifyEnabled = true
isShrinkResources = true
```
2. Use some resources in playground, for example:
```diff
 diff --git a/packages/rn-tester/js/examples/Playground/RNTesterPlayground.js b/packages/rn-tester/js/examples/Playground/RNTesterPlayground.js
index 9dbacb99701..9ac9c231f3f 100644
 --- a/packages/rn-tester/js/examples/Playground/RNTesterPlayground.js
+++ b/packages/rn-tester/js/examples/Playground/RNTesterPlayground.js
@@ -11,16 +11,14 @@

 import type {RNTesterModuleExample} from '../../types/RNTesterTypes';

-import RNTesterText from '../../components/RNTesterText';
 import * as React from 'react';
 import {StyleSheet, View} from 'react-native';
+import {Header} from "react-native/Libraries/NewAppScreen";

 function Playground() {
   return (
     <View style={styles.container}>
-      <RNTesterText>
-        Edit "RNTesterPlayground.js" to change this file
-      </RNTesterText>
+      <Header />
     </View>
   );
 }
```

3. Build app using `hermesRelease` variant
4. See Playground screen

| Before | After |
|---|---|
| <img width="488" alt="Zrzut ekranu 2025-04-10 o 12 17 53" src="https://github.com/user-attachments/assets/24fcaa7b-6ddb-4ba6-9fe5-65c27bcbc931" /> | <img width="488" alt="Zrzut ekranu 2025-04-10 o 12 15 58" src="https://github.com/user-attachments/assets/09a1ce77-be26-4571-a4b8-c466bf19e026" /> |

5. Inspect `packages/rn-tester/android/app/build/outputs/mapping/hermesRelease/resources.txt`

| Before | After |
|---|---|
| `drawable/_reactnative_libraries_newappscreen_components_logo : reachable=false` | `drawable/_reactnative_libraries_newappscreen_components_logo : reachable=true` |

Reviewed By: cortinico

Differential Revision: D72960028

Pulled By: huntie

fbshipit-source-id: df725fa2ea50150cd67687a97986976ffbbb5b40
2025-04-14 07:33:27 -07:00
2025-04-03 16:13:09 -07:00
2025-02-27 03:13:26 -08:00
2025-04-11 23:22:56 -07:00
2023-09-12 09:21:08 -07:00
2025-02-27 03:13:26 -08:00
2025-02-27 03:13:26 -08:00
2025-04-11 23:22:56 -07:00
2025-04-11 23:22:56 -07:00

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