[tomekzaw]

Summary:

ReactActivityResultCaller keys each launcher by "<owner class>:<contract class>". With R8 enabled, it can merge different contract classes into one class (horizontal class merging), so they end up with the same name. For example, in a minified RNTester build, ActivityResultContracts.RequestPermission, PickVisualMedia and GetContent were all merged into a class named e2. Registering a second contract from the same owner then throws IllegalStateException: A launcher is already registered for key '…:e2'. That's why SampleTurboModule fails to initialize in a minified RNTester.

This adds a consumer R8 rule that keeps the names of ActivityResultContract subclasses, which stops R8 from merging or renaming them. Unused contracts can still be removed. It also keeps the keys stable between builds, which the docs ask for. The docs now mention the rule.

Changelog:

[INTERNAL] [FIXED] - Keep ActivityResultContract class names in R8 builds so that activity result launcher keys don't collide

Test Plan:

Minified release RNTester: ./gradlew :packages:rn-tester:android:app:assembleRelease -PreactNativeArchitectures=arm64-v8a, with enableProguardInReleaseBuilds = true.

• R8 mapping:
  • main: ActivityResultContracts$GetContent -> e2, a merged class with an $r8$classId field.
  • This PR: every contract keeps its own name, for example ActivityResultContracts$RequestPermission -> ActivityResultContracts$RequestPermission.
• On a Galaxy A16 (Android 16), from a Playground screen that calls SampleTurboModule:
  • main: Exception in HostObject::get for prop 'SampleTurboModule': java.lang.IllegalStateException: A launcher is already registered for key 'com.facebook.fbreact.specs.SampleTurboModule:e2'
  • This PR: the module initializes, and getObject, getArray and getConstants return the expected values.

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