play-services-code-scanner crashes with R8 full mode (AGP 9+): missing consumer ProGuard rules

[geekflyer]

Bug description

GmsBarcodeScanning.getClient() throws a NullPointerException when the app is built with R8 full mode (default in AGP 9+). Debug builds are unaffected. The issue is that play-services-code-scanner:16.1.0 does not ship consumer ProGuard rules to protect its internal classes from being stripped by R8.

This is the same class of issue documented on the ML Kit Known Issues page for Language ID (com.google.mlkit.nl.languageid.internal.LanguageIdentificationJni), but for the code scanner API.

Stack trace

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
  at com.google.android.gms.internal.mlkit_code_scanner.zzny.<init> (play-services-code-scanner@@16.1.0:8)
  at com.google.android.gms.internal.mlkit_code_scanner.zzoi.create (play-services-code-scanner@@16.1.0:8)
  at com.google.mlkit.common.sdkinternal.LazyInstanceMap.get (LazyInstanceMap.java:3)
  at com.google.android.gms.internal.mlkit_code_scanner.zzoj.zza (zzoj.java:2)
  at com.google.android.gms.internal.mlkit_code_scanner.zzoj.zzb (zzoj.java:3)
  at com.google.mlkit.vision.codescanner.internal.zze.<init> (play-services-code-scanner@@16.1.0:2)
  at com.google.mlkit.vision.codescanner.GmsBarcodeScanning.getClient (GmsBarcodeScanning.java:2)

Environment

• play-services-code-scanner:16.1.0
• AGP 9.1.0 (R8 full mode enabled by default)
• Gradle 9.4.0
• Kotlin 2.3.10
• Reproducible on: Pixel (Android 16), Samsung Galaxy S26 Ultra (Android 16 Beta), Realme GT6 (Android 16)
• compileSdk = 36, targetSdk = 36

Steps to reproduce

1. Add implementation("com.google.android.gms:play-services-code-scanner:16.1.0")
2. Build a release APK with isMinifyEnabled = true using AGP 9.1.0 (R8 full mode is the default)
3. Call GmsBarcodeScanning.getClient(context, options)
4. App crashes with the above NPE

Debug builds (isMinifyEnabled = false) work fine — confirming R8 is stripping classes the library needs at runtime.

Workaround

Adding these keep rules to the app's proguard-rules.pro fixes the crash:

-keep class com.google.mlkit.** { *; }
-keep class com.google.android.gms.internal.mlkit_code_scanner.** { *; }

Expected fix

play-services-code-scanner should ship consumer ProGuard rules in its AAR (via consumer-rules.pro) to keep the classes it accesses via reflection. This is the same approach used by other Google libraries and recommended by Google's own R8 documentation.

Other libraries have had the same issue with AGP 9's R8 full mode:

• aws-sdk-android#3686
• retrofit#3880