RuntimeException in MessageSchema on Android with Proguard

[MatFl]

Version: v3.9.0
Language: Java/Android
Protoc gradle plugin 0.8.10 for java with option "lite"

When running an proguard obfuscated android app a Runtime Exception is thrown when trying to build a Proto with it's Builder.

java.lang.RuntimeException: Field fieldName_ for xxx.yyy.z.b$d not found. Known fields are [private java.lang.String xxx.yyy.z.b$d.h, ...]
        at com.google.e.ck.a(MessageSchema.java:608)
        at com.google.e.ck.a(MessageSchema.java:502)
        at com.google.e.ck.a(MessageSchema.java:221)
        at com.google.e.bz.a(ManifestSchemaFactory.java:85)
        at com.google.e.bz.a(ManifestSchemaFactory.java:71)
        at com.google.e.dc.a(Protobuf.java:93)
        at com.google.e.dc.c(Protobuf.java:107)
        at com.google.e.bh.M(GeneratedMessageLite.java:170)
        at com.google.e.bh$a.ab(GeneratedMessageLite.java:386)
        at com.google.e.bh$a.ac(GeneratedMessageLite.java:394)
        at xxx.yyy.a(XXX)

It seems than since 3.8.0 the new Javalite runtime uses reflection for the Schemas. I thought the lite should NOT be using any reflection at all.

[m0hamed]

Any updates on this? Is this a bug? going forward is javalite runtime always going to use reflection and not work with proguard/r8?

[grill2010]

Is there any workaround for this?
I use proguard in my project and I get the same error message. I know this happens because of accessing fields via reflection with hardcoded variable names but shouldn't it possible to tell proguard to just ignore these generated classes? I've already tried many things now in the proguatd-rules files but I'm not able to get it work. Maybe anyone could point me in the right direction?

---

Edit: adding the following line to your proguard-rules file helps to get rid of the error but keep in mind that your protobuf messages will then not be processed by proguard at all.

-keep class * extends com.google.protobuf.GeneratedMessageLite { *; }

[rafi-kamal]

I've added a proguard config here as a workaround. Please let me know if it doesn't solve the problem.

[MatFl]

Using a proguard exception is a workaround AT MOST, but definitely not a solution! I still think reflection should not be used in lite variant at all.

[rafi-kamal]

I think this was needed to remove unused fields from a message. @donaldchai could you please add more context?

[donaldchai]

MessageSchema is used to avoid generating hashCode/equals/(de)serialization methods since a small schema would be more compact. Reflection is used to initialize the internal schema data structures the first time.

Removal of unused fields is not directly related.

I filed https://issuetracker.google.com/issues/144631039 for R8 to support obfuscation.

[jombie]

I am not able to get around this when using above proguard rule:
-keepclassmembers class * extends com.google.protobuf.GeneratedMessageLite { <fields>; }
Fails with message "Field [fieldName] for [messageClass.getName(]) not found. Known fields are list of [fields]"

Is there any alternative or any other configuration that I should try.

[juanmarin-co]

@jombie I'm running with the same problem, did you find out a solution?

[thaidn]

I am not able to get around this when using above proguard rule:
-keepclassmembers class * extends com.google.protobuf.GeneratedMessageLite { <fields>; }
Fails with message "Field [fieldName] for [messageClass.getName(]) not found. Known fields are list of [fields]"

Is there any alternative or any other configuration that I should try.

The following config works for me:

-keep class * extends com.google.protobuf.GeneratedMessageLite { *; }