MinifyEnabled = true strips away Serializable objects

[mahmed1987]

I am attaching a working project in which the issue can be observed.

As per the documentation of this library , we are not to change add or modify the proguard files (if we are not using named companion objects).

That hasn't been my observation .

I am attaching a code sample to demonstrate the issue i obtain with minifyEnabled true. The project zip file is uploaded here.

Just open this project in android studio and run the android app on a device or simulator. The app would crash with the following stacktrace .

Adding -keep @kotlinx.serialization.Serializable class * {*;} to the proguard file would fix this situation , but this is against what the docs say

[sandwwraith]

Why did you post it as a separate issue from #2858 though?

[mahmed1987]

hey @sandwwraith , I closed that issue because it didn't give satisfactory information in my opinion about the issue at hand .

So I created a sample project to demonstrate the issue and opened a new issue and closed that one .

In hindsight what I could have done is made this more clear by adding a comment on the previous issue between closing that , that I would be opening another issue with more details .

Would remain more vigilant moving forward

[sandwwraith]

It seems there are some problems in the connection between serializable objects and R8 full mode. This code:

@Serializable
class Klas

@Serializable
object Obj

println(serializer(typeOf<Klas>()))
println(serializer(typeOf<Obj>()))

prints

com.syphyr.kmpplayground.android.Klas$$serializer@424ad69
kotlinx.serialization.internal.ObjectSerializer@5aa608f

when R8 full mode is disabled, and throws

com.syphyr.kmpplayground.android.Klas$$serializer@424ad69

kotlinx.serialization.SerializationException: Serializer for class 'Obj' is not found.
Please ensure that class is marked as '@Serializable' and that the serialization compiler plugin is applied.

when R8 full mode is enabled (which is the default for recent versions of AGP).
Perhaps proguard rules inside the library indeed have to be updated.

To workaround this, you can either disable full mode (android.enableR8.fullMode=false in gradle.properties) or apply the -keep @kotlinx.serialization.Serializable class * {*;} rule, which you've already mentioned.

Tested on

agp = "8.6.1"
kotlin = "2.0.20"

[mahmed1987]

@sandwwraith I would raise the issue on android issue tracker channel too

I too believe this must be something to do with the navigation library

[shanshin]

@mahmed1987
could you please check this rule?

-if @kotlinx.serialization.Serializable class **
-keepclassmembers class <1> {
    public static <1> INSTANCE;
    kotlinx.serialization.KSerializer serializer(...);
}

This is a stricter rule compared to -keep @kotlinx.serialization.Serializable class * {*;}, if there are no other errors with it, we will add it to the built-in rules for R8

[shanshin]

Related R8 issue https://issuetracker.google.com/issues/379996140