How to use Kotlin with Proguard

I'm trying to add Kotlin to my project and I need to use proguard. Which rules should I add to proguard to support Kotlin?

Thank you

Solution 1:

You don't need to do anything special. Kotlin works with ProGuard out of the box. But you may face some strange errors when processing your application with ProGuard. In this case just add

-dontwarn kotlin.**

Also if you want to get rid of null checks at runtime you may use the following rule:

-assumenosideeffects class kotlin.jvm.internal.Intrinsics {
    static void checkParameterIsNotNull(java.lang.Object, java.lang.String);
}

Solution 2:

-keep class kotlin.** { *; }
-keep class kotlin.Metadata { *; }
-dontwarn kotlin.**
-keepclassmembers class **$WhenMappings {
    <fields>;
}
-keepclassmembers class kotlin.Metadata {
    public <methods>;
}
-assumenosideeffects class kotlin.jvm.internal.Intrinsics {
    static void checkParameterIsNotNull(java.lang.Object, java.lang.String);
}

build gradle :

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

https://kotlinlang.org/docs/tutorials/kotlin-android.html

Solution 3:

In Kotlin 1.0.2 EAP proguard strips out when mappings for enums, so I have to keep them explicitly, so

-keepclassmembers class **$WhenMappings {
    <fields>;
}

is sufficient for correct obfuscation. Although if you want some performance improvements, you can also add

-assumenosideeffects class kotlin.jvm.internal.Intrinsics {
    static void checkParameterIsNotNull(java.lang.Object, java.lang.String);
}