How to use Kotlin with Proguard

Question

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

Please provide more information, e.g. which rules you tried, how did that work, what errors did you get, etc. — Alexander Udalov, Nov 05 '15 at 17:01

score 42 · Answer 1 · answered Dec 08 '15 at 15:32

42

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);
}

answered Dec 08 '15 at 15:32

Michael

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2

I believe a flag for kotlinc sets the policy for null checks. No need for proguard for that. – voddan May 25 '16 at 08:41
Where did you find the thing about the flag? I would very much like to try that, but can't seem to find it anywhere :/ – daemontus Jan 14 '17 at 14:35
@daemontus `kotlinc -X` yields `-Xno-param-assertions`, `-Xno-receiver-assertions` and `-Xno-call-assertions`; see also [source code](https://github.com/JetBrains/kotlin/blob/v1.2.71/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt#L89-L105) – TWiStErRob Oct 15 '18 at 18:54
Kotlin works with Proguard but Proguard is not working effectively with Kotlin yet. Kotlin support in Proguard is still in beta at this moment. E.g. Proguard cannot distinguish `internal` classes and members from `public` ones. It sees them as `public` because they are marked `public` in the bytecode. – WindRider Feb 24 '20 at 15:24

score 19 · Answer 2 · answered Nov 11 '17 at 11:47

19

-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

answered Nov 11 '17 at 11:47

Misagh

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Where should I add the first one? in `proguard-rules.pro`? – c-an Jun 25 '19 at 09:46
@c-an yes. Add it to your proguard-rules file – Misagh Jun 30 '19 at 11:51

score 11 · Answer 3 · answered May 09 '16 at 10:10

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);
}

score 0 · Answer 4 · answered May 27 '20 at 12:53

if you use android studio, proguards comes with default. But you should on "Enables code shrinking" and "Enables resource shrinking" options for your code security and code optimization.

open your gradile file and check below.

android {
    buildTypes {
        release {
            // Enables code shrinking, obfuscation, and optimization for only
            // your project's release build type.
            minifyEnabled true

            // Enables resource shrinking, which is performed by the
            // Android Gradle plugin.
            shrinkResources true

            // Includes the default ProGuard rules files that are packaged with
            // the Android Gradle plugin. To learn more, go to the section about
            // R8 configuration files.
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

Source : https://developer.android.com/studio/build/shrink-code

score -3 · Answer 5 · edited Jun 05 '18 at 07:44

-3

Check in your build.gradle. Did you include:

implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"

edited Jun 05 '18 at 07:44

David Rawson

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answered Oct 27 '17 at 10:17

TSG anti SO dark forces

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How to use Kotlin with Proguard

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