Сan't find referenced class ClassName$DefaultImpls

[tox1cozZ]

Proguard 7.3.0-beta2
Kotlin 1.7.20

I don't understand why he is looking for the DefaultImpls class for the annotation?
And in general, I have Java 8 and there is a parameter -Xjvm-default=all in the compiler arguments

[rubenpieters]

Hey, thanks for the report. Do you have a small reproducible sample that results in this behavior? As far as I can tell from your report, ProGuard is warning that there is a reference to class NoArg$DefaultImpls from NoArg, but NoArg$DefaultImpls can't be found (which presumably is something the Kotlin compiler has added). We can look into it more closely once you provide a reproducible sample.

Does the code still work after processing with ProGuard or does it result in a crash/different behavior?

[oliver-charlesworth]

I can reproduce this symptom when I use keepkotlinmetadata.

Repro

src/main/kotlin/wat/Foo.kt

package wat

interface Foo

build.gradle.kts

import proguard.gradle.ProGuardTask

buildscript {
    dependencies {
        classpath("com.guardsquare:proguard-gradle:7.3.0-beta2")
    }
}

plugins {
    kotlin("jvm") version "1.7.21"
}

repositories {
    mavenCentral()
}

val proguard by tasks.registering(ProGuardTask::class) {
    injars(tasks.jar)
    outjars(buildDir.resolve("obfuscated/obfuscated.jar"))

    libraryjars(configurations.compileClasspath)

    val javaHome = System.getProperty("java.home")
    libraryjars(
        mapOf(
            "jarfilter" to "!**.jar",
            "filter"    to "!module-info.class",
        ),
        "$javaHome/jmods/java.base.jmod"
    )

    keepkotlinmetadata()
    dontshrink()
    dontoptimize()
    printmapping()
}

Error

ProGuard, version 7.3.0-beta2
Warning: wat.Foo: can't find referenced class wat.Foo$DefaultImpls

If I remove the keepkotlinmetadata(), then this succeeds.

[mrjameshamilton]

Thanks for the sample @oliver-charlesworth ! We tracked down the cause solved the underlying issue in ProGuardCORE. This should make it into the next patch release of ProGuard.

For now, you should be able to add -dontwarn for those classes (e.g. dontwarn("**DefaultImpls")), or use -ignorewarnings.

[mrjameshamilton]

Hi @tox1cozZ , @oliver-charlesworth ! The fix is now in ProGuard 7.3.1.