D8: Type `sun.misc.Unsafe` was not found

Question

After enabling D8 in my android project, I've started seeing these warnings:

/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `void com.google.common.util.concurrent.AbstractFuture$UnsafeAtomicHelper.<clinit>()`
/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `sun.misc.Unsafe com.google.common.cache.Striped64.getUnsafe()`
/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `sun.misc.Unsafe com.google.common.hash.LittleEndianByteArray$UnsafeByteArray.getUnsafe()`
/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `void com.google.common.util.concurrent.AbstractFuture$UnsafeAtomicHelper.<clinit>()`
/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `sun.misc.Unsafe com.google.common.cache.Striped64.getUnsafe()`
/Users/yashasvi/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/27.0.1-android/b7e1c37f66ef193796ccd7ea6e80c2b05426182d/guava-27.0.1-android.jar: D8: Type `sun.misc.Unsafe` was not found, it is required for default or static interface methods desugaring of `sun.misc.Unsafe com.google.common.hash.LittleEndianByteArray$UnsafeByteArray.getUnsafe()`

.

Project builds successfully but at runtime, I see these error logs and due to this, app functionality is affected.

 java.lang.AbstractMethodError: abstract method "java.lang.Object com.google.common.base.e.a(java.lang.Object)"
        at com.google.common.e.a.i$c.a(SourceFile:1464)
        at com.google.common.e.a.i$c.a(SourceFile:1453)
        at com.google.common.e.a.i$a.run(SourceFile:1408)
        at com.google.common.e.a.l$a.execute(SourceFile:456)
        at com.google.common.e.a.i$f.a(SourceFile:153)
        at com.google.common.e.a.i.a(SourceFile:1234)

I haven't been able to find anything useful on this after searching for a while. Please help.

And yes, I don't face this error at runtime if D8 is disabled and everything else remains same.

Answer 1

In your project-proguard file. Please add this:

-keepnames class com.google.common.**

-keep class com.google.common.**

-dontwarn com.google.common.**

It seems to be a sort of bug. But sometimes when you using D8 it tend to renames class names or delete them altogether.

Answer 2

you need to keep sun.misc.Unsafe:

-keep class sun.misc.Unsafe { *; }
-dontnote sun.misc.Unsafe

alternatively, a rule with includedescriptorclasses should keep it dynamically:

-keep,includedescriptorclasses class com.google.common.**

in general:

• adding switch -verbose is quite helpful for writing ProGuard configuration rules.

• adding switch -dontoptimize can be used to disable all optimization, for a test.

just found this:

R8 now understands proguard specs in META-INF/proguard.

but unless this had been added, one has to add custom rules - instead of using consumer rules.