IllegalArgumentException: Stacks have different current sizes [0] and [1] when building with ProGuard optimizations

[cypressious]

Pulling this out of #206:

When building with Proguard optimizations on (getDefaultProguardFile('proguard-android-optimize.txt')), I get the following error:

java.lang.IllegalArgumentException: Stacks have different current sizes [0] and [1]
Unexpected error while performing partial evaluation:
Class = [org/jetbrains/anko/AsyncKt$doAsync$1]
Method = [invoke()Ljava/lang/Object;]
Exception = java.lang.IllegalArgumentException

This is also reported in https://youtrack.jetbrains.com/issue/KT-12866 and https://sourceforge.net/p/proguard/bugs/610/.

The problem lies in the usage of the elvis operator in the catch block in

anko/anko/library/static/common/src/Async.kt

Line 140 in f1f3033

exceptionHandler?.invoke(thr) ?: Unit

@yanex Although this is technically a ProGuard bug, would you consider rewriting the code without the elvis operator and releasing a bugfix build? In the meantime, we're not able to use ProGuard optimizations in our app.

[yanex]

Will be fixed in 0.10.

[dlazerka]

Not sure it it's the same problem, or a bug in Proguard:

 [proguard] Unexpected error while performing partial evaluation:
 [proguard]   Class       = [kotlin/reflect/jvm/internal/impl/renderer/DescriptorRendererImpl]
 [proguard]   Method      = [renderPossiblyInnerType(Ljava/lang/StringBuilder;Lkotlin/reflect/jvm/internal/impl/descriptors/PossiblyInnerType;)V]
 [proguard]   Exception   = [java.lang.IllegalArgumentException] (Stacks have different current sizes [0] and [1])
 [proguard] Error: Stacks have different current sizes [0] and [1]

Can be workarounded by using -dontoptimize Proguard option.

Proguard version 5.2.1
Kotlin version 1.1.2-4