Error: Can't find common super class of

Question

I am trying to process with Proguard a MS Windows desktop application (Java 6 SE using the SWT lib provided by Eclipse). And I get the following critical error:

Answer 1

I had an issue with an application depending on various other projects. I tried the listed solutions, but none of them help. Based on tests, the shrinking and preverify steps were correctly running, the optimization threw the error:

> java.io.IOException: java.lang.IllegalArgumentException: Can't find common super class of [java/io/File] (with 2 known super classes) and [org/antlr/v4/runtime/tree/gui/TreeViewer] (with 1 known super classes)

I tried keeping (-keep options) both classes without any success. Based on other threads I found the minimal solution is to disable variable optimization:

-optimizations !code/allocation/variable

This lets me compile successfully, but has its drawbacks.