title: Error: Can't find common super class of
body: <p>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:</p>
  
  <pre><code>Unexpected error while performing partial evaluation:
  Class = [org/eclipse/swt/widgets/DateTime]
  Method = [&lt;init&gt;(Lorg/eclipse/swt/widgets/Composite;I)V]
  Exception = [java.lang.IllegalArgumentException] (Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR])
  Error: Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR]
  ----------------------------
  </code></pre>
  
  <p>When I tried to Google the error, it came out only on two spots on the entire web, that astonished me greatly.
  I am newbie using Proguard and Java code optimization tools at all.
  Any thoughts and suggestions how to fix this, will be appreciated. Thanks in advance.</p>
  
  <p><strong>Above error is now fixed,</strong> with the using of "-dontskipnonpubliclibraryclasses"</p>
  
  <p><strong>--final update:</strong></p>
  
  <p>I still get another error now.
  The whole output is now the folowing:</p>
  
  <pre><code>D:\eclipse_projs\java_obfuscate\gci&gt;gci.bat
  ProGuard, version 4.4
  Reading program jar [D:\eclipse_projs\java_obfuscate\gci\gci.jar]
  Reading library jar [D:\jre1.6.0_07\lib\rt.jar]
  Unexpected error while evaluating instruction:
    Class       = [org/eclipse/swt/widgets/Synchronizer]
    Method      = [runAsyncMessages(Z)Z]
    Instruction = [60] aload_1 v1
    Exception   = [java.lang.IllegalArgumentException] (Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue])
  Unexpected error while performing partial evaluation:
    Class       = [org/eclipse/swt/widgets/Synchronizer]
    Method      = [runAsyncMessages(Z)Z]
    Exception   = [java.lang.IllegalArgumentException] (Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue])
   Error: Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue]
  
  D:\eclipse_projs\java_obfuscate\gci&gt;
  </code></pre>
  
  <p>This is a problem that i cannot understand for certain :( any help will be much appreciated.</p>
  
  <p>The options I use are the following:</p>
  
  <pre><code>-dontskipnonpubliclibraryclasses
  -dontskipnonpubliclibraryclassmembers
  -optimizationpasses 3
  -overloadaggressively
  -repackageclasses ''
  -allowaccessmodification
  -dontnote
  </code></pre>