title: Error 255 in Xcode 4.5 compiling with LLVM 4.1
body: <p>I'm trying to compile my project with the latest xcode + sdk 6.0
  when the building is almost done, I got this error:</p>
  
  <pre><code>2012-09-26 16:52:24.714 ibtoold[5603:b03] [MT] DVTAssertions: ASSERTION FAILURE in /SourceCache/IDEInterfaceBuilder/IDEInterfaceBuilder-2840/Framework/Document/IBDocument.m:1514
  Details:  Some objects didn't get the ibBeginArchivingDocument:withContext: callback. A class has probably overridden the method without calling through to super.
  Object:   &lt;IBCocoaTouchDocument: 0x40072df00&gt;
  Method:   -willArchiveWithContext:
  Thread:   &lt;NSThread: 0x40010a260&gt;{name = (null), num = 1}
  Hints: None
  Backtrace:  0  0x000000010550e44c -[DVTAssertionHandler handleFailureInMethod:object:fileName:lineNumber:messageFormat:arguments:] (in DVTFoundatio  
  1  0x000000010550e2a5 _DVTAssertionFailureHandler (in DVTFoundatio  
  2  0x0000000104b35245 -[IBDocument willArchiveWithContext:] (in IDEInterfaceBuilderKi  
  3  0x00000001086407d6 (in IDEInterfaceBuilderCocoaTouchIntegratio  
  4  0x0000000108640c3a (in IDEInterfaceBuilderCocoaTouchIntegratio  
  5  0x0000000104b44745 __47-[IBDocument compiledPackageWithOptions:error:]_block_invoke_0 (in IDEInterfaceBuilderKi  
  6  0x0000000104b5b9a1 -[IBDocument assertIfArbitrationIsScheduledDuring:] (in IDEInterfaceBuilderKi  
  7  0x0000000104b44710 -[IBDocument compiledPackageWithOptions:error:] (in IDEInterfaceBuilderKi  
  8  0x0000000104a46f90 (in ibtool  
  9  0x0000000104a440e8 (in ibtool 
  10  0x0000000104a43c5f (in ibtoold 
  11  0x0000000104a43b53 (in ibtoold 
  12  0x0000000104a50165 (in ibtoold 
  13  0x0000000104a43684 (in ibtoold 
  14  0x0000000104a448f1 (in ibtoold 
  15  0x0000000104a42524 (in ibtoold 
  16  0x000000000000000 Command /Applications/Xcode4.5SDK6.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/ibtool failed with exit code 255
  </code></pre>
  
  <p>Only for a XIB I'll not able to build with success...have you got the solution?
  thanks!
  Dario</p>