[Insight-developers] The source of the linking errors on gcc 4.0 (-fvisibility)

[Bradley Lowekamp]

Hello,

I have narrowed down the cause of the linking errors to the addition of GCC feature "-fvisibility=hidden" in the Module/Core/Common/src/CMakeLists.txt file:

if(NOT WIN32 AND CMAKE_COMPILER_IS_GNUCXX AND BUILD_SHARED_LIBS)
  set(ITKCommon_CXX_FLAGS "-fvisibility=hidden -fvisibility-inlines-hidden")
  ITK_CHECK_CXX_COMPILER_FLAG(${ITKCommon_CXX_FLAGS} ITKCommon_HAS_GCC_VISIBILITY_FLAGS)
  if(ITKCommon_HAS_GCC_VISIBILITY_FLAGS)
    set_target_properties(ITKCommon PROPERTIES
      COMPILE_FLAGS "${ITKCommon_CXX_FLAGS}"
    )
  endif(ITKCommon_HAS_GCC_VISIBILITY_FLAGS)
endif()

And then in itkDataObject.cxx the following is added, which should specify the correct linkage:

#include "itkSmartPointerForwardReference.hxx"

// Manual instantiation is necessary to prevent link errors                                                                                 
template class ITK_ABI_EXPORT itk::SmartPointerForwardReference< itk::ProcessObject >;

So the like errors are reproducible with gcc4.0 (i686-apple-darwin10-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5494)) and SHARED libraries turned on, for the mac.

Luis,

You have a linux box with gcc 4.0.1, I would be quite curious if shared libraries work on that system!

I am digging through gcc documentation now trying to find out the histry of these options and if this was a known bug or something.

If anyone knows something helpful about this issue or has a suggested resolution, please share.

Thanks,
Brad



========================================================
Bradley Lowekamp  
Medical Science and Computing for
Office of High Performance Computing and Communications
National Library of Medicine 
blowekamp at mail.nih.gov

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