with c++11 mode ON, clang complains about how we use typeid in itk-mhd

[djboersma]

This is an issue in the "nitpick" category.

Building GATE on MacOSX El Capitan with nomt G4.10.02, using clang; switching C++11 mode ON in cmake, the build is almost clean, except for this warning:

/Users/montecarlo/Software/CERN/GATE/Gate/source/externals/itk-mhd/MetaIO/metaOutput.cxx:579:17: warning: expression with side effects will be evaluated despite being used as an operand to 'typeid' [-Wpotentially-evaluated-expression]
      if(typeid(*(*itStream)) == typeid(MetaFileOutputStream))
                ^

I see that typeid is used to do something that could be done way more elegantly in a proper OO manner. A small, still hackish fix would be to dynamically cast *itStream to a MetaFileOutputStream pointer, and depending on whether that cast succeeds we call this->GenerateXML(...) with or without filename argument. By using that dynamically casted pointer we don't need that C-style static cast anymore either, in line 581.

However, this code was not written by Gate developers, it was copied from ITK or VTK. I see that it is perfectly identical to MetaIO/metaOutput.cxx in ITK 4.7.1 and VTK 5.10.1. However, Kitware seems to have run into the same warnings, because in ITK 4.8.1 (and VTK 6.3.0) they have indeed replaced the typeid by a dynamic cast (but they still do the ugly C-style cast).

So I guess we should not try to patch this ourselves, but rather update the Gate MetaIO directory by copying the MetaIO directory of a more recent release of VTK. How (un)comfortable would you all be with such an operation? A recursive diff of MetaIO in current Gate/develop and VTK 6.3.0 is not terribly long, and to me most changes seem to me of the code-gardening variety.

(Of course this whole point is moot if the user has already ITK/VTK installed on her machine and can use that instead of the "external", but that is a separate discussion.)

[dsarrut]

Right David, MetaIo is copied from ITK and updated from time to time. Currently, I have no time to do this copy and test, but we should plan it for the next release.