cmake GDCM_HAVE_WCHAR_IFSTREAM examples

malaterre/GDCM Source/Common/CMakeLists.txt :64 

CHECK_CXX_SOURCE_COMPILES(
  "\#include <fstream>\nint main() { const wchar_t fn[10] = {}; std::ifstream is( fn ); std::wcerr << fn; return 0;}"
  GDCM_HAVE_WCHAR_IFSTREAM)

InsightSoftwareConsortium/ITK Modules/ThirdParty/GDCM/src/gdcm/Source/Common/CMakeLists.txt :64 

CHECK_CXX_SOURCE_COMPILES(
  "\#include <fstream>\nint main() { const wchar_t fn[10] = {}; std::ifstream is( fn ); std::wcerr << fn; return 0;}"
  GDCM_HAVE_WCHAR_IFSTREAM)