Add better MinGW support for IFCReaderGen big objects

code/CMakeLists.txt

@@ -463,9 +463,13 @@ ADD_ASSIMP_IMPORTER( IFC
   STEPFileEncoding.cpp
   STEPFileEncoding.h
 )
-if (MSVC AND ASSIMP_BUILD_IFC_IMPORTER)
-  set_source_files_properties(IFCReaderGen1.cpp IFCReaderGen2.cpp PROPERTIES COMPILE_FLAGS "/bigobj")
-endif (MSVC AND ASSIMP_BUILD_IFC_IMPORTER)
+if (ASSIMP_BUILD_IFC_IMPORTER)
+  if (MSVC)
+    set_source_files_properties(IFCReaderGen1.cpp IFCReaderGen2.cpp PROPERTIES COMPILE_FLAGS "/bigobj")
+  elseif(CMAKE_COMPILER_IS_MINGW)
+    set_source_files_properties(IFCReaderGen1.cpp IFCReaderGen2.cpp PROPERTIES COMPILE_FLAGS "-O2 -Wa,-mbig-obj")
+  endif()
+endif (ASSIMP_BUILD_IFC_IMPORTER)
 
 ADD_ASSIMP_IMPORTER( XGL
   XGLLoader.cpp