I was pondering how to event or at least warn users when they use a .a compiled with a set of define with an application compiled with divergent options (like having different -D that may cause ODR violation). On IRC, I was linked to this page for MSVC 10: http://msdn.microsoft.com/en-us/library/ee956429.aspx That defiens some pragma that exactly do that. However, it's MSVC 10 specific. After a few brainstorming, we ended up with a simple solution to emulate this. The code source is here: http://dl.dropbox.com/u/3819406/lib_check.tar.gz Here is a use case: g++ -c foo.cpp -o foo.o -I/usr/local/include/boost-1_43 -DGOOD_LIB g++ -c main.cpp -o bmain.o -I/usr/local/include/boost-1_43 -DBAD_LIB -I./ g++ -c main.cpp -o gmain.o -I/usr/local/include/boost-1_43 -DGOOD_LIB -I./ Here, we compiel foo with some settings and try to link it with two different setup for main.o The gcc output, showing the divergence in option is detected: g++ bmain.o foo.o -o bmain bmain.o: In function `__static_initialization_and_destruction_0(int, int)': main.cpp:(.text+0x2a): undefined reference to `boost::config::test_library_version_mismatch_with_version_being_2()' collect2: ld returned 1 exit status Of course, when you link the good pair of .o : g++ gmain.o foo.o -o gmain Nothing happens I guess some details need to be hammered out like visibility and such but could this be a valuable addition to boost (liek boost config for example) or have I overengineered something useless ? Regards