I've been testing this, and it works well for object files being linked into one application (and presumably for static libraries), but appears not to detect mismatches between an application and a DLL, which basically makes it next to useless... unless I'm missing something?
If you're using import libs, that *should* work.
I'm using import libraries - my test project is attached - no errors are generated even though they have hardcoded mismatched #pragma detect_mismatch's.
That doesn't work across PE images out of the box -- and arguably it's not necessarily a good idea to flag these mismatches as an error. So long as DLL & EXE have an interface that doesn't rely on STL constructs, there's no problem. Effectively, the #pragma detect_mismatch causes the corresponding /FAILIFMISMATCH linker option to be emitted in a .drectve section. When the linker encounters an object file it will process the contents of .drectve section as command line switches (there's some additional logic, some switches don't work in directive sections, others including /FAILIFMISMATCH only work in directive sections). In your case, the object files with the directives do not contribute to the same image. Hence link.exe won't complain. If your interface relies on STL constructs, you could add an object file to the import library, make sure it's linked in by the consuming side and so trigger validation. E.g. Lib_interface.hpp: // ... #pragma comment( linker, "/INCLUDE:_dll_impl_interface_mismatch_check") Then add an object file into your import lib (*not* the DLL) which has a public symbol with that name. You can add to an import lib, with the lib command. E.g.: extern "C" const char dll_impl_interface_mismatch_check=0; /* x86 is the only platform to add a leading underscore for C linkage names */ cl /c /Zl foo.cpp lib import.lib foo.obj Now on the consuming side, when a compilation unit sees a comment linker pragma it will emit the /INCLUDE switch in the object file's directive section. The linker will then resolve the symbol by selecting the object file from the hybrid import library. It will then process that object file's directive section which includes the /FAILIFMISMATCH switch, which in turn should trigger a linker error. dumpbin /DIRECTIVES shows linker options embedded in an object file dumpbin /LINKERMEMBER shows the archive symbol table of a .lib dumpbin /ARCHIVEMEMBERS shows object files (including the special import objects) in a .lib -hg