ensuring uniform #defines among all object files

Question

How can I ensure that all object files in my C++ project were compiled with the same conditional defines? Ie if they were not, I want to ensure a linker error pointing to the conflicting define. I want this to happen even with aggressive dead-code elimination by the compiler. Is there a known technique for this?

Answer 1

You can't; individual invocations of the compiler are just that - independent. The only way you can ensure this result is to have a single common source of all of the definitions, whether that's a command line specified in your makefile or a common header file, for example.