This detects differing structure layouts between compilation units which is simple to do given some metadata in the object files. On the other hand it also shows why detecting ODR violations for executable code is non-trivial, because same source code compiled with different compiler flags can lead to different output that might or might not be compatible (enforcing same compiler configuration for all compilation units is certainly non-starter, think JS runtime vs. FFmpeg, 3D renderer vs. physics simulation...).
