Ok, so you have a group of external headers that do evil things like #define uint64_t. Here's what I do in cases like this. 

//evil_prefix.h:

// Note: this file intentionally has no include guards.

#include "evil/a.h" // #defines uint64_t

#if !defined(uint64_t)

// these are the 3 offending lines copied from "evli/a.h":

#endif // uint64_t

//evli_suffix.h:

Armed with the above two header files, in all your files _always_ include all evil headers between the prefix and suffix includes:

#include "evil_prefix.h"

#include "evil/a.h"

#include "evil/b.h"

...

#include "evil_suffix.h"

If you follow the above rule, you can then include your files anywhere in any order, and nothing should explode any more.

Regards,

Kris