Doxygen preprocessing: #ifdef doesn't work in complex inclusion

[Yaroslav]

In C pseudo code below b and c variables will be documented by doxygen, but a - will not. But as we know, this code will be work, because second.h will be included before first.h

first.h

..    
#define MY_MACRO
..

second.h

..
#ifdef MY_MACRO
int a;
#endif
..

all.h

#include first.h
..
#include second.h
..
#ifdef MY_MACRO
int b;
#endif

all.c

#include all.h
..
#ifdef MY_MACRO
int c;
#endif

Is it possible to solve this problem, given that the C project is complex and contains a lot of such cases. (it will be work if second.h will #include first.h, but it seems that this is not the best idea, because there is a lot of files such as first.h and such as second.h too and a lot of dependencies)

[Yaroslav]

in attachment well known project - grbl (ported to stm32) and doxygen config file