I have some code (the margin is too small to put it here) which gives :
./simulateur.c:2768: warning: dereferencing ‘void *’ pointer
./simulateur.c:2768: error: request for member ‘valeur__H2C’ in something not a structure or union
upon compilation (in fact, it's trying to do NULL->valeur__H2C...) without option, but compiles ok with -D.

I haven't been able to reproduce it on a small example, but I thought I could still report it : perhaps someone who knows the compiler better can have a good enough hint...