>>9
Compile-time asserts:
C11: https://en.cppreference.com/w/c/language/_Static_assert
C99: #define STATIC_ASSERT(COND,MSG) typedef char static_assertion_##MSG[(COND)?1:-1]
what is "macros with loops"? If you mean recursion,recursive macros
can be used with void.h for up to 1023 iterations per macros.
(gcc supports 65535 macros arguments, but this will be much slower )
https://github.com/FrozenVoid/C-headers