[thradams]

auto, typeof, _Generic are implemented in cake. Sometimes when they are used inside macros the macros needs to be expanded. Then cake has #pragma expand MACRO. for this task.

Sample macro NEW using c23 typeof.

    #include <stdlib.h>
    #include <string.h>

    static inline void* allocate_and_copy(void* s, size_t n) {
        void* p = malloc(n);
        if (p) {
            memcpy(p, s, n);
        }
        return p;
    }

    #define NEW(...) (typeof(__VA_ARGS__)*) allocate_and_copy(&(__VA_ARGS__), sizeof(__VA_ARGS__))
    #pragma expand NEW

    struct X {
        const int i;
    };

    int main() { 
        auto p = NEW((struct X) {});     
    }

The generated code is

    #include <stdlib.h>
    #include <string.h>

    static inline void* allocate_and_copy(void* s, size_t n) {
        void* p = malloc(n);
        if (p) {
            memcpy(p, s, n);
        }
        return p;
    }

    #define NEW(...) (typeof(__VA_ARGS__)*) allocate_and_copy(&(__VA_ARGS__), sizeof(__VA_ARGS__))
    #pragma expand NEW

    struct X {
        const int i;
    };

    int main() { 
        struct X  * p =  (struct X*) allocate_and_copy(&((struct X) {0}), sizeof((struct X) {0}));     
    }