C struct initialization in C++

init.cpp

#include <cstdio>
#include <cstdlib>

#define INIT_OPEN(type) [] { type _;
#define INIT_CLOSE ; return _; }()
#define INIT(type, body) INIT_OPEN(type) body INIT_CLOSE

struct A {
	int i;
};

#define A(body) INIT(A, body)

static const A g_a = A( _.i = 420 );

int main() {
	A a = A( _.i = rand() );
	printf("%d\n", a.i);
}