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

#define N 1
  
typedef struct _acme {
  int data;
} * acme;

int main(void) {
  acme gizmo[N];
  gizmo[0] = (acme)malloc(sizeof(struct _acme));
  size_t msize = malloc_usable_size(gizmo[0]);
  printf("malloc_usable_size(gizmo[0]) %lu\n", msize);
  free(gizmo[0]);
  return (1);
}