How to initialize const members of structs on the heap

Like so:

ImmutablePoint *make_immutable_point(int x, int y)
{
  ImmutablePoint init = { .x = x, .y = y };
  ImmutablePoint *p = malloc(sizeof *p);

  if (p == NULL) abort();
  memcpy(p, &init, sizeof *p);

  return p;
}

(Note that unlike C++, there is no need to cast the return value of malloc in C, and it is often considered bad form because it can hide other errors).