Function isinstack

extlibs/lua/src/ldebug.c:656–660

** The subtraction of two potentially unrelated pointers is ** not ISO C, but it should not crash a program; the subsequent ** checks are ISO C and ensure a correct result. */

** checks are ISO C and ensure a correct result.
*/
static int isinstack (CallInfo *ci, const TValue *o) {
  StkId base = ci->func + 1;
  ptrdiff_t i = cast(StkId, o) - base;
  return (0 <= i && i < (ci->top - base) && s2v(base + i) == o);
}


/*