Function tryfuncTM

deps/lua/src/ldo.c:244–256

static StkId tryfuncTM (lua_State *L, StkId func) {
  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
  StkId p;
  ptrdiff_t funcr = savestack(L, func);
  if (!ttisfunction(tm))
    luaG_typeerror(L, func, "call");
  /* Open a hole inside the stack at `func' */
  for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
  incr_top(L);
  func = restorestack(L, funcr);  /* previous call may change stack */
  setobj2s(L, func, tm);  /* tag method is the new function to be called */
  return func;
}