Function tryfuncTM

Source/Misc/lua/src/lua.c:5389–5401

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;
}