builtin.c:1891:35: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
        static const time_t time_t_min = TYPE_MINIMUM(time_t);
                                         ^~~~~~~~~~~~~~~~~~~~
builtin.c:48:20: note: expanded from macro 'TYPE_MINIMUM'
                              ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
                                ~~~~~~~ ^
builtin.c:1892:35: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
        static const time_t time_t_max = TYPE_MAXIMUM(time_t);
                                         ^~~~~~~~~~~~~~~~~~~~
builtin.c:49:41: note: expanded from macro 'TYPE_MAXIMUM'
#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
                                        ^~~~~~~~~~~~~~~~
builtin.c:48:20: note: expanded from macro 'TYPE_MINIMUM'
                              ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
                                ~~~~~~~ ^
2 warnings generated.