Support negative integer timestamps too; skip tests that would generate negative timestamps.

Author: jhohm

Lib/test/datetimetester.py

@@ -2730,6 +2730,7 @@ def test_timestamp_limits(self):
             # If that assumption changes, this value can change as well
             self.assertEqual(max_ts, 253402300799.0)
 
+    @unittest.skipIf(sys.platform == "win32", "Windows can't generate negative timestamps")
     def test_fromtimestamp_limits(self):
         try:
             self.theclass.fromtimestamp(-2**32 - 1)
@@ -2769,6 +2770,7 @@ def test_fromtimestamp_limits(self):
                     # OverflowError, especially on 32-bit platforms.
                     self.theclass.fromtimestamp(ts)
 
+    @unittest.skipIf(sys.platform == "win32", "Windows can't generate negative timestamps")
     def test_utcfromtimestamp_limits(self):
         with self.assertWarns(DeprecationWarning):
             try:

Modules/_datetimemodule.c

@@ -5548,23 +5548,19 @@ datetime_from_timestamp(PyObject *cls, TM_FUNC f, PyObject *timestamp,
     time_t timet;
     long us;
 
-#ifdef MS_WINDOWS
-    if (PyFloat_Check(timestamp) && PyFloat_AsDouble(timestamp) < 0) {
-      if (_PyTime_ObjectToTimeval(timestamp,
-				  &timet, &us, _PyTime_ROUND_HALF_EVEN) == -1)
-	return NULL;
+    if (_PyTime_ObjectToTimeval(timestamp,
+                                &timet, &us, _PyTime_ROUND_HALF_EVEN) == -1)
+        return NULL;
 
+#ifdef MS_WINDOWS
+    if (timet < 0) {
       int normalize = 1, factor = 1;
       PyObject *dt = datetime_from_timet_and_us(cls, f, 0, 0, tzinfo);
       PyObject *delta = new_delta(0, (int)timet, us, normalize);
       return add_datetime_timedelta(PyDateTime_CAST(dt), PyDelta_CAST(delta), factor);
     }
 #endif
 
-    if (_PyTime_ObjectToTimeval(timestamp,
-                                &timet, &us, _PyTime_ROUND_HALF_EVEN) == -1)
-        return NULL;
-
     return datetime_from_timet_and_us(cls, f, timet, (int)us, tzinfo);
 }