bpo-33812: Corrected astimezone for naive datetimes. (GH-7578)

A datetime object d is aware if d.tzinfo is not None and
d.tzinfo.utcoffset(d) does  not return None. If d.tzinfo is None,
or if d.tzinfo is not None but d.tzinfo.utcoffset(d) returns None,
 d is naive.

This commit ensures that instances with non-None d.tzinfo, but
d.tzinfo.utcoffset(d) returning None are treated as naive.

In addition, C acceleration code will raise TypeError if
d.tzinfo.utcoffset(d) returns an object with the type other than
timedelta.

* Updated the documentation.

Assume that the term "naive" is defined elsewhere and remove the
not entirely correct clarification.  Thanks, Tim.

1 files changed, 11 insertions, 0 deletions

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index cc7eee6fd7..31aa88d4a2 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -5576,6 +5576,7 @@ datetime_astimezone(PyDateTime_DateTime *self, PyObject *args, PyObject *kw)
         return NULL;
 
     if (!HASTZINFO(self) || self->tzinfo == Py_None) {
+  naive:
         self_tzinfo = local_timezone_from_local(self);
         if (self_tzinfo == NULL)
             return NULL;
@@ -5596,6 +5597,16 @@ datetime_astimezone(PyDateTime_DateTime *self, PyObject *args, PyObject *kw)
     Py_DECREF(self_tzinfo);
     if (offset == NULL)
         return NULL;
+    else if(offset == Py_None) {
+        Py_DECREF(offset);
+        goto naive;
+    }
+    else if (!PyDelta_Check(offset)) {
+        Py_DECREF(offset);
+        PyErr_Format(PyExc_TypeError, "utcoffset() returned %.200s,"
+                     " expected timedelta or None", Py_TYPE(offset)->tp_name);
+        return NULL;
+    }
     /* result = self - offset */
     result = (PyDateTime_DateTime *)add_datetime_timedelta(self,
                                        (PyDateTime_Delta *)offset, -1);