BUG+DEPR: Timestamp.fromtimestamp tz arg (#45083)

Author: jbrockmendel

doc/source/whatsnew/v1.4.0.rst

@@ -609,6 +609,7 @@ Other Deprecations
 - Deprecated :meth:`Index.__getitem__` with a bool key; use ``index.values[key]`` to get the old behavior (:issue:`44051`)
 - Deprecated downcasting column-by-column in :meth:`DataFrame.where` with integer-dtypes (:issue:`44597`)
 - Deprecated ``numeric_only=None`` in :meth:`DataFrame.rank`; in a future version ``numeric_only`` must be either ``True`` or ``False`` (the default) (:issue:`45036`)
+- Deprecated the behavior of :meth:`Timestamp.utcfromtimestamp`, in the future it will return a timezone-aware UTC :class:`Timestamp` (:issue:`22451`)
 - Deprecated :meth:`NaT.freq` (:issue:`45071`)
 -
 
@@ -701,6 +702,7 @@ Datetimelike
 - Bug in :meth:`Index.insert` for inserting ``np.datetime64``, ``np.timedelta64`` or ``tuple`` into :class:`Index` with ``dtype='object'`` with negative loc adding ``None`` and replacing existing value (:issue:`44509`)
 - Bug in :meth:`Series.mode` with ``DatetimeTZDtype`` incorrectly returning timezone-naive and ``PeriodDtype`` incorrectly raising (:issue:`41927`)
 - Bug in :class:`DateOffset`` addition with :class:`Timestamp` where ``offset.nanoseconds`` would not be included in the result (:issue:`43968`, :issue:`36589`)
+- Bug in :meth:`Timestamp.fromtimestamp` not supporting the ``tz`` argument (:issue:`45083`)
 -
 
 Timedelta

pandas/_libs/tslibs/timestamps.pyx

@@ -1164,10 +1164,20 @@ class Timestamp(_Timestamp):
         >>> pd.Timestamp.utcfromtimestamp(1584199972)
         Timestamp('2020-03-14 15:32:52')
         """
+        # GH#22451
+        warnings.warn(
+            "The behavior of Timestamp.utcfromtimestamp is deprecated, in a "
+            "future version will return a timezone-aware Timestamp with UTC "
+            "timezone. To keep the old behavior, use "
+            "Timestamp.utcfromtimestamp(ts).tz_localize(None). "
+            "To get the future behavior, use Timestamp.fromtimestamp(ts, 'UTC')",
+            FutureWarning,
+            stacklevel=1,
+        )
         return cls(datetime.utcfromtimestamp(ts))
 
     @classmethod
-    def fromtimestamp(cls, ts):
+    def fromtimestamp(cls, ts, tz=None):
         """
         Timestamp.fromtimestamp(ts)
 
@@ -1180,7 +1190,8 @@ class Timestamp(_Timestamp):
 
         Note that the output may change depending on your local time.
         """
-        return cls(datetime.fromtimestamp(ts))
+        tz = maybe_get_tz(tz)
+        return cls(datetime.fromtimestamp(ts, tz))
 
     def strftime(self, format):
         """

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -292,13 +292,27 @@ def compare(x, y):
         compare(Timestamp.utcnow(), datetime.utcnow())
         compare(Timestamp.today(), datetime.today())
         current_time = calendar.timegm(datetime.now().utctimetuple())
+        msg = "timezone-aware Timestamp with UTC"
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            # GH#22451
+            ts_utc = Timestamp.utcfromtimestamp(current_time)
         compare(
-            Timestamp.utcfromtimestamp(current_time),
+            ts_utc,
             datetime.utcfromtimestamp(current_time),
         )
         compare(
             Timestamp.fromtimestamp(current_time), datetime.fromtimestamp(current_time)
         )
+        compare(
+            # Support tz kwarg in Timestamp.fromtimestamp
+            Timestamp.fromtimestamp(current_time, "UTC"),
+            datetime.fromtimestamp(current_time, utc),
+        )
+        compare(
+            # Support tz kwarg in Timestamp.fromtimestamp
+            Timestamp.fromtimestamp(current_time, tz="UTC"),
+            datetime.fromtimestamp(current_time, utc),
+        )
 
         date_component = datetime.utcnow()
         time_component = (date_component + timedelta(minutes=10)).time()
@@ -322,8 +336,14 @@ def compare(x, y):
         compare(Timestamp.utcnow(), datetime.utcnow())
         compare(Timestamp.today(), datetime.today())
         current_time = calendar.timegm(datetime.now().utctimetuple())
+
+        msg = "timezone-aware Timestamp with UTC"
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            # GH#22451
+            ts_utc = Timestamp.utcfromtimestamp(current_time)
+
         compare(
-            Timestamp.utcfromtimestamp(current_time),
+            ts_utc,
             datetime.utcfromtimestamp(current_time),
         )
         compare(