BUG: handle nonexistent="shift_forward" with normalize=True in date_range (GH#62602)

doc/source/whatsnew/v3.0.0.rst

@@ -983,6 +983,7 @@ Timedelta
 
 Timezones
 ^^^^^^^^^
+- Bug in :func:`pandas.date_range` where using ``normalize=True`` could raise ``NonExistentTimeError`` or ``AmbiguousTimeError`` when crossing DST transitions, even if ``nonexistent`` or ``ambiguous`` parameters were specified. (:issue:`62602`)
 - Bug in :meth:`DatetimeIndex.union`, :meth:`DatetimeIndex.intersection`, and :meth:`DatetimeIndex.symmetric_difference` changing timezone to UTC when merging two DatetimeIndex objects with the same timezone but different units (:issue:`60080`)
 - Bug in :meth:`Series.dt.tz_localize` with a timezone-aware :class:`ArrowDtype` incorrectly converting to UTC when ``tz=None`` (:issue:`61780`)
 - Fixed bug in :func:`date_range` where tz-aware endpoints with calendar offsets (e.g. ``"MS"``) failed on DST fall-back. These now respect ``ambiguous``/ ``nonexistent``. (:issue:`52908`)

pandas/_libs/tslibs/timestamps.pyi

@@ -191,7 +191,11 @@ class Timestamp(datetime):
         ambiguous: bool | Literal["raise", "NaT"] = ...,
         nonexistent: TimestampNonexistent = ...,
     ) -> Self: ...
-    def normalize(self) -> Self: ...
+    def normalize(
+        self,
+        ambiguous: bool | Literal["raise", "NaT"] = ...,
+        nonexistent: TimestampNonexistent = ...,
+    ) -> Self: ...
     # TODO: round/floor/ceil could return NaT?
     def round(
         self,

pandas/_libs/tslibs/timestamps.pyx

@@ -1308,7 +1308,7 @@ cdef class _Timestamp(ABCTimestamp):
     # -----------------------------------------------------------------
     # Transformation Methods
 
-    def normalize(self) -> "Timestamp":
+    def normalize(self, ambiguous="raise", nonexistent="raise") -> "Timestamp":
         """
         Normalize Timestamp to midnight, preserving tz information.
 
@@ -1346,7 +1346,7 @@ cdef class _Timestamp(ABCTimestamp):
                 "Cannot normalize Timestamp without integer overflow"
             ) from err
         ts = type(self)._from_value_and_reso(normalized, reso=self._creso, tz=None)
-        return ts.tz_localize(self.tzinfo)
+        return ts.tz_localize(self.tzinfo, ambiguous=ambiguous, nonexistent=nonexistent)
 
     # -----------------------------------------------------------------
     # Pickle Methods

pandas/core/arrays/datetimes.py

@@ -447,7 +447,9 @@ def _generate_range(
             end = end.as_unit(unit, round_ok=False)
 
         left_inclusive, right_inclusive = validate_inclusive(inclusive)
-        start, end = _maybe_normalize_endpoints(start, end, normalize)
+        start, end = _maybe_normalize_endpoints(
+            start, end, normalize, ambiguous, nonexistent
+        )
         tz = _infer_tz_from_endpoints(start, end, tz)
 
         if tz is not None:
@@ -466,6 +468,10 @@ def _generate_range(
                 if end is not None and end.tz is not None:
                     end = end.tz_localize(None)
 
+                start, end = _maybe_normalize_endpoints(
+                    start, end, normalize, ambiguous, nonexistent
+                )
+
             if isinstance(freq, (Tick, Day)):
                 i8values = generate_regular_range(start, end, periods, freq, unit=unit)
             else:
@@ -2878,14 +2884,18 @@ def _infer_tz_from_endpoints(
 
 
 def _maybe_normalize_endpoints(
-    start: _TimestampNoneT1, end: _TimestampNoneT2, normalize: bool
+    start: _TimestampNoneT1,
+    end: _TimestampNoneT2,
+    normalize: bool,
+    ambiguous: TimeAmbiguous = "raise",
+    nonexistent: TimeNonexistent = "raise",
 ) -> tuple[_TimestampNoneT1, _TimestampNoneT2]:
     if normalize:
         if start is not None:
-            start = start.normalize()
+            start = start.normalize(ambiguous, nonexistent)
 
         if end is not None:
-            end = end.normalize()
+            end = end.normalize(ambiguous, nonexistent)
 
     return start, end
 

pandas/tests/arrays/test_datetimes.py

@@ -832,6 +832,28 @@ def test_date_range_uppercase_frequency_raises(self, freq):
         with pytest.raises(ValueError, match=msg):
             pd.date_range("1/1/2000", periods=4, freq=freq)
 
+    def test_date_range_normalize_nonexistent_ambiguous_dst(self):
+        # GH#62602: Ensure normalize works with nonexistent/ambiguous times (DST)
+        tz = "Africa/Cairo"
+        start = pd.Timestamp("2024-04-26 01:00:00", tz=tz)
+        end = pd.Timestamp("2024-04-27 00:00:00", tz=tz)
+
+        result = pd.date_range(
+            start=start,
+            end=end,
+            freq="D",
+            tz=tz,
+            nonexistent="shift_forward",
+            ambiguous=True,
+            normalize=True,
+        )
+
+        expected = pd.to_datetime(
+            ["2024-04-26 01:00:00", "2024-04-27 00:00:00"], unit="ns"
+        ).tz_localize(tz)
+
+        tm.assert_index_equal(result, expected)
+
 
 def test_factorize_sort_without_freq():
     dta = DatetimeArray._from_sequence([0, 2, 1], dtype="M8[ns]")