BUG: honor ambiguous/nonexistent for tz-aware endpoints in date_range

Author: floura-angel

pandas/core/arrays/datetimes.py

@@ -456,13 +456,14 @@ def _generate_range(
             end = _maybe_localize_point(end, freq, tz, ambiguous, nonexistent)
 
         if freq is not None:
-            # We break Day arithmetic (fixed 24 hour) here and opt for
-            # Day to mean calendar day (23/24/25 hour). Therefore, strip
-            # tz info from start and day to avoid DST arithmetic
-            if isinstance(freq, Day):
-                if start is not None:
+            # Offset handling:
+            # Ticks (fixed-duration like hours/minutes): keep tz; do absolute-time math.
+            # Other calendar offsets: drop tz; do naive wall time; localize once later
+            # so `ambiguous`/`nonexistent` are applied correctly.
+            if not isinstance(freq, Tick):
+                if start is not None and start.tz is not None:
                     start = start.tz_localize(None)
-                if end is not None:
+                if end is not None and end.tz is not None:
                     end = end.tz_localize(None)
 
             if isinstance(freq, (Tick, Day)):

pandas/tests/indexes/datetimes/test_date_range.py

@@ -1740,3 +1740,23 @@ def test_date_range_negative_freq_year_end_inbounds(self, unit):
             freq="-1YE",
         )
         tm.assert_index_equal(rng, exp)
+
+    def test_date_range_tzaware_endpoints_accept_ambiguous(self):
+        # With tz-aware endpoints and a calendar offset (MS),
+        # date_range should accept `ambiguous=True` and produce
+        # the same result as passing tz explicitly with naive endpoints.
+        start = Timestamp("1916-08-01", tz="Europe/Oslo")
+        end = Timestamp("1916-12-01", tz="Europe/Oslo")
+        res = date_range(start, end, freq="MS", ambiguous=True)
+        exp = date_range(
+            "1916-08-01", "1916-12-01", freq="MS", tz="Europe/Oslo", ambiguous=True
+        )
+        tm.assert_index_equal(res, exp)
+
+    def test_date_range_tzaware_endpoints_raise_ambiguous_raises_by_default(self):
+        # By default (`ambiguous="raise"`), an ambiguous DST transition
+        # should raise instead of guessing.
+        start = Timestamp("1916-08-01", tz="Europe/Oslo")
+        end = Timestamp("1916-12-01", tz="Europe/Oslo")
+        with pytest.raises(ValueError, match="Cannot infer dst time"):
+            date_range(start, end, freq="MS")