annotate, make None explicit

pandas/_libs/tslibs/timedeltas.pyi

@@ -146,3 +146,7 @@ class Timedelta(timedelta):
     def __hash__(self) -> int: ...
     def isoformat(self) -> str: ...
     def to_numpy(self) -> np.timedelta64: ...
+    @property
+    def freq(self) -> None: ...
+    @property
+    def is_populated(self) -> bool: ...

pandas/_libs/tslibs/timedeltas.pyx

@@ -833,16 +833,17 @@ cdef class _Timedelta(timedelta):
     __array_priority__ = 100
 
     @property
-    def freq(self):
+    def freq(self) -> None:
         # GH#46430
         warnings.warn(
             "Timedelta.freq is deprecated and will be removed in a future version",
             FutureWarning,
             stacklevel=1,
         )
+        return None
 
     @property
-    def is_populated(self):
+    def is_populated(self) -> bool:
         # GH#46430
         warnings.warn(
             "Timedelta.is_populated is deprecated and will be removed in a future version",

pandas/tests/scalar/timedelta/test_timedelta.py

@@ -665,7 +665,9 @@ def test_freq_deprecated():
     # GH#46430
     td = Timedelta(123456546, unit="ns")
     with tm.assert_produces_warning(FutureWarning, match="Timedelta.freq"):
-        td.freq
+        freq = td.freq
+
+    assert freq is None
 
     with pytest.raises(AttributeError, match="is not writable"):
         td.freq = offsets.Day()