Regression in offsets caused offsets to be no longer hashable

doc/source/whatsnew/v1.1.4.rst

@@ -22,6 +22,7 @@ Fixed regressions
 - Fixed regression in :class:`RollingGroupby` causing a segmentation fault with Index of dtype object (:issue:`36727`)
 - Fixed regression in :meth:`DataFrame.resample(...).apply(...)` raised ``AttributeError`` when input was a :class:`DataFrame` and only a :class:`Series` was evaluated (:issue:`36951`)
 - Fixed regression in :class:`PeriodDtype` comparing both equal and unequal to its string representation (:issue:`37265`)
+- Fixed regression in :meth:`pd.offsets.Day() <pandas.tseries.offsets.Day>` and associated functions caused that offsets were no longer hashable (:issue:`37267`)
 
 .. ---------------------------------------------------------------------------
 

pandas/_libs/tslibs/offsets.pyx

@@ -752,6 +752,9 @@ cdef class Tick(SingleConstructorOffset):
                 "Tick offset with `normalize=True` are not allowed."
             )
 
+    def __hash__(self) -> int:
+        return hash(self._params)
+
     # FIXME: Without making this cpdef, we get AttributeError when calling
     #  from __mul__
     cpdef Tick _next_higher_resolution(Tick self):

pandas/tests/tseries/offsets/test_ticks.py

@@ -369,3 +369,8 @@ def test_compare_ticks_to_timedeltalike(cls):
         assert not off > other
         assert off <= other
         assert off >= other
+
+
+def test_offsets_hashable():
+    # GH: 37267
+    assert offsets.Day() is not None