REGR: fix calling numpy bitwise ufunc with Index objects

doc/source/whatsnew/v1.4.4.rst

@@ -16,6 +16,7 @@ Fixed regressions
 ~~~~~~~~~~~~~~~~~
 - Fixed regression in taking NULL :class:`objects` from a :class:`DataFrame` causing a segmentation violation. These NULL values are created by :meth:`numpy.empty_like` (:issue:`46848`)
 - Fixed regression in :func:`concat` materializing :class:`Index` during sorting even if :class:`Index` was already sorted (:issue:`47501`)
+- Fixed regression in calling bitwise numpy ufuncs (for example, ``np.bitwise_and``) on Index objects (:issue:`46769`)
 - Fixed regression in :meth:`DataFrame.loc` not updating the cache correctly after values were set (:issue:`47867`)
 - Fixed regression in :meth:`DataFrame.loc` not aligning index in some cases when setting a :class:`DataFrame` (:issue:`47578`)
 - Fixed regression in setting ``None`` or non-string value into a ``string``-dtype Series using a mask (:issue:`47628`)

pandas/_libs/ops_dispatch.pyx

@@ -15,13 +15,22 @@ DISPATCHED_UFUNCS = {
     "ge",
     "remainder",
     "matmul",
-    "or",
-    "xor",
-    "and",
+    # those three are currently set operations, not logical operations, for the
+    # Index dunder method (but this is deprecated)
+    # TODO(2.0) this can be uncommented (and DISPATCHED_UFUNCS_NO_INDEX removed)
+    # once deprecation is enforced in 2.0
+    # "or",
+    # "xor",
+    # "and",
     "neg",
     "pos",
     "abs",
 }
+DISPATCHED_UFUNCS_NO_INDEX = {
+    "or",
+    "xor",
+    "and",
+}
 UNARY_UFUNCS = {
     "neg",
     "pos",
@@ -61,7 +70,7 @@ REVERSED_NAMES = {
 
 
 def maybe_dispatch_ufunc_to_dunder_op(
-    object self, object ufunc, str method, *inputs, **kwargs
+    object self, object ufunc, str method, *inputs, bint _no_index=True, **kwargs
 ):
     """
     Dispatch a ufunc to the equivalent dunder method.
@@ -94,7 +103,11 @@ def maybe_dispatch_ufunc_to_dunder_op(
     if kwargs or ufunc.nin > 2:
         return NotImplemented
 
-    if method == "__call__" and op_name in DISPATCHED_UFUNCS:
+    if method == "__call__" and (
+        op_name in DISPATCHED_UFUNCS or (
+            _no_index and op_name in DISPATCHED_UFUNCS_NO_INDEX
+        )
+    ):
 
         if inputs[0] is self:
             name = f"__{op_name}__"

pandas/core/indexes/base.py

@@ -940,7 +940,7 @@ def __array_ufunc__(self, ufunc: np.ufunc, method: str_t, *inputs, **kwargs):
             return NotImplemented
 
         result = arraylike.maybe_dispatch_ufunc_to_dunder_op(
-            self, ufunc, method, *inputs, **kwargs
+            self, ufunc, method, *inputs, _no_index=False, **kwargs
         )
         if result is not NotImplemented:
             return result

pandas/tests/indexes/test_numpy_compat.py

@@ -178,3 +178,16 @@ def test_numpy_ufuncs_reductions(index, func, request):
         assert isna(expected)
     else:
         assert result == expected
+
+
+@pytest.mark.parametrize("func", [np.bitwise_and, np.bitwise_or, np.bitwise_xor])
+def test_numpy_ufuncs_bitwise(func):
+    # https://github.com/pandas-dev/pandas/issues/46769
+    idx1 = Index([1, 2, 3, 4], dtype="int64")
+    idx2 = Index([3, 4, 5, 6], dtype="int64")
+
+    with tm.assert_produces_warning(None):
+        result = func(idx1, idx2)
+
+    expected = Index(func(idx1.values, idx2.values))
+    tm.assert_index_equal(result, expected)