ARROW-15210: [Python] Pyarrow compute functions convert args with `__…

…arrow_array__`.

python/pyarrow/_compute.pyx

@@ -416,7 +416,8 @@ cdef class MetaFunction(Function):
 
 cdef _pack_compute_args(object values, vector[CDatum]* out):
     for val in values:
-        if isinstance(val, (list, np.ndarray)):
+        if isinstance(val, (list, np.ndarray)) or \
+                hasattr(val, '__arrow_array__'):
             val = lib.asarray(val)
 
         if isinstance(val, Array):

python/pyarrow/tests/test_compute.py

@@ -293,6 +293,15 @@ def test_input_type_conversion():
                     "foo").to_pylist() == [True, False, None]
 
 
+def test_input_array_conversion():
+    class convertible:
+        def __arrow_array__(self, type=None):
+            return pa.array(range(5), type)
+
+    assert pc.sum(np.arange(5)).as_py() == 10
+    assert pc.sum(convertible()).as_py() == 10
+
+
 @pytest.mark.parametrize('arrow_type', numerical_arrow_types)
 def test_sum_array(arrow_type):
     arr = pa.array([1, 2, 3, 4], type=arrow_type)