Merge pull request #10068 from seberg/issue-10066

BUG: Fix memory leak for subclass slicing

2 files changed, 56 insertions, 4 deletions

diff --git a/numpy/core/src/multiarray/methods.c b/numpy/core/src/multiarray/methods.c
index 3f461b375..2c958989f 100644
--- a/numpy/core/src/multiarray/methods.c
+++ b/numpy/core/src/multiarray/methods.c
@@ -2452,7 +2452,7 @@ array_complex(PyArrayObject *self, PyObject *NPY_UNUSED(args))
 static PyObject *
 array_getslice(PyArrayObject *self, PyObject *args)
 {
-    PyObject *start, *stop, *slice;
+    PyObject *start, *stop, *slice, *result;
     if (!PyArg_ParseTuple(args, "OO:__getslice__", &start, &stop)) {
         return NULL;
     }
@@ -2463,7 +2463,9 @@ array_getslice(PyArrayObject *self, PyObject *args)
     }
 
     /* Deliberately delegate to subclasses */
-    return PyObject_GetItem((PyObject *)self, slice);
+    result = PyObject_GetItem((PyObject *)self, slice);
+    Py_DECREF(slice);
+    return result;
 }
 
 static PyObject *
@@ -2481,9 +2483,10 @@ array_setslice(PyArrayObject *self, PyObject *args)
 
     /* Deliberately delegate to subclasses */
     if (PyObject_SetItem((PyObject *)self, slice, value) < 0) {
+        Py_DECREF(slice);
         return NULL;
     }
-
+    Py_DECREF(slice);
     Py_RETURN_NONE;
 }
 
diff --git a/numpy/core/tests/test_indexing.py b/numpy/core/tests/test_indexing.py
index 7cfb81da7..df9eca627 100644
--- a/numpy/core/tests/test_indexing.py
+++ b/numpy/core/tests/test_indexing.py
@@ -10,7 +10,7 @@ from numpy.core.multiarray_tests import array_indexing
 from itertools import product
 from numpy.testing import (
     run_module_suite, assert_, assert_equal, assert_raises,
-    assert_array_equal, assert_warns, HAS_REFCOUNT
+    assert_array_equal, assert_warns, dec, HAS_REFCOUNT, suppress_warnings,
 )
 
 
@@ -622,6 +622,55 @@ class TestSubclasses(object):
         assert_array_equal(new_s.finalize_status, new_s)
         assert_array_equal(new_s.old, s)
 
+    @dec.skipif(not HAS_REFCOUNT)
+    def test_slice_decref_getsetslice(self):
+        # See gh-10066, a temporary slice object should be discarted.
+        # This test is only really interesting on Python 2 since
+        # it goes through `__set/getslice__` here and can probably be
+        # removed. Use 0:7 to make sure it is never None:7.
+        class KeepIndexObject(np.ndarray):
+            def __getitem__(self, indx):
+                self.indx = indx
+                if indx == slice(0, 7):
+                    raise ValueError
+
+            def __setitem__(self, indx, val):
+                self.indx = indx
+                if indx == slice(0, 4):
+                    raise ValueError
+
+        k = np.array([1]).view(KeepIndexObject)
+        k[0:5]
+        assert_equal(k.indx, slice(0, 5))
+        assert_equal(sys.getrefcount(k.indx), 2)
+        try:
+            k[0:7]
+            raise AssertionError
+        except ValueError:
+            # The exception holds a reference to the slice so clear on Py2
+            if hasattr(sys, 'exc_clear'):
+                with suppress_warnings() as sup:
+                    sup.filter(DeprecationWarning)
+                    sys.exc_clear()
+        assert_equal(k.indx, slice(0, 7))
+        assert_equal(sys.getrefcount(k.indx), 2)
+
+        k[0:3] = 6
+        assert_equal(k.indx, slice(0, 3))
+        assert_equal(sys.getrefcount(k.indx), 2)
+        try:
+            k[0:4] = 2
+            raise AssertionError
+        except ValueError:
+            # The exception holds a reference to the slice so clear on Py2
+            if hasattr(sys, 'exc_clear'):
+                with suppress_warnings() as sup:
+                    sup.filter(DeprecationWarning)
+                    sys.exc_clear()
+        assert_equal(k.indx, slice(0, 4))
+        assert_equal(sys.getrefcount(k.indx), 2)
+
+
 class TestFancyIndexingCast(object):
     def test_boolean_index_cast_assign(self):
         # Setup the boolean index and float arrays.