BUG: Add void field at end of dtype.descr to match itemsize

seberg · jaimefrio · commit f52359b467b9 · 2016-03-15T08:21:25.000+01:00
dtype.descr returns void fields to explain the padding part of the dtype. The last void field for the itemsize itself was however not included. Closes numpygh-6359
diff --git a/numpy/core/_internal.py b/numpy/core/_internal.py
@@ -121,6 +121,10 @@ def _array_descr(descriptor):
         offset += field[0].itemsize
         result.append(tup)
 
+    if descriptor.itemsize > offset:
+        num = descriptor.itemsize - offset
+        result.append(('', '|V%d' % num))
+
     return result
 
 # Build a new array from the information in a pickle.
diff --git a/numpy/core/tests/test_dtype.py b/numpy/core/tests/test_dtype.py
@@ -535,7 +535,7 @@ def test_empty_string_to_object(self):
         # Pull request #4722
         np.array(["", ""]).astype(object)
 
-class TestDtypeAttributeDeletion(object):
+class TestDtypeAttributeDeletion(TestCase):
 
     def test_dtype_non_writable_attributes_deletion(self):
         dt = np.dtype(np.double)
@@ -552,6 +552,19 @@ def test_dtype_writable_attributes_deletion(self):
         for s in attr:
             assert_raises(AttributeError, delattr, dt, s)
 
+
+class TestDtypeAttributes(TestCase):
+    def test_descr_has_trailing_void(self):
+        # see gh-6359
+        dtype = np.dtype({
+            'names': ['A', 'B'],
+            'formats': ['f4', 'f4'],
+            'offsets': [0, 8],
+            'itemsize': 16})
+        new_dtype = np.dtype(dtype.descr)
+        assert_equal(new_dtype.itemsize, 16)
+
+
 class TestDtypeAttributes(TestCase):
 
     def test_name_builtin(self):
