BUG: Make dtype.descr error for out-of-order fields. (#10562)

charris · web-flow · commit e651b502bc0b · 2018-02-09T14:39:31.000-07:00
* BUG: Instead of returning garbage, make dtype.descr error for out-of-order fields

* MAINT: Fixup test for descr failure for out-of-order field

* typo
diff --git a/numpy/core/_internal.py b/numpy/core/_internal.py
@@ -110,6 +110,10 @@ def _array_descr(descriptor):
             num = field[1] - offset
             result.append(('', '|V%d' % num))
             offset += num
+        elif field[1] < offset:
+            raise ValueError(
+                "dtype.descr is not defined for types with overlapping or "
+                "out-of-order fields")
         if len(field) > 3:
             name = (field[2], field[3])
         else:
diff --git a/numpy/core/tests/test_records.py b/numpy/core/tests/test_records.py
@@ -355,6 +355,13 @@ def test_nonwriteable_setfield(self):
         with assert_raises(ValueError):
             r.setfield([2,3], *r.dtype.fields['f'])
 
+    def test_out_of_order_fields(self):
+        dt = np.dtype({'names': ['a', 'b'],
+                    'formats': ['i4', 'i4'],
+                    'offsets': [4, 0]})
+        y = np.rec.fromrecords([(1, 2), (4, 5)], dtype=dt)
+        assert_raises(ValueError, lambda: y.dtype.descr)
+
     def test_pickle_1(self):
         # Issue #1529
         a = np.array([(1, [])], dtype=[('a', np.int32), ('b', np.int32, 0)])
