Merge pull request #6780 from ahaldane/preserve_metadata

BUG: metadata is not copied to base_dtype

2 files changed, 12 insertions, 0 deletions

diff --git a/numpy/core/src/multiarray/descriptor.c b/numpy/core/src/multiarray/descriptor.c
index 83cd64bdc..03a4654a0 100644
--- a/numpy/core/src/multiarray/descriptor.c
+++ b/numpy/core/src/multiarray/descriptor.c
@@ -806,11 +806,19 @@ _use_inherit(PyArray_Descr *type, PyObject *newobj, int *errflag)
     }
     new->elsize = conv->elsize;
     if (PyDataType_HASFIELDS(conv)) {
+        Py_XDECREF(new->fields);
         new->fields = conv->fields;
         Py_XINCREF(new->fields);
+
+        Py_XDECREF(new->names);
         new->names = conv->names;
         Py_XINCREF(new->names);
     }
+    if (conv->metadata != NULL) {
+        Py_XDECREF(new->metadata);
+        new->metadata = conv->metadata;
+        Py_XINCREF(new->metadata);
+    }
     new->flags = conv->flags;
     Py_DECREF(conv);
     *errflag = 0;
diff --git a/numpy/core/tests/test_dtype.py b/numpy/core/tests/test_dtype.py
index 29f2ee7bd..6d898eaa1 100644
--- a/numpy/core/tests/test_dtype.py
+++ b/numpy/core/tests/test_dtype.py
@@ -408,6 +408,10 @@ class TestMetadata(TestCase):
         d = np.dtype([('a', np.dtype(int, metadata={'datum': 1}))])
         self.assertEqual(d['a'].metadata, {'datum': 1})
 
+    def base_metadata_copied(self):
+        d = np.dtype((np.void, np.dtype('i4,i4', metadata={'datum': 1})))
+        assert_equal(d.metadata, {'datum': 1})
+
 class TestString(TestCase):
     def test_complex_dtype_str(self):
         dt = np.dtype([('top', [('tiles', ('>f4', (64, 64)), (1,)),