Fix normalize_fill_value for structured arrays (#1397)

* Add failing test case for normalize_fill_value

* Fix normalize_fill_value for structured arrays

* Add changelog

---------

Co-authored-by: Josh Moore <josh@openmicroscopy.org>

Author: alanhdu

docs/release.rst

@@ -52,6 +52,9 @@ Bug fixes
 * Fix ``ReadOnlyError`` when opening V3 store via fsspec reference file system.
   By :user:`Joe Hamman <jhamman>` :issue:`1383`.
 
+* Fix ``normalize_fill_value`` for structured arrays.
+  By :user:`Alan Du <alanhdu>` :issue:`1397`.
+
 .. _release_2.14.2:
 
 2.14.2

zarr/tests/test_util.py

@@ -119,6 +119,7 @@ def test_normalize_fill_value():
     structured_dtype = np.dtype([('foo', 'S3'), ('bar', 'i4'), ('baz', 'f8')])
     expect = np.array((b'', 0, 0.), dtype=structured_dtype)[()]
     assert expect == normalize_fill_value(0, dtype=structured_dtype)
+    assert expect == normalize_fill_value(expect, dtype=structured_dtype)
     assert '' == normalize_fill_value(0, dtype=np.dtype('U1'))
 
 

zarr/util.py

@@ -295,7 +295,7 @@ def normalize_fill_value(fill_value, dtype: np.dtype):
     if fill_value is None or dtype.hasobject:
         # no fill value
         pass
-    elif fill_value == 0:
+    elif not isinstance(fill_value, np.void) and fill_value == 0:
         # this should be compatible across numpy versions for any array type, including
         # structured arrays
         fill_value = np.zeros((), dtype=dtype)[()]