BUG: Fix crash on genfromtxt with nested empty structured array

Previously this would fail with `ValueError: could not assign tuple of length 2 to structure with 3 fields.`, now it raises `NotImplementedError`.

1 files changed, 7 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_io.py b/numpy/lib/tests/test_io.py
index 7ef25538b..038d08acf 100644
--- a/numpy/lib/tests/test_io.py
+++ b/numpy/lib/tests/test_io.py
@@ -1517,6 +1517,13 @@ M   33  21.99
             test = np.genfromtxt(TextIO(data), delimiter=";",
                                  dtype=ndtype, converters=converters)
 
+        # nested but empty fields also aren't supported
+        ndtype = [('idx', int), ('code', object), ('nest', [])]
+        with assert_raises_regex(NotImplementedError,
+                                 'Nested fields.* not supported.*'):
+            test = np.genfromtxt(TextIO(data), delimiter=";",
+                                 dtype=ndtype, converters=converters)
+
     def test_userconverters_with_explicit_dtype(self):
         # Test user_converters w/ explicit (standard) dtype
         data = TextIO('skip,skip,2001-01-01,1.0,skip')