BUG: Fix default fallback in genfromtxt

This affected (for example?) if the `dtype=object` was used
without a converter, meaning that the default one is used.
And this is currently the last one, which is `string_` (and thus
bytes).

Closes gh-16189

1 files changed, 5 insertions, 3 deletions

diff --git a/numpy/lib/_iotools.py b/numpy/lib/_iotools.py
index 84aff5e5d..ac5f4f9b4 100644
--- a/numpy/lib/_iotools.py
+++ b/numpy/lib/_iotools.py
@@ -506,13 +506,15 @@ class StringConverter:
     _mapper.extend([(nx.float64, float, nx.nan),
                     (nx.complex128, complex, nx.nan + 0j),
                     (nx.longdouble, nx.longdouble, nx.nan),
-                    (nx.unicode_, asunicode, '???'),
-                    (nx.string_, asbytes, '???'),
                     # If a non-default dtype is passed, fall back to generic
                     # ones (should only be used for the converter)
                     (nx.integer, int, -1),
                     (nx.floating, float, nx.nan),
-                    (nx.complexfloating, complex, nx.nan + 0j),])
+                    (nx.complexfloating, complex, nx.nan + 0j),
+                    # Last, try with the string types (must be last, because
+                    # `_mapper[-1]` is used as default in some cases)
+                    (nx.unicode_, asunicode, '???'),
+                    (nx.string_, asbytes, '???'),])
 
     @classmethod
     def _getdtype(cls, val):