From 79eff02e7e2c3b1865ee47fa66ae40f44894cadb Mon Sep 17 00:00:00 2001
From: Sha Liu <liushapku@users.noreply.github.com>
Date: Tue, 28 Jan 2020 11:30:20 +0800
Subject: BUG: np.load does not handle empty array with an empty descr (#15397)

The bug occurs since numpy 1.16. Before that empty descr corresponds to
`np.dtype([])`. This fixes the problem by following numpy 1.15's
behavior.

Closes gh-15396
---
 numpy/lib/format.py            | 17 ++++++++++-------
 numpy/lib/tests/test_format.py |  4 +++-
 2 files changed, 13 insertions(+), 8 deletions(-)

(limited to 'numpy')

diff --git a/numpy/lib/format.py b/numpy/lib/format.py
index b31340314..e2696c286 100644
--- a/numpy/lib/format.py
+++ b/numpy/lib/format.py
@@ -295,7 +295,11 @@ def descr_to_dtype(descr):
         # subtype, will always have a shape descr[1]
         dt = descr_to_dtype(descr[0])
         return numpy.dtype((dt, descr[1]))
-    fields = []
+
+    titles = []
+    names = []
+    formats = []
+    offsets = []
     offset = 0
     for field in descr:
         if len(field) == 2:
@@ -309,14 +313,13 @@ def descr_to_dtype(descr):
         # Once support for blank names is removed, only "if name == ''" needed)
         is_pad = (name == '' and dt.type is numpy.void and dt.names is None)
         if not is_pad:
-            fields.append((name, dt, offset))
-
+            title, name = name if isinstance(name, tuple) else (None, name)
+            titles.append(title)
+            names.append(name)
+            formats.append(dt)
+            offsets.append(offset)
         offset += dt.itemsize
 
-    names, formats, offsets = zip(*fields)
-    # names may be (title, names) tuples
-    nametups = (n  if isinstance(n, tuple) else (None, n) for n in names)
-    titles, names = zip(*nametups)
     return numpy.dtype({'names': names, 'formats': formats, 'titles': titles,
                         'offsets': offsets, 'itemsize': offset})
 
diff --git a/numpy/lib/tests/test_format.py b/numpy/lib/tests/test_format.py
index 24593d7b3..2dbaeb8cb 100644
--- a/numpy/lib/tests/test_format.py
+++ b/numpy/lib/tests/test_format.py
@@ -535,8 +535,10 @@ dt4 = np.dtype({'names': ['a', '', 'b'], 'formats': ['i4']*3})
 # titles
 dt5 = np.dtype({'names': ['a', 'b'], 'formats': ['i4', 'i4'],
                 'offsets': [1, 6], 'titles': ['aa', 'bb']})
+# empty
+dt6 = np.dtype({'names': [], 'formats': [], 'itemsize': 8})
 
-@pytest.mark.parametrize("dt", [dt1, dt2, dt3, dt4, dt5])
+@pytest.mark.parametrize("dt", [dt1, dt2, dt3, dt4, dt5, dt6])
 def test_load_padded_dtype(dt):
     arr = np.zeros(3, dt)
     for i in range(3):
-- 
cgit v1.2.1