commit c4c9866064f03646c686d7e08b00aeb203c35c19
author Shane Harvey <shane.harvey@mongodb.com> Fri Aug 04 01:45:00 2017 -0700
committer Serhiy Storchaka <storchaka@gmail.com> Fri Aug 04 11:45:00 2017 +0300
tree 9af64a872544117d7a3f41469b3018555c18e213
parent 778928b0c7aa438c282727535814d73df850693a

bpo-31107: Fix copyreg mangled slot names calculation. (#2989)

Lib/copyreg.py

diff --git a/Lib/copyreg.py b/Lib/copyreg.py
index ed29d71..bbe1af4 100644
--- a/Lib/copyreg.py
+++ b/Lib/copyreg.py
@@ -128,7 +128,11 @@
                         continue
                     # mangled names
                     elif name.startswith('__') and not name.endswith('__'):
-                        names.append('_%s%s' % (c.__name__, name))
+                        stripped = c.__name__.lstrip('_')
+                        if stripped:
+                            names.append('_%s%s' % (stripped, name))
+                        else:
+                            names.append(name)
                     else:
                         names.append(name)
 

Lib/test/test_copyreg.py

diff --git a/Lib/test/test_copyreg.py b/Lib/test/test_copyreg.py
index 52e887c..e3f1cd8 100644
--- a/Lib/test/test_copyreg.py
+++ b/Lib/test/test_copyreg.py
@@ -16,6 +16,12 @@
 class WithPrivate(object):
     __slots__ = ('__spam',)
 
+class _WithLeadingUnderscoreAndPrivate(object):
+    __slots__ = ('__spam',)
+
+class ___(object):
+    __slots__ = ('__spam',)
+
 class WithSingleString(object):
     __slots__ = 'spam'
 
@@ -104,6 +110,10 @@
         self.assertEqual(copyreg._slotnames(WithWeakref), [])
         expected = ['_WithPrivate__spam']
         self.assertEqual(copyreg._slotnames(WithPrivate), expected)
+        expected = ['_WithLeadingUnderscoreAndPrivate__spam']
+        self.assertEqual(copyreg._slotnames(_WithLeadingUnderscoreAndPrivate),
+                         expected)
+        self.assertEqual(copyreg._slotnames(___), ['__spam'])
         self.assertEqual(copyreg._slotnames(WithSingleString), ['spam'])
         expected = ['eggs', 'spam']
         expected.sort()

Misc/ACKS

diff --git a/Misc/ACKS b/Misc/ACKS
index f1f6c14..ec7d481 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -598,6 +598,7 @@
 Brian Harring
 Jonathan Hartley
 Travis B. Hartwell
+Shane Harvey
 Larry Hastings
 Tim Hatch
 Shane Hathaway

Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst

diff --git a/Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst b/Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst
new file mode 100644
index 0000000..3c2a155
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst
@@ -0,0 +1,2 @@
+Fix `copyreg._slotnames()` mangled attribute calculation for classes whose
+name begins with an underscore. Patch by Shane Harvey.