[Python-checkins] [2.7] bpo-31107: Fix copyreg mangled slot names calculation. (GH-2989). (#3004)

[Serhiy Storchaka]

https://github.com/python/cpython/commit/88ffff5ddbb8692ecb2c661aa29000dbde9eff8c
commit: 88ffff5ddbb8692ecb2c661aa29000dbde9eff8c
branch: 2.7
author: Shane Harvey <shane.harvey at mongodb.com>
committer: Serhiy Storchaka <storchaka at gmail.com>
date: 2017-08-05T18:03:01+03:00
summary:

[2.7] bpo-31107: Fix copyreg mangled slot names calculation. (GH-2989). (#3004)

(cherry picked from commit c4c9866064f03646c686d7e08b00aeb203c35c19)

files:
A Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst
M Lib/copy_reg.py
M Lib/test/test_copy_reg.py
M Misc/ACKS

diff --git a/Lib/copy_reg.py b/Lib/copy_reg.py
index db1715092c5..8943077593d 100644
--- a/Lib/copy_reg.py
+++ b/Lib/copy_reg.py
@@ -127,7 +127,11 @@ class found there.  (This assumes classes don't modify their
                         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)
 
diff --git a/Lib/test/test_copy_reg.py b/Lib/test/test_copy_reg.py
index 8cdb8b7d2ab..17ccbd084d6 100644
--- a/Lib/test/test_copy_reg.py
+++ b/Lib/test/test_copy_reg.py
@@ -17,6 +17,12 @@ class WithWeakref(object):
 class WithPrivate(object):
     __slots__ = ('__spam',)
 
+class _WithLeadingUnderscoreAndPrivate(object):
+    __slots__ = ('__spam',)
+
+class ___(object):
+    __slots__ = ('__spam',)
+
 class WithSingleString(object):
     __slots__ = 'spam'
 
@@ -105,6 +111,10 @@ def test_slotnames(self):
         self.assertEqual(copy_reg._slotnames(WithWeakref), [])
         expected = ['_WithPrivate__spam']
         self.assertEqual(copy_reg._slotnames(WithPrivate), expected)
+        expected = ['_WithLeadingUnderscoreAndPrivate__spam']
+        self.assertEqual(copy_reg._slotnames(_WithLeadingUnderscoreAndPrivate),
+                         expected)
+        self.assertEqual(copy_reg._slotnames(___), ['__spam'])
         self.assertEqual(copy_reg._slotnames(WithSingleString), ['spam'])
         expected = ['eggs', 'spam']
         expected.sort()
diff --git a/Misc/ACKS b/Misc/ACKS
index 662db9f40f7..229a874ffc2 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -543,6 +543,7 @@ David Harrigan
 Brian Harring
 Jonathan Hartley
 Travis B. Hartwell
+Shane Harvey
 Larry Hastings
 Tim Hatch
 Shane Hathaway
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 00000000000..09807058b4c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-08-02-12-48-15.bpo-31107.1t2hn5.rst
@@ -0,0 +1,2 @@
+Fix `copy_reg._slotnames()` mangled attribute calculation for classes whose
+name begins with an underscore. Patch by Shane Harvey.