From 78d15faf6c522619098e94be3e7f6d88a9e61123 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Mon, 9 Sep 2019 09:24:16 -0700
Subject: [PATCH] bpo-38006: Avoid closure in weakref.WeakValueDictionary
 (GH-15641)

weakref.WeakValueDictionary defines a local remove() function used as
callback for weak references. This function was created with a
closure.  Modify the implementation to avoid the closure.
(cherry picked from commit a2af05a0d3f0da06b8d432f52efa3ecf29038532)

Co-authored-by: Victor Stinner <vstinner@redhat.com>
---
 Lib/test/test_weakref.py                                     | 5 +++++
 Lib/weakref.py                                               | 4 ++--
 .../next/Library/2019-09-02-13-37-27.bpo-38006.Y7vA0Q.rst    | 3 +++
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2019-09-02-13-37-27.bpo-38006.Y7vA0Q.rst

diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index 6f15c03ac52..d9e1b201f65 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -1785,6 +1785,11 @@ class MappingTestCase(TestBase):
         # copying should not result in a crash.
         self.check_threaded_weak_dict_copy(weakref.WeakValueDictionary, True)
 
+    @support.cpython_only
+    def test_remove_closure(self):
+        d = weakref.WeakValueDictionary()
+        self.assertIsNone(d._remove.__closure__)
+
 
 from test import mapping_tests
 
diff --git a/Lib/weakref.py b/Lib/weakref.py
index 8d71af653b7..9d7008947f0 100644
--- a/Lib/weakref.py
+++ b/Lib/weakref.py
@@ -108,12 +108,12 @@ class WeakValueDictionary(_collections_abc.MutableMapping):
                 else:
                     # Atomic removal is necessary since this function
                     # can be called asynchronously by the GC
-                    _atomic_removal(d, wr.key)
+                    _atomic_removal(self.data, wr.key)
         self._remove = remove
         # A list of keys to be removed
         self._pending_removals = []
         self._iterating = set()
-        self.data = d = {}
+        self.data = {}
         self.update(other, **kw)
 
     def _commit_removals(self):
diff --git a/Misc/NEWS.d/next/Library/2019-09-02-13-37-27.bpo-38006.Y7vA0Q.rst b/Misc/NEWS.d/next/Library/2019-09-02-13-37-27.bpo-38006.Y7vA0Q.rst
new file mode 100644
index 00000000000..ff064ad3f1a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-02-13-37-27.bpo-38006.Y7vA0Q.rst
@@ -0,0 +1,3 @@
+weakref.WeakValueDictionary defines a local remove() function used as
+callback for weak references. This function was created with a closure.
+Modify the implementation to avoid the closure.