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-rw-r--r--Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst2
-rw-r--r--Objects/setobject.c1
2 files changed, 3 insertions, 0 deletions
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst b/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst
new file mode 100644
index 0000000..163b9e0
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-01-14-20-32-47.bpo-26163.xv9Iuv.rst
@@ -0,0 +1,2 @@
+Improved frozenset() hash to create more distinct hash values when faced
+with datasets containing many similar values.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index c920fb9..4bc1020 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -795,6 +795,7 @@ frozenset_hash(PyObject *self)
hash ^= ((Py_uhash_t)PySet_GET_SIZE(self) + 1) * 1927868237UL;
/* Disperse patterns arising in nested frozensets */
+ hash ^= (hash >> 11) ^ (~hash >> 25);
hash = hash * 69069U + 907133923UL;
/* -1 is reserved as an error code */