SF bug #1054139: serious string hashing error in 2.4b1
_PyString_Resize() readied strings for mutation but did not invalidate
the cached hash value.
diff --git a/Lib/test/string_tests.py b/Lib/test/string_tests.py
index 4335965..c8ed07c 100644
--- a/Lib/test/string_tests.py
+++ b/Lib/test/string_tests.py
@@ -80,6 +80,15 @@
args = self.fixtype(args)
getattr(object, methodname)(*args)
+ def test_hash(self):
+ # SF bug 1054139: += optimization was not invalidating cached hash value
+ a = self.type2test('DNSSEC')
+ b = self.type2test('')
+ for c in a:
+ b += c
+ hash(b)
+ self.assertEqual(hash(a), hash(b))
+
def test_capitalize(self):
self.checkequal(' hello ', ' hello ', 'capitalize')
self.checkequal('Hello ', 'Hello ','capitalize')
diff --git a/Misc/NEWS b/Misc/NEWS
index e5437e1..6c0935e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -32,7 +32,7 @@
Core and builtins
-----------------
-...
+- Bug #1054139 _PyString_Resize() now invalidates its cached hash value.
Extension Modules
-----------------
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index c87b688..b8e5f41 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -3530,6 +3530,7 @@
sv = (PyStringObject *) *pv;
sv->ob_size = newsize;
sv->ob_sval[newsize] = '\0';
+ sv->ob_shash = -1; /* invalidate cached hash value */
return 0;
}