Fix SF bug #489581: __slots__ leak.
It was easier than I thought, assuming that no other things contribute
to the instance size besides slots -- a pretty good bet. With a test
suite, no less!
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index b73025b..481ca0f 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1000,6 +1000,40 @@
vereq(x.b, 2)
vereq(x.c, 3)
+ # Test leaks
+ class Counted(object):
+ counter = 0 # counts the number of instances alive
+ def __init__(self):
+ Counted.counter += 1
+ def __del__(self):
+ Counted.counter -= 1
+ class C(object):
+ __slots__ = ['a', 'b', 'c']
+ x = C()
+ x.a = Counted()
+ x.b = Counted()
+ x.c = Counted()
+ vereq(Counted.counter, 3)
+ del x
+ vereq(Counted.counter, 0)
+ class D(C):
+ pass
+ x = D()
+ x.a = Counted()
+ x.z = Counted()
+ vereq(Counted.counter, 2)
+ del x
+ vereq(Counted.counter, 0)
+ class E(D):
+ __slots__ = ['e']
+ x = E()
+ x.a = Counted()
+ x.z = Counted()
+ x.e = Counted()
+ vereq(Counted.counter, 3)
+ del x
+ vereq(Counted.counter, 0)
+
def dynamics():
if verbose: print "Testing class attribute propagation..."
class D(object):
diff --git a/Misc/NEWS b/Misc/NEWS
index 58119ea..eabe9b6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -4,6 +4,9 @@
Type/class unification and new-style classes
+- Fixed a leak: instance variables declared with __slots__ were never
+ deleted!
+
- The "delete attribute" method of descriptor objects is called
__delete__, not __del__. In previous releases, it was mistakenly
called __del__, which created an unfortunate overloading condition
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 14a7e86..37ab4cb 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -304,7 +304,7 @@
static void
subtype_dealloc(PyObject *self)
{
- PyTypeObject *type, *base;
+ PyTypeObject *type, *base, *temp;
destructor f;
/* This exists so we can DECREF self->ob_type */
@@ -314,10 +314,30 @@
/* Find the nearest base with a different tp_dealloc */
type = self->ob_type;
- base = type->tp_base;
+ base = type;
while ((f = base->tp_dealloc) == subtype_dealloc) {
+ temp = base;
base = base->tp_base;
assert(base);
+ /* While we're at it, clear __slots__ variables */
+ if (temp->tp_basicsize != base->tp_basicsize &&
+ temp->tp_itemsize == 0)
+ {
+ char *addr = ((char *)self);
+ char *p = addr + base->tp_basicsize;
+ char *q = addr + temp->tp_basicsize;
+ for (; p < q; p += sizeof(PyObject *)) {
+ PyObject **pp;
+ if (p == addr + type->tp_dictoffset ||
+ p == addr + type->tp_weaklistoffset)
+ continue;
+ pp = (PyObject **)p;
+ if (*pp != NULL) {
+ Py_DECREF(*pp);
+ *pp = NULL;
+ }
+ }
+ }
}
/* If we added a dict, DECREF it */