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[3.14] gh-158095: Fix reference cycles in re scanners (GH-158100) #161245

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Merged
eendebakpt merged 1 commit into from
Nov 3, 2026
Merged

[3.14] gh-158095: Fix reference cycles in re scanners (GH-158100) #161245

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22 changes: 22 additions & 0 deletions Lib/test/test_re.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
import sys
import unittest
import warnings
import weakref
from re import Scanner
from weakref import proxy

Expand Down Expand Up @@ -1705,6 +1706,27 @@ def test_finditer(self):
self.assertEqual([item.group(0) for item in iter],
["::", "::"])

def test_finditer_gc(self):
class Text(str):
pass

class Buffer(bytearray):
pass

text = Text('a')
text.iterator = re.finditer('a', text)
ref = weakref.ref(text)
del text
gc_collect()
self.assertIsNone(ref())

buffer = Buffer(b'a')
buffer.iterator = re.finditer(b'a', buffer)
ref = weakref.ref(buffer)
del buffer
gc_collect()
self.assertIsNone(ref())

def test_bug_926075(self):
self.assertIsNot(re.compile('bug_926075'),
re.compile(b'bug_926075'))
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-09-24-14-59-08.gh-issue-158095.lcKOT4.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix a memory leak in :func:`re.finditer` and regular expression scanners when
their input participates in a reference cycle.
7 changes: 6 additions & 1 deletion Modules/_sre/sre.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2813,14 +2813,19 @@ scanner_traverse(PyObject *op, visitproc visit, void *arg)
ScannerObject *self = _ScannerObject_CAST(op);
Py_VISIT(Py_TYPE(self));
Py_VISIT(self->pattern);
Py_VISIT(self->state.string);
Py_VISIT(self->state.buffer.obj);
return 0;
}

static int
scanner_clear(PyObject *op)
{
ScannerObject *self = _ScannerObject_CAST(op);
self->state.start = NULL;
Py_CLEAR(self->pattern);
Py_CLEAR(self->state.string);
PyBuffer_Release(&self->state.buffer);
return 0;
}

Expand All @@ -2830,8 +2835,8 @@ scanner_dealloc(PyObject *self)
PyTypeObject *tp = Py_TYPE(self);
PyObject_GC_UnTrack(self);
ScannerObject *scanner = _ScannerObject_CAST(self);
state_fini(&scanner->state);
(void)scanner_clear(self);
state_fini(&scanner->state);
tp->tp_free(self);
Py_DECREF(tp);
}
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