diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py index 63fe83e..612ca17 100644 --- a/Lib/test/test_functools.py +++ b/Lib/test/test_functools.py @@ -90,6 +90,15 @@ class TestPartial: p(b=7) self.assertEqual(d, {'a':3}) + def test_kwargs_copy(self): + # Issue #29532: Altering a kwarg dictionary passed to a constructor + # should not affect a partial object after creation + d = {'a': 3} + p = self.partial(capture, **d) + self.assertEqual(p(), ((), {'a': 3})) + d['a'] = 5 + self.assertEqual(p(), ((), {'a': 3})) + def test_arg_combinations(self): # exercise special code paths for zero args in either partial # object or the caller diff --git a/Misc/NEWS b/Misc/NEWS index 48d786d..b713c9b 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -225,6 +225,9 @@ Extension Modules Library ------- +- Issue #29532: Altering a kwarg dictionary passed to functools.partial() + no longer affects a partial object after creation. + - Issue #29100: Fix datetime.fromtimestamp() regression introduced in Python 3.6.0: check minimum and maximum years. diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c index 4170883..c856505 100644 --- a/Modules/_functoolsmodule.c +++ b/Modules/_functoolsmodule.c @@ -88,10 +88,13 @@ partial_new(PyTypeObject *type, PyObject *args, PyObject *kw) if (kw == NULL) { pto->kw = PyDict_New(); } - else { + else if (Py_REFCNT(kw) == 1) { Py_INCREF(kw); pto->kw = kw; } + else { + pto->kw = PyDict_Copy(kw); + } } else { pto->kw = PyDict_Copy(pkw);