https://github.com/python/cpython/commit/c8a0fbf2a6851a060270e53c045b2b7d1c06bf95 commit: c8a0fbf2a6851a060270e53c045b2b7d1c06bf95 branch: 3.13 author: Serhiy Storchaka <[email protected]> committer: serhiy-storchaka <[email protected]> date: 2026-07-17T08:26:14Z summary:
[3.13] gh-85943: Fix BytesWarning in the struct format cache under -bb (GH-153627) (GH-153836) Normalize bytes format strings to str before using them as the cache key, so that equal str and bytes formats no longer collide and get compared. (cherry picked from commit 190d2ffbb969ad571fd12d4988b37519091194d5) Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]> files: A Misc/NEWS.d/next/Library/2026-07-12-00-00-00.gh-issue-85943.8f906e.rst M Lib/test/test_struct.py M Modules/_struct.c diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py index 460e9e94aacf81..a5a1edcb0d193c 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -176,6 +176,16 @@ def test_calcsize(self): self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('i')) self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('P')) + def test_cache_bytes_vs_str_bb(self): + # Mixing str and bytes formats must not raise BytesWarning under -bb. + code = ( + 'import struct\n' + 'struct.calcsize(b"!d"); struct.calcsize("!d")\n' + 'struct.calcsize(">d"); struct.calcsize(b">d")\n' + 'struct.Struct(b"i"); struct.Struct("i")\n' + ) + assert_python_ok('-bb', '-c', code) + def test_integers(self): # Integer tests (bBhHiIlLqQnN). import binascii diff --git a/Misc/NEWS.d/next/Library/2026-07-12-00-00-00.gh-issue-85943.8f906e.rst b/Misc/NEWS.d/next/Library/2026-07-12-00-00-00.gh-issue-85943.8f906e.rst new file mode 100644 index 00000000000000..0a93bf2e7b803e --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-07-12-00-00-00.gh-issue-85943.8f906e.rst @@ -0,0 +1,4 @@ +Fix :mod:`struct` functions raising :exc:`BytesWarning` under the ``-bb`` +command line option when a :class:`str` format is used after an equal +:class:`bytes` format (or vice versa). The internal format cache no longer +mixes :class:`str` and :class:`bytes` keys. diff --git a/Modules/_struct.c b/Modules/_struct.c index 1195f6f0d7434f..36d5ece390e8a2 100644 --- a/Modules/_struct.c +++ b/Modules/_struct.c @@ -2289,7 +2289,8 @@ static PyType_Spec PyStructType_spec = { static int cache_struct_converter(PyObject *module, PyObject *fmt, PyStructObject **ptr) { - PyObject * s_object; + PyObject *s_object; + PyObject *key; _structmodulestate *state = get_struct_state(module); if (fmt == NULL) { @@ -2297,24 +2298,41 @@ cache_struct_converter(PyObject *module, PyObject *fmt, PyStructObject **ptr) return 1; } - if (PyDict_GetItemRef(state->cache, fmt, &s_object) < 0) { + /* Use a str cache key: an equal str and bytes would collide and be + compared, raising BytesWarning under -bb. */ + if (PyBytes_Check(fmt)) { + key = PyUnicode_DecodeASCII(PyBytes_AS_STRING(fmt), + PyBytes_GET_SIZE(fmt), "surrogateescape"); + if (key == NULL) { + return 0; + } + } + else { + key = Py_NewRef(fmt); + } + + if (PyDict_GetItemRef(state->cache, key, &s_object) < 0) { + Py_DECREF(key); return 0; } if (s_object != NULL) { + Py_DECREF(key); *ptr = (PyStructObject *)s_object; return Py_CLEANUP_SUPPORTED; } - s_object = PyObject_CallOneArg(state->PyStructType, fmt); + s_object = PyObject_CallOneArg(state->PyStructType, key); if (s_object != NULL) { if (PyDict_GET_SIZE(state->cache) >= MAXCACHE) PyDict_Clear(state->cache); /* Attempt to cache the result */ - if (PyDict_SetItem(state->cache, fmt, s_object) == -1) + if (PyDict_SetItem(state->cache, key, s_object) == -1) PyErr_Clear(); + Py_DECREF(key); *ptr = (PyStructObject *)s_object; return Py_CLEANUP_SUPPORTED; } + Py_DECREF(key); return 0; } _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
