https://github.com/python/cpython/commit/190d2ffbb969ad571fd12d4988b37519091194d5 commit: 190d2ffbb969ad571fd12d4988b37519091194d5 branch: main author: Serhiy Storchaka <[email protected]> committer: serhiy-storchaka <[email protected]> date: 2026-07-17T10:49:11+03:00 summary:
gh-85943: Fix BytesWarning in the struct format cache under -bb (GH-153627) 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. 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 f9803abb3db91f..3809f2d2643895 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -182,6 +182,16 @@ 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 260dc85faf9fb9..352312fb0b4c19 100644 --- a/Modules/_struct.c +++ b/Modules/_struct.c @@ -2642,7 +2642,8 @@ 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) { @@ -2650,24 +2651,41 @@ 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_CAST(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]
