Make _pyc_magic_number private

Author: mdboom

Doc/library/sys.rst

@@ -1122,11 +1122,6 @@ always available.
    ``cache_tag`` is set to ``None``, it indicates that module caching should
    be disabled.
 
-   *pyc_magic_number* is the magic number used to identify that cached ``.pyc``
-   files match the running version of Python.
-
-   .. versionadded:: 3.14
-
    :data:`sys.implementation` may contain additional attributes specific to
    the Python implementation.  These non-standard attributes must start with
    an underscore, and are not described here.  Regardless of its contents,

Lib/importlib/_bootstrap_external.py

@@ -221,7 +221,7 @@ def _write_atomic(path, data, mode=0o666):
 
 _code_type = type(_write_atomic.__code__)
 
-MAGIC_NUMBER = (sys.implementation.pyc_magic_number).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (sys.implementation._pyc_magic_number).to_bytes(2, 'little') + b'\r\n'
 
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # for import.c
 

Python/sysmodule.c

@@ -3323,7 +3323,7 @@ make_impl_info(PyObject *version_info)
     value = PyLong_FromLong(PYC_MAGIC_NUMBER);
     if (value == NULL)
         goto error;
-    res = PyDict_SetItemString(impl_info, "pyc_magic_number", value);
+    res = PyDict_SetItemString(impl_info, "_pyc_magic_number", value);
     Py_DECREF(value);
     if (res < 0)
         goto error;