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bpo-43908: Add Py_TPFLAGS_IMMUTABLETYPE flag (GH-25520) 

Introduce Py_TPFLAGS_IMMUTABLETYPE flag for immutable type objects, and
modify PyType_Ready() to set it for static types.

Co-authored-by: Victor Stinner <vstinner@python.org>
This commit is contained in:
Erlend Egeberg Aasland 2021-04-28 19:02:42 +02:00 committed by GitHub
parent 3cc481b9de
commit 3b52c8d66b
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 24 additions and 1 deletions
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12
Doc/c-api/typeobj.rst
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@ -1177,6 +1177,18 @@ and :c:type:`PyType_Type` effectively act as defaults.)
.. versionadded:: 3.10 .. versionadded:: 3.10
.. data:: Py_TPFLAGS_IMMUTABLETYPE
This bit is set for type objects that are immutable: type attributes cannot be set nor deleted.
:c:func:`PyType_Ready` automatically applies this flag to static types.
**Inheritance:**
This flag is not inherited.
.. versionadded:: 3.10
.. c:member:: const char* PyTypeObject.tp_doc .. c:member:: const char* PyTypeObject.tp_doc

3
Include/object.h
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@ -320,6 +320,9 @@ Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
given type object has a specified feature. given type object has a specified feature.
*/ */
/* Set if the type object is immutable: type attributes cannot be set nor deleted */
#define Py_TPFLAGS_IMMUTABLETYPE (1UL << 8)
/* Set if the type object is dynamically allocated */ /* Set if the type object is dynamically allocated */
#define Py_TPFLAGS_HEAPTYPE (1UL << 9) #define Py_TPFLAGS_HEAPTYPE (1UL << 9)

3
Misc/NEWS.d/next/C API/2021-04-22-10-46-40.bpo-43908.Co3YhZ.rst Normal file
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@ -0,0 +1,3 @@
Introduce :const:`Py_TPFLAGS_IMMUTABLETYPE` flag for immutable type objects, and
modify :c:func:`PyType_Ready` to set it for static types. Patch by
Erlend E. Aasland.

7
Objects/typeobject.c
View File

@ -3875,7 +3875,7 @@ static int
type_setattro(PyTypeObject *type, PyObject *name, PyObject *value) type_setattro(PyTypeObject *type, PyObject *name, PyObject *value)
{ {
int res; int res;
if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) { if (type->tp_flags & Py_TPFLAGS_IMMUTABLETYPE) {
PyErr_Format( PyErr_Format(
PyExc_TypeError, PyExc_TypeError,
"can't set attributes of built-in/extension type '%s'", "can't set attributes of built-in/extension type '%s'",
@ -6229,6 +6229,11 @@ PyType_Ready(PyTypeObject *type)
type->tp_flags |= Py_TPFLAGS_READYING; type->tp_flags |= Py_TPFLAGS_READYING;
/* Historically, all static types were immutable. See bpo-43908 */
if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
type->tp_flags |= Py_TPFLAGS_IMMUTABLETYPE;
}
if (type_ready(type) < 0) { if (type_ready(type) < 0) {
type->tp_flags &= ~Py_TPFLAGS_READYING; type->tp_flags &= ~Py_TPFLAGS_READYING;
return -1; return -1;