[Python-checkins] bpo-32388: Remove cross-version binary compatibility requirement in tp_flags (GH-4944)
Antoine Pitrou
webhook-mailer at python.org
Wed May 29 16:12:42 EDT 2019
https://github.com/python/cpython/commit/ada319bb6d0ebcc68d3e0ef2b4279ea061877ac8
commit: ada319bb6d0ebcc68d3e0ef2b4279ea061877ac8
branch: master
author: Antoine Pitrou <antoine at python.org>
committer: GitHub <noreply at github.com>
date: 2019-05-29T22:12:38+02:00
summary:
bpo-32388: Remove cross-version binary compatibility requirement in tp_flags (GH-4944)
It is now allowed to add new fields at the end of the PyTypeObject struct without having to allocate a dedicated compatibility flag in tp_flags.
This will reduce the risk of running out of bits in the 32-bit tp_flags value.
files:
A Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst
M Doc/c-api/typeobj.rst
M Doc/whatsnew/3.8.rst
M Include/object.h
M Modules/_asynciomodule.c
M Modules/_io/bufferedio.c
M Modules/_io/fileio.c
M Modules/_io/iobase.c
M Modules/_io/textio.c
M Modules/_io/winconsoleio.c
M Modules/_testmultiphase.c
M Modules/gcmodule.c
M Modules/posixmodule.c
M Modules/socketmodule.c
M Modules/xxlimited.c
M Objects/genobject.c
M Objects/object.c
M Objects/typeobject.c
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index aa667846a0da..e2f8f54be79a 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -1099,6 +1099,11 @@ and :c:type:`PyType_Type` effectively act as defaults.)
.. versionadded:: 3.4
+ .. deprecated:: 3.8
+ This flag isn't necessary anymore, as the interpreter assumes the
+ :c:member:`~PyTypeObject.tp_finalize` slot is always present in the
+ type structure.
+
.. c:member:: const char* PyTypeObject.tp_doc
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index b4a803091701..5cd9a8edc793 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -1265,6 +1265,15 @@ Changes in the C API
(Contributed by Zackery Spytz in :issue:`33407`.)
+* The interpreter does not pretend to support binary compatibility of
+ extension types accross feature releases, anymore. A :c:type:`PyTypeObject`
+ exported by a third-party extension module is supposed to have all the
+ slots expected in the current Python version, including
+ :c:member:`~PyTypeObject.tp_finalize` (:const:`Py_TPFLAGS_HAVE_FINALIZE`
+ is not checked anymore before reading :c:member:`~PyTypeObject.tp_finalize`).
+
+ (Contributed by Antoine Pitrou in :issue:`32388`.)
+
CPython bytecode changes
------------------------
diff --git a/Include/object.h b/Include/object.h
index 11ba2bb8e238..cc98d8a1def7 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -263,17 +263,14 @@ PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
#define Py_PRINT_RAW 1 /* No string quotes etc. */
/*
-`Type flags (tp_flags)
+Type flags (tp_flags)
-These flags are used to extend the type structure in a backwards-compatible
-fashion. Extensions can use the flags to indicate (and test) when a given
-type structure contains a new feature. The Python core will use these when
-introducing new functionality between major revisions (to avoid mid-version
-changes in the PYTHON_API_VERSION).
+These flags are used to change expected features and behavior for a
+particular type.
Arbitration of the flag bit positions will need to be coordinated among
all extension writers who publicly release their extensions (this will
-be fewer than you might expect!)..
+be fewer than you might expect!).
Most flags were removed as of Python 3.0 to make room for new flags. (Some
flags are not for backwards compatibility but to indicate the presence of an
@@ -302,7 +299,7 @@ given type object has a specified feature.
/* Set while the type is being 'readied', to prevent recursive ready calls */
#define Py_TPFLAGS_READYING (1UL << 13)
-/* Objects support garbage collection (see objimp.h) */
+/* Objects support garbage collection (see objimpl.h) */
#define Py_TPFLAGS_HAVE_GC (1UL << 14)
/* These two bits are preserved for Stackless Python, next after this is 17 */
@@ -340,6 +337,11 @@ given type object has a specified feature.
/* NOTE: The following flags reuse lower bits (removed as part of the
* Python 3.0 transition). */
+/* The following flag is kept for compatibility. Starting with 3.8,
+ * binary compatibility of C extensions accross feature releases of
+ * Python is not supported anymore, except when using the stable ABI.
+ */
+
/* Type structure has tp_finalize member (3.4) */
#define Py_TPFLAGS_HAVE_FINALIZE (1UL << 0)
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst b/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst
new file mode 100644
index 000000000000..60615d47f60d
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-12-21-20-37-40.bpo-32388.6w-i5t.rst
@@ -0,0 +1 @@
+Remove cross-version binary compatibility requirement in tp_flags.
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 60136082a7ee..d8b631b7c7a2 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -1430,8 +1430,7 @@ static PyTypeObject FutureType = {
.tp_dealloc = FutureObj_dealloc,
.tp_as_async = &FutureType_as_async,
.tp_repr = (reprfunc)FutureObj_repr,
- .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_FINALIZE,
+ .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE,
.tp_doc = _asyncio_Future___init____doc__,
.tp_traverse = (traverseproc)FutureObj_traverse,
.tp_clear = (inquiry)FutureObj_clear,
@@ -2461,8 +2460,7 @@ static PyTypeObject TaskType = {
.tp_dealloc = TaskObj_dealloc,
.tp_as_async = &FutureType_as_async,
.tp_repr = (reprfunc)FutureObj_repr,
- .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_FINALIZE,
+ .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE,
.tp_doc = _asyncio_Task___init____doc__,
.tp_traverse = (traverseproc)TaskObj_traverse,
.tp_clear = (inquiry)TaskObj_clear,
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 6f855b9edd08..9c0eeb56860e 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -2342,8 +2342,7 @@ PyTypeObject PyBufferedIOBase_Type = {
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
bufferediobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@@ -2434,7 +2433,7 @@ PyTypeObject PyBufferedReader_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
_io_BufferedReader___init____doc__, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
@@ -2520,7 +2519,7 @@ PyTypeObject PyBufferedWriter_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
_io_BufferedWriter___init____doc__, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
@@ -2597,7 +2596,7 @@ PyTypeObject PyBufferedRWPair_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ | Py_TPFLAGS_HAVE_GC, /* tp_flags */
_io_BufferedRWPair___init____doc__, /* tp_doc */
(traverseproc)bufferedrwpair_traverse, /* tp_traverse */
(inquiry)bufferedrwpair_clear, /* tp_clear */
@@ -2691,7 +2690,7 @@ PyTypeObject PyBufferedRandom_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
_io_BufferedRandom___init____doc__, /* tp_doc */
(traverseproc)buffered_traverse, /* tp_traverse */
(inquiry)buffered_clear, /* tp_clear */
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 52a6f49e1d32..582a8130f622 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -1200,12 +1200,12 @@ PyTypeObject PyFileIO_Type = {
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ | Py_TPFLAGS_HAVE_GC, /* tp_flags */
_io_FileIO___init____doc__, /* tp_doc */
(traverseproc)fileio_traverse, /* tp_traverse */
(inquiry)fileio_clear, /* tp_clear */
0, /* tp_richcompare */
- offsetof(fileio, weakreflist), /* tp_weaklistoffset */
+ offsetof(fileio, weakreflist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
fileio_methods, /* tp_methods */
@@ -1215,7 +1215,7 @@ PyTypeObject PyFileIO_Type = {
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
- offsetof(fileio, dict), /* tp_dictoffset */
+ offsetof(fileio, dict), /* tp_dictoffset */
_io_FileIO___init__, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
fileio_new, /* tp_new */
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index a5727b8deed3..8c8112d10f0b 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -856,7 +856,7 @@ PyTypeObject PyIOBase_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
iobase_doc, /* tp_doc */
(traverseproc)iobase_traverse, /* tp_traverse */
(inquiry)iobase_clear, /* tp_clear */
@@ -1051,7 +1051,7 @@ PyTypeObject PyRawIOBase_Type = {
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
rawiobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index a08ab5b0e27f..3eb0dcc865ba 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -183,8 +183,7 @@ PyTypeObject PyTextIOBase_Type = {
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
textiobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@@ -3258,7 +3257,7 @@ PyTypeObject PyTextIOWrapper_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
+ | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
_io_TextIOWrapper___init____doc__, /* tp_doc */
(traverseproc)textiowrapper_traverse, /* tp_traverse */
(inquiry)textiowrapper_clear, /* tp_clear */
diff --git a/Modules/_io/winconsoleio.c b/Modules/_io/winconsoleio.c
index 70a723ed746a..7700bd5b7c0d 100644
--- a/Modules/_io/winconsoleio.c
+++ b/Modules/_io/winconsoleio.c
@@ -1133,7 +1133,7 @@ PyTypeObject PyWindowsConsoleIO_Type = {
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ | Py_TPFLAGS_HAVE_GC, /* tp_flags */
_io__WindowsConsoleIO___init____doc__, /* tp_doc */
(traverseproc)winconsoleio_traverse, /* tp_traverse */
(inquiry)winconsoleio_clear, /* tp_clear */
diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index db5bb7d6b8a2..4933abbabbe3 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -98,7 +98,7 @@ static PyType_Spec Example_Type_spec = {
"_testimportexec.Example",
sizeof(ExampleObject),
0,
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
Example_Type_slots
};
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 3b15c7ba5b62..0cf00e839661 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -858,7 +858,6 @@ finalize_garbage(PyGC_Head *collectable)
PyObject *op = FROM_GC(gc);
gc_list_move(gc, &seen);
if (!_PyGCHead_FINALIZED(gc) &&
- PyType_HasFeature(Py_TYPE(op), Py_TPFLAGS_HAVE_FINALIZE) &&
(finalize = Py_TYPE(op)->tp_finalize) != NULL) {
_PyGCHead_SET_FINALIZED(gc);
Py_INCREF(op);
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index a3d979c3bcd7..a25ff7a895c0 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -13032,8 +13032,7 @@ static PyTypeObject ScandirIteratorType = {
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT
- | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 74cdc0f2f6ca..ca4d760f8cb4 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -5286,8 +5286,7 @@ static PyTypeObject sock_type = {
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
- | Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
sock_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
diff --git a/Modules/xxlimited.c b/Modules/xxlimited.c
index 190f9937d0de..ffc04e0310e3 100644
--- a/Modules/xxlimited.c
+++ b/Modules/xxlimited.c
@@ -123,7 +123,7 @@ static PyType_Spec Xxo_Type_spec = {
"xxlimited.Xxo",
sizeof(XxoObject),
0,
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
Xxo_Type_slots
};
diff --git a/Objects/genobject.c b/Objects/genobject.c
index e2def38af541..0d0a02d76ccf 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -742,8 +742,7 @@ PyTypeObject PyGen_Type = {
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
- Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
(traverseproc)gen_traverse, /* tp_traverse */
0, /* tp_clear */
@@ -997,8 +996,7 @@ PyTypeObject PyCoro_Type = {
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
- Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
(traverseproc)gen_traverse, /* tp_traverse */
0, /* tp_clear */
@@ -1394,8 +1392,7 @@ PyTypeObject PyAsyncGen_Type = {
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
- Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
0, /* tp_doc */
(traverseproc)async_gen_traverse, /* tp_traverse */
0, /* tp_clear */
diff --git a/Objects/object.c b/Objects/object.c
index 87dba9898e3a..f9c75b7c6a4e 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -298,10 +298,7 @@ PyObject_CallFinalizer(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
- /* The former could happen on heaptypes created from the C API, e.g.
- PyType_FromSpec(). */
- if (!PyType_HasFeature(tp, Py_TPFLAGS_HAVE_FINALIZE) ||
- tp->tp_finalize == NULL)
+ if (tp->tp_finalize == NULL)
return;
/* tp_finalize should only be called once. */
if (PyType_IS_GC(tp) && _PyGC_FINALIZED(self))
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c14cbad875b4..071ff27d5323 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -248,8 +248,8 @@ PyType_Modified(PyTypeObject *type)
Invariants:
- Py_TPFLAGS_VALID_VERSION_TAG is never set if
- Py_TPFLAGS_HAVE_VERSION_TAG is not set (e.g. on type
- objects coming from non-recompiled extension modules)
+ Py_TPFLAGS_HAVE_VERSION_TAG is not set (in case of a
+ bizarre MRO, see type_mro_modified()).
- before Py_TPFLAGS_VALID_VERSION_TAG can be set on a type,
it must first be set on all super types.
@@ -2571,7 +2571,7 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
/* Initialize tp_flags */
type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE |
- Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE;
+ Py_TPFLAGS_BASETYPE;
if (base->tp_flags & Py_TPFLAGS_HAVE_GC)
type->tp_flags |= Py_TPFLAGS_HAVE_GC;
@@ -5179,10 +5179,7 @@ inherit_slots(PyTypeObject *type, PyTypeObject *base)
COPYSLOT(tp_init);
COPYSLOT(tp_alloc);
COPYSLOT(tp_is_gc);
- if ((type->tp_flags & Py_TPFLAGS_HAVE_FINALIZE) &&
- (base->tp_flags & Py_TPFLAGS_HAVE_FINALIZE)) {
- COPYSLOT(tp_finalize);
- }
+ COPYSLOT(tp_finalize);
if ((type->tp_flags & Py_TPFLAGS_HAVE_GC) ==
(base->tp_flags & Py_TPFLAGS_HAVE_GC)) {
/* They agree about gc. */
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