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bpo-43908: Types with Py_TPFLAGS_IMMUTABLETYPE can now inherit the vectorcall protocol #27001

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Merged
merged 15 commits into from
Jul 8, 2021
Merged

bpo-43908: Types with Py_TPFLAGS_IMMUTABLETYPE can now inherit the vectorcall protocol #27001

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6f2a997
bpo-43908: Let Py_TPFLAGS_IMMUTABLETYPE decide if Py_TPFLAGS_HAVE_VEC…
Jul 2, 2021
c1db2ce
Adjust test_call comments
Jul 2, 2021
dd42fdf
Py_TPFLAGS_METHOD_DESCRIPTOR is inherited if Py_TPFLAGS_IMMUTABLETYPE…
Jul 2, 2021
f3aedd3
Update docs
Jul 2, 2021
0e421ab
Add a note in Porting to 3.11
Jul 2, 2021
a99cd5c
Add NEWS
Jul 2, 2021
e9ee79c
Simplify What's New/NEWS wording
Jul 2, 2021
593a19f
Fix whitespace
Jul 2, 2021
6adc9e5
Move What's New entry from 3.11 to 3.10
Jul 6, 2021
c9cdfa6
Revert "Move What's New entry from 3.11 to 3.10"
Jul 6, 2021
634d1d9
Minor adjustment of What's New wording
Jul 6, 2021
1b035eb
Address review: reword NEWS entry
Jul 6, 2021
b6ed6bd
Also adjust What's New entry
Jul 6, 2021
fd33dcc
Address review: change wording in NEWS entry (specify heap types)
Jul 7, 2021
49362db
Also adjust What's New entry
Jul 7, 2021
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17 changes: 9 additions & 8 deletions Doc/c-api/typeobj.rst
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Expand Up @@ -710,7 +710,7 @@ and :c:type:`PyType_Type` effectively act as defaults.)

.. warning::

It is not recommended for :ref:`heap types <heap-types>` to implement
It is not recommended for :ref:`mutable heap types <heap-types>` to implement
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Note: It's non-obvious what "mutable" means. It would be nice to add (in a separated PR) a new "Immutable types" section near https://docs.python.org/dev/c-api/typeobj.html#heap-types to explain the effects of the Py_TPFLAGS_IMMUTABLETYPE flag and explains that static types get this flag automatically.

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I agree. I'll see if I can find time for it. Thanks again for reviewing!

the vectorcall protocol.
When a user sets :attr:`__call__` in Python code, only *tp_call* is updated,
likely making it inconsistent with the vectorcall function.
Expand All @@ -734,8 +734,9 @@ and :c:type:`PyType_Type` effectively act as defaults.)
always inherited. If it's not, then the subclass won't use
:ref:`vectorcall <vectorcall>`, except when
:c:func:`PyVectorcall_Call` is explicitly called.
This is in particular the case for :ref:`heap types <heap-types>`
(including subclasses defined in Python).
This is in particular the case for types without the
:const:`Py_TPFLAGS_IMMUTABLETYPE` flag set (including subclasses defined in
Python).


.. c:member:: getattrfunc PyTypeObject.tp_getattr
Expand Down Expand Up @@ -1125,9 +1126,9 @@ and :c:type:`PyType_Type` effectively act as defaults.)

**Inheritance:**

This flag is never inherited by :ref:`heap types <heap-types>`.
For extension types, it is inherited whenever
:c:member:`~PyTypeObject.tp_descr_get` is inherited.
This flag is never inherited by types without the
:const:`Py_TPFLAGS_IMMUTABLETYPE` flag set. For extension types, it is
inherited whenever :c:member:`~PyTypeObject.tp_descr_get` is inherited.


.. XXX Document more flags here?
Expand Down Expand Up @@ -1172,9 +1173,9 @@ and :c:type:`PyType_Type` effectively act as defaults.)

**Inheritance:**

This bit is inherited for :ref:`static subtypes <static-types>` if
This bit is inherited for types with the
:const:`Py_TPFLAGS_IMMUTABLETYPE` flag set, if
:c:member:`~PyTypeObject.tp_call` is also inherited.
:ref:`Heap types <heap-types>` do not inherit ``Py_TPFLAGS_HAVE_VECTORCALL``.

.. versionadded:: 3.9

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5 changes: 5 additions & 0 deletions Doc/whatsnew/3.11.rst
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Expand Up @@ -211,6 +211,11 @@ Porting to Python 3.11
(:c:member:`PyTypeObject.tp_traverse`).
(Contributed by Victor Stinner in :issue:`44263`.)

* Heap types with the :const:`Py_TPFLAGS_IMMUTABLETYPE` flag can now inherit
the :pep:`590` vectorcall protocol. Previously, this was only possible for
:ref:`static types <static-types>`.
(Contributed by Erlend E. Aasland in :issue:`43908`)

Deprecated
----------

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4 changes: 2 additions & 2 deletions Lib/test/test_call.py
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Expand Up @@ -563,7 +563,7 @@ def test_method_descriptor_flag(self):
self.assertTrue(_testcapi.MethodDescriptorDerived.__flags__ & Py_TPFLAGS_METHOD_DESCRIPTOR)
self.assertFalse(_testcapi.MethodDescriptorNopGet.__flags__ & Py_TPFLAGS_METHOD_DESCRIPTOR)

# Heap type should not inherit Py_TPFLAGS_METHOD_DESCRIPTOR
# Mutable heap types should not inherit Py_TPFLAGS_METHOD_DESCRIPTOR
class MethodDescriptorHeap(_testcapi.MethodDescriptorBase):
pass
self.assertFalse(MethodDescriptorHeap.__flags__ & Py_TPFLAGS_METHOD_DESCRIPTOR)
Expand All @@ -574,7 +574,7 @@ def test_vectorcall_flag(self):
self.assertFalse(_testcapi.MethodDescriptorNopGet.__flags__ & Py_TPFLAGS_HAVE_VECTORCALL)
self.assertTrue(_testcapi.MethodDescriptor2.__flags__ & Py_TPFLAGS_HAVE_VECTORCALL)

# Heap type should not inherit Py_TPFLAGS_HAVE_VECTORCALL
# Mutable heap types should not inherit Py_TPFLAGS_HAVE_VECTORCALL
class MethodDescriptorHeap(_testcapi.MethodDescriptorBase):
pass
self.assertFalse(MethodDescriptorHeap.__flags__ & Py_TPFLAGS_HAVE_VECTORCALL)
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2021-07-03-00-20-39.bpo-43908.YHuV_s.rst
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@@ -0,0 +1,3 @@
Heap types with the :const:`Py_TPFLAGS_IMMUTABLETYPE` flag can now inherit the
:pep:`590` vectorcall protocol. Previously, this was only possible for
:ref:`static types <static-types>`. Patch by Erlend E. Aasland.
8 changes: 4 additions & 4 deletions Objects/typeobject.c
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Expand Up @@ -5881,8 +5881,8 @@ inherit_slots(PyTypeObject *type, PyTypeObject *base)
/* Inherit Py_TPFLAGS_HAVE_VECTORCALL for non-heap types
* if tp_call is not overridden */
if (!type->tp_call &&
(base->tp_flags & Py_TPFLAGS_HAVE_VECTORCALL) &&
!(type->tp_flags & Py_TPFLAGS_HEAPTYPE))
_PyType_HasFeature(base, Py_TPFLAGS_HAVE_VECTORCALL) &&
_PyType_HasFeature(type, Py_TPFLAGS_IMMUTABLETYPE))
{
type->tp_flags |= Py_TPFLAGS_HAVE_VECTORCALL;
}
Expand Down Expand Up @@ -5915,8 +5915,8 @@ inherit_slots(PyTypeObject *type, PyTypeObject *base)
* but only for extension types */
if (base->tp_descr_get &&
type->tp_descr_get == base->tp_descr_get &&
!(type->tp_flags & Py_TPFLAGS_HEAPTYPE) &&
(base->tp_flags & Py_TPFLAGS_METHOD_DESCRIPTOR))
_PyType_HasFeature(type, Py_TPFLAGS_IMMUTABLETYPE) &&
_PyType_HasFeature(base, Py_TPFLAGS_METHOD_DESCRIPTOR))
{
type->tp_flags |= Py_TPFLAGS_METHOD_DESCRIPTOR;
}
Expand Down