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[3.11] gh-102304: Add links to the Stable ABI and Limited C API docs (#…
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…105345) (#105371) (#109901)

* Add "limited-c-api" and "stable-api" targets
* Rename the "stable-abi-list" target to "limited-api-list"
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AA-Turner authored Sep 29, 2023
1 parent 6024a75 commit d81bcc2
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4 changes: 2 additions & 2 deletions Doc/c-api/exceptions.rst
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Expand Up @@ -806,15 +806,15 @@ because the :ref:`call protocol <call>` takes care of recursion handling.
depth limit.
.. versionchanged:: 3.9
This function is now also available in the limited API.
This function is now also available in the :ref:`limited API <limited-c-api>`.
.. c:function:: void Py_LeaveRecursiveCall(void)
Ends a :c:func:`Py_EnterRecursiveCall`. Must be called once for each
*successful* invocation of :c:func:`Py_EnterRecursiveCall`.
.. versionchanged:: 3.9
This function is now also available in the limited API.
This function is now also available in the :ref:`limited API <limited-c-api>`.
Properly implementing :c:member:`~PyTypeObject.tp_repr` for container types requires
special recursion handling. In addition to protecting the stack,
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49 changes: 31 additions & 18 deletions Doc/c-api/stable.rst
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Expand Up @@ -25,19 +25,19 @@ are private API that can change without notice even in patch releases.
Stable Application Binary Interface
===================================

For simplicity, this document talks about *extensions*, but the Limited API
and Stable ABI work the same way for all uses of the API – for example,
embedding Python.

.. _limited-c-api:

Limited C API
-------------

Python 3.2 introduced the *Limited API*, a subset of Python's C API.
Extensions that only use the Limited API can be
compiled once and work with multiple versions of Python.
Contents of the Limited API are :ref:`listed below <stable-abi-list>`.

To enable this, Python provides a *Stable ABI*: a set of symbols that will
remain compatible across Python 3.x versions. The Stable ABI contains symbols
exposed in the Limited API, but also other ones – for example, functions
necessary to support older versions of the Limited API.

(For simplicity, this document talks about *extensions*, but the Limited API
and Stable ABI work the same way for all uses of the API – for example,
embedding Python.)
Contents of the Limited API are :ref:`listed below <limited-api-list>`.

.. c:macro:: Py_LIMITED_API
Expand All @@ -57,6 +57,19 @@ embedding Python.)
You can also define ``Py_LIMITED_API`` to ``3``. This works the same as
``0x03020000`` (Python 3.2, the version that introduced Limited API).


.. _stable-abi:

Stable ABI
----------

To enable this, Python provides a *Stable ABI*: a set of symbols that will
remain compatible across Python 3.x versions.

The Stable ABI contains symbols exposed in the :ref:`Limited API
<limited-c-api>`, but also other ones – for example, functions necessary to
support older versions of the Limited API.

On Windows, extensions that use the Stable ABI should be linked against
``python3.dll`` rather than a version-specific library such as
``python39.dll``.
Expand Down Expand Up @@ -101,9 +114,9 @@ Limited API Caveats
-------------------

Note that compiling with ``Py_LIMITED_API`` is *not* a complete guarantee that
code conforms to the Limited API or the Stable ABI. ``Py_LIMITED_API`` only
covers definitions, but an API also includes other issues, such as expected
semantics.
code conforms to the :ref:`Limited API <limited-c-api>` or the :ref:`Stable ABI
<stable-abi>`. ``Py_LIMITED_API`` only covers definitions, but an API also
includes other issues, such as expected semantics.

One issue that ``Py_LIMITED_API`` does not guard against is calling a function
with arguments that are invalid in a lower Python version.
Expand Down Expand Up @@ -136,9 +149,9 @@ Platform Considerations
=======================

ABI stability depends not only on Python, but also on the compiler used,
lower-level libraries and compiler options. For the purposes of the Stable ABI,
these details define a “platform”. They usually depend on the OS
type and processor architecture
lower-level libraries and compiler options. For the purposes of
the :ref:`Stable ABI <stable-abi>`, these details define a “platform”. They
usually depend on the OS type and processor architecture

It is the responsibility of each particular distributor of Python
to ensure that all Python versions on a particular platform are built
Expand All @@ -147,12 +160,12 @@ This is the case with Windows and macOS releases from ``python.org`` and many
third-party distributors.


.. _stable-abi-list:
.. _limited-api-list:

Contents of Limited API
=======================


Currently, the Limited API includes the following items:
Currently, the :ref:`Limited API <limited-c-api>` includes the following items:

.. limited-api-list::
2 changes: 1 addition & 1 deletion Doc/c-api/structures.rst
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Expand Up @@ -318,7 +318,7 @@ There are these calling conventions:
.. versionchanged:: 3.10
``METH_FASTCALL`` is now part of the stable ABI.
``METH_FASTCALL`` is now part of the :ref:`stable ABI <stable-abi>`.
.. _METH_FASTCALL-METH_KEYWORDS:
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4 changes: 2 additions & 2 deletions Doc/c-api/type.rst
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Expand Up @@ -42,7 +42,7 @@ Type Objects
Return the :c:member:`~PyTypeObject.tp_flags` member of *type*. This function is primarily
meant for use with ``Py_LIMITED_API``; the individual flag bits are
guaranteed to be stable across Python releases, but access to
:c:member:`~PyTypeObject.tp_flags` itself is not part of the limited API.
:c:member:`~PyTypeObject.tp_flags` itself is not part of the :ref:`limited API <limited-c-api>`.
.. versionadded:: 3.2
Expand Down Expand Up @@ -301,7 +301,7 @@ The following functions and structs are used to create
.. versionchanged:: 3.11
:c:member:`~PyBufferProcs.bf_getbuffer` and
:c:member:`~PyBufferProcs.bf_releasebuffer` are now available
under the limited API.
under the :ref:`limited API <limited-c-api>`.
.. c:member:: void *PyType_Slot.pfunc
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2 changes: 1 addition & 1 deletion Doc/c-api/typeobj.rst
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Expand Up @@ -2082,7 +2082,7 @@ This results in types that are limited relative to types defined in Python:
include any subinterpreter-specific state.

Also, since :c:type:`PyTypeObject` is only part of the :ref:`Limited API
<stable>` as an opaque struct, any extension modules using static types must be
<limited-c-api>` as an opaque struct, any extension modules using static types must be
compiled for a specific Python minor version.


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2 changes: 1 addition & 1 deletion Doc/c-api/unicode.rst
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Expand Up @@ -1084,7 +1084,7 @@ These are the UTF-8 codec APIs:
The return type is now ``const char *`` rather of ``char *``.
.. versionchanged:: 3.10
This function is a part of the :ref:`limited API <stable>`.
This function is a part of the :ref:`limited API <limited-c-api>`.
.. c:function:: const char* PyUnicode_AsUTF8(PyObject *unicode)
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2 changes: 1 addition & 1 deletion Doc/howto/isolating-extensions.rst
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Expand Up @@ -461,7 +461,7 @@ Module State Access from Slot Methods, Getters and Setters

.. After adding to limited API:
If you use the :ref:`limited API <stable>,
If you use the :ref:`limited API <limited-c-api>`,
you must update ``Py_LIMITED_API`` to ``0x030b0000``, losing ABI
compatibility with earlier versions.
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2 changes: 1 addition & 1 deletion Doc/whatsnew/3.11.rst
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Expand Up @@ -2654,7 +2654,7 @@ Removed
* :c:func:`PyMarshal_WriteObjectToString`
* the ``Py_MARSHAL_VERSION`` macro

These are not part of the :ref:`limited API <stable-abi-list>`.
These are not part of the :ref:`limited API <limited-api-list>`.

(Contributed by Victor Stinner in :issue:`45474`.)

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2 changes: 1 addition & 1 deletion Misc/NEWS.d/3.11.0a1.rst
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Expand Up @@ -4980,7 +4980,7 @@ Removed documentation for the removed ``PyParser_*`` C API.
.. nonce: fy0AXK
.. section: C API
The list in :ref:`stable-abi-list` now shows the public name
The list in :ref:`limited-api-list` now shows the public name
:c:struct:`PyFrameObject` rather than ``_frame``. The non-existing entry
``_node`` no longer appears in the list.

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2 changes: 1 addition & 1 deletion Misc/NEWS.d/3.11.0a2.rst
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Expand Up @@ -1234,7 +1234,7 @@ defined:
* :c:func:`PyMarshal_WriteObjectToString`
* the ``Py_MARSHAL_VERSION`` macro

These are not part of the :ref:`limited API <stable-abi-list>`.
These are not part of the :ref:`limited API <limited-api-list>`.

Patch by Victor Stinner.

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