gh-102304: doc: Add links to Stable ABI and Limited C API (#105345)

* Add "limited-c-api" and "stable-api" references.
* Rename "stable-abi-list" reference to "limited-api-list".
* Makefile: Document files regenerated by "make regen-limited-abi"
* Remove first empty line in generated files:

  - Lib/test/test_stable_abi_ctypes.py
  - PC/python3dll.c
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Victor Stinner 2023-06-06 10:40:32 +02:00 • committed by GitHub
parent 00d73caf80
commit bae415ad02
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17 changed files with 58 additions and 42 deletions

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@ -887,7 +887,7 @@ 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)
@ -895,7 +895,7 @@ because the :ref:`call protocol <call>` takes care of recursion handling.
*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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@ -20,9 +20,9 @@ but will need to be compiled separately for 3.9.x and 3.10.x.
There are two tiers of C API with different stability exepectations:
- *Unstable API*, may change in minor versions without a deprecation period.
It is marked by the ``PyUnstable`` prefix in names.
- *Limited API*, is compatible across several minor releases.
- :ref:`Unstable API <unstable-c-api>`, may change in minor versions without
a deprecation period. It is marked by the ``PyUnstable`` prefix in names.
- :ref:`Limited API <limited-c-api>`, is compatible across several minor releases.
When :c:macro:`Py_LIMITED_API` is defined, only this subset is exposed
from ``Python.h``.
@ -55,19 +55,15 @@ CPython development and spend extra effort adjusting to changes.
Stable Application Binary Interface
===================================
.. _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
@ -87,6 +83,23 @@ 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.
(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.)
On Windows, extensions that use the Stable ABI should be linked against
``python3.dll`` rather than a version-specific library such as
``python39.dll``.
@ -131,9 +144,9 @@ 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.
@ -166,9 +179,9 @@ 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
@ -177,12 +190,12 @@ 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::

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@ -288,7 +288,7 @@ 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>`.
.. data:: METH_FASTCALL | METH_KEYWORDS

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@ -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
@ -472,7 +472,7 @@ 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 *pfunc

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@ -2150,7 +2150,7 @@ 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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@ -994,7 +994,7 @@ 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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@ -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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@ -803,7 +803,7 @@ The :mod:`test.support` module defines the following functions:
.. decorator:: requires_limited_api
Decorator for only running the test if :ref:`Limited C API <stable>`
Decorator for only running the test if :ref:`Limited C API <limited-c-api>`
is available.

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@ -2650,7 +2650,7 @@ 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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@ -1580,7 +1580,7 @@ New Features
(Contributed by Petr Viktorin in :gh:`103509`.)
* Added the new limited C API function :c:func:`PyType_FromMetaclass`,
* Added the new :ref:`limited C API <limited-c-api>` function :c:func:`PyType_FromMetaclass`,
which generalizes the existing :c:func:`PyType_FromModuleAndSpec` using
an additional metaclass argument.
(Contributed by Wenzel Jakob in :gh:`93012`.)

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@ -1,5 +1,4 @@
# Generated by Tools/scripts/stable_abi.py
# Generated by Tools/build/stable_abi.py
"""Test that all symbols of the Stable ABI are accessible using ctypes
"""

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@ -1309,6 +1309,11 @@ check-abidump: all
.PHONY: regen-limited-abi
regen-limited-abi: all
# Regenerate files using using Tools/build/stable_abi.py:
# - Doc/data/stable_abi.dat
# - Lib/test/test_stable_abi_ctypes.py
# - Modules/_testcapi_feature_macros.inc
# - PC/python3dll.c
$(RUNSHARED) ./$(BUILDPYTHON) $(srcdir)/Tools/build/stable_abi.py --generate-all $(srcdir)/Misc/stable_abi.toml
############################################################################

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@ -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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@ -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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@ -1,4 +1,4 @@
// Generated by Tools/scripts/stable_abi.py
// Generated by Tools/build/stable_abi.py
// Add an entry in dict `result` for each Stable ABI feature macro.

1
PC/python3dll.c generated
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@ -1,4 +1,3 @@
/* Re-export stable Python ABI */
/* Generated by Tools/build/stable_abi.py */

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@ -183,7 +183,7 @@ def generator(var_name, default_path):
def gen_python3dll(manifest, args, outfile):
"""Generate/check the source for the Windows stable ABI library"""
write = partial(print, file=outfile)
content = f"""
content = f"""\
/* Re-export stable Python ABI */
/* Generated by {SCRIPT_NAME} */
@ -267,8 +267,8 @@ def gen_doc_annotations(manifest, args, outfile):
def gen_ctypes_test(manifest, args, outfile):
"""Generate/check the ctypes-based test for exported symbols"""
write = partial(print, file=outfile)
write(textwrap.dedent('''
# Generated by Tools/scripts/stable_abi.py
write(textwrap.dedent(f'''\
# Generated by {SCRIPT_NAME}
"""Test that all symbols of the Stable ABI are accessible using ctypes
"""
@ -341,7 +341,7 @@ def gen_ctypes_test(manifest, args, outfile):
def gen_testcapi_feature_macros(manifest, args, outfile):
"""Generate/check the stable ABI list for documentation annotations"""
write = partial(print, file=outfile)
write('// Generated by Tools/scripts/stable_abi.py')
write(f'// Generated by {SCRIPT_NAME}')
write()
write('// Add an entry in dict `result` for each Stable ABI feature macro.')
write()