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gh-141226: Deprecate PEP-456 support for embedders #141287

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gh-141226: Deprecate PEP-456 support for embedders #141287

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46bd556
Deprecate PEP 456 support for embedders
picnixz Nov 9, 2025
8d1ff1c
Merge branch 'main' into feat/deprecate/external-141226
picnixz Feb 7, 2026
bc00153
defer removal to Python 3.19
picnixz Feb 7, 2026
07e32b0
fixup
picnixz Feb 7, 2026
077d808
move deprecation notice under the C API section instead
picnixz Feb 7, 2026
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4 changes: 4 additions & 0 deletions Doc/deprecations/c-api-pending-removal-in-3.19.rst
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Pending removal in Python 3.19
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* :pep:`456` embedders support for the string hashing scheme definition.
4 changes: 4 additions & 0 deletions Doc/deprecations/index.rst
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Expand Up @@ -20,8 +20,12 @@ C API deprecations

.. include:: c-api-pending-removal-in-3.15.rst

.. include:: c-api-pending-removal-in-3.16.rst
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@hugovk hugovk Nov 9, 2025

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Good spot, we'll also need to backport this fix.

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@picnixz picnixz Nov 9, 2025

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Do you prefer that I open a separate PR for that? I can definitely do so for miss-ilington.


.. include:: c-api-pending-removal-in-3.18.rst

.. include:: c-api-pending-removal-in-3.19.rst

.. include:: c-api-pending-removal-in-3.20.rst

.. include:: c-api-pending-removal-in-future.rst
10 changes: 10 additions & 0 deletions Doc/whatsnew/3.15.rst
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Expand Up @@ -1538,6 +1538,16 @@ on Python 3.13 and older.
Deprecated C APIs
-----------------

* Deprecate :pep:`456` support for providing an external definition
of the string hashing scheme. Removal is scheduled for Python 3.19.

Previously, embedders could define :c:macro:`Py_HASH_ALGORITHM` to be
``Py_HASH_EXTERNAL`` to indicate that the hashing scheme was provided
externally but this feature was undocumented, untested and most likely
unused.

(Contributed by Bénédikt Tran in :gh:`141226`.)

* For unsigned integer formats in :c:func:`PyArg_ParseTuple`,
accepting Python integers with value that is larger than the maximal value
for the C type or less than the minimal value for the corresponding
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-11-09-15-44-58.gh-issue-141226.KTb_3F.rst
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Deprecate :pep:`456` support for providing an external definition
of the string hashing scheme. Removal is scheduled for Python 3.19.
Patch by Bénédikt Tran.
2 changes: 1 addition & 1 deletion Python/pyhash.c
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Expand Up @@ -17,7 +17,7 @@
_Py_HashSecret_t _Py_HashSecret = {{0}};

#if Py_HASH_ALGORITHM == Py_HASH_EXTERNAL
extern PyHash_FuncDef PyHash_Func;
Py_DEPRECATED(3.15) extern PyHash_FuncDef PyHash_Func;
#else
static PyHash_FuncDef PyHash_Func;
#endif
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