Adding Py_HashBuffer to the Stable ABI

Feature or enhancement

Proposal:

The function Py_HashBuffer was added in PR: #122854

This was included in Python 3.14

Would like to propose adding this to the Stable ABI

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

This came up in discussion in the PR, but hadn't been done there as it wasn't determined previously. So would like to open this discussion

Linked PRs

@vstinner

cc @vstinner

The function is properly documented and tested (by test_capi.test_hash). It has a well defined API. It's a good candidate for the stable ABI.

I went ahead and created github.com/capi-workgroup/decisions/issues/102 in the C API Working Group.

The C API Working Group voted in favor of adding Py_HashBuffer() to the stable ABI. I created #157966 to move Py_HashBuffer() to the limited C API.

gh-148233: Add Py_HashBuffer() to the limited C API (#157966)

@jakirkham

I merged my PR. Py_HashBuffer() is now available on Python 3.16 limited C API. Thanks for your suggestion @jakirkham.

On older versions, I suppose that you should create a bytes string and call PyObject_Hash().

pythongh-148233: Group stable_abi.toml entries per Python version

gh-148233: Group stable_abi.toml entries per Python version (GH-157990)

[3.15] gh-158886: Add INCREF/DECREF macros to stable_abi.toml (GH-158941

[3.14] gh-158886: Add INCREF/DECREF macros to stable_abi.toml (GH-158941

Thank you Victor! Appreciate your help navigating this process 🙏

FYI I added the function to pythoncapi-compat with this implementation for older Python versions:

#if !defined(PYPY_VERSION) && !defined(Py_LIMITED_API)
PyAPI_FUNC(Py_hash_t) _Py_HashBytes(const void *src, Py_ssize_t len);
#endif

static inline Py_hash_t Py_HashBuffer(const void *ptr, Py_ssize_t len)
{
#if !defined(PYPY_VERSION) && !defined(Py_LIMITED_API)
    return _Py_HashBytes(ptr, len);
#else
    Py_hash_t hash;
    PyObject *bytes = PyBytes_FromStringAndSize((const char*)ptr, len);
    if (bytes == NULL) {
        return -1;
    }
    hash = PyObject_Hash(bytes);
    Py_DECREF(bytes);
    return hash;
#endif
}

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Adding `Py_HashBuffer` to the Stable ABI #148233

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Adding Py_HashBuffer to the Stable ABI #148233

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Feature or enhancement

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Has this already been discussed elsewhere?

Links to previous discussion of this feature:

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picnixz commented on Apr 8, 2026

vstinner commented on Apr 9, 2026

vstinner commented on Apr 9, 2026

vstinner commented on Sep 22, 2026

vstinner commented on Sep 23, 2026

jakirkham commented on Oct 13, 2026

vstinner commented on Oct 13, 2026

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Adding `Py_HashBuffer` to the Stable ABI #148233