Deprecate Py_IS_NAN/INFINITY/FINITE?

[skirpichev]

Feature or enhancement

Proposal:

isnan(), isinf() and isfinite() are part of C99, which is a requirement for 3.11+. Probably, it does make sense to deprecate (undocumented) public macros and switch codebase to use C stdlib functions.

JFR: #119457 (comment)

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:

No response

Linked PRs

• gh-119613: use C99+ functions instead of Py_IS_NAN/INFINITY/FINITE #119619
• gh-119613: deprecate Py_IS_NAN/INFINITY and Py_IS_FINITE #119701
• gh-119613: Soft deprecate the Py_MEMCPY() macro #120020

[skirpichev]

CC @vstinner as author of 194a952

I'll work on a patch.

[skirpichev]

First part: #119619

[vstinner]

isnan(), isinf() and isfinite() are part of C99, which is a requirement for 3.11+. Probably, it does make sense to deprecate (undocumented) public macros and switch codebase to use C stdlib functions.

A code search on PyPI top 7,500 projects found 10 projects using these macros:

• Nuitka (2.1.2)
• aim (3.19.1)
• fastcluster (1.2.6)
• gmpy2 (2.1.5)
• msgspec (0.18.6)
• numba (0.59.0)
• pandas (2.2.1)
• python-rapidjson (1.16)
• simplejson (3.19.2)
• vowpalwabbit (9.9.0)

I suggest to update all of these projects before considering to deprecate these macros.

I would be fine with a soft deprecation. It's the kind of the issue which fall into PEP 743 – Add Py_COMPAT_API_VERSION to the Python C API territory: having a way to opt-out from deprecated macros, without forcing all projects to update their code.

[skirpichev]

@vstinner, these macroses were undocumented. Should we (1) document them (with "deprecated" statement) and (2) add news entry? Or (2) is enough?

I would be fine with a soft deprecation.

If we don't announce removal (e.g. deprecated-removed statement) wouldn't this be a soft deprecation?

---

• Nuitka (2.1.2)
• aim (3.19.1)
• fastcluster (1.2.6)
• gmpy2 (2.1.5) // Use C99+ math.h functions instead of Py_IS_NAN/INFINITY/FINITE aleaxit/gmpy#485
• msgspec (0.18.6)
• numba (0.59.0)
• pandas (2.2.1) // CLN: use isnan() instead of the Py_IS_NAN macro pandas-dev/pandas#58850
• python-rapidjson (1.16)
• simplejson (3.19.2)
• vowpalwabbit (9.9.0)

[vstinner]

You can announce the soft deprecation in What's New in Python 3.14 and add a comment to explain that these macros are soft deprecated.

[skirpichev]

Maybe this could go to 3.13?

[vstinner]

Maybe this could go to 3.13?

Deprecations cannot be added after beta1.

[skirpichev]

Ok, last part: #119701