backports/_datetime_fromisoformat.cpython-312-darwin.so: Mach-O 64-bit bundle arm64

[mockodin]

The backports should be conditional - this throws errors for ARM on py3.12+

Site packages contain compiled extensions with mismatched architecture. Expected x86_64, found:

• .../python3.12/site-packages/backports/_datetime_fromisoformat.cpython-312-darwin.so: .../python3.12/site-packages/backports/_datetime_fromisoformat.cpython-312-darwin.so: Mach-O 64-bit bundle arm64

marshmallow/src/marshmallow/fields.py

Lines 23 to 29 in 27bfa77

	# Remove when dropping Python 3.10
	try:
	from backports.datetime_fromisoformat import MonkeyPatch
	except ImportError:
	pass
	else:
	MonkeyPatch.patch_fromisoformat()

Recommend adding a Python version check to only import backports.datetime_fromisoformat for Python < 3.11.

Currently, marshmallow unconditionally attempts to import the backport (and its compiled extension), which is not needed or appropriate for Python 3.11+ (where datetime.fromisoformat is built-in). On Python 3.12 ARM Macs, this can fail at load time due to a Mach-O architecture mismatch (arm64 vs x86_64) for the compiled extension.

Suggested fix:

import sys

# Remove when dropping Python 3.10
if sys.version_info < (3, 11):
    try:
        from backports.datetime_fromisoformat import MonkeyPatch
    except ImportError:
        pass
    else:
        MonkeyPatch.patch_fromisoformat()

This ensures the patch is only attempted on versions that actually require it, avoiding both unnecessary imports and potential architecture errors on newer Python versions.

[deckar01]

I can’t reproduce this with marshmallow 4.3.0 on an M1 Mac using python 3.12.13 or 3.13.2.

marshmallow/pyproject.toml

Line 25 in 27bfa77

"backports-datetime-fromisoformat; python_version < '3.11'",

That dependency should not have been included by our requirements. It has been conditional on the python version since it was added. Even if I manually install it I don’t get that error.

It sounds like a broken package that can be fixed with pip uninstall backports-datetime-fromisoformat.

[mockodin]

Presumably another module also importing doesn't include "backports-datetime-fromisoformat; python_version < '3.11'" however unconditionally importing within code is unperdiectable, case in point. Could be package evaulation by pygralde, in any case adding a conditional on the import ensures consistency.

To ackowledge - this doesn't appear to be a marshmallow at fault issue. It is one that could still be worth as a standard consideration however.