Remove redundant decref from _PyLong_Negate

[eendebakpt]

Feature or enhancement

Proposal:

In _PyLong_Negate there is a fast path for unique referenced longs. The slow path assumes the argument is a small int. We can add an assert for this condition, and remove the final decref (small ints are immortal).

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-143050: Remove redundant decref in _PyLong_Negate #143051

[serhiy-storchaka]

Even if they are immortal, I prefer to keep incref/decref balanced. This saves time when you read code.

[sergey-miryanov]

Maybe it is worth to replace Py_DECREF with something like Py_DECREF_IMMORTAL?

[eendebakpt]

Maybe it is worth to replace Py_DECREF with something like Py_DECREF_IMMORTAL?

I would be in favor of that. There is a related discussion here #124074