The datetime module was partially converted to Argument Clinic. The following PR converts more functions. This adds signatures for some classes and methods. As a side effect, this may improve performance.

Usually we avoid behavior changes in conversions to Argument Clinic, but there is one such change in the following PR. Currently, fromisocalendar() always raises ValueError for out of range arguments. After conversion, it will raise OverflowError for values that can't fit in the C int. This is a regression. But all other methods that take integer arguments raise OverflowError. It is better to raise ValueError, but this should be consistent for all methods.

Linked PRs

• gh-136571: Convert more code in datetime to Argument Clinic #136573