[3.9] bpo-40777: Initialize PyDateTime_IsoCalendarDateType.tp_base at run-time (GH-20493) by miss-islington · Pull Request #20495 · python/cpython

Recent changes to _datetimemodule broke compilation on mingw; see the comments in this change for details.

FWIW, @corona10: this issue is why PyType_FromModuleAndSpec & friends take the bases argument at run time.
(cherry picked from commit 459acc5)

Co-authored-by: Petr Viktorin encukou@gmail.com

https://bugs.python.org/issue40777

Automerge-Triggered-By: @encukou