commit eceee544de4b0f885729022c135c53291b6bbb23
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Thu May 28 09:41:41 2020 -0700
committer GitHub <noreply@github.com> Thu May 28 09:41:41 2020 -0700
tree ad8ba3b254b0d92eaac5f21b07c3843e90669c49
parent a5936ad6323b2cda712726a25d9301f766146cff

[3.9] bpo-40777: Initialize PyDateTime_IsoCalendarDateType.tp_base at run-time (GH-20493) (GH-20495)



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 459acc551656785bc4a3363d65c7a60f822da8e3)


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

Modules/_datetimemodule.c

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 7a5efd2..acdde83 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3325,7 +3325,7 @@
     .tp_doc = iso_calendar_date__doc__,
     .tp_methods = iso_calendar_date_methods,
     .tp_getset = iso_calendar_date_getset,
-    .tp_base = &PyTuple_Type,
+    // .tp_base = &PyTuple_Type,  // filled in PyInit__datetime
     .tp_new = iso_calendar_date_new,
 };
 
@@ -4079,7 +4079,7 @@
     timezone_methods,                 /* tp_methods */
     0,                                /* tp_members */
     0,                                /* tp_getset */
-    &PyDateTime_TZInfoType,           /* tp_base */
+    0,                                /* tp_base; filled in PyInit__datetime */
     0,                                /* tp_dict */
     0,                                /* tp_descr_get */
     0,                                /* tp_descr_set */
@@ -6458,7 +6458,8 @@
     datetime_methods,                           /* tp_methods */
     0,                                          /* tp_members */
     datetime_getset,                            /* tp_getset */
-    &PyDateTime_DateType,                       /* tp_base */
+    0,                                          /* tp_base; filled in
+                                                   PyInit__datetime */
     0,                                          /* tp_dict */
     0,                                          /* tp_descr_get */
     0,                                          /* tp_descr_set */
@@ -6524,6 +6525,12 @@
     if (m == NULL)
         return NULL;
 
+    // `&...` is not a constant expression according to a strict reading
+    // of C standards. Fill tp_base at run-time rather than statically.
+    // See https://bugs.python.org/issue40777
+    PyDateTime_IsoCalendarDateType.tp_base = &PyTuple_Type;
+    PyDateTime_TimeZoneType.tp_base = &PyDateTime_TZInfoType;
+    PyDateTime_DateTimeType.tp_base = &PyDateTime_DateType;
 
     PyTypeObject *types[] = {
         &PyDateTime_DateType,