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gh-141563: make PyDateTime_IMPORT thread-safe #144210

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Merged
kumaraditya303 merged 6 commits into from
Feb 9, 2026
+18 −2
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gh-141563: make PyDateTime_IMPORT thread-safe #144210

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c3f4649
make PyDateTime_IMPORT thread-safe
kumaraditya303 Jan 24, 2026
36a06c8
use static inline function
kumaraditya303 Jan 24, 2026
8488875
macro magic
kumaraditya303 Feb 2, 2026
9a58924
Merge branch 'main' into datetime
kumaraditya303 Feb 2, 2026
12a008d
📜🤖 Added by blurb_it.
blurb-it[bot] Feb 2, 2026
a1bbafd
Merge branch 'main' into datetime
kumaraditya303 Feb 9, 2026
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19 changes: 17 additions & 2 deletions Include/datetime.h
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Original file line number Diff line number Diff line change
Expand Up @@ -196,8 +196,23 @@ typedef struct {
/* Define global variable for the C API and a macro for setting it. */
static PyDateTime_CAPI *PyDateTimeAPI = NULL;

#define PyDateTime_IMPORT \
PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)
static inline PyDateTime_CAPI *
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@mekrix777mekort-ops mekrix777mekort-ops Feb 9, 2026

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Sup non invert,'s ok!

_PyDateTime_IMPORT(void) {
PyDateTime_CAPI *val = _Py_atomic_load_ptr(&PyDateTimeAPI);
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@scoder scoder Feb 10, 2026

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I'm now seeing this error in external code that includes datetime.h:

…/cpython_install/include/python3.15/datetime.h:201:22: error: cannot initialize a variable of type 'PyDateTime_CAPI *' with an rvalue of type 'void *'
  201 |     PyDateTime_CAPI *val = _Py_atomic_load_ptr(&PyDateTimeAPI);
      |                      ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Probably just missing a cast.

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@vstinner vstinner Feb 10, 2026

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Do you get the error with C or C++?

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@vstinner vstinner Feb 10, 2026

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Ah, there is a compiler error in C++. I wrote #144667 to add the missing cast, but also to add checks for compiler warnings (to test_cext and test_cppext).

if (val == NULL) {
PyDateTime_CAPI *capi = (PyDateTime_CAPI *)PyCapsule_Import(
PyDateTime_CAPSULE_NAME, 0);
if (capi != NULL) {
/* if the compare exchange fails then in that case
another thread would have initialized it */
_Py_atomic_compare_exchange_ptr(&PyDateTimeAPI, &val, (void *)capi);
return capi;
}
}
return val;
}

#define PyDateTime_IMPORT _PyDateTime_IMPORT()

/* Macro for access to the UTC singleton */
#define PyDateTime_TimeZone_UTC PyDateTimeAPI->TimeZone_UTC
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-02-02-17-07-34.gh-issue-141563.GheXjr.rst
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@@ -0,0 +1 @@
Fix thread safety of :c:macro:`! PyDateTime_IMPORT`.
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