Sync pre-release CPython main branch from GitHub (2026-08-01)

Summary:
Imported python/cpython `3.16.0a0` from upstream rev [`7b4165b`](https://www.github.com/python/cpython/commit/7b4165b3b07638d8aeab79a880c52f2b51c56f37) (committed 2026-08-01 19:54:04+00:00).

# Commit Info

- Base: (`3.16.0a0`) - [`a646c99`](https://www.github.com/python/cpython/commit/a646c99ee12fbf421394a74955d42fd3fe850b7e) (commit date: 2026-07-31 16:18:49+00:00)
- Imported: (`3.16.0a0`) - [`7b4165b`](https://www.github.com/python/cpython/commit/7b4165b3b07638d8aeab79a880c52f2b51c56f37) (commit date: 2026-08-01 19:54:04+00:00)

# Noteworthy file changes

- Low-signal files (3 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GJqWfC0NOZZN-6MDABOP4Fp6mmMSbr0LAAAz

Reviewed By: itamaro

Differential Revision: D114507654

fbshipit-source-id: 4c8d0adc6c51375d478ef2fd0b64437669049c67

Author: generatedunixname1734921407115435

.github/workflows/build.yml

@@ -338,7 +338,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Build and test
-        run: JAVA_HOME="${JAVA_HOME_21_X64:-$JAVA_HOME_21_arm64}" python3 Platforms/Android ci --fast-ci ${{ matrix.arch }}-linux-android
+        run: python3 Platforms/Android ci --fast-ci ${{ matrix.arch }}-linux-android
 
   build-ios:
     name: iOS

Include/internal/pycore_lock.h

@@ -34,6 +34,11 @@ _PyMutex_at_fork_reinit(PyMutex *m)
 
 typedef enum _PyLockFlags {
     // Do not detach/release the GIL when waiting on the lock.
+    //
+    // Note that code executed while holding a mutex with this flag must
+    // not detach, reach a safepoint or initiate a stop-the-world pause.
+    // Otherwise, a non-detaching waiter may remain waiting for this mutex and
+    // prevent the pause from completing.
     _Py_LOCK_DONT_DETACH = 0,
 
     // Detach/release the GIL while waiting on the lock.

Lib/test/test_asyncio/test_tasks.py

@@ -2924,6 +2924,16 @@ async def coro():
         with self.assertRaises(AttributeError):
             del task._log_destroy_pending
 
+    def test_get_context_uninitialized_segfault(self):
+        # https://github.com/python/cpython/issues/154871
+
+        class UninitializedTask(self.Task):
+            def __init__(self, *args, **kwargs):
+                pass
+
+        task = UninitializedTask()
+        self.assertIsNone(task.get_context())
+
 
 @unittest.skipUnless(hasattr(futures, '_CFuture') and
                      hasattr(tasks, '_CTask'),

Lib/test/test_free_threading/test_collections.py

@@ -1,5 +1,5 @@
 import unittest
-from collections import deque
+from collections import OrderedDict, deque
 from copy import copy
 from test.support import threading_helper
 
@@ -49,5 +49,30 @@ def mutate():
         )
 
 
+class TestOrderedDict(unittest.TestCase):
+    def test_iterator_update_clear_race(self):
+        # gh-151627: OrderedDict iterator construction must not race with
+        # concurrent clear()/update() operations that mutate the linked list.
+        od = OrderedDict((i, i) for i in range(100))
+
+        def mutate():
+            for i in range(5000):
+                od.clear()
+                od.update(((i, i), (i + 1, i + 1), (i + 2, i + 2)))
+
+        def iterate():
+            for _ in range(5000):
+                try:
+                    for _ in od:
+                        pass
+                    list(reversed(od))
+                except RuntimeError:
+                    pass
+
+        threading_helper.run_concurrently(
+            [mutate, *[iterate for _ in range(8)]],
+        )
+
+
 if __name__ == "__main__":
     unittest.main()

Lib/test/test_zoneinfo/test_zoneinfo.py

@@ -316,6 +316,18 @@ def test_unambiguous(self):
                 self.assertEqual(dt.utcoffset(), offset.utcoffset, dt)
                 self.assertEqual(dt.dst(), offset.dst, dt)
 
+    def test_datetime_subclass_negative_components(self):
+        class MinusOneDateTime(datetime):
+            hour = minute = second = -1
+
+        zi = self.zone_from_key("UTC")
+        dt = MinusOneDateTime(2024, 1, 1, tzinfo=zi)
+
+        self.assertEqual(dt.utcoffset(), ZERO)
+        self.assertEqual(dt.dst(), ZERO)
+        self.assertEqual(dt.tzname(), "UTC")
+        self.assertEqual(zi.fromutc(dt), datetime(2024, 1, 1, tzinfo=zi))
+
     def test_folds_and_gaps(self):
         test_cases = []
         for key in self.zones():

Misc/NEWS.d/next/Library/2026-06-19-08-30-00.gh-issue-151627.xY7kLm.rst

@@ -0,0 +1,2 @@
+Fix a crash in :class:`collections.OrderedDict` iterators in free-threaded
+builds when the dictionary is concurrently cleared or updated.

Misc/NEWS.d/next/Library/2026-07-29-19-48-59.gh-issue-154871.tgZILS.rst

@@ -0,0 +1,2 @@
+Fixed a crash in :meth:`asyncio.Task.get_context`
+when called on an uninitialized task.

Misc/NEWS.d/next/Library/2026-07-29-21-37-39.gh-issue-154892.eQyJ3Z.rst

@@ -0,0 +1,3 @@
+Fix a bug in the C accelerator for :mod:`zoneinfo` where
+:class:`datetime.datetime` subclasses returning ``-1`` for ``hour``,
+``minute``, or ``second`` could incorrectly raise a :exc:`SystemError`.

Modules/_asynciomodule.c

@@ -2786,7 +2786,11 @@ static PyObject *
 _asyncio_Task_get_context_impl(TaskObj *self)
 /*[clinic end generated code: output=6996f53d3dc01aef input=87c0b209b8fceeeb]*/
 {
-    return Py_NewRef(self->task_context);
+    if (self->task_context) {
+        return Py_NewRef(self->task_context);
+    }
+
+    Py_RETURN_NONE;
 }
 
 /*[clinic input]

Modules/_zoneinfo.c

@@ -2311,7 +2311,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
         }
         hour = PyLong_AsLong(num);
         Py_DECREF(num);
-        if (hour == -1) {
+        if (hour == -1 && PyErr_Occurred()) {
             return -1;
         }
 
@@ -2321,7 +2321,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
         }
         minute = PyLong_AsLong(num);
         Py_DECREF(num);
-        if (minute == -1) {
+        if (minute == -1 && PyErr_Occurred()) {
             return -1;
         }
 
@@ -2331,7 +2331,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
         }
         second = PyLong_AsLong(num);
         Py_DECREF(num);
-        if (second == -1) {
+        if (second == -1 && PyErr_Occurred()) {
             return -1;
         }
     }