Sync pre-release CPython 3.15 branch from GitHub (2026-08-02)

Summary:
Imported python/cpython `3.15.0b4+dev` from upstream rev [`07e73c0`](https://www.github.com/python/cpython/commit/07e73c01c5ba2f8ff6b5f237a8a87dfb88787383) (committed 2026-08-02 18:49:20+00:00).

# Commit Info

- Base: (`3.15.0b4+dev`) - [`74887c9`](https://www.github.com/python/cpython/commit/74887c9b832ef316c83e3bff14de0c866e305c7b) (commit date: 2026-08-01 20:22:23+00:00)
- Imported: (`3.15.0b4+dev`) - [`07e73c0`](https://www.github.com/python/cpython/commit/07e73c01c5ba2f8ff6b5f237a8a87dfb88787383) (commit date: 2026-08-02 18:49:20+00:00)

# Noteworthy file changes

- Low-signal files (2 added) (NEWS.d, docs, .github)
- Other files (3 added, 10 removed)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GGZjCRNdm7vP55cDAAnhr8_Yt1Y4br0LAAAz

Reviewed By: itamaro

Differential Revision: D114556804

fbshipit-source-id: 58a6e7e74df2a865d404294d7313e85ced2ba7d9

Author: generatedunixname1734921407115435

.github/workflows/reusable-san.yml

@@ -39,6 +39,8 @@ jobs:
       run: |
         sudo ./.github/workflows/posix-deps-apt.sh
         # On ubuntu-26.04 image, clang is clang-21 by default
+        # NOTE: when bumping to a new version of clang,
+        # please update the versions in `Tools/pixi-packages/variants.yaml` too.
         echo "CC=clang" >> "$GITHUB_ENV"
         echo "CXX=clang++" >> "$GITHUB_ENV"
     - name: TSan option setup

Doc/library/functools.rst

@@ -386,9 +386,9 @@ The :mod:`!functools` module defines the following functions:
    only one positional argument is provided, but there are two placeholders
    that must be filled in.
 
-   If :func:`!partial` is applied to an existing :func:`!partial` object,
-   :data:`!Placeholder` sentinels of the input object are filled in with
-   new positional arguments.
+   If :func:`!partial` is applied to an existing
+   :ref:`partial object <partial-objects>`, :data:`!Placeholder` sentinels of the
+   input object are filled in with new positional arguments.
    A placeholder can be retained by inserting a new
    :data:`!Placeholder` sentinel to the place held by a previous :data:`!Placeholder`:
 

Lib/logging/__init__.py

@@ -1697,7 +1697,11 @@ def removeHandler(self, hdlr):
         """
         with _lock:
             if hdlr in self.handlers:
-                self.handlers.remove(hdlr)
+                # Replace the list instead of mutating it in place, so that
+                # callHandlers() can iterate it without a lock (gh-79366).
+                handlers = self.handlers.copy()
+                handlers.remove(hdlr)
+                self.handlers = handlers
 
     def hasHandlers(self):
         """

Lib/test/test_logging.py

@@ -814,6 +814,23 @@ def lock_holder_thread_fn():
 
             support.wait_process(pid, exitcode=0)
 
+    def test_remove_handler_while_emitting(self):
+        # Removing a handler while callHandlers() iterates over the handlers
+        # should not cause the following handlers to be skipped (gh-79366).
+        logger = logging.Logger('test_remove_handler_while_emitting')
+        calls = []
+        class RemovingHandler(logging.Handler):
+            def emit(self, record):
+                calls.append('removing')
+                logger.removeHandler(self)
+        class CountingHandler(logging.Handler):
+            def emit(self, record):
+                calls.append('counting')
+        logger.addHandler(RemovingHandler())
+        logger.addHandler(CountingHandler())
+        logger.error('spam')
+        self.assertEqual(calls, ['removing', 'counting'])
+
 
 class BadStream(object):
     def write(self, data):

Misc/NEWS.d/next/Library/2026-07-23-06-53-01.gh-issue-79366.3gMT7I.rst

@@ -0,0 +1,3 @@
+Fixed a race condition in :mod:`logging`:
+if a handler was removed while a record was being emitted,
+the following handlers of the same logger could be skipped.

Misc/NEWS.d/next/Tools-Demos/2026-07-10-14-38-31.gh-issue-152384.uaPADM.rst

@@ -0,0 +1,8 @@
+The CPython Pixi packages are now all accessible at the same
+``Tools/pixi-packages`` subdirectory, rather than at
+``Tools/pixi-packages/{variant}`` as before. Variants are now selected not
+via subdirectory but via ``flags``; see
+https://pixi.prefix.dev/latest/concepts/package_specifications/#extras-and-flags
+for usage instructions. The ``tsan-freethreading`` variant has been renamed
+to ``tsan_freethreading``, while the ``default``, ``asan``, and
+``freethreading`` variants retain their previous names.

Modules/_decimal/_decimal.c

@@ -1690,12 +1690,12 @@ _decimal.Context.copy
 
     cls: defining_class
 
-Return a duplicate of the context with all flags cleared.
+Return a duplicate of the context.
 [clinic start generated code]*/
 
 static PyObject *
 _decimal_Context_copy_impl(PyObject *self, PyTypeObject *cls)
-/*[clinic end generated code: output=31c9c8eeb0c0cf77 input=aef1c0bddabdf8f0]*/
+/*[clinic end generated code: output=31c9c8eeb0c0cf77 input=87f8b92b1c7462a5]*/
 {
     decimal_state *state = PyType_GetModuleState(cls);
 

Modules/_decimal/clinic/_decimal.c.h

@@ -10,34 +10,34 @@ in a [Pixi workspace](https://pixi.sh/latest/first_workspace/), like:
 ```toml
 [dependencies]
 python.git = "https://github.com/python/cpython"
-python.subdirectory = "Tools/pixi-packages/asan"
+python.subdirectory = "Tools/pixi-packages"
+python.flags = ["asan"]
 ```
 
 This is particularly useful when developers need to build CPython from source
 (for example, for an ASan or TSan-instrumented build), as it does not require any manual
 clone or build steps. Instead, Pixi will automatically handle both the build
 and installation of the package.
 
-Each package definition is contained in a subdirectory, but they share the build script
-`build.sh` in this directory. Currently defined package variants:
+Each package variant carries a 'flag' to enable selection of that variant — see
+[the Pixi docs](https://pixi.prefix.dev/latest/concepts/package_specifications/#extras-and-flags)
+for details of how to use this. Currently defined package variants:
 
 - `default`
 - `freethreading`
 - `asan`: ASan-instrumented build
-- `tsan-freethreading`: TSan-instrumented free-threading build
+- `tsan_freethreading`: TSan-instrumented free-threading build
 
 ## Maintenance
 
-- Keep the `abi_tag` and `version` fields in each `variants.yaml` up to date with the
+- Keep the `version` field in `variants.yaml` up to date with the
   Python version
 - Update `build.sh` for any breaking changes in the `configure` and `make` workflow
 
 ## Opportunities for future improvement
 
 - More package variants (such as UBSan)
 - Support for Windows
-- Using a single `pixi.toml` for all package variants is blocked on
-  [pixi#5248](https://github.com/prefix-dev/pixi/issues/5248)
 
 ## Troubleshooting