Sync pre-release CPython 3.15 branch from GitHub (2026-05-13)

Summary:
Imported python/cpython `3.15.0b1+` from upstream rev [`894ec10`](https://www.github.com/python/cpython/commit/894ec10b56d93743e082ac9569abf896e082a919) (committed 2026-05-13 23:34:59+00:00).

# Commit Info

Base: (`3.15.0b1+`) - [`15a597e`](https://www.github.com/python/cpython/commit/15a597e9ba0dd79bf953e181251788782fff6164) (commit date: 2026-05-13 03:36:32+00:00)
Imported: (`3.15.0b1+`) - [`894ec10`](https://www.github.com/python/cpython/commit/894ec10b56d93743e082ac9569abf896e082a919) (commit date: 2026-05-13 23:34:59+00:00)

# Noteworthy file changes

- Build system files (2 added): `PCbuild/xxlimited_3_13.vcxproj`, `PCbuild/xxlimited_3_13.vcxproj.filters`
- C files (1 added):
  ```
  + Modules/xxlimited_3_13.c
  ```
- Low-signal files (7 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GOrtwyZAmPcuvNQFADAHKwYkT7VDbr0LAAAz

Differential Revision: D105116672

fbshipit-source-id: dc7ea0e1991747986fe6cb34486802ae922069cf

Author: generatedunixname1734921407115435

.github/CODEOWNERS

@@ -573,9 +573,9 @@ Lib/shutil.py                 @giampaolo
 Lib/test/test_shutil.py       @giampaolo
 
 # Site
-Lib/site.py                   @FFY00
-Lib/test/test_site.py         @FFY00
-Doc/library/site.rst          @FFY00
+Lib/site.py                   @FFY00 @warsaw
+Lib/test/test_site.py         @FFY00 @warsaw
+Doc/library/site.rst          @FFY00 @warsaw
 
 # string.templatelib
 Doc/library/string.templatelib.rst        @lysnikolaou @AA-Turner

.github/workflows/mypy.yml

@@ -69,12 +69,11 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           persist-credentials: false
-      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+      - uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
         with:
           python-version: "3.15"
-          allow-prereleases: true
-          cache: pip
-          cache-dependency-path: Tools/requirements-dev.txt
-      - run: pip install -r Tools/requirements-dev.txt
+          activate-environment: true
+          cache-dependency-glob: Tools/requirements-dev.txt
+      - run: uv pip install -r Tools/requirements-dev.txt
       - run: python3 Misc/mypy/make_symlinks.py --symlink
-      - run: mypy --config-file ${{ matrix.target }}/mypy.ini
+      - run: mypy --num-workers 4 --config-file ${{ matrix.target }}/mypy.ini

Doc/c-api/sentinel.rst

@@ -14,8 +14,20 @@ Sentinel objects
 
 .. c:function:: int PySentinel_Check(PyObject *o)
 
-   Return true if *o* is a :class:`sentinel` object.  The :class:`sentinel` type
-   does not allow subclasses, so this check is exact.
+   Return true if *o* is a :class:`sentinel` object or a subtype.
+   The :class:`sentinel` type does not currently allow subclasses,
+   so this check is exact.
+   Future Python versions may choose to allow subtyping.
+   This function always succeeds.
+
+   .. versionadded:: 3.15
+
+.. c:function:: int PySentinel_CheckExact(PyObject *o)
+
+   Return true if *o* is a :class:`sentinel` object, but not a subtype.
+   The :class:`sentinel` type does not currently allow subclasses.
+   Future Python versions may choose to allow subtyping.
+   This function always succeeds.
 
    .. versionadded:: 3.15
 

Doc/c-api/stable.rst

@@ -114,7 +114,7 @@ versions of Python.
 
 All functions in Stable ABI are present as functions in Python's shared
 library, not solely as macros.
-This makes them usable are usable from languages that don't use the C
+This makes them usable in languages that don't use the C
 preprocessor, including Python's :py:mod:`ctypes`.
 
 

Include/cpython/sentinelobject.h

@@ -1,15 +1,18 @@
 /* Sentinel object interface */
 
 #ifndef Py_LIMITED_API
-#ifndef Py_SENTINELOBJECT_H
-#define Py_SENTINELOBJECT_H
+#ifndef _Py_SENTINELOBJECT_H
+#define _Py_SENTINELOBJECT_H
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 PyAPI_DATA(PyTypeObject) PySentinel_Type;
 
-#define PySentinel_Check(op) Py_IS_TYPE((op), &PySentinel_Type)
+#define PySentinel_CheckExact(op) Py_IS_TYPE((op), &PySentinel_Type)
+
+/* Alias as long as subclasses are not allowed. */
+#define PySentinel_Check(op) PySentinel_CheckExact(op)
 
 PyAPI_FUNC(PyObject *) PySentinel_New(
     const char *name,
@@ -18,5 +21,5 @@ PyAPI_FUNC(PyObject *) PySentinel_New(
 #ifdef __cplusplus
 }
 #endif
-#endif /* !Py_SENTINELOBJECT_H */
+#endif /* !_Py_SENTINELOBJECT_H */
 #endif /* !Py_LIMITED_API */

Include/cpython/sliceobject.h

@@ -1,4 +1,4 @@
-#ifndef Py_CPYTHON_SLICEOBJECT_H
+#ifndef _Py_CPYTHON_SLICEOBJECT_H
 #  error "this header file must not be included directly"
 #endif
 

Include/cpython/structseq.h

@@ -1,4 +1,4 @@
-#ifndef Py_CPYTHON_STRUCTSEQ_H
+#ifndef _Py_CPYTHON_STRUCTSEQ_H
 #  error "this header file must not be included directly"
 #endif
 

Include/internal/pycore_jit_unwind.h

@@ -11,7 +11,7 @@
 #if defined(_Py_JIT) && defined(__linux__) && defined(__ELF__)
 #  define PY_HAVE_JIT_GDB_UNWIND
 #  if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
-          defined(HAVE_LIBGCC_EH_FRAME_REGISTRATION)
+          defined(_Py_HAVE_LIBGCC_EH_FRAME_REGISTRATION)
 #    define PY_HAVE_JIT_GNU_BACKTRACE_UNWIND
 #  endif
 #endif

Include/internal/pycore_mmap.h

@@ -11,12 +11,12 @@ extern "C" {
 
 #include "pycore_pystate.h"
 
-#if defined(HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
+#if defined(_Py_HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
 #  include <linux/prctl.h>
 #  include <sys/prctl.h>
 #endif
 
-#if defined(HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
+#if defined(_Py_HAVE_PR_SET_VMA_ANON_NAME) && defined(__linux__)
 static inline int
 _PyAnnotateMemoryMap(void *addr, size_t size, const char *name)
 {

Include/sliceobject.h

@@ -45,9 +45,9 @@ PyAPI_FUNC(Py_ssize_t) PySlice_AdjustIndices(Py_ssize_t length,
 #endif
 
 #ifndef Py_LIMITED_API
-#  define Py_CPYTHON_SLICEOBJECT_H
+#  define _Py_CPYTHON_SLICEOBJECT_H
 #  include "cpython/sliceobject.h"
-#  undef Py_CPYTHON_SLICEOBJECT_H
+#  undef _Py_CPYTHON_SLICEOBJECT_H
 #endif
 
 #ifdef __cplusplus