Sync pre-release CPython 3.15 branch from GitHub (2026-08-27)

Summary:
Imported python/cpython `3.15.0rc1+dev` from upstream rev [`431f526`](https://www.github.com/python/cpython/commit/431f526550dd683978b146d2b318ddd1933acf2f) (committed 2026-08-27 14:03:46+00:00).

# Commit Info

- Base: (`3.15.0rc1+dev`) - [`1c826a4`](https://www.github.com/python/cpython/commit/1c826a40a2f9606e284fd3d6d5f7c7c6732327ed) (commit date: 2026-08-26 00:59:49+00:00)
- Imported: (`3.15.0rc1+dev`) - [`431f526`](https://www.github.com/python/cpython/commit/431f526550dd683978b146d2b318ddd1933acf2f) (commit date: 2026-08-27 14:03:46+00:00)

# Noteworthy file changes

- Low-signal files (8 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GDwh9i5mcJlzFRgGAHLO_yxfQHYvbr0LAAAz

Differential Revision: D117820797

fbshipit-source-id: 9a9c07f8d98117b454a2587fefae2583b2f58c9d

Author: generatedunixname1734921407115435

Doc/Makefile

@@ -32,6 +32,7 @@ help:
 	@echo "Please use \`make <target>' where <target> is one of"
 	@echo "  clean      to remove build files"
 	@echo "  venv       to create a venv with necessary tools"
+	@echo "  lock       to regenerate the pinned dependencies in $(REQUIREMENTS)"
 	@echo "  html       to make standalone HTML files"
 	@echo "  gettext    to generate POT files"
 	@echo "  htmlview   to open the index page built by the html target in your browser"
@@ -185,6 +186,19 @@ venv:
 		echo "The venv has been created in the $(VENVDIR) directory"; \
 	fi
 
+.PHONY: lock
+lock:
+# Dependencies have a 14 day cooldown period to mitigate supply chain attacks,
+# except for sphinx_linklint and python-docs-theme, which are maintained by
+# core team members.
+	uv pip compile requirements.txt \
+		--exclude-newer P14D \
+		--exclude-newer-package sphinx_linklint=PT0S \
+		--exclude-newer-package python-docs-theme=PT0S \
+		--no-cache --output-file $(REQUIREMENTS) \
+		--python-version 3.12 --universal \
+		--custom-compile-command="make lock"
+
 .PHONY: dist-no-html
 dist-no-html: dist-text dist-epub dist-texinfo
 

Doc/c-api/import.rst

@@ -146,7 +146,7 @@ Importing Modules
       alternatives.
 
    .. versionchanged:: 3.15
-      ``__cached__`` is no longer set.
+      The ``__cached__`` attribute is no longer set.
 
 
 .. c:function:: PyObject* PyImport_ExecCodeModuleEx(const char *name, PyObject *co, const char *pathname)
@@ -170,7 +170,7 @@ Importing Modules
       :class:`~importlib.machinery.ModuleSpec` for alternatives.
 
    .. versionchanged:: 3.15
-      ``__cached__`` no longer set.
+      The ``__cached__`` attribute no longer set.
 
 
 .. c:function:: PyObject* PyImport_ExecCodeModuleWithPathnames(const char *name, PyObject *co, const char *pathname, const char *cpathname)

Doc/conf.py

@@ -41,7 +41,7 @@
 
 # Skip if downstream redistributors haven't installed them
 _OPTIONAL_EXTENSIONS = (
-    'linklint.ext',
+    'sphinx_linklint.ext',
     'notfound.extension',
     'sphinxext.opengraph',
     'sphinxcontrib.rsvgconverter',

Doc/library/asyncio-stream.rst

@@ -49,7 +49,7 @@ and work with streams:
 
 
 .. function:: open_connection(host=None, port=None, *, \
-                 limit=None, ssl=None, family=0, proto=0, \
+                 limit=65536, ssl=None, family=0, proto=0, \
                  flags=0, sock=None, local_addr=None, \
                  server_hostname=None, ssl_handshake_timeout=None, \
                  ssl_shutdown_timeout=None, \
@@ -89,7 +89,7 @@ and work with streams:
 
 
 .. function:: start_server(client_connected_cb, host=None, \
-                 port=None, *, limit=None, \
+                 port=None, *, limit=65536, \
                  family=socket.AF_UNSPEC, \
                  flags=socket.AI_PASSIVE, sock=None, \
                  backlog=100, ssl=None, reuse_address=None, \
@@ -137,7 +137,7 @@ and work with streams:
 
 .. rubric:: Unix Sockets
 
-.. function:: open_unix_connection(path=None, *, limit=None, \
+.. function:: open_unix_connection(path=None, *, limit=65536, \
                ssl=None, sock=None, server_hostname=None, \
                ssl_handshake_timeout=None, ssl_shutdown_timeout=None)
    :async:
@@ -169,7 +169,7 @@ and work with streams:
 
 
 .. function:: start_unix_server(client_connected_cb, path=None, \
-                 *, limit=None, sock=None, backlog=100, ssl=None, \
+                 *, limit=65536, sock=None, backlog=100, ssl=None, \
                  ssl_handshake_timeout=None, \
                  ssl_shutdown_timeout=None, start_serving=True, cleanup_socket=True)
    :async:

Doc/library/asyncio-subprocess.rst

@@ -62,7 +62,7 @@ Creating Subprocesses
 =====================
 
 .. function:: create_subprocess_exec(program, *args, stdin=None, \
-                 stdout=None, stderr=None, limit=None, **kwds)
+                 stdout=None, stderr=None, limit=65536, **kwds)
    :async:
 
    Create a subprocess.
@@ -84,7 +84,7 @@ Creating Subprocesses
 
 
 .. function:: create_subprocess_shell(cmd, stdin=None, \
-                 stdout=None, stderr=None, limit=None, **kwds)
+                 stdout=None, stderr=None, limit=65536, **kwds)
    :async:
 
    Run the *cmd* shell command.

Doc/library/asyncio-task.rst

@@ -843,17 +843,13 @@ Timeouts
    Wait for the *aw* :ref:`awaitable <asyncio-awaitables>`
    to complete with a timeout.
 
-   If *aw* is a coroutine it is automatically scheduled as a Task.
-
    *timeout* can either be ``None`` or a float or int number of seconds
    to wait for.  If *timeout* is ``None``, block until the future
    completes.
 
-   If a timeout occurs, it cancels the task and raises
-   :exc:`TimeoutError`.
+   If a timeout occurs, it cancels *aw* and raises :exc:`TimeoutError`.
 
-   To avoid the task :meth:`cancellation <Task.cancel>`,
-   wrap it in :func:`shield`.
+   To prevent *aw* from being cancelled, wrap it in :func:`shield`.
 
    The function will wait until the future is actually cancelled,
    so the total wait time may exceed the *timeout*. If an exception
@@ -894,6 +890,10 @@ Timeouts
    .. versionchanged:: 3.11
       Raises :exc:`TimeoutError` instead of :exc:`asyncio.TimeoutError`.
 
+   .. versionchanged:: 3.12
+      Implemented using :func:`asyncio.timeout`, a coroutine passed as *aw*
+      is no longer wrapped in a :class:`Task` when *timeout* is positive.
+
 
 Waiting primitives
 ==================

Doc/library/csv.rst

@@ -475,6 +475,10 @@ Dialects support the following attributes:
    On reading, the *escapechar* removes any special meaning from
    the following character. It defaults to :const:`None`, which disables escaping.
 
+   .. versionchanged:: 3.10
+      Previously the *escapechar* itself was not escaped,
+      which lost it on reading.
+
    .. versionchanged:: 3.11
       An empty *escapechar* is not allowed.
 

Doc/library/curses.rst

@@ -27,10 +27,24 @@ Linux and the BSD variants of Unix.
 
    Whenever the documentation mentions a *character* it can be specified
    as an integer, a one-character Unicode string or a one-byte byte string.
+   An integer is the code of a single encoded byte, optionally combined with
+   attributes and a color pair, as returned by :meth:`window.inch`.
 
    Whenever the documentation mentions a *character string* it can be specified
    as a Unicode string or a byte string.
 
+.. note::
+
+   Whether curses may be used from several threads
+   depends on the underlying library and how it was built.
+   In many implementations, including the default build of ncurses,
+   the screen state is shared and not thread-safe;
+   since the blocking and refresh methods
+   (such as :meth:`~window.getch` and :meth:`~window.refresh`)
+   release the :term:`GIL`,
+   unsynchronized use from several threads can then crash the interpreter.
+   Serialize the calls.
+
 .. seealso::
 
    Module :mod:`curses.ascii`
@@ -490,8 +504,8 @@ The module :mod:`!curses` defines the following functions:
 .. function:: putp(str)
 
    Equivalent to ``tputs(str, 1, putchar)``; emit the value of a specified
-   terminfo capability for the current terminal.  Note that the output of :func:`putp`
-   always goes to standard output.
+   terminfo capability, a bytes object, for the current terminal.
+   Note that the output of :func:`putp` always goes to standard output.
 
    :func:`setupterm` (or :func:`initscr`) must be called first.
 
@@ -662,7 +676,7 @@ The module :mod:`!curses` defines the following functions:
 .. function:: tparm(str[, ...])
 
    Instantiate the bytes object *str* with the supplied parameters, where *str* should
-   be a parameterized string obtained from the terminfo database.  For example,
+   be a parameterized byte string obtained from the terminfo database.  For example,
    ``tparm(tigetstr("cup"), 5, 3)`` could result in ``b'\033[6;4H'``, the exact
    result depending on terminal type.  Up to nine integer parameters may be supplied.
 
@@ -683,7 +697,8 @@ The module :mod:`!curses` defines the following functions:
 
 .. function:: unctrl(ch)
 
-   Return a bytes object which is a printable representation of the character *ch*.
+   Return a bytes object which is a printable representation of the character *ch*;
+   any attributes and color pair are ignored.
    Control characters are represented as a caret followed by the character, for
    example as ``b'^C'``. Printing characters are left as they are.
 
@@ -692,6 +707,9 @@ The module :mod:`!curses` defines the following functions:
 
    Push *ch* so the next :meth:`~window.getch` will return it.
 
+   *ch* may be an integer (a key code or the code of an encoded byte), a byte,
+   or a string of length 1 which encodes to a single byte.
+
    .. note::
 
       Only one *ch* can be pushed before :meth:`!getch` is called.
@@ -709,6 +727,9 @@ The module :mod:`!curses` defines the following functions:
 
    Push *ch* so the next :meth:`~window.get_wch` will return it.
 
+   *ch* may be an integer (a character code, not a key code) or a string of
+   length 1.
+
    .. note::
 
       Only one *ch* can be pushed before :meth:`!get_wch` is called.
@@ -989,27 +1010,58 @@ Window objects
 
 .. method:: window.getch([y, x])
 
-   Get a character. Note that the integer returned does *not* have to be in ASCII
-   range: function keys, keypad keys and so on are represented by numbers higher
-   than 255.  In no-delay mode, return ``-1`` if there is no input, otherwise
-   wait until a key is pressed.
+   Read a key press, after moving the cursor to *y*, *x* if specified,
+   and return it as an integer.
+   The window is refreshed first if it is not a pad and was modified since
+   the last refresh.
+   Wait until a key is pressed, or return ``-1`` if the read is non-blocking
+   or times out (see :meth:`nodelay` and :meth:`timeout`).
+
+   An ordinary key is returned as the code of a single byte of its encoding
+   in the current locale,
+   so a character encoded with several bytes takes several calls.
+   For example, in a UTF-8 locale ``'é'`` is read as ``195``, then ``169``.
+   Use :meth:`get_wch` to read it as a single character.
+
+   In keypad mode (see :meth:`keypad`) function keys and other special keys
+   are returned as one of the :ref:`KEY_* constants <curses-key-constants>`,
+   which cannot be mistaken for an ordinary key.
+   Otherwise, or if their escape sequence does not arrive in time
+   (see :meth:`notimeout` and :func:`set_escdelay`),
+   their bytes are returned one at a time.
+
+   In echo mode (see :func:`echo`) the key is added to the window as by
+   :meth:`addch`; special keys are not echoed.
 
 
 .. method:: window.get_wch([y, x])
 
-   Get a wide character. Return a character for most keys, or an integer for
-   function keys, keypad keys, and other special keys.
-   In no-delay mode, raise an exception if there is no input.
+   Read a key press, after moving the cursor to *y*, *x* if specified,
+   and return it as a one-character :class:`str`.
+   The window is refreshed first if it is not a pad and was modified since
+   the last refresh.
+   Wait until a key is pressed, or raise :exc:`error` if the read is
+   non-blocking or times out (see :meth:`nodelay` and :meth:`timeout`).
+
+   In keypad mode (see :meth:`keypad`) function keys and other special keys
+   are returned as one of the :ref:`KEY_* constants <curses-key-constants>`,
+   an integer.
+   Otherwise, or if their escape sequence does not arrive in time
+   (see :meth:`notimeout` and :func:`set_escdelay`),
+   their characters are returned one at a time.
+
+   In echo mode (see :func:`echo`) the key is added to the window as by
+   :meth:`addch`; special keys are not echoed.
 
    .. versionadded:: 3.3
 
 
 .. method:: window.getkey([y, x])
 
-   Get a character, returning a string instead of an integer, as :meth:`getch`
-   does. Function keys, keypad keys and other special keys return a multibyte
-   string containing the key name.  In no-delay mode, raise an exception if
-   there is no input.
+   Read a key press as :meth:`getch` does, but return it as a :class:`str`:
+   an ordinary key as a one-character string, the byte decoded as Latin-1,
+   and a special key as its name, such as ``'KEY_UP'`` (see :func:`keyname`).
+   Raise :exc:`error` instead of returning ``-1`` if there is no input.
 
 
 .. method:: window.getmaxyx()
@@ -1029,8 +1081,11 @@ Window objects
             window.getstr(y, x)
             window.getstr(y, x, n)
 
-   Read a bytes object from the user, with primitive line editing capacity.
-   At most *n* characters are read;
+   Read a line of input from the user, with primitive line editing capacity,
+   after moving the cursor to *y*, *x* if specified.
+   Return it as a bytes object, in the encoding of the current locale
+   and without the terminating newline.
+   At most *n* bytes are read;
    *n* defaults to and cannot exceed 2047.
 
    .. versionchanged:: 3.14
@@ -1132,12 +1187,11 @@ Window objects
 .. method:: window.instr([n])
             window.instr(y, x[, n])
 
-   Return a bytes object of characters, extracted from the window starting at the
-   current cursor position, or at *y*, *x* if specified, and stopping at the end
-   of the line. Attributes and color information are stripped
-   from the characters.  If *n* is specified, :meth:`instr` returns a string
-   at most *n* characters long (exclusive of the trailing NUL).
-   The maximum value for *n* is 2047.
+   Read the text of the window from the current cursor position,
+   or from *y*, *x* if specified, to the end of the line,
+   and return it as a bytes object, in the encoding of the current locale.
+   Attributes and color pairs are stripped.
+   At most *n* bytes are read; *n* defaults to and cannot exceed 2047.
 
    .. versionchanged:: 3.14
       The maximum value for *n* was increased from 1023 to 2047.
@@ -1161,6 +1215,8 @@ Window objects
    If *flag* is ``True``, escape sequences generated by some keys (keypad,  function keys)
    will be interpreted by :mod:`!curses`. If *flag* is ``False``, escape sequences will be
    left as is in the input stream.
+   Keypad mode is disabled by default, but :func:`wrapper` enables it for the
+   main window.
 
 
 .. method:: window.leaveok(flag)
@@ -1513,6 +1569,8 @@ by some methods.
 |                         | color-pair field information  |
 +-------------------------+-------------------------------+
 
+.. _curses-key-constants:
+
 Keys are referred to by integer constants with names starting with  ``KEY_``.
 The exact keycaps available are system dependent.
 

Doc/library/os.path.rst

@@ -59,6 +59,18 @@ the :mod:`glob` module.)
    Return a normalized absolutized version of the pathname *path*. On most
    platforms, this is equivalent to calling ``normpath(join(os.getcwd(), path))``.
 
+   On Windows the path is normalized by the operating system,
+   therefore the result can differ from ``normpath(join(os.getcwd(), path))``.
+   A drive-relative path is resolved against the current directory
+   of the specified drive, and the drive letter is capitalized.
+   Trailing dots and spaces are stripped.
+   For example::
+
+      >>> os.path.abspath('c:spam')
+      'C:\\Temp\\spam'
+      >>> os.path.abspath('c:/temp/spam. . .')
+      'c:\\temp\\spam'
+
    .. seealso:: :func:`os.path.join` and :func:`os.path.normpath`.
 
    .. versionchanged:: 3.6
@@ -435,6 +447,9 @@ the :mod:`glob` module.)
    links encountered in the path (if they are supported by the operating
    system). On Windows, this function will also resolve MS-DOS (also called 8.3)
    style names such as ``C:\\PROGRA~1`` to ``C:\\Program Files``.
+   The returned path uses the case reported by the operating system,
+   which can differ from the case of *path*,
+   in particular the drive letter is capitalized.
 
    By default, the path is evaluated up to the first component that does not
    exist, is a symlink loop, or whose evaluation raises :exc:`OSError`.

Doc/library/runpy.rst

@@ -97,7 +97,7 @@ The :mod:`!runpy` module provides two functions:
       :class:`~importlib.machinery.ModuleSpec` for alternatives.
 
    .. versionchanged:: 3.15
-      ``__cached__`` is no longer set.
+      The global variable ``__cached__`` is no longer set.
 
 .. function:: run_path(path_name, init_globals=None, run_name=None)
 
@@ -175,7 +175,7 @@ The :mod:`!runpy` module provides two functions:
       ``__package__`` are deprecated.
 
    .. versionchanged:: 3.15
-      ``__cached__`` is no longer set.
+      The global variable ``__cached__`` is no longer set.
 
 .. seealso::