Merge branch 'main' into docs/pep750-first-pass

Author: davepeck

Doc/library/codecs.rst

@@ -53,6 +53,14 @@ any codec:
    :exc:`UnicodeDecodeError`). Refer to :ref:`codec-base-classes` for more
    information on codec error handling.
 
+.. function:: charmap_build(string)
+
+   Return a mapping suitable for encoding with a custom single-byte encoding.
+   Given a :class:`str` *string* of up to 256 characters representing a
+   decoding table, returns either a compact internal mapping object
+   ``EncodingMap`` or a :class:`dictionary <dict>` mapping character ordinals
+   to byte values. Raises a :exc:`TypeError` on invalid input.
+
 The full details for each codec can also be looked up directly:
 
 .. function:: lookup(encoding, /)

Doc/library/csv.rst

@@ -53,7 +53,7 @@ The :mod:`csv` module defines the following functions:
 .. index::
    single: universal newlines; csv.reader function
 
-.. function:: reader(csvfile, dialect='excel', **fmtparams)
+.. function:: reader(csvfile, /, dialect='excel', **fmtparams)
 
    Return a :ref:`reader object <reader-objects>` that will process
    lines from the given *csvfile*.  A csvfile must be an iterable of
@@ -84,7 +84,7 @@ The :mod:`csv` module defines the following functions:
       Spam, Lovely Spam, Wonderful Spam
 
 
-.. function:: writer(csvfile, dialect='excel', **fmtparams)
+.. function:: writer(csvfile, /, dialect='excel', **fmtparams)
 
    Return a writer object responsible for converting the user's data into delimited
    strings on the given file-like object.  *csvfile* can be any object with a
@@ -323,8 +323,8 @@ The :mod:`csv` module defines the following constants:
 .. data:: QUOTE_MINIMAL
 
    Instructs :class:`writer` objects to only quote those fields which contain
-   special characters such as *delimiter*, *quotechar* or any of the characters in
-   *lineterminator*.
+   special characters such as *delimiter*, *quotechar*, ``'\r'``, ``'\n'``
+   or any of the characters in *lineterminator*.
 
 
 .. data:: QUOTE_NONNUMERIC
@@ -342,10 +342,13 @@ The :mod:`csv` module defines the following constants:
 
 .. data:: QUOTE_NONE
 
-   Instructs :class:`writer` objects to never quote fields.  When the current
-   *delimiter* occurs in output data it is preceded by the current *escapechar*
-   character.  If *escapechar* is not set, the writer will raise :exc:`Error` if
+   Instructs :class:`writer` objects to never quote fields.
+   When the current *delimiter*, *quotechar*, *escapechar*, ``'\r'``, ``'\n'``
+   or any of the characters in *lineterminator* occurs in output data
+   it is preceded by the current *escapechar* character.
+   If *escapechar* is not set, the writer will raise :exc:`Error` if
    any characters that require escaping are encountered.
+   Set *quotechar* to ``None`` to prevent its escaping.
 
    Instructs :class:`reader` objects to perform no special processing of quote characters.
 
@@ -414,9 +417,16 @@ Dialects support the following attributes:
 
 .. attribute:: Dialect.escapechar
 
-   A one-character string used by the writer to escape the *delimiter* if *quoting*
-   is set to :const:`QUOTE_NONE` and the *quotechar* if *doublequote* is
-   :const:`False`. On reading, the *escapechar* removes any special meaning from
+   A one-character string used by the writer to escape characters that
+   require escaping:
+
+      * the *delimiter*, the *quotechar*, ``'\r'``, ``'\n'`` and any of the
+        characters in *lineterminator* are escaped if *quoting* is set to
+        :const:`QUOTE_NONE`;
+      * the *quotechar* is escaped if *doublequote* is :const:`False`;
+      * the *escapechar* itself.
+
+   On reading, the *escapechar* removes any special meaning from
    the following character. It defaults to :const:`None`, which disables escaping.
 
    .. versionchanged:: 3.11
@@ -436,9 +446,12 @@ Dialects support the following attributes:
 
 .. attribute:: Dialect.quotechar
 
-   A one-character string used to quote fields containing special characters, such
-   as the *delimiter* or *quotechar*, or which contain new-line characters.  It
-   defaults to ``'"'``.
+   A one-character string used to quote fields containing special characters,
+   such as the *delimiter* or the *quotechar*, or which contain new-line
+   characters (``'\r'``, ``'\n'`` or any of the characters in *lineterminator*).
+   It defaults to ``'"'``.
+   Can be set to ``None`` to prevent escaping ``'"'`` if *quoting* is set
+   to :const:`QUOTE_NONE`.
 
    .. versionchanged:: 3.11
       An empty *quotechar* is not allowed.
@@ -447,7 +460,8 @@ Dialects support the following attributes:
 
    Controls when quotes should be generated by the writer and recognised by the
    reader.  It can take on any of the :ref:`QUOTE_\* constants <csv-constants>`
-   and defaults to :const:`QUOTE_MINIMAL`.
+   and defaults to :const:`QUOTE_MINIMAL` if *quotechar* is not ``None``,
+   and :const:`QUOTE_NONE` otherwise.
 
 
 .. attribute:: Dialect.skipinitialspace

Doc/library/venv.rst

@@ -105,36 +105,52 @@ The command, if run with ``-h``, will show the available options::
 
    Creates virtual Python environments in one or more target directories.
 
-   positional arguments:
-     ENV_DIR               A directory to create the environment in.
-
-   options:
-     -h, --help            show this help message and exit
-     --system-site-packages
-                           Give the virtual environment access to the system
-                           site-packages dir.
-     --symlinks            Try to use symlinks rather than copies, when
-                           symlinks are not the default for the platform.
-     --copies              Try to use copies rather than symlinks, even when
-                           symlinks are the default for the platform.
-     --clear               Delete the contents of the environment directory
-                           if it already exists, before environment creation.
-     --upgrade             Upgrade the environment directory to use this
-                           version of Python, assuming Python has been
-                           upgraded in-place.
-     --without-pip         Skips installing or upgrading pip in the virtual
-                           environment (pip is bootstrapped by default)
-     --prompt PROMPT       Provides an alternative prompt prefix for this
-                           environment.
-     --upgrade-deps        Upgrade core dependencies (pip) to the latest
-                           version in PyPI
-     --without-scm-ignore-files
-                           Skips adding SCM ignore files to the environment
-                           directory (Git is supported by default).
-
    Once an environment has been created, you may wish to activate it, e.g. by
    sourcing an activate script in its bin directory.
 
+.. _venv-cli:
+.. program:: venv
+
+.. option:: ENV_DIR
+
+   A required argument specifying the directory to create the environment in.
+
+.. option:: --system-site-packages
+
+   Give the virtual environment access to the system site-packages directory.
+
+.. option:: --symlinks
+
+   Try to use symlinks rather than copies, when symlinks are not the default for the platform.
+
+.. option:: --copies
+
+   Try to use copies rather than symlinks, even when symlinks are the default for the platform.
+
+.. option:: --clear
+
+   Delete the contents of the environment directory if it already exists, before environment creation.
+
+.. option:: --upgrade
+
+   Upgrade the environment directory to use this version of Python, assuming Python has been upgraded in-place.
+
+.. option:: --without-pip
+
+   Skips installing or upgrading pip in the virtual environment (pip is bootstrapped by default).
+
+.. option:: --prompt <PROMPT>
+
+   Provides an alternative prompt prefix for this environment.
+
+.. option:: --upgrade-deps
+
+   Upgrade core dependencies (pip) to the latest version in PyPI.
+
+.. option:: --without-scm-ignore-files
+
+   Skips adding SCM ignore files to the environment directory (Git is supported by default).
+
 
 .. versionchanged:: 3.4
    Installs pip by default, added the ``--without-pip``  and ``--copies``

Include/internal/pycore_weakref.h

@@ -29,6 +29,12 @@ extern "C" {
     PyMutex_LockFlags(wr->weakrefs_lock, _Py_LOCK_DONT_DETACH)
 #define UNLOCK_WEAKREFS_FOR_WR(wr) PyMutex_Unlock(wr->weakrefs_lock)
 
+#define FT_CLEAR_WEAKREFS(obj, weakref_list)    \
+    do {                                        \
+        assert(Py_REFCNT(obj) == 0);            \
+        PyObject_ClearWeakRefs(obj);            \
+    } while (0)
+
 #else
 
 #define LOCK_WEAKREFS(obj)
@@ -37,6 +43,14 @@ extern "C" {
 #define LOCK_WEAKREFS_FOR_WR(wr)
 #define UNLOCK_WEAKREFS_FOR_WR(wr)
 
+#define FT_CLEAR_WEAKREFS(obj, weakref_list)        \
+    do {                                            \
+        assert(Py_REFCNT(obj) == 0);                \
+        if (weakref_list != NULL) {                 \
+            PyObject_ClearWeakRefs(obj);            \
+        }                                           \
+    } while (0)
+
 #endif
 
 static inline int _is_dead(PyObject *obj)

Lib/os.py

@@ -10,7 +10,7 @@
   - os.extsep is the extension separator (always '.')
   - os.altsep is the alternate pathname separator (None or '/')
   - os.pathsep is the component separator used in $PATH etc
-  - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
+  - os.linesep is the line separator in text files ('\n' or '\r\n')
   - os.defpath is the default search path for executables
   - os.devnull is the file path of the null device ('/dev/null', etc.)
 

Lib/test/test_free_threading/test_itertools.py

@@ -1,6 +1,6 @@
 import unittest
 from threading import Thread, Barrier
-from itertools import batched, cycle
+from itertools import batched, chain, cycle
 from test.support import threading_helper
 
 
@@ -17,7 +17,7 @@ def work(it):
             barrier.wait()
             while True:
                 try:
-                    _ = next(it)
+                    next(it)
                 except StopIteration:
                     break
 
@@ -62,6 +62,34 @@ def work(it):
 
             barrier.reset()
 
+    @threading_helper.reap_threads
+    def test_chain(self):
+        number_of_threads = 6
+        number_of_iterations = 20
+
+        barrier = Barrier(number_of_threads)
+        def work(it):
+            barrier.wait()
+            while True:
+                try:
+                    next(it)
+                except StopIteration:
+                    break
+
+        data = [(1, )] * 200
+        for it in range(number_of_iterations):
+            chain_iterator = chain(*data)
+            worker_threads = []
+            for ii in range(number_of_threads):
+                worker_threads.append(
+                    Thread(target=work, args=[chain_iterator]))
+
+            with threading_helper.start_threads(worker_threads):
+                pass
+
+            barrier.reset()
+
+
 
 if __name__ == "__main__":
     unittest.main()

Lib/test/test_free_threading/test_itertools_combinatoric.py

@@ -0,0 +1,51 @@
+import unittest
+from threading import Thread, Barrier
+from itertools import combinations, product
+from test.support import threading_helper
+
+
+threading_helper.requires_working_threading(module=True)
+
+def test_concurrent_iteration(iterator, number_of_threads):
+    barrier = Barrier(number_of_threads)
+    def iterator_worker(it):
+        barrier.wait()
+        while True:
+            try:
+                _ = next(it)
+            except StopIteration:
+                return
+
+    worker_threads = []
+    for ii in range(number_of_threads):
+        worker_threads.append(
+            Thread(target=iterator_worker, args=[iterator]))
+
+    with threading_helper.start_threads(worker_threads):
+        pass
+
+    barrier.reset()
+
+class ItertoolsThreading(unittest.TestCase):
+
+    @threading_helper.reap_threads
+    def test_combinations(self):
+        number_of_threads = 10
+        number_of_iterations = 24
+
+        for it in range(number_of_iterations):
+            iterator = combinations((1, 2, 3, 4, 5), 2)
+            test_concurrent_iteration(iterator, number_of_threads)
+
+    @threading_helper.reap_threads
+    def test_product(self):
+        number_of_threads = 10
+        number_of_iterations = 24
+
+        for it in range(number_of_iterations):
+            iterator = product((1, 2, 3, 4, 5), (10, 20, 30))
+            test_concurrent_iteration(iterator, number_of_threads)
+
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Core_and_Builtins/2025-06-17-22-34-58.gh-issue-135607.ucsLVu.rst

@@ -0,0 +1,2 @@
+Fix potential :mod:`weakref` races in an object's destructor on the :term:`free threaded <free
+threading>` build.

Misc/NEWS.d/next/Library/2025-04-22-21-00-23.gh-issue-123471.asOLA2.rst

@@ -0,0 +1 @@
+Make concurrent iterations over :class:`itertools.combinations` and :class:`itertools.product` safe under free-threading.

Misc/NEWS.d/next/Library/2025-06-18-19-25-32.gh-issue-123471.lx1Xbt.rst

@@ -0,0 +1 @@
+Make concurrent iterations over :class:`itertools.chain` safe under :term:`free threading`.