Sync pre-release CPython main branch from GitHub (2026-07-08)

Summary:
Imported python/cpython `3.16.0a0` from upstream rev [`4572903`](https://www.github.com/python/cpython/commit/45729033bff28f8abc36c42e802cb2853c205737) (committed 2026-07-08 00:40:54+00:00).

# Commit Info

- Base: (`3.16.0a0`) - [`35c6779`](https://www.github.com/python/cpython/commit/35c6779c7b5c4c2e2d9723803996050b711da0dd) (commit date: 2026-07-06 23:54:16+00:00)
- Imported: (`3.16.0a0`) - [`4572903`](https://www.github.com/python/cpython/commit/45729033bff28f8abc36c42e802cb2853c205737) (commit date: 2026-07-08 00:40:54+00:00)

# Noteworthy file changes

- Test files (1 added)
- Low-signal files (6 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GM3p_RyP4bxhqzsKAOIHYrk3nts2br0LAAAz

Differential Revision: D110994014

fbshipit-source-id: 4dd46a696265b7e0c79b69de2f45dc9ada17c0ac

Author: generatedunixname1734921407115435

.github/workflows/build.yml

@@ -554,7 +554,6 @@ jobs:
         - Thread
         free-threading:
         - false
-        - true
         sanitizer:
         - TSan
         include:
@@ -566,6 +565,17 @@ jobs:
       sanitizer: ${{ matrix.sanitizer }}
       free-threading: ${{ matrix.free-threading }}
 
+  # XXX: Temporarily allow this job to fail to not block PRs.
+  build-san-free-threading:
+    # ${{ '' } is a hack to nest jobs under the same sidebar category.
+    name: Sanitizers${{ '' }}  # zizmor: ignore[obfuscation]
+    needs: build-context
+    if: needs.build-context.outputs.run-ubuntu == 'true'
+    uses: ./.github/workflows/reusable-san.yml
+    with:
+      sanitizer: TSan
+      free-threading: true
+
   cross-build-linux:
     name: Cross build Linux
     runs-on: ubuntu-26.04
@@ -669,6 +679,7 @@ jobs:
     - test-hypothesis
     - build-asan
     - build-san
+    - build-san-free-threading
     - cross-build-linux
     - cifuzz
     if: always()
@@ -680,6 +691,7 @@ jobs:
         allowed-failures: >-
           build-android,
           build-emscripten,
+          build-san-free-threading,
           build-windows-msi,
           build-ubuntu-ssltests,
           test-hypothesis,

Doc/deprecations/pending-removal-in-3.21.rst

@@ -23,3 +23,8 @@ Pending removal in Python 3.21
   * Soft-deprecated since Python 3.15, using ``'F'`` and ``'D'`` type codes are now
     deprecated.  These codes will be removed in Python 3.21.  Use instead
     two-letter forms ``'Zf'`` and ``'Zd'``.
+
+* :mod:`tempfile`:
+
+  * ``tempfile._TemporaryFileWrapper`` will be removed in Python 3.21. Use the
+    public :class:`tempfile.TemporaryFileWrapper` instead.

Doc/library/string.rst

@@ -971,7 +971,8 @@ attributes:
 
 Alternatively, you can provide the entire regular expression pattern by
 overriding the class attribute *pattern*.  If you do this, the value must be a
-regular expression object with four named capturing groups.  The capturing
+regular expression pattern string, or a compiled regular expression
+object, with four named capturing groups.  The capturing
 groups correspond to the rules given above, along with the invalid placeholder
 rule:
 

Doc/library/sys.rst

@@ -2240,8 +2240,9 @@ always available. Unless explicitly noted otherwise, all variables are read-only
 
       The name of the lock implementation:
 
-      * ``"semaphore"``: a lock uses a semaphore
-      * ``"mutex+cond"``: a lock uses a mutex and a condition variable
+      * ``"semaphore"``: a lock uses a semaphore (Python 3.14 and older)
+      * ``"mutex+cond"``: a lock uses a mutex and a condition variable (Python 3.14 and older)
+      * ``"pymutex"``: a lock uses the :c:type:`PyMutex` implementation (Python 3.15 and newer)
       * ``None`` if this information is unknown
 
    .. attribute:: thread_info.version

Doc/library/tempfile.rst

@@ -14,10 +14,11 @@
 
 This module creates temporary files and directories.  It works on all
 supported platforms. :class:`TemporaryFile`, :class:`NamedTemporaryFile`,
-:class:`TemporaryDirectory`, and :class:`SpooledTemporaryFile` are high-level
-interfaces which provide automatic cleanup and can be used as
-:term:`context managers <context manager>`. :func:`mkstemp` and
-:func:`mkdtemp` are lower-level functions which require manual cleanup.
+:class:`TemporaryFileWrapper`, :class:`TemporaryDirectory`, and
+:class:`SpooledTemporaryFile` are high-level interfaces which provide
+automatic cleanup and can be used as :term:`context managers
+<context manager>`. :func:`mkstemp` and :func:`mkdtemp` are lower-level
+functions which require manual cleanup.
 
 All the user-callable functions and constructors take additional arguments which
 allow direct control over the location and name of temporary files and
@@ -84,13 +85,13 @@ The module defines the following user-callable items:
      :func:`TemporaryFile` with *delete* and *delete_on_close* parameters that
      determine whether and how the named file should be automatically deleted.
 
-   The returned object is always a :term:`file-like object` whose :attr:`!file`
-   attribute is the underlying true file object. This file-like object
-   can be used in a :keyword:`with` statement, just like a normal file.  The
-   name of the temporary file can be retrieved from the :attr:`!name` attribute
-   of the returned file-like object. On Unix, unlike with the
-   :func:`TemporaryFile`, the directory entry does not get unlinked immediately
-   after the file creation.
+   The returned object is always a :class:`TemporaryFileWrapper` instance
+   (a :term:`file-like object`) whose :attr:`~TemporaryFileWrapper.file` attribute is the underlying
+   true file object. This file-like object can be used in a :keyword:`with`
+   statement, just like a normal file.  The name of the temporary file can be
+   retrieved from the :attr:`!name` attribute of the returned file-like object.
+   On Unix, unlike with the :func:`TemporaryFile`, the directory entry does not
+   get unlinked immediately after the file creation.
 
    If *delete* is true (the default) and *delete_on_close* is true (the
    default), the file is deleted as soon as it is closed. If *delete* is true
@@ -140,6 +141,34 @@ The module defines the following user-callable items:
    .. versionchanged:: 3.12
       Added *delete_on_close* parameter.
 
+.. class:: TemporaryFileWrapper(file, name, delete=True, delete_on_close=True)
+
+   A mutable wrapper returned by :func:`NamedTemporaryFile`. It wraps the
+   underlying file object, delegating attribute access to it, and ensures
+   the temporary file is deleted when appropriate.
+
+   .. attribute:: file
+
+      The underlying :term:`file-like object`.
+
+   .. attribute:: name
+
+      The file name of the temporary file.
+
+   .. method:: close()
+
+      Close the temporary file, possibly deleting it depending on the
+      *delete* and *delete_on_close* arguments passed to
+      :func:`NamedTemporaryFile`.
+
+   .. note::
+
+      ``tempfile._TemporaryFileWrapper`` is kept as a backwards compatible
+      deprecated alias for this class.
+      It will be removed in Python 3.21
+
+   .. versionadded:: next
+
 
 .. class:: SpooledTemporaryFile(max_size=0, mode='w+b', buffering=-1, encoding=None, newline=None, suffix=None, prefix=None, dir=None, *, errors=None)
 

Doc/library/tkinter.font.rst

@@ -20,33 +20,53 @@ The different font weights and slants are:
 
 .. class:: Font(root=None, font=None, name=None, exists=False, **options)
 
-   The :class:`Font` class represents a named font. *Font* instances are given
-   unique names and can be specified by their family, size, and style
-   configuration. Named fonts are Tk's method of creating and identifying
-   fonts as a single object, rather than specifying a font by its attributes
-   with each occurrence.
+   The :class:`Font` class represents a font used by Tk widgets.
+   It either creates a new *named font* or refers to an existing font.
+   A named font is Tk's way of identifying a font as a single object that can
+   be referred to by name and reconfigured in place,
+   rather than respecifying its attributes at each use.
+
+   With *exists* false (the default), a new named font is created.
+   Its attributes are taken from the font description *font* if it is given,
+   overridden by any keyword *options*.
+   The new font is named *name*, or a generated unique name if *name* is
+   omitted.
+
+   With *exists* true, an existing font is referred to instead of being
+   created.
+   If *name* is given, it is the name of the font,
+   which is reconfigured by *font* and *options* if either is given.
+   If *name* is omitted, the font description *font* is wrapped as is,
+   without creating a named font,
+   so that it is used without loss of precision by :meth:`actual`,
+   :meth:`measure` and :meth:`metrics`.
+   In this case no keyword options are accepted,
+   and the :attr:`!name` attribute is the description itself rather than a
+   string.
+
+   The font description *font* is a tuple of the family name, the size and
+   zero or more styles,
+   or any other form accepted by Tk, such as the name of a named font.
+
+   The keyword *options* are:
+
+      | *family* - font family, for example, Courier, Times
+      | *size* - font size
+      |     If *size* is positive it is interpreted as size in points.
+      |     If *size* is a negative number its absolute value is treated
+      |     as size in pixels.
+      | *weight* - font emphasis (NORMAL, BOLD)
+      | *slant* - ROMAN, ITALIC
+      | *underline* - font underlining (0 - none, 1 - underline)
+      | *overstrike* - font strikeout (0 - none, 1 - strikeout)
 
    .. versionchanged:: 3.10
       Two fonts now compare equal (``==``) only when both are :class:`Font`
       instances with the same name belonging to the same Tcl interpreter.
 
-    arguments:
-
-       | *font* - font specifier tuple (family, size, options)
-       | *name* - unique font name
-       | *exists* - self points to existing named font if true
-
-    additional keyword options (ignored if *font* is specified):
-
-       | *family* - font family, for example, Courier, Times
-       | *size* - font size
-       |     If *size* is positive it is interpreted as size in points.
-       |     If *size* is a negative number its absolute value is treated
-       |     as size in pixels.
-       | *weight* - font emphasis (NORMAL, BOLD)
-       | *slant* - ROMAN, ITALIC
-       | *underline* - font underlining (0 - none, 1 - underline)
-       | *overstrike* - font strikeout (0 - none, 1 - strikeout)
+   .. versionchanged:: next
+      A font description can now be wrapped without creating a new named font,
+      and keyword options now override the attributes of the specified *font*.
 
    .. method:: actual(option=None, displayof=None)
 
@@ -59,6 +79,12 @@ The different font weights and slants are:
 
       Retrieve an attribute of the font.
 
+      .. note::
+
+         :meth:`!cget` and :meth:`configure` operate on a named font and raise
+         :exc:`~tkinter.TclError` for a wrapped font description.
+         Use :meth:`actual` to query the attributes of the latter.
+
    .. method:: config(**options)
       :no-typesetting:
 

Doc/pylock.toml

@@ -2,6 +2,7 @@
 #    uv pip compile Doc/requirements.txt --exclude-newer P14D --exclude-newer-package linklint=PT0S --exclude-newer-package python-docs-theme=PT0S --no-cache --output-file Doc/pylock.toml --python-version 3.12 --universal
 lock-version = "1.0"
 created-by = "uv"
+requires-python = ">=3.12"
 
 [[packages]]
 name = "alabaster"
@@ -23,9 +24,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/b4/03/374bd9e31b58e8a
 
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 [[packages]]
 name = "charset-normalizer"
@@ -114,9 +115,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/8f/d7/9322c609343d929
 
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+version = "3.18"
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 [[packages]]
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@@ -132,9 +133,9 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/62/a1/3d680cbfd5f4b8f
 
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@@ -162,8 +163,7 @@ wheels = [{ url = "https://files.pythonhosted.org/packages/88/ef/eb23f262cca3c0c
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+archive = { url = "https://github.com/pygments/pygments/archive/2cad2642058441b59782a6a18f03c98c42d081f1.tar.gz", hashes = { sha256 = "e6ae46831285e86355eabb969bf2d0520655b001dd882147637f4bc500e56bfb" } }
 
 [[packages]]
 name = "python-docs-theme"
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Doc/requirements.txt

@@ -9,6 +9,10 @@
 # Keep this version in sync with ``Doc/conf.py``.
 sphinx<9.0.0
 
+# Temporary direct requirement, pending release of Pygments > 2.20.0
+# https://github.com/pygments/pygments/discussions/3145
+pygments @ https://github.com/pygments/pygments/archive/2cad2642058441b59782a6a18f03c98c42d081f1.tar.gz
+
 blurb
 
 sphinxext-opengraph~=0.13.0

Doc/whatsnew/3.16.rst

@@ -408,6 +408,12 @@ tkinter
   them.
   (Contributed by Serhiy Storchaka in :gh:`59396`.)
 
+* :class:`tkinter.font.Font` can now wrap a font description without creating a
+  new named font, by passing it as *font* with ``exists=True`` and no *name*.
+  This avoids a loss of precision in :meth:`~tkinter.font.Font.actual`,
+  :meth:`~tkinter.font.Font.measure` and :meth:`~tkinter.font.Font.metrics`.
+  (Contributed by Serhiy Storchaka in :gh:`143990`.)
+
 xml
 ---
 
@@ -582,6 +588,13 @@ New deprecations
     two-letter forms ``'Zf'`` and ``'Zd'``.
     (Contributed by Sergey B Kirpichev in :gh:`121249`.)
 
+* :mod:`tempfile`
+
+  * The private ``tempfile._TemporaryFileWrapper`` name is deprecated
+    and is slated for removal in Python 3.21.
+    Use the new public :class:`tempfile.TemporaryFileWrapper` instead,
+    which is the return type of :func:`tempfile.NamedTemporaryFile`.
+
 .. Add deprecations above alphabetically, not here at the end.
 
 .. include:: ../deprecations/pending-removal-in-3.17.rst