Sync pre-release CPython main branch from GitHub (2026-07-31)

Summary:
Imported python/cpython `3.16.0a0` from upstream rev [`ac8ba0c`](https://www.github.com/python/cpython/commit/ac8ba0ca5a04cd7b27b44822d31df640e817fd78) (committed 2026-07-31 01:28:20+00:00).

# Commit Info

- Base: (`3.16.0a0`) - [`f4b1d3e`](https://www.github.com/python/cpython/commit/f4b1d3e891d0d2055e53df3ccb84030bcaa148b5) (commit date: 2026-07-30 02:31:40+00:00)
- Imported: (`3.16.0a0`) - [`ac8ba0c`](https://www.github.com/python/cpython/commit/ac8ba0ca5a04cd7b27b44822d31df640e817fd78) (commit date: 2026-07-31 01:28:20+00:00)

# Noteworthy file changes

- Low-signal files (4 added) (NEWS.d, docs, .github)

Complete list of added/removed files: https://www.internalfb.com/intern/everpaste/?color=0&handle=GBaB3Sm_ySiuTa0DAHesB0Gfs8gnbr0LAAAz

Reviewed By: itamaro

Differential Revision: D114318870

fbshipit-source-id: f836d91f5db0006a8037a560ec01a15bca2571f1

Author: generatedunixname1734921407115435

.github/CODEOWNERS

@@ -171,9 +171,6 @@ Mac/                          @python/macos-team
 Lib/_osx_support.py           @python/macos-team
 Lib/test/test__osx_support.py @python/macos-team
 
-# WebAssembly
-Tools/wasm/README.md          @brettcannon @freakboy3742 @emmatyping
-
 # WebAssembly (Emscripten)
 Platforms/emscripten          @freakboy3742 @emmatyping
 Tools/wasm/emscripten         @freakboy3742 @emmatyping
@@ -335,7 +332,6 @@ Modules/_remote_debugging/          @pablogsal
 
 # Sub-Interpreters
 **/*crossinterp*                          @ericsnowcurrently
-**/*interpreteridobject.*                 @ericsnowcurrently
 Doc/library/concurrent.interpreters.rst   @ericsnowcurrently
 Lib/concurrent/futures/interpreter.py     @ericsnowcurrently
 Lib/concurrent/interpreters/              @ericsnowcurrently
@@ -646,3 +642,6 @@ Modules/**/clinic/
 Objects/**/clinic/
 PC/**/clinic/
 Python/**/clinic/
+
+# Exclude HTML IDs list
+Doc/tools/removed-ids.txt

.github/workflows/reusable-san.yml

@@ -55,7 +55,7 @@ jobs:
         SAN_LOG_OPTION: log_path=${{ github.workspace }}/san_log
         SUPPRESSIONS_SUFFIX: >-
           ${{
-            fromJSON(inputs.free-threading)
+            inputs.free-threading
             && '_free_threading'
             || ''
           }}
@@ -101,7 +101,7 @@ jobs:
         }}
         --with-pydebug
         ${{ inputs.sanitizer == 'TSan' && '--with-openssl="$OPENSSL_DIR" --with-openssl-rpath=auto' || '' }}
-        ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
+        ${{ inputs.free-threading && '--disable-gil' || '' }}
     - name: Build CPython
       run: make -j4
     - name: Display build info
@@ -114,7 +114,7 @@ jobs:
     - name: Parallel tests
       if: >-
         inputs.sanitizer == 'TSan'
-        && fromJSON(inputs.free-threading)
+        && inputs.free-threading
       run: ./python -m test --tsan-parallel --parallel-threads=4 -j4 -W --timeout=600 --slowest
     - name: Display logs
       if: always()
@@ -125,7 +125,7 @@ jobs:
       with:
         name: >-
           ${{ inputs.sanitizer }}-logs-${{
-            fromJSON(inputs.free-threading)
+            inputs.free-threading
             && 'free-threading'
             || 'default'
           }}

.github/workflows/reusable-ubuntu.yml

@@ -14,14 +14,14 @@ on:
         type: boolean
         default: false
       os:
-         description: OS to run the job
-         required: true
-         type: string
+        description: OS to run the job
+        required: true
+        type: string
       test-opts:
-         description: Extra options to pass to the test runner via TESTOPTS
-         required: false
-         type: string
-         default: ''
+        description: Extra options to pass to the test runner via TESTOPTS
+        required: false
+        type: string
+        default: ''
 
 permissions:
   contents: read
@@ -47,7 +47,7 @@ jobs:
     - name: Install dependencies
       run: sudo ./.github/workflows/posix-deps-apt.sh
     - name: Install Clang and BOLT
-      if: ${{ fromJSON(inputs.bolt-optimizations) }}
+      if: inputs.bolt-optimizations
       run: |
         # On ubuntu-26.04 image, LLVM is LLVM-21 by default
         sudo apt-get install --no-install-recommends bolt-21
@@ -88,10 +88,10 @@ jobs:
         --enable-slower-safety
         --enable-safety
         --with-openssl="$OPENSSL_DIR"
-        ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
-        ${{ fromJSON(inputs.bolt-optimizations) && '--enable-bolt' || '' }}
+        ${{ inputs.free-threading && '--disable-gil' || '' }}
+        ${{ inputs.bolt-optimizations && '--enable-bolt' || '' }}
     - name: Build CPython out-of-tree
-      if: ${{ inputs.free-threading }}
+      if: inputs.free-threading
       working-directory: ${{ env.CPYTHON_BUILDDIR }}
       run: make -j
     - name: Build CPython out-of-tree (for compiler warning check)

.github/workflows/reusable-windows.yml

@@ -45,7 +45,7 @@ jobs:
         -e -v
         ${{ inputs.interpreter == 'switch-case' && '-d' || '--tail-call-interp -c Release' }}
         -p "${ARCH}"
-        ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
+        ${{ inputs.free-threading && '--disable-gil' || '' }}
       shell: bash
     - name: Display build info
       run: .\\python.bat -m test.pythoninfo
@@ -55,5 +55,5 @@ jobs:
         -p "${ARCH}"
         -q --fast-ci
         ${{ inputs.interpreter == 'switch-case' && '-d' || '' }}
-        ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
+        ${{ inputs.free-threading && '--disable-gil' || '' }}
       shell: bash

Doc/c-api/exceptions.rst

@@ -119,6 +119,21 @@ Printing and clearing
    .. versionadded:: 3.12
 
 
+.. c:function:: void PyErr_Display(PyObject *unused, PyObject *value, PyObject *tb)
+
+   Legacy variant of :c:func:`PyErr_DisplayException`.
+
+   Print the exception *value* with its traceback to :data:`sys.stderr`.
+   If *value* has no traceback set, *tb* is used as its traceback.
+   The first argument is ignored.
+
+   If :data:`sys.stderr` is ``None``, nothing is printed.
+   If :data:`sys.stderr` is not set, the exception is dumped to the
+   C ``stderr`` stream instead.
+
+   .. deprecated:: 3.12
+      Use :c:func:`PyErr_DisplayException` instead.
+
 Raising exceptions
 ==================
 

Doc/c-api/init_config.rst

@@ -1235,9 +1235,9 @@ PyConfig
 
    .. c:member:: wchar_t* base_executable
 
-      Python base executable: :data:`sys._base_executable`.
+      Python base executable: ``sys._base_executable``.
 
-      Set by the :envvar:`__PYVENV_LAUNCHER__` environment variable.
+      Set by the ``__PYVENV_LAUNCHER__`` environment variable.
 
       Set from :c:member:`PyConfig.executable` if ``NULL``.
 
@@ -1748,7 +1748,7 @@ PyConfig
 
       * On macOS, use :envvar:`PYTHONEXECUTABLE` environment variable if set.
       * If the ``WITH_NEXT_FRAMEWORK`` macro is defined, use
-        :envvar:`__PYVENV_LAUNCHER__` environment variable if set.
+        ``__PYVENV_LAUNCHER__`` environment variable if set.
       * Use ``argv[0]`` of :c:member:`~PyConfig.argv` if available and
         non-empty.
       * Otherwise, use ``L"python"`` on Windows, or ``L"python3"`` on other
@@ -1984,8 +1984,7 @@ PyConfig
 
       The :mod:`warnings` module adds :data:`sys.warnoptions` in the reverse
       order: the last :c:member:`PyConfig.warnoptions` item becomes the first
-      item of :data:`warnings.filters` which is checked first (highest
-      priority).
+      item of ``warnings.filters`` which is checked first (highest priority).
 
       The :option:`-W` command line options adds its value to
       :c:member:`~PyConfig.warnoptions`, it can be used multiple times.

Doc/c-api/intro.rst

@@ -1163,7 +1163,7 @@ when defined by the compiler, will also implicitly enable :c:macro:`!Py_DEBUG`.
 In addition to the reference count debugging described below, extra checks are
 performed. See :ref:`Python Debug Build <debug-build>` for more details.
 
-Defining :c:macro:`Py_TRACE_REFS` enables reference tracing
+Defining ``Py_TRACE_REFS`` enables reference tracing
 (see the :option:`configure --with-trace-refs option <--with-trace-refs>`).
 When defined, a circular doubly linked list of active objects is maintained by adding two extra
 fields to every :c:type:`PyObject`.  Total allocations are tracked as well.  Upon

Doc/library/collections.rst

@@ -268,6 +268,15 @@ For example::
         >>> c['sausage'] = 0                        # counter entry with a zero count
         >>> del c['sausage']                        # del actually removes the entry
 
+    Counters maintain insertion order internally but display from most common to
+    least common when possible:
+
+        >>> c = Counter(a=1, b=2, c=3)
+        >>> c                                       # display most common to least
+        Counter({'c': 3, 'b': 2, 'a': 1})
+        >>> list(c.items())                         # original insertion order
+        [('a', 1), ('b', 2), ('c', 3)]
+
     .. versionadded:: 3.1
 
     .. versionchanged:: 3.7 As a :class:`dict` subclass, :class:`Counter`

Doc/library/tempfile.rst

@@ -257,7 +257,8 @@ The module defines the following user-callable items:
    The file descriptor is :ref:`not inherited by child processes <fd_inheritance>`.
 
    Unlike :func:`TemporaryFile`, the user of :func:`mkstemp` is responsible
-   for deleting the temporary file when done with it.
+   for closing the file descriptor (for example, using :func:`os.close`) and
+   deleting the temporary file (for example, using :func:`os.remove`).
 
    If *suffix* is not ``None``, the file name will end with that suffix,
    otherwise there will be no suffix.  :func:`mkstemp` does not put a dot

Doc/tools/.nitignore

@@ -2,9 +2,6 @@
 # as tested on the CI via check-warnings.py in reusable-docs.yml.
 # Keep lines sorted lexicographically to help avoid merge conflicts.
 
-Doc/c-api/init_config.rst
-Doc/c-api/intro.rst
-Doc/c-api/stable.rst
 Doc/library/ast.rst
 Doc/library/asyncio-extending.rst
 Doc/library/email.charset.rst
@@ -32,4 +29,3 @@ Doc/library/xml.sax.reader.rst
 Doc/library/xml.sax.rst
 Doc/library/xmlrpc.client.rst
 Doc/library/xmlrpc.server.rst
-Doc/whatsnew/2.6.rst