Merge remote-tracking branch 'upstream' into fix-issue-140715--C

Author: jyalim

.github/workflows/build.yml

@@ -165,13 +165,21 @@ jobs:
         free-threading:
           - false
           - true
+        interpreter:
+          - switch-case
         exclude:
           # Skip Win32 on free-threaded builds
           - { arch: Win32, free-threading: true }
+        include:
+          # msvc::musttail is currently only supported on x64,
+          # and only supported on 3.15+.
+          - { arch: x64, free-threading: false, interpreter: tail-call }
+          - { arch: x64, free-threading: true,  interpreter: tail-call }
     uses: ./.github/workflows/reusable-windows.yml
     with:
       arch: ${{ matrix.arch }}
       free-threading: ${{ matrix.free-threading }}
+      interpreter: ${{ matrix.interpreter }}
 
   build-windows-msi:
     # ${{ '' } is a hack to nest jobs under the same sidebar category.

.github/workflows/reusable-emscripten.yml

@@ -10,7 +10,7 @@ jobs:
   build-emscripten-reusable:
     name: 'build and test'
     runs-on: ubuntu-24.04
-    timeout-minutes: 60
+    timeout-minutes: 40
     steps:
     - uses: actions/checkout@v6
       with:

.github/workflows/reusable-windows.yml

@@ -12,6 +12,10 @@ on:
         required: false
         type: boolean
         default: false
+      interpreter:
+        description: Which interpreter to build (switch-case or tail-call)
+        required: true
+        type: string
 
 env:
   FORCE_COLOR: 1
@@ -20,7 +24,7 @@ env:
 
 jobs:
   build:
-    name: Build and test (${{ inputs.arch }})
+    name: Build and test (${{ inputs.arch }}, ${{ inputs.interpreter }})
     runs-on: ${{ inputs.arch == 'arm64' && 'windows-11-arm' || 'windows-2025-vs2026' }}
     timeout-minutes: 60
     env:
@@ -33,9 +37,12 @@ jobs:
       if: inputs.arch != 'Win32'
       run: echo "::add-matcher::.github/problem-matchers/msvc.json"
     - name: Build CPython
+      # msvc::musttail is not supported for debug builds, so we have to
+      # switch to release.
       run: >-
         .\\PCbuild\\build.bat
-        -e -d -v
+        -e -v
+        ${{ inputs.interpreter == 'switch-case' && '-d' || '--tail-call-interp -c Release' }}
         -p "${ARCH}"
         ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
       shell: bash
@@ -45,6 +52,7 @@ jobs:
       run: >-
         .\\PCbuild\\rt.bat
         -p "${ARCH}"
-        -d -q --fast-ci
+        -q --fast-ci
+        ${{ inputs.interpreter == 'switch-case' && '-d' || '' }}
         ${{ fromJSON(inputs.free-threading) && '--disable-gil' || '' }}
       shell: bash

.github/workflows/tail-call.yml

@@ -23,41 +23,6 @@ env:
   LLVM_VERSION: 21
 
 jobs:
-  windows:
-    name: ${{ matrix.target }}
-    runs-on: ${{ matrix.runner }}
-    timeout-minutes: 60
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - target: x86_64-pc-windows-msvc/msvc
-            architecture: x64
-            runner: windows-2025-vs2026
-            build_flags: ""
-            run_tests: true
-          - target: x86_64-pc-windows-msvc/msvc-free-threading
-            architecture: x64
-            runner: windows-2025-vs2026
-            build_flags: --disable-gil
-            run_tests: false
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-      - uses: actions/setup-python@v6
-        with:
-          python-version: '3.11'
-      - name: Build
-        shell: pwsh
-        run: |
-          ./PCbuild/build.bat --tail-call-interp ${{ matrix.build_flags }} -c Release -p ${{ matrix.architecture }}
-      - name: Test
-        if: matrix.run_tests
-        shell: pwsh
-        run: |
-          ./PCbuild/rt.bat -p ${{ matrix.architecture }} -q --multiprocess 0 --timeout 4500 --verbose2 --verbose3
-
   macos:
     name: ${{ matrix.target }}
     runs-on: ${{ matrix.runner }}

Doc/library/array.rst

@@ -42,13 +42,15 @@ defined:
 +-----------+--------------------+-------------------+-----------------------+-------+
 | ``'Q'``   | unsigned long long | int               | 8                     |       |
 +-----------+--------------------+-------------------+-----------------------+-------+
+| ``'e'``   | _Float16           | float             | 2                     | \(3)  |
++-----------+--------------------+-------------------+-----------------------+-------+
 | ``'f'``   | float              | float             | 4                     |       |
 +-----------+--------------------+-------------------+-----------------------+-------+
 | ``'d'``   | double             | float             | 8                     |       |
 +-----------+--------------------+-------------------+-----------------------+-------+
-| ``'F'``   | float complex      | complex           | 8                     | \(3)  |
+| ``'F'``   | float complex      | complex           | 8                     | \(4)  |
 +-----------+--------------------+-------------------+-----------------------+-------+
-| ``'D'``   | double complex     | complex           | 16                    | \(3)  |
+| ``'D'``   | double complex     | complex           | 16                    | \(4)  |
 +-----------+--------------------+-------------------+-----------------------+-------+
 
 
@@ -69,6 +71,15 @@ Notes:
    .. versionadded:: 3.13
 
 (3)
+   The IEEE 754 binary16 "half precision" type was introduced in the 2008
+   revision of the `IEEE 754 standard <ieee 754 standard_>`_.
+   This type is not widely supported by C compilers.  It's available
+   as :c:expr:`_Float16` type, if the compiler supports the Annex H
+   of the C23 standard.
+
+   .. versionadded:: next
+
+(4)
    Complex types (``F`` and ``D``) are available unconditionally,
    regardless on support for complex types (the Annex G of the C11 standard)
    by the C compiler.
@@ -304,3 +315,5 @@ Examples::
 
    `NumPy <https://numpy.org/>`_
       The NumPy package defines another array type.
+
+.. _ieee 754 standard: https://en.wikipedia.org/wiki/IEEE_754-2008_revision

Doc/library/getpass.rst

@@ -39,13 +39,27 @@ The :mod:`!getpass` module provides two functions:
       On Unix systems, when *echo_char* is set, the terminal will be
       configured to operate in
       :manpage:`noncanonical mode <termios(3)#Canonical_and_noncanonical_mode>`.
-      In particular, this means that line editing shortcuts such as
-      :kbd:`Ctrl+U` will not work and may insert unexpected characters into
-      the input.
+      Common terminal control characters are supported:
+
+      * :kbd:`Ctrl+A` - Move cursor to beginning of line
+      * :kbd:`Ctrl+E` - Move cursor to end of line
+      * :kbd:`Ctrl+K` - Kill (delete) from cursor to end of line
+      * :kbd:`Ctrl+U` - Kill (delete) entire line
+      * :kbd:`Ctrl+W` - Erase previous word
+      * :kbd:`Ctrl+V` - Insert next character literally (quote)
+      * :kbd:`Backspace`/:kbd:`DEL` - Delete character before cursor
+
+      These shortcuts work by reading the terminal's configured control
+      character mappings from termios settings.
 
    .. versionchanged:: 3.14
       Added the *echo_char* parameter for keyboard feedback.
 
+   .. versionchanged:: next
+      When using non-empty *echo_char* on Unix, keyboard shortcuts (including
+      cursor movement and line editing) are now properly handled using the
+      terminal's control character configuration.
+
 .. exception:: GetPassWarning
 
    A :exc:`UserWarning` subclass issued when password input may be echoed.

Doc/library/profiling.sampling.rst

@@ -1003,6 +1003,47 @@ at the top indicate functions that consume significant time either directly
 or through their callees.
 
 
+Differential flame graphs
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Differential flame graphs compare two profiling runs to highlight where
+performance changed. This helps identify regressions introduced by code changes
+and validate that optimizations achieved their intended effect::
+
+   # Capture baseline profile
+   python -m profiling.sampling run --binary -o baseline.bin script.py
+
+   # After modifying code, generate differential flamegraph
+   python -m profiling.sampling run --diff-flamegraph baseline.bin -o diff.html script.py
+
+The visualization draws the current profile with frame widths showing current
+time consumption, then applies color to indicate how each function changed
+relative to the baseline.
+
+**Color coding**:
+
+- **Red**: Functions consuming more time (regressions). Lighter shades indicate
+  modest increases, while darker shades show severe regressions.
+
+- **Blue**: Functions consuming less time (improvements). Lighter shades for
+  modest reductions, darker shades for significant speedups.
+
+- **Gray**: Minimal or no change.
+
+- **Purple**: New functions not present in the baseline.
+
+Frame colors indicate changes in **direct time** (time when the function was at
+the top of the stack, actively executing), not cumulative time including callees.
+Hovering over a frame shows comparison details including baseline time, current
+time, and the percentage change.
+
+Some call paths may disappear entirely between profiles. These are called
+**elided stacks** and occur when optimizations eliminate code paths or certain
+branches stop executing. If elided stacks are present, an elided toggle appears
+allowing you to switch between the main differential view and an elided-only
+view that shows just the removed paths (colored purple).
+
+
 Gecko format
 ------------
 
@@ -1488,6 +1529,10 @@ Output options
 
    Generate self-contained HTML flame graph.
 
+.. option:: --diff-flamegraph <baseline.bin>
+
+   Generate differential flamegraph comparing to a baseline binary profile.
+
 .. option:: --gecko
 
    Generate Gecko JSON format for Firefox Profiler.

Doc/library/select.rst

@@ -62,7 +62,7 @@ The module defines the following:
 
    *sizehint* informs epoll about the expected number of events to be
    registered.  It must be positive, or ``-1`` to use the default. It is only
-   used on older systems where :c:func:`!epoll_create1` is not available;
+   used on older systems where :manpage:`epoll_create1(2)` is not available;
    otherwise it has no effect (though its value is still checked).
 
    *flags* is deprecated and completely ignored.  However, when supplied, its
@@ -89,6 +89,11 @@ The module defines the following:
       The *flags* parameter.  ``select.EPOLL_CLOEXEC`` is used by default now.
       Use :func:`os.set_inheritable` to make the file descriptor inheritable.
 
+   .. versionchanged:: next
+
+      When CPython is built, this function may be disabled using
+      :option:`--disable-epoll`.
+
 
 .. function:: poll()
 

Doc/library/xml.etree.elementtree.rst

@@ -691,7 +691,7 @@ Functions
    .. versionadded:: 3.2
 
 
-.. function:: SubElement(parent, tag, attrib={}, **extra)
+.. function:: SubElement(parent, tag, /, attrib={}, **extra)
 
    Subelement factory.  This function creates an element instance, and appends
    it to an existing element.
@@ -705,6 +705,9 @@ Functions
    .. versionchanged:: 3.15
       *attrib* can now be a :class:`frozendict`.
 
+   .. versionchanged:: next
+      *parent* and *tag* are now positional-only parameters.
+
 
 .. function:: tostring(element, encoding="us-ascii", method="xml", *, \
                        xml_declaration=None, default_namespace=None, \
@@ -880,7 +883,7 @@ Element Objects
    :noindex:
    :no-index:
 
-.. class:: Element(tag, attrib={}, **extra)
+.. class:: Element(tag, /, attrib={}, **extra)
 
    Element class.  This class defines the Element interface, and provides a
    reference implementation of this interface.
@@ -893,6 +896,9 @@ Element Objects
    .. versionchanged:: 3.15
       *attrib* can now be a :class:`frozendict`.
 
+   .. versionchanged:: next
+      *tag* is now a positional-only parameter.
+
 
    .. attribute:: tag
 

Doc/using/configure.rst

@@ -463,6 +463,17 @@ General Options
 
    ``pkg-config`` options.
 
+.. option:: --disable-epoll
+
+   Build without ``epoll``, meaning that :py:func:`select.epoll` will not be
+   present even if the system provides an
+   :manpage:`epoll_create <epoll_create(2)>` function.
+   This may be used on systems where :manpage:`!epoll_create` or
+   :manpage:`epoll_create1 <epoll_create1(2)>` is available
+   but incompatible with Linux semantics.
+
+   .. versionadded:: next
+
 
 C compiler options
 ------------------