Merge 505c63be1a into ab955f158c

.appveyor.yml

@@ -9,7 +9,7 @@ platform:
 - x86
 environment:
   matrix:
-  - PYTHON: 38
+  - PYTHON: 36
     CONFIG: Debug
 install:
 - ps: |

.clang-tidy

@@ -57,12 +57,10 @@ Checks: |
   readability-string-compare,
   readability-suspicious-call-argument,
   readability-uniqueptr-delete-release,
-  -bugprone-chained-comparison,
   -bugprone-easily-swappable-parameters,
   -bugprone-exception-escape,
   -bugprone-reserved-identifier,
   -bugprone-unused-raii,
-  -performance-enum-size,
 
 CheckOptions:
 - key:             modernize-use-equals-default.IgnoreMacros

.github/CONTRIBUTING.md

@@ -81,7 +81,7 @@ nox -s build
 ### Full setup
 
 To setup an ideal development environment, run the following commands on a
-system with CMake 3.15+:
+system with CMake 3.14+:
 
 ```bash
 python3 -m venv venv
@@ -96,8 +96,8 @@ Tips:
 * You can use `virtualenv` (faster, from PyPI) instead of `venv`.
 * You can select any name for your environment folder; if it contains "env" it
   will be ignored by git.
-* If you don't have CMake 3.15+, just add "cmake" to the pip install command.
-* You can use `-DPYBIND11_FINDPYTHON=ON` to use FindPython.
+* If you don't have CMake 3.14+, just add "cmake" to the pip install command.
+* You can use `-DPYBIND11_FINDPYTHON=ON` to use FindPython on CMake 3.12+
 * In classic mode, you may need to set `-DPYTHON_EXECUTABLE=/path/to/python`.
   FindPython uses `-DPython_ROOT_DIR=/path/to` or
   `-DPython_EXECUTABLE=/path/to/python`.
@@ -149,8 +149,8 @@ To run the tests, you can "build" the check target:
 cmake --build build --target check
 ```
 
-`--target` can be spelled `-t`. You can also run individual tests with these
-targets:
+`--target` can be spelled `-t` in CMake 3.15+. You can also run individual
+tests with these targets:
 
 * `pytest`: Python tests only, using the
 [pytest](https://docs.pytest.org/en/stable/) framework

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
       matrix:
         runs-on: [ubuntu-20.04, windows-2022, macos-13]
         python:
-        - '3.8'
+        - '3.6'
         - '3.9'
         - '3.12'
         - '3.13'
@@ -48,17 +48,16 @@ jobs:
         include:
           # Just add a key
           - runs-on: ubuntu-20.04
-            python: '3.8'
+            python: '3.6'
             args: >
               -DPYBIND11_FINDPYTHON=ON
               -DCMAKE_CXX_FLAGS="-D_=1"
-            exercise_D_: 1
           - runs-on: ubuntu-20.04
             python: 'pypy-3.8'
             args: >
               -DPYBIND11_FINDPYTHON=ON
           - runs-on: windows-2019
-            python: '3.8'
+            python: '3.6'
             args: >
               -DPYBIND11_FINDPYTHON=ON
           # Inject a couple Windows 2019 runs
@@ -83,7 +82,7 @@ jobs:
 
     - name: Setup Boost (Linux)
       # Can't use boost + define _
-      if: runner.os == 'Linux' && matrix.exercise_D_ != 1
+      if: runner.os == 'Linux' && matrix.python != '3.6'
       run: sudo apt-get install libboost-dev
 
     - name: Setup Boost (macOS)
@@ -134,7 +133,9 @@ jobs:
       run: cmake --build . --target pytest -j 2
 
     - name: C++11 tests
-      run: cmake --build . --target cpptest -j 2
+      # TODO: Figure out how to load the DLL on Python 3.8+
+      if: "!(runner.os == 'Windows' && (matrix.python == 3.8 || matrix.python == 3.9 || matrix.python == '3.10' || matrix.python == '3.11' || matrix.python == 'pypy-3.8'))"
+      run: cmake --build .  --target cpptest -j 2
 
     - name: Interface test C++11
       run: cmake --build . --target test_cmake_build
@@ -163,6 +164,8 @@ jobs:
       run: cmake --build build2 --target pytest
 
     - name: C++ tests
+      # TODO: Figure out how to load the DLL on Python 3.8+
+      if: "!(runner.os == 'Windows' && (matrix.python == 3.8 || matrix.python == 3.9 || matrix.python == '3.10' || matrix.python == '3.11' || matrix.python == 'pypy-3.8'))"
       run: cmake --build build2 --target cpptest
 
     # Third build - C++17 mode with unstable ABI
@@ -243,7 +246,7 @@ jobs:
     - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python-version }} (deadsnakes)
-      uses: deadsnakes/action@v3.2.0
+      uses: deadsnakes/action@v3.1.0
       with:
         python-version: ${{ matrix.python-version }}
         debug: ${{ matrix.python-debug }}
@@ -311,6 +314,11 @@ jobs:
       fail-fast: false
       matrix:
         clang:
+          - 3.6
+          - 3.7
+          - 3.9
+          - 7
+          - 9
           - dev
         std:
           - 11
@@ -319,6 +327,8 @@ jobs:
         include:
           - clang: 5
             std: 14
+          - clang: 10
+            std: 17
           - clang: 11
             std: 20
           - clang: 12
@@ -333,12 +343,6 @@ jobs:
           - clang: 16
             std: 20
             container_suffix: "-bullseye"
-          - clang: 17
-            std: 20
-            container_suffix: "-bookworm"
-          - clang: 18
-            std: 20
-            container_suffix: "-bookworm"
 
     name: "🐍 3 • Clang ${{ matrix.clang }} • C++${{ matrix.std }} • x64"
     container: "silkeh/clang:${{ matrix.clang }}${{ matrix.container_suffix }}"
@@ -496,9 +500,11 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - { gcc: 9, std: 20 }
+          - { gcc: 7, std: 11 }
+          - { gcc: 7, std: 17 }
+          - { gcc: 8, std: 14 }
+          - { gcc: 8, std: 17 }
           - { gcc: 10, std: 17 }
-          - { gcc: 10, std: 20 }
           - { gcc: 11, std: 20 }
           - { gcc: 12, std: 20 }
           - { gcc: 13, std: 20 }
@@ -653,13 +659,15 @@ jobs:
         cmake --build build-17 --target test_cmake_build
 
 
-  # Testing on CentOS (manylinux uses a centos base).
+  # Testing on CentOS (manylinux uses a centos base, and this is an easy way
+  # to get GCC 4.8, which is the manylinux1 compiler).
   centos:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
         container:
+          - "centos:7"  # GCC 4.8
           - "almalinux:8"
           - "almalinux:9"
 
@@ -669,13 +677,18 @@ jobs:
     steps:
     - name: Latest actions/checkout
       uses: actions/checkout@v4
+      if: matrix.container != 'centos:7'
 
-    - name: Add Python 3.8
-      if: matrix.container == 'almalinux:8'
-      run: dnf update -y && dnf install -y python38-devel gcc-c++ make git
+    - name: Pin actions/checkout as required for centos:7
+      uses: actions/checkout@v3
+      if: matrix.container == 'centos:7'
 
-    - name: Add Python 3 (default)
-      if: matrix.container != 'almalinux:8'
+    - name: Add Python 3 (RHEL 7)
+      if: matrix.container == 'centos:7'
+      run: yum update -y && yum install -y python3-devel gcc-c++ make git
+
+    - name: Add Python 3 (RHEL 8+)
+      if: matrix.container != 'centos:7'
       run: dnf update -y && dnf install -y python3-devel gcc-c++ make git
 
     - name: Update pip
@@ -716,9 +729,9 @@ jobs:
 
   # This tests an "install" with the CMake tools
   install-classic:
-    name: "🐍 3.9 • Debian • x86 •  Install"
+    name: "🐍 3.7 • Debian • x86 •  Install"
     runs-on: ubuntu-latest
-    container: i386/debian:bullseye
+    container: i386/debian:buster
 
     steps:
     - uses: actions/checkout@v1  # v1 is required to run inside docker
@@ -798,23 +811,18 @@ jobs:
       fail-fast: false
       matrix:
         python:
-        - '3.8'
-        - '3.9'
-        - '3.10'
-        - '3.11'
-        - '3.12'
+        - 3.6
+        - 3.7
+        - 3.8
+        - 3.9
 
         include:
-          - python: '3.12'
+          - python: 3.9
             args: -DCMAKE_CXX_STANDARD=20
-          - python: '3.11'
-            args: -DCMAKE_CXX_STANDARD=20
-          - python: '3.10'
-            args: -DCMAKE_CXX_STANDARD=20
-          - python: '3.9'
-            args: -DCMAKE_CXX_STANDARD=20
-          - python: '3.8'
+          - python: 3.8
             args: -DCMAKE_CXX_STANDARD=17
+          - python: 3.7
+            args: -DCMAKE_CXX_STANDARD=14
 
 
     name: "🐍 ${{ matrix.python }} • MSVC 2019 • x86 ${{ matrix.args }}"
@@ -1103,7 +1111,7 @@ jobs:
         uses: jwlawson/actions-setup-cmake@v2.0
 
       - name: Install ninja-build tool
-        uses: seanmiddleditch/gha-setup-ninja@v5
+        uses: seanmiddleditch/gha-setup-ninja@v4
 
       - name: Run pip installs
         run: |

.github/workflows/configure.yml

@@ -31,7 +31,7 @@ jobs:
         include:
         - runs-on: ubuntu-20.04
           arch: x64
-          cmake: "3.15"
+          cmake: "3.5"
 
         - runs-on: ubuntu-20.04
           arch: x64
@@ -39,22 +39,22 @@ jobs:
 
         - runs-on: macos-13
           arch: x64
-          cmake: "3.15"
+          cmake: "3.7"
 
         - runs-on: windows-2019
           arch: x64 # x86 compilers seem to be missing on 2019 image
           cmake: "3.18"
 
-    name: 🐍 3.8 • CMake ${{ matrix.cmake }} • ${{ matrix.runs-on }}
+    name: 🐍 3.7 • CMake ${{ matrix.cmake }} • ${{ matrix.runs-on }}
     runs-on: ${{ matrix.runs-on }}
 
     steps:
     - uses: actions/checkout@v4
 
-    - name: Setup Python 3.8
+    - name: Setup Python 3.7
       uses: actions/setup-python@v5
       with:
-        python-version: 3.8
+        python-version: 3.7
         architecture: ${{ matrix.arch }}
 
     - name: Prepare env

.github/workflows/emscripten.yaml

@@ -1,30 +0,0 @@
-name: WASM
-
-on:
-  workflow_dispatch:
-  pull_request:
-    branches:
-    - master
-    - stable
-    - v*
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true
-
-jobs:
-  build-wasm-emscripten:
-    name: Pyodide wheel
-    runs-on: ubuntu-22.04
-    steps:
-    - uses: actions/checkout@v4
-      with:
-        submodules: true
-        fetch-depth: 0
-
-    - uses: pypa/cibuildwheel@v2.21
-      env:
-        PYODIDE_BUILD_EXPORTS: whole_archive
-      with:
-        package-dir: tests
-        only: cp312-pyodide_wasm32

.github/workflows/format.yml

@@ -41,7 +41,7 @@ jobs:
     # in .github/CONTRIBUTING.md and update as needed.
     name: Clang-Tidy
     runs-on: ubuntu-latest
-    container: silkeh/clang:18-bookworm
+    container: silkeh/clang:15-bullseye
     steps:
     - uses: actions/checkout@v4
 

.github/workflows/pip.yml

@@ -21,18 +21,19 @@ env:
 
 jobs:
   # This builds the sdists and wheels and makes sure the files are exactly as
-  # expected.
+  # expected. Using Windows and Python 3.6, since that is often the most
+  # challenging matrix element.
   test-packaging:
-    name: 🐍 3.8 • 📦 tests • windows-latest
+    name: 🐍 3.6 • 📦 tests • windows-latest
     runs-on: windows-latest
 
     steps:
     - uses: actions/checkout@v4
 
-    - name: Setup 🐍 3.8
+    - name: Setup 🐍 3.6
       uses: actions/setup-python@v5
       with:
-        python-version: 3.8
+        python-version: 3.6
 
     - name: Prepare env
       run: |
@@ -91,30 +92,23 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name == 'release' && github.event.action == 'published'
     needs: [packaging]
-    environment:
-      name: pypi
-      url: https://pypi.org/p/pybind11
-    permissions:
-      id-token: write
-      attestations: write
 
     steps:
+    - uses: actions/setup-python@v5
+      with:
+        python-version: "3.x"
+
     # Downloads all to directories matching the artifact names
     - uses: actions/download-artifact@v4
 
-    - name: Generate artifact attestation for sdist and wheel
-      uses: actions/attest-build-provenance@1c608d11d69870c2092266b3f9a6f3abbf17002c # v1.4.3
-      with:
-        subject-path: "*/pybind11*"
-
     - name: Publish standard package
       uses: pypa/gh-action-pypi-publish@release/v1
       with:
+        password: ${{ secrets.pypi_password }}
         packages-dir: standard/
-        attestations: true
 
     - name: Publish global package
       uses: pypa/gh-action-pypi-publish@release/v1
       with:
+        password: ${{ secrets.pypi_password_global }}
         packages-dir: global/
-        attestations: true

.pre-commit-config.yaml

@@ -25,14 +25,14 @@ repos:
 
 # Clang format the codebase automatically
 - repo: https://github.com/pre-commit/mirrors-clang-format
-  rev: "v18.1.8"
+  rev: "v18.1.5"
   hooks:
   - id: clang-format
     types_or: [c++, c, cuda]
 
 # Ruff, the Python auto-correcting linter/formatter written in Rust
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.6.3
+  rev: v0.4.7
   hooks:
   - id: ruff
     args: ["--fix", "--show-fixes"]
@@ -40,7 +40,7 @@ repos:
 
 # Check static types with mypy
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: "v1.11.2"
+  rev: "v1.10.0"
   hooks:
   - id: mypy
     args: []
@@ -79,7 +79,7 @@ repos:
 
 # Also code format the docs
 - repo: https://github.com/adamchainz/blacken-docs
-  rev: "1.18.0"
+  rev: "1.16.0"
   hooks:
   - id: blacken-docs
     additional_dependencies:
@@ -93,7 +93,7 @@ repos:
 
 # Avoid directional quotes
 - repo: https://github.com/sirosen/texthooks
-  rev: "0.6.7"
+  rev: "0.6.6"
   hooks:
   - id: fix-ligatures
   - id: fix-smartquotes
@@ -142,14 +142,14 @@ repos:
 
 # PyLint has native support - not always usable, but works for us
 - repo: https://github.com/PyCQA/pylint
-  rev: "v3.2.7"
+  rev: "v3.2.2"
   hooks:
   - id: pylint
     files: ^pybind11
 
 # Check schemas on some of our YAML files
 - repo: https://github.com/python-jsonschema/check-jsonschema
-  rev: 0.29.2
+  rev: 0.28.4
   hooks:
   - id: check-readthedocs
   - id: check-github-workflows

CMakeLists.txt

@@ -10,7 +10,16 @@ if(NOT CMAKE_VERSION VERSION_LESS "3.27")
   cmake_policy(GET CMP0148 _pybind11_cmp0148)
 endif()
 
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 if(_pybind11_cmp0148)
   cmake_policy(SET CMP0148 ${_pybind11_cmp0148})
@@ -18,7 +27,9 @@ if(_pybind11_cmp0148)
 endif()
 
 # Avoid infinite recursion if tests include this as a subdirectory
-include_guard(GLOBAL)
+if(DEFINED PYBIND11_MASTER_PROJECT)
+  return()
+endif()
 
 # Extract project version from source
 file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/include/pybind11/detail/common.h"
@@ -63,6 +74,14 @@ if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
 
   set(PYBIND11_MASTER_PROJECT ON)
 
+  if(OSX AND CMAKE_VERSION VERSION_LESS 3.7)
+    # Bug in macOS CMake < 3.7 is unable to download catch
+    message(WARNING "CMAKE 3.7+ needed on macOS to download catch, and newer HIGHLY recommended")
+  elseif(WINDOWS AND CMAKE_VERSION VERSION_LESS 3.8)
+    # Only tested with 3.8+ in CI.
+    message(WARNING "CMAKE 3.8+ tested on Windows, previous versions untested")
+  endif()
+
   message(STATUS "CMake ${CMAKE_VERSION}")
 
   if(CMAKE_CXX_STANDARD)
@@ -114,7 +133,8 @@ cmake_dependent_option(
   "Install pybind11 headers in Python include directory instead of default installation prefix"
   OFF "PYBIND11_INSTALL" OFF)
 
-option(PYBIND11_FINDPYTHON "Force new FindPython" ${_pybind11_findpython_default})
+cmake_dependent_option(PYBIND11_FINDPYTHON "Force new FindPython" ${_pybind11_findpython_default}
+                       "NOT CMAKE_VERSION VERSION_LESS 3.12" OFF)
 
 # Allow PYTHON_EXECUTABLE if in FINDPYTHON mode and building pybind11's tests
 # (makes transition easier while we support both modes).
@@ -129,14 +149,11 @@ endif()
 set(PYBIND11_HEADERS
     include/pybind11/detail/class.h
     include/pybind11/detail/common.h
-    include/pybind11/detail/cpp_conduit.h
     include/pybind11/detail/descr.h
     include/pybind11/detail/init.h
     include/pybind11/detail/internals.h
     include/pybind11/detail/type_caster_base.h
     include/pybind11/detail/typeid.h
-    include/pybind11/detail/value_and_holder.h
-    include/pybind11/detail/exception_translation.h
     include/pybind11/attr.h
     include/pybind11/buffer_info.h
     include/pybind11/cast.h
@@ -162,11 +179,10 @@ set(PYBIND11_HEADERS
     include/pybind11/stl_bind.h
     include/pybind11/stl/filesystem.h
     include/pybind11/type_caster_pyobject_ptr.h
-    include/pybind11/typing.h
-    include/pybind11/warnings.h)
+    include/pybind11/typing.h)
 
 # Compare with grep and warn if mismatched
-if(PYBIND11_MASTER_PROJECT)
+if(PYBIND11_MASTER_PROJECT AND NOT CMAKE_VERSION VERSION_LESS 3.12)
   file(
     GLOB_RECURSE _pybind11_header_check
     LIST_DIRECTORIES false
@@ -184,7 +200,10 @@ if(PYBIND11_MASTER_PROJECT)
   endif()
 endif()
 
-list(TRANSFORM PYBIND11_HEADERS PREPEND "${CMAKE_CURRENT_SOURCE_DIR}/")
+# CMake 3.12 added list(TRANSFORM <list> PREPEND
+# But we can't use it yet
+string(REPLACE "include/" "${CMAKE_CURRENT_SOURCE_DIR}/include/" PYBIND11_HEADERS
+               "${PYBIND11_HEADERS}")
 
 # Cache variable so this can be used in parent projects
 set(pybind11_INCLUDE_DIR
@@ -254,11 +273,25 @@ if(PYBIND11_INSTALL)
     tools/${PROJECT_NAME}Config.cmake.in "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
     INSTALL_DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
 
-  # CMake natively supports header-only libraries
-  write_basic_package_version_file(
-    ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
-    VERSION ${PROJECT_VERSION}
-    COMPATIBILITY AnyNewerVersion ARCH_INDEPENDENT)
+  if(CMAKE_VERSION VERSION_LESS 3.14)
+    # Remove CMAKE_SIZEOF_VOID_P from ConfigVersion.cmake since the library does
+    # not depend on architecture specific settings or libraries.
+    set(_PYBIND11_CMAKE_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
+    unset(CMAKE_SIZEOF_VOID_P)
+
+    write_basic_package_version_file(
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
+      VERSION ${PROJECT_VERSION}
+      COMPATIBILITY AnyNewerVersion)
+
+    set(CMAKE_SIZEOF_VOID_P ${_PYBIND11_CMAKE_SIZEOF_VOID_P})
+  else()
+    # CMake 3.14+ natively supports header-only libraries
+    write_basic_package_version_file(
+      ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
+      VERSION ${PROJECT_VERSION}
+      COMPATIBILITY AnyNewerVersion ARCH_INDEPENDENT)
+  endif()
 
   install(
     FILES ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake

README.rst

@@ -34,7 +34,7 @@ dependency.
 Think of this library as a tiny self-contained version of Boost.Python
 with everything stripped away that isn't relevant for binding
 generation. Without comments, the core header files only require ~4K
-lines of code and depend on Python (3.8+, or PyPy) and the C++
+lines of code and depend on Python (3.6+, or PyPy) and the C++
 standard library. This compact implementation was possible thanks to
 some C++11 language features (specifically: tuples, lambda functions and
 variadic templates). Since its creation, this library has grown beyond
@@ -79,7 +79,7 @@ Goodies
 In addition to the core functionality, pybind11 provides some extra
 goodies:
 
-- Python 3.8+, and PyPy3 7.3 are supported with an implementation-agnostic
+- Python 3.6+, and PyPy3 7.3 are supported with an implementation-agnostic
   interface (pybind11 2.9 was the last version to support Python 2 and 3.5).
 
 - It is possible to bind C++11 lambda functions with captured

docs/advanced/cast/eigen.rst

@@ -259,7 +259,7 @@ copying to take place:
         "small"_a            // <- This one can be copied if needed
     );
 
-With the above binding code, attempting to call the ``some_method(m)``
+With the above binding code, attempting to call the the ``some_method(m)``
 method on a ``MyClass`` object, or attempting to call ``some_function(m, m2)``
 will raise a ``RuntimeError`` rather than making a temporary copy of the array.
 It will, however, allow the ``m2`` argument to be copied into a temporary if

docs/advanced/cast/stl.rst

@@ -162,7 +162,7 @@ the declaration
 
 .. code-block:: cpp
 
-    PYBIND11_MAKE_OPAQUE(std::vector<int>)
+    PYBIND11_MAKE_OPAQUE(std::vector<int>);
 
 before any binding code (e.g. invocations to ``class_::def()``, etc.). This
 macro must be specified at the top level (and outside of any namespaces), since
@@ -207,8 +207,8 @@ The following example showcases usage of :file:`pybind11/stl_bind.h`:
     // Don't forget this
     #include <pybind11/stl_bind.h>
 
-    PYBIND11_MAKE_OPAQUE(std::vector<int>)
-    PYBIND11_MAKE_OPAQUE(std::map<std::string, double>)
+    PYBIND11_MAKE_OPAQUE(std::vector<int>);
+    PYBIND11_MAKE_OPAQUE(std::map<std::string, double>);
 
     // ...
 

docs/advanced/classes.rst

@@ -826,7 +826,8 @@ An instance can now be pickled as follows:
     always use the latest available version. Beware: failure to follow these
     instructions will cause important pybind11 memory allocation routines to be
     skipped during unpickling, which will likely lead to memory corruption
-    and/or segmentation faults.
+    and/or segmentation faults. Python defaults to version 3 (Python 3-3.7) and
+    version 4 for Python 3.8+.
 
 .. seealso::
 

docs/advanced/embedding.rst

@@ -18,7 +18,7 @@ information, see :doc:`/compiling`.
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.15...3.30)
+    cmake_minimum_required(VERSION 3.5...3.29)
     project(example)
 
     find_package(pybind11 REQUIRED)  # or `add_subdirectory(pybind11)`

docs/advanced/exceptions.rst

@@ -368,7 +368,8 @@ Should they throw or fail to catch any exceptions in their call graph,
 the C++ runtime calls ``std::terminate()`` to abort immediately.
 
 Similarly, Python exceptions raised in a class's ``__del__`` method do not
-propagate, but ``sys.unraisablehook()`` `is triggered
+propagate, but are logged by Python as an unraisable error. In Python 3.8+, a
+`system hook is triggered
 <https://docs.python.org/3/library/sys.html#sys.unraisablehook>`_
 and an auditing event is logged.
 

docs/advanced/smart_ptrs.rst

@@ -124,7 +124,7 @@ top namespace level before any binding code:
 
 .. code-block:: cpp
 
-    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>)
+    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>);
 
 The first argument of :func:`PYBIND11_DECLARE_HOLDER_TYPE` should be a
 placeholder name that is used as a template parameter of the second argument.
@@ -136,7 +136,7 @@ by default. Specify
 
 .. code-block:: cpp
 
-    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>, true)
+    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>, true);
 
 if ``SmartPtr<T>`` can always be initialized from a ``T*`` pointer without the
 risk of inconsistencies (such as multiple independent ``SmartPtr`` instances
@@ -154,7 +154,7 @@ specialized:
 .. code-block:: cpp
 
     // Always needed for custom holder types
-    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>)
+    PYBIND11_DECLARE_HOLDER_TYPE(T, SmartPtr<T>);
 
     // Only needed if the type's `.get()` goes by another name
     namespace PYBIND11_NAMESPACE { namespace detail {

docs/basics.rst

@@ -78,13 +78,6 @@ For brevity, all code examples assume that the following two lines are present:
 
     namespace py = pybind11;
 
-.. note::
-
-    ``pybind11/pybind11.h`` includes ``Python.h``, as such it must be the first file
-    included in any source file or header for `the same reasons as Python.h`_.
-
-.. _`the same reasons as Python.h`: https://docs.python.org/3/extending/extending.html#a-simple-example
-
 Some features may require additional headers, but those will be specified as needed.
 
 .. _simple_example:

docs/benchmark.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import datetime as dt
 import os
 import random

docs/changelog.rst

@@ -15,273 +15,6 @@ IN DEVELOPMENT
 
 Changes will be summarized here periodically.
 
-New Features:
-
-* Support for Python 3.7 was removed. (Official end-of-life: 2023-06-27).
-  `#5191 <https://github.com/pybind/pybind11/pull/5191>`_
-
-* stl.h ``list|set|map_caster`` were made more user friendly: it is no longer
-  necessary to explicitly convert Python iterables to ``tuple()``, ``set()``,
-  or ``map()`` in many common situations.
-  `#4686 <https://github.com/pybind/pybind11/pull/4686>`_
-
-* Support for CMake older than 3.15 removed. CMake 3.15-3.30 supported.
-  `#5304 <https://github.com/pybind/pybind11/pull/5304>`_
-
-* The ``array_caster`` in pybind11/stl.h was enhanced to support value types that are not default-constructible.
-  `#5305 <https://github.com/pybind/pybind11/pull/5305>`_
-
-* Added ``py::warnings`` namespace with ``py::warnings::warn`` and ``py::warnings::new_warning_type`` that provides the interface for Python warnings.
-  `#5291 <https://github.com/pybind/pybind11/pull/5291>`_
-
-Version 2.13.6 (September 13, 2024)
------------------------------------
-
-New Features:
-
-* A new ``self._pybind11_conduit_v1_()`` method is automatically added to all
-  ``py::class_``-wrapped types, to enable type-safe interoperability between
-  different independent Python/C++ bindings systems, including pybind11
-  versions with different ``PYBIND11_INTERNALS_VERSION``'s. Supported on
-  pybind11 2.11.2, 2.12.1, and 2.13.6+.
-  `#5296 <https://github.com/pybind/pybind11/pull/5296>`_
-
-
-Bug fixes:
-
-* Using ``__cpp_nontype_template_args`` instead of ``__cpp_nontype_template_parameter_class``.
-  `#5330 <https://github.com/pybind/pybind11/pull/5330>`_
-
-* Properly translate C++ exception to Python exception when creating Python buffer from wrapped object.
-  `#5324 <https://github.com/pybind/pybind11/pull/5324>`_
-
-
-Documentation:
-
-* Adds an answer (FAQ) for "What is a highly conclusive and simple way to find memory leaks?".
-  `#5340 <https://github.com/pybind/pybind11/pull/5340>`_
-
-
-Version 2.13.5 (August 22, 2024)
---------------------------------
-
-Bug fixes:
-
-* Fix includes when using Windows long paths (``\\?\`` prefix).
-  `#5321 <https://github.com/pybind/pybind11/pull/5321>`_
-
-* Support ``-Wpedantic`` in C++20 mode.
-  `#5322 <https://github.com/pybind/pybind11/pull/5322>`_
-
-* Fix and test ``<ranges>`` support for ``py::tuple`` and ``py::list``.
-  `#5314 <https://github.com/pybind/pybind11/pull/5314>`_
-
-Version 2.13.4 (August 14, 2024)
---------------------------------
-
-Bug fixes:
-
-* Fix paths with spaces, including on Windows.
-  (Replaces regression from `#5302 <https://github.com/pybind/pybind11/pull/5302>`_)
-  `#4874 <https://github.com/pybind/pybind11/pull/4874>`_
-
-Documentation:
-
-* Remove repetitive words.
-  `#5308 <https://github.com/pybind/pybind11/pull/5308>`_
-
-
-Version 2.13.3 (August 13, 2024)
---------------------------------
-
-Bug fixes:
-
-* Quote paths from pybind11-config
-  `#5302 <https://github.com/pybind/pybind11/pull/5302>`_
-
-
-* Fix typo in Emscripten support when in config mode (CMake)
-  `#5301 <https://github.com/pybind/pybind11/pull/5301>`_
-
-
-Version 2.13.2 (August 13, 2024)
---------------------------------
-
-New Features:
-
-* A ``pybind11::detail::type_caster_std_function_specializations`` feature was added, to support specializations for
-  ``std::function``'s with return types that require custom to-Python conversion behavior (to primary use case is to catch and
-  convert exceptions).
-  `#4597 <https://github.com/pybind/pybind11/pull/4597>`_
-
-
-Changes:
-
-
-* Use ``PyMutex`` instead of ``std::mutex`` for internal locking in the free-threaded build.
-  `#5219 <https://github.com/pybind/pybind11/pull/5219>`_
-
-* Add a special type annotation for C++ empty tuple.
-  `#5214 <https://github.com/pybind/pybind11/pull/5214>`_
-
-* When compiling for WebAssembly, add the required exception flags (CMake 3.13+).
-  `#5298 <https://github.com/pybind/pybind11/pull/5298>`_
-
-Bug fixes:
-
-* Make ``gil_safe_call_once_and_store`` thread-safe in free-threaded CPython.
-  `#5246 <https://github.com/pybind/pybind11/pull/5246>`_
-
-* A missing ``#include <algorithm>`` in pybind11/typing.h was added to fix build errors (in case user code does not already depend
-  on that include).
-  `#5208 <https://github.com/pybind/pybind11/pull/5208>`_
-
-* Fix regression introduced in #5201 for GCC<10.3 in C++20 mode.
-  `#5205 <https://github.com/pybind/pybind11/pull/5205>`_
-
-
-.. fix(cmake)
-
-* Remove extra = when assigning flto value in the case for Clang in CMake.
-  `#5207 <https://github.com/pybind/pybind11/pull/5207>`_
-
-
-Tests:
-
-* Adding WASM testing to our CI (Pyodide / Emscripten via scikit-build-core).
-  `#4745 <https://github.com/pybind/pybind11/pull/4745>`_
-
-* clang-tidy (in GitHub Actions) was updated from clang 15 to clang 18.
-  `#5272 <https://github.com/pybind/pybind11/pull/5272>`_
-
-
-Version 2.13.1 (June 26, 2024)
-------------------------------
-
-New Features:
-
-* Add support for ``Typing.Callable[..., T]``.
-  `#5202 <https://github.com/pybind/pybind11/pull/5202>`_
-
-Bug fixes:
-
-* Avoid aligned allocation in free-threaded build in order to support macOS
-  versions before 10.14.
-  `#5200 <https://github.com/pybind/pybind11/pull/5200>`_
-
-Version 2.13.0 (June 25, 2024)
-------------------------------
-
-New Features:
-
-* Support free-threaded CPython (3.13t). Add ``py::mod_gil_not_used()`` tag to
-  indicate if a module supports running with the GIL disabled.
-  `#5148 <https://github.com/pybind/pybind11/pull/5148>`_
-
-* Support for Python 3.6 was removed. (Official end-of-life: 2021-12-23).
-  `#5177 <https://github.com/pybind/pybind11/pull/5177>`_
-
-* ``py::list`` gained a ``.clear()`` method.
-  `#5153 <https://github.com/pybind/pybind11/pull/5153>`_
-
-
-.. feat(types)
-
-* Support for ``Union``, ``Optional``, ``type[T]``, ``typing.TypeGuard``,
-  ``typing.TypeIs``, ``typing.Never``, ``typing.NoReturn`` and
-  ``typing.Literal`` was added to ``pybind11/typing.h``.
-  `#5166 <https://github.com/pybind/pybind11/pull/5166>`_
-  `#5165 <https://github.com/pybind/pybind11/pull/5165>`_
-  `#5194 <https://github.com/pybind/pybind11/pull/5194>`_
-  `#5193 <https://github.com/pybind/pybind11/pull/5193>`_
-  `#5192 <https://github.com/pybind/pybind11/pull/5192>`_
-
-
-.. feat(cmake)
-
-* In CMake, if ``PYBIND11_USE_CROSSCOMPILING`` is enabled, then
-  ``CMAKE_CROSSCOMPILING`` will be respected and will keep pybind11 from
-  accessing the interpreter during configuration. Several CMake variables will
-  be required in this case, but can be deduced from the environment variable
-  ``SETUPTOOLS_EXT_SUFFIX``. The default (currently ``OFF``) may be changed in
-  the future.
-  `#5083 <https://github.com/pybind/pybind11/pull/5083>`_
-
-
-Bug fixes:
-
-* A refcount bug (leading to heap-use-after-free) involving trampoline
-  functions with ``PyObject *`` return type was fixed.
-  `#5156 <https://github.com/pybind/pybind11/pull/5156>`_
-
-* Return ``py::ssize_t`` from ``.ref_count()`` instead of ``int``.
-  `#5139 <https://github.com/pybind/pybind11/pull/5139>`_
-
-* A subtle bug involving C++ types with unusual ``operator&`` overrides
-  was fixed.
-  `#5189 <https://github.com/pybind/pybind11/pull/5189>`_
-
-* Support Python 3.13 with minor fix, add to CI.
-  `#5127 <https://github.com/pybind/pybind11/pull/5127>`_
-
-
-.. fix(cmake)
-
-* Fix mistake affecting old cmake and old boost.
-  `#5149 <https://github.com/pybind/pybind11/pull/5149>`_
-
-
-Documentation:
-
-* Build docs updated to feature scikit-build-core and meson-python, and updated
-  setuptools instructions.
-  `#5168 <https://github.com/pybind/pybind11/pull/5168>`_
-
-
-Tests:
-
-* Avoid immortal objects in tests.
-  `#5150 <https://github.com/pybind/pybind11/pull/5150>`_
-
-
-CI:
-
-* Compile against Python 3.13t in CI.
-
-* Use ``macos-13`` (Intel) for CI jobs for now (will drop Python 3.7 soon).
-  `#5109 <https://github.com/pybind/pybind11/pull/5109>`_
-
-* Releases now have artifact attestations, visible at
-  https://github.com/pybind/pybind11/attestations.
-  `#5196 <https://github.com/pybind/pybind11/pull/5196>`_
-
-Other:
-
-* Some cleanup in preparation for 3.13 support.
-  `#5137 <https://github.com/pybind/pybind11/pull/5137>`_
-
-* Avoid a warning by ensuring an iterator end check is included in release mode.
-  `#5129 <https://github.com/pybind/pybind11/pull/5129>`_
-
-* Bump max cmake to 3.29.
-  `#5075 <https://github.com/pybind/pybind11/pull/5075>`_
-
-* Update docs and noxfile.
-  `#5071 <https://github.com/pybind/pybind11/pull/5071>`_
-
-Version 2.12.1 (September 13, 2024)
------------------------------------
-
-New Features:
-
-* A new ``self._pybind11_conduit_v1_()`` method is automatically added to all
-  ``py::class_``-wrapped types, to enable type-safe interoperability between
-  different independent Python/C++ bindings systems, including pybind11
-  versions with different ``PYBIND11_INTERNALS_VERSION``'s. Supported on
-  pybind11 2.11.2, 2.12.1, and 2.13.6+.
-  `#5296 <https://github.com/pybind/pybind11/pull/5296>`_
-
-
 Version 2.12.0 (March 27, 2024)
 -------------------------------
 
@@ -456,18 +189,6 @@ Other:
 * An ``assert()`` was added to help Coverty avoid generating a false positive.
   `#4817 <https://github.com/pybind/pybind11/pull/4817>`_
 
-Version 2.11.2 (September 13, 2024)
------------------------------------
-
-New Features:
-
-* A new ``self._pybind11_conduit_v1_()`` method is automatically added to all
-  ``py::class_``-wrapped types, to enable type-safe interoperability between
-  different independent Python/C++ bindings systems, including pybind11
-  versions with different ``PYBIND11_INTERNALS_VERSION``'s. Supported on
-  pybind11 2.11.2, 2.12.1, and 2.13.6+.
-  `#5296 <https://github.com/pybind/pybind11/pull/5296>`_
-
 
 Version 2.11.1 (July 17, 2023)
 ------------------------------

docs/compiling.rst

@@ -3,123 +3,15 @@
 Build systems
 #############
 
-For an overview of Python packaging including compiled packaging with a pybind11
-example, along with a cookiecutter that includes several pybind11 options, see
-the `Scientific Python Development Guide`_.
-
-.. _Scientific Python Development Guide: https://learn.scientific-python.org/development/guides/packaging-compiled/
-
-.. scikit-build-core:
-
-Modules with CMake
-==================
-
-A Python extension module can be created with just a few lines of code:
-
-.. code-block:: cmake
-
-    cmake_minimum_required(VERSION 3.15...3.30)
-    project(example LANGUAGES CXX)
-
-    set(PYBIND11_FINDPYTHON ON)
-    find_package(pybind11 CONFIG REQUIRED)
-
-    pybind11_add_module(example example.cpp)
-    install(TARGETS example DESTINATION .)
-
-(You use the ``add_subdirectory`` instead, see the example in :ref:`cmake`.) In
-this example, the code is located in a file named :file:`example.cpp`.  Either
-method will import the pybind11 project which provides the
-``pybind11_add_module`` function. It will take care of all the details needed
-to build a Python extension module on any platform.
-
-To build with pip, build, cibuildwheel, uv, or other Python tools, you can
-add a ``pyproject.toml`` file like this:
-
-.. code-block:: toml
-
-    [build-system]
-    requires = ["scikit-build-core", "pybind11"]
-    build-backend = "scikit_build_core.build"
-
-    [project]
-    name = "example"
-    version = "0.1.0"
-
-You don't need setuptools files like ``MANIFEST.in``, ``setup.py``, or
-``setup.cfg``, as this is not setuptools. See `scikit-build-core`_ for details.
-For projects you plan to upload to PyPI, be sure to fill out the ``[project]``
-table with other important metadata as well (see `Writing pyproject.toml`_).
-
-A working sample project can be found in the [scikit_build_example]_
-repository. An older and harder-to-maintain method is in [cmake_example]_. More
-details about our cmake support can be found below in :ref:`cmake`.
-
-.. _scikit-build-core: https://scikit-build-core.readthedocs.io
-
-.. [scikit_build_example] https://github.com/pybind/scikit_build_example
-
-.. [cmake_example] https://github.com/pybind/cmake_example
-
-.. _modules-meson-python:
-
-Modules with meson-python
-=========================
-
-You can also build a package with `Meson`_ using `meson-python`_, if you prefer
-that. Your ``meson.build`` file would look something like this:
-
-.. _meson-example:
-
-.. code-block:: meson
-
-   project(
-       'example',
-       'cpp',
-       version: '0.1.0',
-       default_options: [
-           'cpp_std=c++11',
-       ],
-   )
-
-   py = import('python').find_installation(pure: false)
-   pybind11_dep = dependency('pybind11')
-
-   py.extension_module('example',
-       'example.cpp',
-       install: true,
-       dependencies : [pybind11_dep],
-   )
-
-
-And you would need a ``pyproject.toml`` file like this:
-
-.. code-block:: toml
-
-   [build-system]
-   requires = ["meson-python", "pybind11"]
-   build-backend = "mesonpy"
-
-Meson-python *requires* your project to be in git (or mercurial) as it uses it
-for the SDist creation. For projects you plan to upload to PyPI, be sure to fill out the
-``[project]`` table as well (see `Writing pyproject.toml`_).
-
-
-.. _Writing pyproject.toml: https://packaging.python.org/en/latest/guides/writing-pyproject-toml
-
-.. _meson: https://mesonbuild.com
-
-.. _meson-python: https://meson-python.readthedocs.io/en/latest
-
 .. _build-setuptools:
 
-Modules with setuptools
-=======================
+Building with setuptools
+========================
 
-For projects on PyPI, a historically popular option is setuptools. Sylvain
-Corlay has kindly provided an example project which shows how to set up
-everything, including automatic generation of documentation using Sphinx.
-Please refer to the [python_example]_ repository.
+For projects on PyPI, building with setuptools is the way to go. Sylvain Corlay
+has kindly provided an example project which shows how to set up everything,
+including automatic generation of documentation using Sphinx. Please refer to
+the [python_example]_ repository.
 
 .. [python_example] https://github.com/pybind/python_example
 
@@ -129,11 +21,11 @@ To use pybind11 inside your ``setup.py``, you have to have some system to
 ensure that ``pybind11`` is installed when you build your package. There are
 four possible ways to do this, and pybind11 supports all four: You can ask all
 users to install pybind11 beforehand (bad), you can use
-:ref:`setup_helpers-pep518` (good), ``setup_requires=`` (discouraged), or you
-can :ref:`setup_helpers-copy-manually` (works but you have to manually sync
-your copy to get updates). Third party packagers like conda-forge generally
-strongly prefer the ``pyproject.toml`` method, as it gives them control over
-the ``pybind11`` version, and they may apply patches, etc.
+:ref:`setup_helpers-pep518` (good, but very new and requires Pip 10),
+:ref:`setup_helpers-setup_requires` (discouraged by Python packagers now that
+PEP 518 is available, but it still works everywhere), or you can
+:ref:`setup_helpers-copy-manually` (always works but you have to manually sync
+your copy to get updates).
 
 An example of a ``setup.py`` using pybind11's helpers:
 
@@ -230,41 +122,70 @@ version number that includes the number of commits since your last tag and a
 hash for a dirty directory. Another way to force a rebuild is purge your cache
 or use Pip's ``--no-cache-dir`` option.
 
-You also need a ``MANIFEST.in`` file to include all relevant files so that you
-can make an SDist. If you use `pypa-build`_, that will build an SDist then a
-wheel from that SDist by default, so you can look inside those files (wheels
-are just zip files with a ``.whl`` extension) to make sure you aren't missing
-files.  `check-manifest`_ (setuptools specific) or `check-sdist`_ (general) are
-CLI tools that can compare the SDist contents with your source control.
-
 .. [Ccache] https://ccache.dev
 
 .. [setuptools_scm] https://github.com/pypa/setuptools_scm
 
 .. _setup_helpers-pep518:
 
-Build requirements
-------------------
+PEP 518 requirements (Pip 10+ required)
+---------------------------------------
 
-With a ``pyproject.toml`` file, you can ensure that ``pybind11`` is available
-during the compilation of your project.  When this file exists, Pip will make a
-new virtual environment, download just the packages listed here in
-``requires=``, and build a wheel (binary Python package). It will then throw
-away the environment, and install your wheel.
+If you use `PEP 518's <https://www.python.org/dev/peps/pep-0518/>`_
+``pyproject.toml`` file, you can ensure that ``pybind11`` is available during
+the compilation of your project.  When this file exists, Pip will make a new
+virtual environment, download just the packages listed here in ``requires=``,
+and build a wheel (binary Python package). It will then throw away the
+environment, and install your wheel.
 
 Your ``pyproject.toml`` file will likely look something like this:
 
 .. code-block:: toml
 
     [build-system]
-    requires = ["setuptools", "pybind11"]
+    requires = ["setuptools>=42", "pybind11>=2.6.1"]
     build-backend = "setuptools.build_meta"
 
+.. note::
+
+    The main drawback to this method is that a `PEP 517`_ compliant build tool,
+    such as Pip 10+, is required for this approach to work; older versions of
+    Pip completely ignore this file. If you distribute binaries (called wheels
+    in Python) using something like `cibuildwheel`_, remember that ``setup.py``
+    and ``pyproject.toml`` are not even contained in the wheel, so this high
+    Pip requirement is only for source builds, and will not affect users of
+    your binary wheels. If you are building SDists and wheels, then
+    `pypa-build`_ is the recommended official tool.
+
 .. _PEP 517: https://www.python.org/dev/peps/pep-0517/
-.. _cibuildwheel: https://cibuildwheel.pypa.io
-.. _pypa-build: https://build.pypa.io/en/latest/
-.. _check-manifest: https://pypi.io/project/check-manifest
-.. _check-sdist: https://pypi.io/project/check-sdist
+.. _cibuildwheel: https://cibuildwheel.readthedocs.io
+.. _pypa-build: https://pypa-build.readthedocs.io/en/latest/
+
+.. _setup_helpers-setup_requires:
+
+Classic ``setup_requires``
+--------------------------
+
+If you want to support old versions of Pip with the classic
+``setup_requires=["pybind11"]`` keyword argument to setup, which triggers a
+two-phase ``setup.py`` run, then you will need to use something like this to
+ensure the first pass works (which has not yet installed the ``setup_requires``
+packages, since it can't install something it does not know about):
+
+.. code-block:: python
+
+    try:
+        from pybind11.setup_helpers import Pybind11Extension
+    except ImportError:
+        from setuptools import Extension as Pybind11Extension
+
+
+It doesn't matter that the Extension class is not the enhanced subclass for the
+first pass run; and the second pass will have the ``setup_requires``
+requirements.
+
+This is obviously more of a hack than the PEP 518 method, but it supports
+ancient versions of Pip.
 
 .. _setup_helpers-copy-manually:
 
@@ -310,22 +231,32 @@ the C++ source file. Python is then able to find the module and load it.
 
 .. [cppimport] https://github.com/tbenthompson/cppimport
 
-
-
 .. _cmake:
 
 Building with CMake
 ===================
 
 For C++ codebases that have an existing CMake-based build system, a Python
-extension module can be created with just a few lines of code, as seen above in
-the module section. Pybind11 currently defaults to the old mechanism, though be
-aware that CMake 3.27 removed the old mechanism, so pybind11 will automatically
-switch if the old mechanism is not available. Please opt into the new mechanism
-if at all possible. Our default may change in future versions. This is the
-minimum required:
+extension module can be created with just a few lines of code:
 
+.. code-block:: cmake
 
+    cmake_minimum_required(VERSION 3.5...3.29)
+    project(example LANGUAGES CXX)
+
+    add_subdirectory(pybind11)
+    pybind11_add_module(example example.cpp)
+
+This assumes that the pybind11 repository is located in a subdirectory named
+:file:`pybind11` and that the code is located in a file named :file:`example.cpp`.
+The CMake command ``add_subdirectory`` will import the pybind11 project which
+provides the ``pybind11_add_module`` function. It will take care of all the
+details needed to build a Python extension module on any platform.
+
+A working sample project, including a way to invoke CMake from :file:`setup.py` for
+PyPI integration, can be found in the [cmake_example]_  repository.
+
+.. [cmake_example] https://github.com/pybind/cmake_example
 
 .. versionchanged:: 2.6
    CMake 3.4+ is required.
@@ -333,10 +264,6 @@ minimum required:
 .. versionchanged:: 2.11
    CMake 3.5+ is required.
 
-.. versionchanged:: 2.14
-   CMake 3.15+ is required.
-
-
 Further information can be found at :doc:`cmake/index`.
 
 pybind11_add_module
@@ -391,7 +318,7 @@ that will be respected instead of the built-in flag search.
 
 The ``OPT_SIZE`` flag enables size-based optimization equivalent to the
 standard ``/Os`` or ``-Os`` compiler flags and the ``MinSizeRel`` build type,
-which avoid optimizations that can substantially increase the size of the
+which avoid optimizations that that can substantially increase the size of the
 resulting binary. This flag is particularly useful in projects that are split
 into performance-critical parts and associated bindings. In this case, we can
 compile the project in release mode (and hence, optimize performance globally),
@@ -429,7 +356,7 @@ with ``PYTHON_EXECUTABLE``.  For example:
 
 .. code-block:: bash
 
-    cmake -DPYBIND11_PYTHON_VERSION=3.8 ..
+    cmake -DPYBIND11_PYTHON_VERSION=3.6 ..
 
     # Another method:
     cmake -DPYTHON_EXECUTABLE=/path/to/python ..
@@ -447,7 +374,7 @@ See the `Config file`_ docstring for details of relevant CMake variables.
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.15...3.30)
+    cmake_minimum_required(VERSION 3.4...3.18)
     project(example LANGUAGES CXX)
 
     find_package(pybind11 REQUIRED)
@@ -486,16 +413,17 @@ can refer to the same [cmake_example]_ repository for a full sample project
 FindPython mode
 ---------------
 
-Modern CMake (3.18.2+ ideal) added a new module called FindPython that had a
-highly improved search algorithm and modern targets and tools. If you use
-FindPython, pybind11 will detect this and use the existing targets instead:
+CMake 3.12+ (3.15+ recommended, 3.18.2+ ideal) added a new module called
+FindPython that had a highly improved search algorithm and modern targets
+and tools. If you use FindPython, pybind11 will detect this and use the
+existing targets instead:
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.15...3.30)
+    cmake_minimum_required(VERSION 3.15...3.22)
     project(example LANGUAGES CXX)
 
-    find_package(Python 3.8 COMPONENTS Interpreter Development REQUIRED)
+    find_package(Python 3.6 COMPONENTS Interpreter Development REQUIRED)
     find_package(pybind11 CONFIG REQUIRED)
     # or add_subdirectory(pybind11)
 
@@ -543,7 +471,7 @@ available in all modes. The targets provided are:
      Just the "linking" part of pybind11:module
 
    ``pybind11::module``
-     Everything for extension modules - ``pybind11::pybind11`` + ``Python::Module`` (FindPython) or ``pybind11::python_link_helper``
+     Everything for extension modules - ``pybind11::pybind11`` + ``Python::Module`` (FindPython CMake 3.15+) or ``pybind11::python_link_helper``
 
    ``pybind11::embed``
      Everything for embedding the Python interpreter - ``pybind11::pybind11`` + ``Python::Python`` (FindPython) or Python libs
@@ -570,7 +498,7 @@ You can use these targets to build complex applications. For example, the
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.15...3.30)
+    cmake_minimum_required(VERSION 3.5...3.29)
     project(example LANGUAGES CXX)
 
     find_package(pybind11 REQUIRED)  # or add_subdirectory(pybind11)
@@ -628,7 +556,7 @@ information about usage in C++, see :doc:`/advanced/embedding`.
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.15...3.30)
+    cmake_minimum_required(VERSION 3.5...3.29)
     project(example LANGUAGES CXX)
 
     find_package(pybind11 REQUIRED)  # or add_subdirectory(pybind11)
@@ -688,13 +616,6 @@ Building with Bazel
 You can build with the Bazel build system using the `pybind11_bazel
 <https://github.com/pybind/pybind11_bazel>`_ repository.
 
-Building with Meson
-===================
-
-You can use Meson, which has support for ``pybind11`` as a dependency (internally
-relying on our ``pkg-config`` support). See the :ref:`module example above <meson-example>`.
-
-
 Generating binding code automatically
 =====================================
 
@@ -721,7 +642,7 @@ customizable pybind11-based wrappers by parsing C++ header files.
 
 [litgen]_ is an automatic python bindings generator with a focus on generating
 documented and discoverable bindings: bindings will nicely reproduce the documentation
-found in headers. It is based on srcML (srcml.org), a highly scalable, multi-language
+found in headers. It is is based on srcML (srcml.org), a highly scalable, multi-language
 parsing tool with a developer centric approach. The API that you want to expose to python
 must be C++14 compatible (but your implementation can use more modern constructs).
 

docs/conf.py

@@ -11,7 +11,6 @@
 #
 # All configuration values have a default; values that are commented out
 # serve to show the default.
-from __future__ import annotations
 
 import os
 import re

docs/faq.rst

@@ -247,50 +247,6 @@ been received, you must either explicitly interrupt execution by throwing
         });
     }
 
-What is a highly conclusive and simple way to find memory leaks (e.g. in pybind11 bindings)?
-============================================================================================
-
-Use ``while True`` & ``top`` (Linux, macOS).
-
-For example, locally change tests/test_type_caster_pyobject_ptr.py like this:
-
-.. code-block:: diff
-
-     def test_return_list_pyobject_ptr_reference():
-    +  while True:
-         vec_obj = m.return_list_pyobject_ptr_reference(ValueHolder)
-         assert [e.value for e in vec_obj] == [93, 186]
-         # Commenting out the next `assert` will leak the Python references.
-         # An easy way to see evidence of the leaks:
-         # Insert `while True:` as the first line of this function and monitor the
-         # process RES (Resident Memory Size) with the Unix top command.
-    -    assert m.dec_ref_each_pyobject_ptr(vec_obj) == 2
-    +    # assert m.dec_ref_each_pyobject_ptr(vec_obj) == 2
-
-Then run the test as you would normally do, which will go into the infinite loop.
-
-**In another shell, but on the same machine** run:
-
-.. code-block:: bash
-
-    top
-
-This will show:
-
-.. code-block::
-
-        PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
-    1266095 rwgk      20   0 5207496 611372  45696 R 100.0   0.3   0:08.01 test_type_caste
-
-Look for the number under ``RES`` there. You'll see it going up very quickly.
-
-**Don't forget to Ctrl-C the test command** before your machine becomes
-unresponsive due to swapping.
-
-This method only takes a couple minutes of effort and is very conclusive.
-What you want to see is that the ``RES`` number is stable after a couple
-seconds.
-
 CMake doesn't detect the right Python version
 =============================================
 
@@ -302,9 +258,9 @@ CMake configure line. (Replace ``$(which python)`` with a path to python if
 your prefer.)
 
 You can alternatively try ``-DPYBIND11_FINDPYTHON=ON``, which will activate the
-new CMake FindPython support instead of pybind11's custom search. Newer CMake,
-like, 3.18.2+, is recommended. You can set this in your ``CMakeLists.txt``
-before adding or finding pybind11, as well.
+new CMake FindPython support instead of pybind11's custom search. Requires
+CMake 3.12+, and 3.15+ or 3.18.2+ are even better. You can set this in your
+``CMakeLists.txt`` before adding or finding pybind11, as well.
 
 Inconsistent detection of Python version in CMake and pybind11
 ==============================================================
@@ -325,11 +281,11 @@ There are three possible solutions:
    from CMake and rely on pybind11 in detecting Python version. If this is not
    possible, the CMake machinery should be called *before* including pybind11.
 2. Set ``PYBIND11_FINDPYTHON`` to ``True`` or use ``find_package(Python
-   COMPONENTS Interpreter Development)`` on modern CMake ( 3.18.2+ best).
-   Pybind11 in these cases uses the new CMake FindPython instead of the old,
-   deprecated search tools, and these modules are much better at finding the
-   correct Python. If FindPythonLibs/Interp are not available (CMake 3.27+),
-   then this will be ignored and FindPython will be used.
+   COMPONENTS Interpreter Development)`` on modern CMake (3.12+, 3.15+ better,
+   3.18.2+ best). Pybind11 in these cases uses the new CMake FindPython instead
+   of the old, deprecated search tools, and these modules are much better at
+   finding the correct Python. If FindPythonLibs/Interp are not available
+   (CMake 3.27+), then this will be ignored and FindPython will be used.
 3. Set ``PYBIND11_NOPYTHON`` to ``TRUE``. Pybind11 will not search for Python.
    However, you will have to use the target-based system, and do more setup
    yourself, because it does not know about or include things that depend on

docs/limitations.rst

@@ -50,6 +50,10 @@ clean, well written patch would likely be accepted to solve them.
   One consequence is that containers of ``char *`` are currently not supported.
   `#2245 <https://github.com/pybind/pybind11/issues/2245>`_
 
+- The ``cpptest`` does not run on Windows with Python 3.8 or newer, due to DLL
+  loader changes. User code that is correctly installed should not be affected.
+  `#2560 <https://github.com/pybind/pybind11/issue/2560>`_
+
 Python 3.9.0 warning
 ^^^^^^^^^^^^^^^^^^^^
 

docs/requirements.txt

@@ -16,9 +16,9 @@ breathe==4.35.0 \
     --hash=sha256:5165541c3c67b6c7adde8b3ecfe895c6f7844783c4076b6d8d287e4f33d62386 \
     --hash=sha256:52c581f42ca4310737f9e435e3851c3d1f15446205a85fbc272f1f97ed74f5be
     # via -r requirements.in
-certifi==2024.7.4 \
-    --hash=sha256:5a1e7645bc0ec61a09e26c36f6106dd4cf40c6db3a1fb6352b0244e7fb057c7b \
-    --hash=sha256:c198e21b1289c2ab85ee4e67bb4b4ef3ead0892059901a8d5b622f24a1101e90
+certifi==2024.2.2 \
+    --hash=sha256:0569859f95fc761b18b45ef421b1290a0f65f147e92a1e5eb3e635f9a5e4e66f \
+    --hash=sha256:dc383c07b76109f368f6106eee2b593b04a011ea4d55f652c6ca24a754d1cdd1
     # via requests
 charset-normalizer==3.3.2 \
     --hash=sha256:06435b539f889b1f6f4ac1758871aae42dc3a8c0e24ac9e60c2384973ad73027 \
@@ -269,7 +269,7 @@ sphinxcontrib-svg2pdfconverter==1.2.2 \
     --hash=sha256:04ec767b55780a6b18d89cc1a8ada6d900c6efde9d1683abdb98a49b144465ca \
     --hash=sha256:80a55ca61f70eae93efc65f3814f2f177c86ba55934a9f6c5022f1778b62146b
     # via -r requirements.in
-urllib3==2.2.2 \
-    --hash=sha256:a448b2f64d686155468037e1ace9f2d2199776e17f0a46610480d311f73e3472 \
-    --hash=sha256:dd505485549a7a552833da5e6063639d0d177c04f23bc3864e41e5dc5f612168
+urllib3==2.2.1 \
+    --hash=sha256:450b20ec296a467077128bff42b73080516e71b56ff59a60a02bef2232c4fa9d \
+    --hash=sha256:d0570876c61ab9e520d776c38acbbb5b05a776d3f9ff98a5c8fd5162a444cf19
     # via requests

include/pybind11/cast.h

@@ -158,7 +158,7 @@ public:
         } else {
             handle src_or_index = src;
             // PyPy: 7.3.7's 3.8 does not implement PyLong_*'s __index__ calls.
-#if defined(PYPY_VERSION)
+#if PY_VERSION_HEX < 0x03080000 || defined(PYPY_VERSION)
             object index;
             if (!PYBIND11_LONG_CHECK(src.ptr())) { // So: index_check(src.ptr())
                 index = reinterpret_steal<object>(PyNumber_Index(src.ptr()));
@@ -740,13 +740,6 @@ class type_caster<std::pair<T1, T2>> : public tuple_caster<std::pair, T1, T2> {}
 template <typename... Ts>
 class type_caster<std::tuple<Ts...>> : public tuple_caster<std::tuple, Ts...> {};
 
-template <>
-class type_caster<std::tuple<>> : public tuple_caster<std::tuple> {
-public:
-    // PEP 484 specifies this syntax for an empty tuple
-    static constexpr auto name = const_name("tuple[()]");
-};
-
 /// Helper class which abstracts away certain actions. Users can provide specializations for
 /// custom holders, but it's only necessary if the type has a non-standard interface.
 template <typename T>
@@ -794,11 +787,11 @@ protected:
         }
     }
 
-    void load_value(value_and_holder &&v_h) {
+    bool load_value(value_and_holder &&v_h) {
         if (v_h.holder_constructed()) {
             value = v_h.value_ptr();
             holder = v_h.template holder<holder_type>();
-            return;
+            return true;
         }
         throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
 #if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
@@ -1503,7 +1496,7 @@ struct kw_only {};
 
 /// \ingroup annotations
 /// Annotation indicating that all previous arguments are positional-only; the is the equivalent of
-/// an unnamed '/' argument
+/// an unnamed '/' argument (in Python 3.8)
 struct pos_only {};
 
 template <typename T>

include/pybind11/detail/class.h

@@ -9,10 +9,8 @@
 
 #pragma once
 
-#include <pybind11/attr.h>
-#include <pybind11/options.h>
-
-#include "exception_translation.h"
+#include "../attr.h"
+#include "../options.h"
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
@@ -207,40 +205,39 @@ extern "C" inline PyObject *pybind11_meta_call(PyObject *type, PyObject *args, P
 
 /// Cleanup the type-info for a pybind11-registered type.
 extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
-    with_internals([obj](internals &internals) {
-        auto *type = (PyTypeObject *) obj;
+    auto *type = (PyTypeObject *) obj;
+    auto &internals = get_internals();
 
-        // A pybind11-registered type will:
-        // 1) be found in internals.registered_types_py
-        // 2) have exactly one associated `detail::type_info`
-        auto found_type = internals.registered_types_py.find(type);
-        if (found_type != internals.registered_types_py.end() && found_type->second.size() == 1
-            && found_type->second[0]->type == type) {
+    // A pybind11-registered type will:
+    // 1) be found in internals.registered_types_py
+    // 2) have exactly one associated `detail::type_info`
+    auto found_type = internals.registered_types_py.find(type);
+    if (found_type != internals.registered_types_py.end() && found_type->second.size() == 1
+        && found_type->second[0]->type == type) {
 
-            auto *tinfo = found_type->second[0];
-            auto tindex = std::type_index(*tinfo->cpptype);
-            internals.direct_conversions.erase(tindex);
+        auto *tinfo = found_type->second[0];
+        auto tindex = std::type_index(*tinfo->cpptype);
+        internals.direct_conversions.erase(tindex);
 
-            if (tinfo->module_local) {
-                get_local_internals().registered_types_cpp.erase(tindex);
-            } else {
-                internals.registered_types_cpp.erase(tindex);
-            }
-            internals.registered_types_py.erase(tinfo->type);
-
-            // Actually just `std::erase_if`, but that's only available in C++20
-            auto &cache = internals.inactive_override_cache;
-            for (auto it = cache.begin(), last = cache.end(); it != last;) {
-                if (it->first == (PyObject *) tinfo->type) {
-                    it = cache.erase(it);
-                } else {
-                    ++it;
-                }
-            }
-
-            delete tinfo;
+        if (tinfo->module_local) {
+            get_local_internals().registered_types_cpp.erase(tindex);
+        } else {
+            internals.registered_types_cpp.erase(tindex);
         }
-    });
+        internals.registered_types_py.erase(tinfo->type);
+
+        // Actually just `std::erase_if`, but that's only available in C++20
+        auto &cache = internals.inactive_override_cache;
+        for (auto it = cache.begin(), last = cache.end(); it != last;) {
+            if (it->first == (PyObject *) tinfo->type) {
+                it = cache.erase(it);
+            } else {
+                ++it;
+            }
+        }
+
+        delete tinfo;
+    }
 
     PyType_Type.tp_dealloc(obj);
 }
@@ -313,20 +310,19 @@ inline void traverse_offset_bases(void *valueptr,
 }
 
 inline bool register_instance_impl(void *ptr, instance *self) {
-    with_instance_map(ptr, [&](instance_map &instances) { instances.emplace(ptr, self); });
+    get_internals().registered_instances.emplace(ptr, self);
     return true; // unused, but gives the same signature as the deregister func
 }
 inline bool deregister_instance_impl(void *ptr, instance *self) {
-    return with_instance_map(ptr, [&](instance_map &instances) {
-        auto range = instances.equal_range(ptr);
-        for (auto it = range.first; it != range.second; ++it) {
-            if (self == it->second) {
-                instances.erase(it);
-                return true;
-            }
+    auto &registered_instances = get_internals().registered_instances;
+    auto range = registered_instances.equal_range(ptr);
+    for (auto it = range.first; it != range.second; ++it) {
+        if (self == it->second) {
+            registered_instances.erase(it);
+            return true;
         }
-        return false;
-    });
+    }
+    return false;
 }
 
 inline void register_instance(instance *self, void *valptr, const type_info *tinfo) {
@@ -381,32 +377,27 @@ extern "C" inline int pybind11_object_init(PyObject *self, PyObject *, PyObject
 }
 
 inline void add_patient(PyObject *nurse, PyObject *patient) {
+    auto &internals = get_internals();
     auto *instance = reinterpret_cast<detail::instance *>(nurse);
     instance->has_patients = true;
     Py_INCREF(patient);
-
-    with_internals([&](internals &internals) { internals.patients[nurse].push_back(patient); });
+    internals.patients[nurse].push_back(patient);
 }
 
 inline void clear_patients(PyObject *self) {
     auto *instance = reinterpret_cast<detail::instance *>(self);
-    std::vector<PyObject *> patients;
+    auto &internals = get_internals();
+    auto pos = internals.patients.find(self);
 
-    with_internals([&](internals &internals) {
-        auto pos = internals.patients.find(self);
-
-        if (pos == internals.patients.end()) {
-            pybind11_fail(
-                "FATAL: Internal consistency check failed: Invalid clear_patients() call.");
-        }
-
-        // Clearing the patients can cause more Python code to run, which
-        // can invalidate the iterator. Extract the vector of patients
-        // from the unordered_map first.
-        patients = std::move(pos->second);
-        internals.patients.erase(pos);
-    });
+    if (pos == internals.patients.end()) {
+        pybind11_fail("FATAL: Internal consistency check failed: Invalid clear_patients() call.");
+    }
 
+    // Clearing the patients can cause more Python code to run, which
+    // can invalidate the iterator. Extract the vector of patients
+    // from the unordered_map first.
+    auto patients = std::move(pos->second);
+    internals.patients.erase(pos);
     instance->has_patients = false;
     for (PyObject *&patient : patients) {
         Py_CLEAR(patient);
@@ -468,9 +459,19 @@ extern "C" inline void pybind11_object_dealloc(PyObject *self) {
 
     type->tp_free(self);
 
+#if PY_VERSION_HEX < 0x03080000
+    // `type->tp_dealloc != pybind11_object_dealloc` means that we're being called
+    // as part of a derived type's dealloc, in which case we're not allowed to decref
+    // the type here. For cross-module compatibility, we shouldn't compare directly
+    // with `pybind11_object_dealloc`, but with the common one stashed in internals.
+    auto pybind11_object_type = (PyTypeObject *) get_internals().instance_base;
+    if (type->tp_dealloc == pybind11_object_type->tp_dealloc)
+        Py_DECREF(type);
+#else
     // This was not needed before Python 3.8 (Python issue 35810)
     // https://github.com/pybind/pybind11/issues/1946
     Py_DECREF(type);
+#endif
 }
 
 std::string error_string();
@@ -559,9 +560,17 @@ inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     type->tp_traverse = pybind11_traverse;
     type->tp_clear = pybind11_clear;
 
-    static PyGetSetDef getset[]
-        = {{"__dict__", PyObject_GenericGetDict, PyObject_GenericSetDict, nullptr, nullptr},
-           {nullptr, nullptr, nullptr, nullptr, nullptr}};
+    static PyGetSetDef getset[] = {{
+#if PY_VERSION_HEX < 0x03070000
+                                       const_cast<char *>("__dict__"),
+#else
+                                       "__dict__",
+#endif
+                                       PyObject_GenericGetDict,
+                                       PyObject_GenericSetDict,
+                                       nullptr,
+                                       nullptr},
+                                   {nullptr, nullptr, nullptr, nullptr, nullptr}};
     type->tp_getset = getset;
 }
 
@@ -583,18 +592,7 @@ extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int fla
         return -1;
     }
     std::memset(view, 0, sizeof(Py_buffer));
-    buffer_info *info = nullptr;
-    try {
-        info = tinfo->get_buffer(obj, tinfo->get_buffer_data);
-    } catch (...) {
-        try_translate_exceptions();
-        raise_from(PyExc_BufferError, "Error getting buffer");
-        return -1;
-    }
-    if (info == nullptr) {
-        pybind11_fail("FATAL UNEXPECTED SITUATION: tinfo->get_buffer() returned nullptr.");
-    }
-
+    buffer_info *info = tinfo->get_buffer(obj, tinfo->get_buffer_data);
     if ((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE && info->readonly) {
         delete info;
         // view->obj = nullptr;  // Was just memset to 0, so not necessary
@@ -664,13 +662,10 @@ inline PyObject *make_new_python_type(const type_record &rec) {
 
     char *tp_doc = nullptr;
     if (rec.doc && options::show_user_defined_docstrings()) {
-        /* Allocate memory for docstring (Python will free this later on) */
+        /* Allocate memory for docstring (using PyObject_MALLOC, since
+           Python will free this later on) */
         size_t size = std::strlen(rec.doc) + 1;
-#if PY_VERSION_HEX >= 0x030D0000
-        tp_doc = (char *) PyMem_MALLOC(size);
-#else
         tp_doc = (char *) PyObject_MALLOC(size);
-#endif
         std::memcpy((void *) tp_doc, rec.doc, size);
     }
 

include/pybind11/detail/common.h

@@ -10,12 +10,12 @@
 #pragma once
 
 #define PYBIND11_VERSION_MAJOR 2
-#define PYBIND11_VERSION_MINOR 14
+#define PYBIND11_VERSION_MINOR 13
 #define PYBIND11_VERSION_PATCH 0.dev1
 
 // Similar to Python's convention: https://docs.python.org/3/c-api/apiabiversion.html
 // Additional convention: 0xD = dev
-#define PYBIND11_VERSION_HEX 0x020E00D1
+#define PYBIND11_VERSION_HEX 0x020D00D1
 
 // Define some generic pybind11 helper macros for warning management.
 //
@@ -272,8 +272,9 @@ PYBIND11_WARNING_DISABLE_MSVC(4505)
 #endif
 
 #include <Python.h>
-#if PY_VERSION_HEX < 0x03080000
-#    error "PYTHON < 3.8 IS UNSUPPORTED. pybind11 v2.13 was the last to support Python 3.7."
+// Reminder: WITH_THREAD is always defined if PY_VERSION_HEX >= 0x03070000
+#if PY_VERSION_HEX < 0x03060000
+#    error "PYTHON < 3.6 IS UNSUPPORTED. pybind11 v2.9 was the last to support Python 2 and 3.5."
 #endif
 #include <frameobject.h>
 #include <pythread.h>
@@ -462,26 +463,8 @@ PYBIND11_WARNING_POP
                 return "Hello, World!";
             });
         }
-
-    The third macro argument is optional (available since 2.13.0), and can be used to
-    mark the extension module as safe to run without the GIL under a free-threaded CPython
-    interpreter. Passing this argument has no effect on other interpreters.
-
-    .. code-block:: cpp
-
-        PYBIND11_MODULE(example, m, py::mod_gil_not_used()) {
-            m.doc() = "pybind11 example module safe to run without the GIL";
-
-            // Add bindings here
-            m.def("foo", []() {
-                return "Hello, Free-threaded World!";
-            });
-        }
-
 \endrst */
-PYBIND11_WARNING_PUSH
-PYBIND11_WARNING_DISABLE_CLANG("-Wgnu-zero-variadic-macro-arguments")
-#define PYBIND11_MODULE(name, variable, ...)                                                      \
+#define PYBIND11_MODULE(name, variable)                                                           \
     static ::pybind11::module_::module_def PYBIND11_CONCAT(pybind11_module_def_, name)            \
         PYBIND11_MAYBE_UNUSED;                                                                    \
     PYBIND11_MAYBE_UNUSED                                                                         \
@@ -490,10 +473,7 @@ PYBIND11_WARNING_DISABLE_CLANG("-Wgnu-zero-variadic-macro-arguments")
         PYBIND11_CHECK_PYTHON_VERSION                                                             \
         PYBIND11_ENSURE_INTERNALS_READY                                                           \
         auto m = ::pybind11::module_::create_extension_module(                                    \
-            PYBIND11_TOSTRING(name),                                                              \
-            nullptr,                                                                              \
-            &PYBIND11_CONCAT(pybind11_module_def_, name),                                         \
-            ##__VA_ARGS__);                                                                       \
+            PYBIND11_TOSTRING(name), nullptr, &PYBIND11_CONCAT(pybind11_module_def_, name));      \
         try {                                                                                     \
             PYBIND11_CONCAT(pybind11_init_, name)(m);                                             \
             return m.ptr();                                                                       \
@@ -501,7 +481,6 @@ PYBIND11_WARNING_DISABLE_CLANG("-Wgnu-zero-variadic-macro-arguments")
         PYBIND11_CATCH_INIT_EXCEPTIONS                                                            \
     }                                                                                             \
     void PYBIND11_CONCAT(pybind11_init_, name)(::pybind11::module_ & (variable))
-PYBIND11_WARNING_POP
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
@@ -557,7 +536,7 @@ enum class return_value_policy : uint8_t {
         object without taking ownership similar to the above
         return_value_policy::reference policy. In contrast to that policy, the
         function or property's implicit this argument (called the parent) is
-        considered to be the owner of the return value (the child).
+        considered to be the the owner of the return value (the child).
         pybind11 then couples the lifetime of the parent to the child via a
         reference relationship that ensures that the parent cannot be garbage
         collected while Python is still using the child. More advanced

include/pybind11/detail/cpp_conduit.h

@@ -1,77 +0,0 @@
-// Copyright (c) 2024 The pybind Community.
-
-#pragma once
-
-#include <pybind11/pytypes.h>
-
-#include "common.h"
-#include "internals.h"
-
-#include <typeinfo>
-
-PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
-PYBIND11_NAMESPACE_BEGIN(detail)
-
-// Forward declaration needed here: Refactoring opportunity.
-extern "C" inline PyObject *pybind11_object_new(PyTypeObject *type, PyObject *, PyObject *);
-
-inline bool type_is_managed_by_our_internals(PyTypeObject *type_obj) {
-#if defined(PYPY_VERSION)
-    auto &internals = get_internals();
-    return bool(internals.registered_types_py.find(type_obj)
-                != internals.registered_types_py.end());
-#else
-    return bool(type_obj->tp_new == pybind11_object_new);
-#endif
-}
-
-inline bool is_instance_method_of_type(PyTypeObject *type_obj, PyObject *attr_name) {
-    PyObject *descr = _PyType_Lookup(type_obj, attr_name);
-    return bool((descr != nullptr) && PyInstanceMethod_Check(descr));
-}
-
-inline object try_get_cpp_conduit_method(PyObject *obj) {
-    if (PyType_Check(obj)) {
-        return object();
-    }
-    PyTypeObject *type_obj = Py_TYPE(obj);
-    str attr_name("_pybind11_conduit_v1_");
-    bool assumed_to_be_callable = false;
-    if (type_is_managed_by_our_internals(type_obj)) {
-        if (!is_instance_method_of_type(type_obj, attr_name.ptr())) {
-            return object();
-        }
-        assumed_to_be_callable = true;
-    }
-    PyObject *method = PyObject_GetAttr(obj, attr_name.ptr());
-    if (method == nullptr) {
-        PyErr_Clear();
-        return object();
-    }
-    if (!assumed_to_be_callable && PyCallable_Check(method) == 0) {
-        Py_DECREF(method);
-        return object();
-    }
-    return reinterpret_steal<object>(method);
-}
-
-inline void *try_raw_pointer_ephemeral_from_cpp_conduit(handle src,
-                                                        const std::type_info *cpp_type_info) {
-    object method = try_get_cpp_conduit_method(src.ptr());
-    if (method) {
-        capsule cpp_type_info_capsule(const_cast<void *>(static_cast<const void *>(cpp_type_info)),
-                                      typeid(std::type_info).name());
-        object cpp_conduit = method(bytes(PYBIND11_PLATFORM_ABI_ID),
-                                    cpp_type_info_capsule,
-                                    bytes("raw_pointer_ephemeral"));
-        if (isinstance<capsule>(cpp_conduit)) {
-            return reinterpret_borrow<capsule>(cpp_conduit).get_pointer();
-        }
-    }
-    return nullptr;
-}
-
-#define PYBIND11_HAS_CPP_CONDUIT 1
-
-PYBIND11_NAMESPACE_END(detail)
-PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/detail/exception_translation.h

@@ -1,71 +0,0 @@
-/*
-    pybind11/detail/exception_translation.h: means to translate C++ exceptions to Python exceptions
-
-    Copyright (c) 2024 The Pybind Development Team.
-
-    All rights reserved. Use of this source code is governed by a
-    BSD-style license that can be found in the LICENSE file.
-*/
-
-#pragma once
-
-#include "common.h"
-#include "internals.h"
-
-PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
-PYBIND11_NAMESPACE_BEGIN(detail)
-
-// Apply all the extensions translators from a list
-// Return true if one of the translators completed without raising an exception
-// itself. Return of false indicates that if there are other translators
-// available, they should be tried.
-inline bool apply_exception_translators(std::forward_list<ExceptionTranslator> &translators) {
-    auto last_exception = std::current_exception();
-
-    for (auto &translator : translators) {
-        try {
-            translator(last_exception);
-            return true;
-        } catch (...) {
-            last_exception = std::current_exception();
-        }
-    }
-    return false;
-}
-
-inline void try_translate_exceptions() {
-    /* When an exception is caught, give each registered exception
-        translator a chance to translate it to a Python exception. First
-        all module-local translators will be tried in reverse order of
-        registration. If none of the module-locale translators handle
-        the exception (or there are no module-locale translators) then
-        the global translators will be tried, also in reverse order of
-        registration.
-
-        A translator may choose to do one of the following:
-
-        - catch the exception and call py::set_error()
-            to set a standard (or custom) Python exception, or
-        - do nothing and let the exception fall through to the next translator, or
-        - delegate translation to the next translator by throwing a new type of exception.
-        */
-
-    bool handled = with_exception_translators(
-        [&](std::forward_list<ExceptionTranslator> &exception_translators,
-            std::forward_list<ExceptionTranslator> &local_exception_translators) {
-            if (detail::apply_exception_translators(local_exception_translators)) {
-                return true;
-            }
-            if (detail::apply_exception_translators(exception_translators)) {
-                return true;
-            }
-            return false;
-        });
-
-    if (!handled) {
-        set_error(PyExc_SystemError, "Exception escaped from default exception translator!");
-    }
-}
-
-PYBIND11_NAMESPACE_END(detail)
-PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/detail/init.h

@@ -128,13 +128,11 @@ void construct(value_and_holder &v_h, Cpp<Class> *ptr, bool need_alias) {
         // the holder and destruction happens when we leave the C++ scope, and the holder
         // class gets to handle the destruction however it likes.
         v_h.value_ptr() = ptr;
-        v_h.set_instance_registered(true); // Trick to prevent init_instance from registering it
-        // DANGER ZONE BEGIN: exceptions will leave v_h in an invalid state.
-        v_h.type->init_instance(v_h.inst, nullptr);                        // Set up the holder
+        v_h.set_instance_registered(true);          // To prevent init_instance from registering it
+        v_h.type->init_instance(v_h.inst, nullptr); // Set up the holder
         Holder<Class> temp_holder(std::move(v_h.holder<Holder<Class>>())); // Steal the holder
         v_h.type->dealloc(v_h); // Destroys the moved-out holder remains, resets value ptr to null
         v_h.set_instance_registered(false);
-        // DANGER ZONE END.
 
         construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(*ptr));
     } else {

include/pybind11/detail/internals.h

@@ -11,15 +11,13 @@
 
 #include "common.h"
 
-#if defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
-#    include <pybind11/gil.h>
+#if defined(WITH_THREAD) && defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
+#    include "../gil.h"
 #endif
 
-#include <pybind11/pytypes.h>
+#include "../pytypes.h"
 
 #include <exception>
-#include <mutex>
-#include <thread>
 
 /// Tracks the `internals` and `type_info` ABI version independent of the main library version.
 ///
@@ -39,11 +37,7 @@
 #    if PY_VERSION_HEX >= 0x030C0000 || defined(_MSC_VER)
 // Version bump for Python 3.12+, before first 3.12 beta release.
 // Version bump for MSVC piggy-backed on PR #4779. See comments there.
-#        ifdef Py_GIL_DISABLED
-#            define PYBIND11_INTERNALS_VERSION 6
-#        else
-#            define PYBIND11_INTERNALS_VERSION 5
-#        endif
+#        define PYBIND11_INTERNALS_VERSION 5
 #    else
 #        define PYBIND11_INTERNALS_VERSION 4
 #    endif
@@ -68,41 +62,65 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass);
 
 // The old Python Thread Local Storage (TLS) API is deprecated in Python 3.7 in favor of the new
 // Thread Specific Storage (TSS) API.
+#if PY_VERSION_HEX >= 0x03070000
 // Avoid unnecessary allocation of `Py_tss_t`, since we cannot use
 // `Py_LIMITED_API` anyway.
-#if PYBIND11_INTERNALS_VERSION > 4
-#    define PYBIND11_TLS_KEY_REF Py_tss_t &
-#    if defined(__clang__)
-#        define PYBIND11_TLS_KEY_INIT(var)                                                        \
-            _Pragma("clang diagnostic push")                                         /**/         \
-                _Pragma("clang diagnostic ignored \"-Wmissing-field-initializers\"") /**/         \
-                Py_tss_t var                                                                      \
-                = Py_tss_NEEDS_INIT;                                                              \
-            _Pragma("clang diagnostic pop")
-#    elif defined(__GNUC__) && !defined(__INTEL_COMPILER)
-#        define PYBIND11_TLS_KEY_INIT(var)                                                        \
-            _Pragma("GCC diagnostic push")                                         /**/           \
-                _Pragma("GCC diagnostic ignored \"-Wmissing-field-initializers\"") /**/           \
-                Py_tss_t var                                                                      \
-                = Py_tss_NEEDS_INIT;                                                              \
-            _Pragma("GCC diagnostic pop")
+#    if PYBIND11_INTERNALS_VERSION > 4
+#        define PYBIND11_TLS_KEY_REF Py_tss_t &
+#        if defined(__clang__)
+#            define PYBIND11_TLS_KEY_INIT(var)                                                    \
+                _Pragma("clang diagnostic push")                                         /**/     \
+                    _Pragma("clang diagnostic ignored \"-Wmissing-field-initializers\"") /**/     \
+                    Py_tss_t var                                                                  \
+                    = Py_tss_NEEDS_INIT;                                                          \
+                _Pragma("clang diagnostic pop")
+#        elif defined(__GNUC__) && !defined(__INTEL_COMPILER)
+#            define PYBIND11_TLS_KEY_INIT(var)                                                    \
+                _Pragma("GCC diagnostic push")                                         /**/       \
+                    _Pragma("GCC diagnostic ignored \"-Wmissing-field-initializers\"") /**/       \
+                    Py_tss_t var                                                                  \
+                    = Py_tss_NEEDS_INIT;                                                          \
+                _Pragma("GCC diagnostic pop")
+#        else
+#            define PYBIND11_TLS_KEY_INIT(var) Py_tss_t var = Py_tss_NEEDS_INIT;
+#        endif
+#        define PYBIND11_TLS_KEY_CREATE(var) (PyThread_tss_create(&(var)) == 0)
+#        define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get(&(key))
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set(&(key), (value))
+#        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set(&(key), nullptr)
+#        define PYBIND11_TLS_FREE(key) PyThread_tss_delete(&(key))
 #    else
-#        define PYBIND11_TLS_KEY_INIT(var) Py_tss_t var = Py_tss_NEEDS_INIT;
+#        define PYBIND11_TLS_KEY_REF Py_tss_t *
+#        define PYBIND11_TLS_KEY_INIT(var) Py_tss_t *var = nullptr;
+#        define PYBIND11_TLS_KEY_CREATE(var)                                                      \
+            (((var) = PyThread_tss_alloc()) != nullptr && (PyThread_tss_create((var)) == 0))
+#        define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get((key))
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set((key), (value))
+#        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set((key), nullptr)
+#        define PYBIND11_TLS_FREE(key) PyThread_tss_free(key)
 #    endif
-#    define PYBIND11_TLS_KEY_CREATE(var) (PyThread_tss_create(&(var)) == 0)
-#    define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get(&(key))
-#    define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set(&(key), (value))
-#    define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set(&(key), nullptr)
-#    define PYBIND11_TLS_FREE(key) PyThread_tss_delete(&(key))
 #else
-#    define PYBIND11_TLS_KEY_REF Py_tss_t *
-#    define PYBIND11_TLS_KEY_INIT(var) Py_tss_t *var = nullptr;
-#    define PYBIND11_TLS_KEY_CREATE(var)                                                          \
-        (((var) = PyThread_tss_alloc()) != nullptr && (PyThread_tss_create((var)) == 0))
-#    define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get((key))
-#    define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set((key), (value))
-#    define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set((key), nullptr)
-#    define PYBIND11_TLS_FREE(key) PyThread_tss_free(key)
+// Usually an int but a long on Cygwin64 with Python 3.x
+#    define PYBIND11_TLS_KEY_REF decltype(PyThread_create_key())
+#    define PYBIND11_TLS_KEY_INIT(var) PYBIND11_TLS_KEY_REF var = 0;
+#    define PYBIND11_TLS_KEY_CREATE(var) (((var) = PyThread_create_key()) != -1)
+#    define PYBIND11_TLS_GET_VALUE(key) PyThread_get_key_value((key))
+#    if defined(PYPY_VERSION)
+// On CPython < 3.4 and on PyPy, `PyThread_set_key_value` strangely does not set
+// the value if it has already been set.  Instead, it must first be deleted and
+// then set again.
+inline void tls_replace_value(PYBIND11_TLS_KEY_REF key, void *value) {
+    PyThread_delete_key_value(key);
+    PyThread_set_key_value(key, value);
+}
+#        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_delete_key_value(key)
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value)                                            \
+            ::pybind11::detail::tls_replace_value((key), (value))
+#    else
+#        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_set_key_value((key), nullptr)
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_set_key_value((key), (value))
+#    endif
+#    define PYBIND11_TLS_FREE(key) (void) key
 #endif
 
 // Python loads modules by default with dlopen with the RTLD_LOCAL flag; under libc++ and possibly
@@ -150,49 +168,15 @@ struct override_hash {
     }
 };
 
-using instance_map = std::unordered_multimap<const void *, instance *>;
-
-#ifdef Py_GIL_DISABLED
-// Wrapper around PyMutex to provide BasicLockable semantics
-class pymutex {
-    PyMutex mutex;
-
-public:
-    pymutex() : mutex({}) {}
-    void lock() { PyMutex_Lock(&mutex); }
-    void unlock() { PyMutex_Unlock(&mutex); }
-};
-
-// Instance map shards are used to reduce mutex contention in free-threaded Python.
-struct instance_map_shard {
-    instance_map registered_instances;
-    pymutex mutex;
-    // alignas(64) would be better, but causes compile errors in macOS before 10.14 (see #5200)
-    char padding[64 - (sizeof(instance_map) + sizeof(pymutex)) % 64];
-};
-
-static_assert(sizeof(instance_map_shard) % 64 == 0,
-              "instance_map_shard size is not a multiple of 64 bytes");
-#endif
-
 /// Internal data structure used to track registered instances and types.
 /// Whenever binary incompatible changes are made to this structure,
 /// `PYBIND11_INTERNALS_VERSION` must be incremented.
 struct internals {
-#ifdef Py_GIL_DISABLED
-    pymutex mutex;
-    pymutex exception_translator_mutex;
-#endif
     // std::type_index -> pybind11's type information
     type_map<type_info *> registered_types_cpp;
     // PyTypeObject* -> base type_info(s)
     std::unordered_map<PyTypeObject *, std::vector<type_info *>> registered_types_py;
-#ifdef Py_GIL_DISABLED
-    std::unique_ptr<instance_map_shard[]> instance_shards; // void * -> instance*
-    size_t instance_shards_mask;
-#else
-    instance_map registered_instances; // void * -> instance*
-#endif
+    std::unordered_multimap<const void *, instance *> registered_instances; // void * -> instance*
     std::unordered_set<std::pair<const PyObject *, const char *>, override_hash>
         inactive_override_cache;
     type_map<std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
@@ -208,27 +192,28 @@ struct internals {
     PyTypeObject *static_property_type;
     PyTypeObject *default_metaclass;
     PyObject *instance_base;
+#if defined(WITH_THREAD)
     // Unused if PYBIND11_SIMPLE_GIL_MANAGEMENT is defined:
     PYBIND11_TLS_KEY_INIT(tstate)
-#if PYBIND11_INTERNALS_VERSION > 4
+#    if PYBIND11_INTERNALS_VERSION > 4
     PYBIND11_TLS_KEY_INIT(loader_life_support_tls_key)
-#endif // PYBIND11_INTERNALS_VERSION > 4
+#    endif // PYBIND11_INTERNALS_VERSION > 4
     // Unused if PYBIND11_SIMPLE_GIL_MANAGEMENT is defined:
     PyInterpreterState *istate = nullptr;
 
-#if PYBIND11_INTERNALS_VERSION > 4
+#    if PYBIND11_INTERNALS_VERSION > 4
     // Note that we have to use a std::string to allocate memory to ensure a unique address
     // We want unique addresses since we use pointer equality to compare function records
     std::string function_record_capsule_name = internals_function_record_capsule_name;
-#endif
+#    endif
 
     internals() = default;
     internals(const internals &other) = delete;
     internals &operator=(const internals &other) = delete;
     ~internals() {
-#if PYBIND11_INTERNALS_VERSION > 4
+#    if PYBIND11_INTERNALS_VERSION > 4
         PYBIND11_TLS_FREE(loader_life_support_tls_key);
-#endif // PYBIND11_INTERNALS_VERSION > 4
+#    endif // PYBIND11_INTERNALS_VERSION > 4
 
         // This destructor is called *after* Py_Finalize() in finalize_interpreter().
         // That *SHOULD BE* fine. The following details what happens when PyThread_tss_free is
@@ -239,6 +224,7 @@ struct internals {
         // that the `tstate` be allocated with the CPython allocator.
         PYBIND11_TLS_FREE(tstate);
     }
+#endif
 };
 
 /// Additional type information which does not fit into the PyTypeObject.
@@ -323,20 +309,22 @@ struct type_info {
 #endif
 
 #ifndef PYBIND11_INTERNALS_KIND
-#    define PYBIND11_INTERNALS_KIND ""
+#    if defined(WITH_THREAD)
+#        define PYBIND11_INTERNALS_KIND ""
+#    else
+#        define PYBIND11_INTERNALS_KIND "_without_thread"
+#    endif
 #endif
 
-#define PYBIND11_PLATFORM_ABI_ID                                                                  \
-    PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI             \
-        PYBIND11_BUILD_TYPE
-
 #define PYBIND11_INTERNALS_ID                                                                     \
     "__pybind11_internals_v" PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION)                        \
-        PYBIND11_PLATFORM_ABI_ID "__"
+        PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB                            \
+            PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
 
 #define PYBIND11_MODULE_LOCAL_ID                                                                  \
     "__pybind11_module_local_v" PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION)                     \
-        PYBIND11_PLATFORM_ABI_ID "__"
+        PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB                            \
+            PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
 
 /// Each module locally stores a pointer to the `internals` data. The data
 /// itself is shared among modules with the same `PYBIND11_INTERNALS_ID`.
@@ -454,7 +442,7 @@ inline void translate_local_exception(std::exception_ptr p) {
 
 inline object get_python_state_dict() {
     object state_dict;
-#if PYBIND11_INTERNALS_VERSION <= 4 || defined(PYPY_VERSION)
+#if PYBIND11_INTERNALS_VERSION <= 4 || PY_VERSION_HEX < 0x03080000 || defined(PYPY_VERSION)
     state_dict = reinterpret_borrow<object>(PyEval_GetBuiltins());
 #else
 #    if PY_VERSION_HEX < 0x03090000
@@ -474,8 +462,7 @@ inline object get_python_state_dict() {
 }
 
 inline object get_internals_obj_from_state_dict(handle state_dict) {
-    return reinterpret_steal<object>(
-        dict_getitemstringref(state_dict.ptr(), PYBIND11_INTERNALS_ID));
+    return reinterpret_borrow<object>(dict_getitemstring(state_dict.ptr(), PYBIND11_INTERNALS_ID));
 }
 
 inline internals **get_internals_pp_from_capsule(handle obj) {
@@ -487,20 +474,6 @@ inline internals **get_internals_pp_from_capsule(handle obj) {
     return static_cast<internals **>(raw_ptr);
 }
 
-inline uint64_t round_up_to_next_pow2(uint64_t x) {
-    // Round-up to the next power of two.
-    // See https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
-    x--;
-    x |= (x >> 1);
-    x |= (x >> 2);
-    x |= (x >> 4);
-    x |= (x >> 8);
-    x |= (x >> 16);
-    x |= (x >> 32);
-    x++;
-    return x;
-}
-
 /// Return a reference to the current `internals` data
 PYBIND11_NOINLINE internals &get_internals() {
     auto **&internals_pp = get_internals_pp();
@@ -508,9 +481,10 @@ PYBIND11_NOINLINE internals &get_internals() {
         return **internals_pp;
     }
 
-#if defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
+#if defined(WITH_THREAD)
+#    if defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
     gil_scoped_acquire gil;
-#else
+#    else
     // Ensure that the GIL is held since we will need to make Python calls.
     // Cannot use py::gil_scoped_acquire here since that constructor calls get_internals.
     struct gil_scoped_acquire_local {
@@ -520,6 +494,7 @@ PYBIND11_NOINLINE internals &get_internals() {
         ~gil_scoped_acquire_local() { PyGILState_Release(state); }
         const PyGILState_STATE state;
     } gil;
+#    endif
 #endif
     error_scope err_scope;
 
@@ -544,6 +519,7 @@ PYBIND11_NOINLINE internals &get_internals() {
         }
         auto *&internals_ptr = *internals_pp;
         internals_ptr = new internals();
+#if defined(WITH_THREAD)
 
         PyThreadState *tstate = PyThreadState_Get();
         // NOLINTNEXTLINE(bugprone-assignment-in-if-condition)
@@ -552,29 +528,20 @@ PYBIND11_NOINLINE internals &get_internals() {
         }
         PYBIND11_TLS_REPLACE_VALUE(internals_ptr->tstate, tstate);
 
-#if PYBIND11_INTERNALS_VERSION > 4
+#    if PYBIND11_INTERNALS_VERSION > 4
         // NOLINTNEXTLINE(bugprone-assignment-in-if-condition)
         if (!PYBIND11_TLS_KEY_CREATE(internals_ptr->loader_life_support_tls_key)) {
             pybind11_fail("get_internals: could not successfully initialize the "
                           "loader_life_support TSS key!");
         }
-#endif
+#    endif
         internals_ptr->istate = tstate->interp;
-        state_dict[PYBIND11_INTERNALS_ID] = capsule(reinterpret_cast<void *>(internals_pp));
+#endif
+        state_dict[PYBIND11_INTERNALS_ID] = capsule(internals_pp);
         internals_ptr->registered_exception_translators.push_front(&translate_exception);
         internals_ptr->static_property_type = make_static_property_type();
         internals_ptr->default_metaclass = make_default_metaclass();
         internals_ptr->instance_base = make_object_base_type(internals_ptr->default_metaclass);
-#ifdef Py_GIL_DISABLED
-        // Scale proportional to the number of cores. 2x is a heuristic to reduce contention.
-        auto num_shards
-            = static_cast<size_t>(round_up_to_next_pow2(2 * std::thread::hardware_concurrency()));
-        if (num_shards == 0) {
-            num_shards = 1;
-        }
-        internals_ptr->instance_shards.reset(new instance_map_shard[num_shards]);
-        internals_ptr->instance_shards_mask = num_shards - 1;
-#endif // Py_GIL_DISABLED
     }
     return **internals_pp;
 }
@@ -588,7 +555,7 @@ PYBIND11_NOINLINE internals &get_internals() {
 struct local_internals {
     type_map<type_info *> registered_types_cpp;
     std::forward_list<ExceptionTranslator> registered_exception_translators;
-#if PYBIND11_INTERNALS_VERSION == 4
+#if defined(WITH_THREAD) && PYBIND11_INTERNALS_VERSION == 4
 
     // For ABI compatibility, we can't store the loader_life_support TLS key in
     // the `internals` struct directly.  Instead, we store it in `shared_data` and
@@ -621,7 +588,7 @@ struct local_internals {
         loader_life_support_tls_key
             = static_cast<shared_loader_life_support_data *>(ptr)->loader_life_support_tls_key;
     }
-#endif //  PYBIND11_INTERNALS_VERSION == 4
+#endif //  defined(WITH_THREAD) && PYBIND11_INTERNALS_VERSION == 4
 };
 
 /// Works like `get_internals`, but for things which are locally registered.
@@ -635,93 +602,13 @@ inline local_internals &get_local_internals() {
     return *locals;
 }
 
-#ifdef Py_GIL_DISABLED
-#    define PYBIND11_LOCK_INTERNALS(internals) std::unique_lock<pymutex> lock((internals).mutex)
-#else
-#    define PYBIND11_LOCK_INTERNALS(internals)
-#endif
-
-template <typename F>
-inline auto with_internals(const F &cb) -> decltype(cb(get_internals())) {
-    auto &internals = get_internals();
-    PYBIND11_LOCK_INTERNALS(internals);
-    return cb(internals);
-}
-
-template <typename F>
-inline auto with_exception_translators(const F &cb)
-    -> decltype(cb(get_internals().registered_exception_translators,
-                   get_local_internals().registered_exception_translators)) {
-    auto &internals = get_internals();
-#ifdef Py_GIL_DISABLED
-    std::unique_lock<pymutex> lock((internals).exception_translator_mutex);
-#endif
-    auto &local_internals = get_local_internals();
-    return cb(internals.registered_exception_translators,
-              local_internals.registered_exception_translators);
-}
-
-inline std::uint64_t mix64(std::uint64_t z) {
-    // David Stafford's variant 13 of the MurmurHash3 finalizer popularized
-    // by the SplitMix PRNG.
-    // https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
-    z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
-    z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
-    return z ^ (z >> 31);
-}
-
-template <typename F>
-inline auto with_instance_map(const void *ptr,
-                              const F &cb) -> decltype(cb(std::declval<instance_map &>())) {
-    auto &internals = get_internals();
-
-#ifdef Py_GIL_DISABLED
-    // Hash address to compute shard, but ignore low bits. We'd like allocations
-    // from the same thread/core to map to the same shard and allocations from
-    // other threads/cores to map to other shards. Using the high bits is a good
-    // heuristic because memory allocators often have a per-thread
-    // arena/superblock/segment from which smaller allocations are served.
-    auto addr = reinterpret_cast<std::uintptr_t>(ptr);
-    auto hash = mix64(static_cast<std::uint64_t>(addr >> 20));
-    auto idx = static_cast<size_t>(hash & internals.instance_shards_mask);
-
-    auto &shard = internals.instance_shards[idx];
-    std::unique_lock<pymutex> lock(shard.mutex);
-    return cb(shard.registered_instances);
-#else
-    (void) ptr;
-    return cb(internals.registered_instances);
-#endif
-}
-
-// Returns the number of registered instances for testing purposes.  The result may not be
-// consistent if other threads are registering or unregistering instances concurrently.
-inline size_t num_registered_instances() {
-    auto &internals = get_internals();
-#ifdef Py_GIL_DISABLED
-    size_t count = 0;
-    for (size_t i = 0; i <= internals.instance_shards_mask; ++i) {
-        auto &shard = internals.instance_shards[i];
-        std::unique_lock<pymutex> lock(shard.mutex);
-        count += shard.registered_instances.size();
-    }
-    return count;
-#else
-    return internals.registered_instances.size();
-#endif
-}
-
 /// Constructs a std::string with the given arguments, stores it in `internals`, and returns its
 /// `c_str()`.  Such strings objects have a long storage duration -- the internal strings are only
 /// cleared when the program exits or after interpreter shutdown (when embedding), and so are
 /// suitable for c-style strings needed by Python internals (such as PyTypeObject's tp_name).
 template <typename... Args>
 const char *c_str(Args &&...args) {
-    // GCC 4.8 doesn't like parameter unpack within lambda capture, so use
-    // PYBIND11_LOCK_INTERNALS.
-    auto &internals = get_internals();
-    PYBIND11_LOCK_INTERNALS(internals);
-    auto &strings = internals.static_strings;
+    auto &strings = get_internals().static_strings;
     strings.emplace_front(std::forward<Args>(args)...);
     return strings.front().c_str();
 }
@@ -751,18 +638,15 @@ PYBIND11_NAMESPACE_END(detail)
 /// pybind11 version) running in the current interpreter. Names starting with underscores
 /// are reserved for internal usage. Returns `nullptr` if no matching entry was found.
 PYBIND11_NOINLINE void *get_shared_data(const std::string &name) {
-    return detail::with_internals([&](detail::internals &internals) {
-        auto it = internals.shared_data.find(name);
-        return it != internals.shared_data.end() ? it->second : nullptr;
-    });
+    auto &internals = detail::get_internals();
+    auto it = internals.shared_data.find(name);
+    return it != internals.shared_data.end() ? it->second : nullptr;
 }
 
 /// Set the shared data that can be later recovered by `get_shared_data()`.
 PYBIND11_NOINLINE void *set_shared_data(const std::string &name, void *data) {
-    return detail::with_internals([&](detail::internals &internals) {
-        internals.shared_data[name] = data;
-        return data;
-    });
+    detail::get_internals().shared_data[name] = data;
+    return data;
 }
 
 /// Returns a typed reference to a shared data entry (by using `get_shared_data()`) if
@@ -770,15 +654,14 @@ PYBIND11_NOINLINE void *set_shared_data(const std::string &name, void *data) {
 /// added to the shared data under the given name and a reference to it is returned.
 template <typename T>
 T &get_or_create_shared_data(const std::string &name) {
-    return *detail::with_internals([&](detail::internals &internals) {
-        auto it = internals.shared_data.find(name);
-        T *ptr = (T *) (it != internals.shared_data.end() ? it->second : nullptr);
-        if (!ptr) {
-            ptr = new T();
-            internals.shared_data[name] = ptr;
-        }
-        return ptr;
-    });
+    auto &internals = detail::get_internals();
+    auto it = internals.shared_data.find(name);
+    T *ptr = (T *) (it != internals.shared_data.end() ? it->second : nullptr);
+    if (!ptr) {
+        ptr = new T();
+        internals.shared_data[name] = ptr;
+    }
+    return *ptr;
 }
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/detail/type_caster_base.h

@@ -9,20 +9,15 @@
 
 #pragma once
 
-#include <pybind11/pytypes.h>
-
+#include "../pytypes.h"
 #include "common.h"
-#include "cpp_conduit.h"
 #include "descr.h"
 #include "internals.h"
 #include "typeid.h"
-#include "value_and_holder.h"
 
 #include <cstdint>
-#include <cstring>
 #include <iterator>
 #include <new>
-#include <stdexcept>
 #include <string>
 #include <type_traits>
 #include <typeindex>
@@ -41,13 +36,14 @@ private:
     loader_life_support *parent = nullptr;
     std::unordered_set<PyObject *> keep_alive;
 
+#if defined(WITH_THREAD)
     // Store stack pointer in thread-local storage.
     static PYBIND11_TLS_KEY_REF get_stack_tls_key() {
-#if PYBIND11_INTERNALS_VERSION == 4
+#    if PYBIND11_INTERNALS_VERSION == 4
         return get_local_internals().loader_life_support_tls_key;
-#else
+#    else
         return get_internals().loader_life_support_tls_key;
-#endif
+#    endif
     }
     static loader_life_support *get_stack_top() {
         return static_cast<loader_life_support *>(PYBIND11_TLS_GET_VALUE(get_stack_tls_key()));
@@ -55,6 +51,15 @@ private:
     static void set_stack_top(loader_life_support *value) {
         PYBIND11_TLS_REPLACE_VALUE(get_stack_tls_key(), value);
     }
+#else
+    // Use single global variable for stack.
+    static loader_life_support **get_stack_pp() {
+        static loader_life_support *global_stack = nullptr;
+        return global_stack;
+    }
+    static loader_life_support *get_stack_top() { return *get_stack_pp(); }
+    static void set_stack_top(loader_life_support *value) { *get_stack_pp() = value; }
+#endif
 
 public:
     /// A new patient frame is created when a function is entered
@@ -212,15 +217,12 @@ inline detail::type_info *get_local_type_info(const std::type_index &tp) {
 }
 
 inline detail::type_info *get_global_type_info(const std::type_index &tp) {
-    return with_internals([&](internals &internals) {
-        detail::type_info *type_info = nullptr;
-        auto &types = internals.registered_types_cpp;
-        auto it = types.find(tp);
-        if (it != types.end()) {
-            type_info = it->second;
-        }
-        return type_info;
-    });
+    auto &types = get_internals().registered_types_cpp;
+    auto it = types.find(tp);
+    if (it != types.end()) {
+        return it->second;
+    }
+    return nullptr;
 }
 
 /// Return the type info for a given C++ type; on lookup failure can either throw or return
@@ -251,19 +253,78 @@ PYBIND11_NOINLINE handle get_type_handle(const std::type_info &tp, bool throw_if
 // Searches the inheritance graph for a registered Python instance, using all_type_info().
 PYBIND11_NOINLINE handle find_registered_python_instance(void *src,
                                                          const detail::type_info *tinfo) {
-    return with_instance_map(src, [&](instance_map &instances) {
-        auto it_instances = instances.equal_range(src);
-        for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
-            for (auto *instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
-                if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype)) {
-                    return handle((PyObject *) it_i->second).inc_ref();
-                }
+    auto it_instances = get_internals().registered_instances.equal_range(src);
+    for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
+        for (auto *instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
+            if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype)) {
+                return handle((PyObject *) it_i->second).inc_ref();
             }
         }
-        return handle();
-    });
+    }
+    return handle();
 }
 
+struct value_and_holder {
+    instance *inst = nullptr;
+    size_t index = 0u;
+    const detail::type_info *type = nullptr;
+    void **vh = nullptr;
+
+    // Main constructor for a found value/holder:
+    value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index)
+        : inst{i}, index{index}, type{type},
+          vh{inst->simple_layout ? inst->simple_value_holder
+                                 : &inst->nonsimple.values_and_holders[vpos]} {}
+
+    // Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
+    value_and_holder() = default;
+
+    // Used for past-the-end iterator
+    explicit value_and_holder(size_t index) : index{index} {}
+
+    template <typename V = void>
+    V *&value_ptr() const {
+        return reinterpret_cast<V *&>(vh[0]);
+    }
+    // True if this `value_and_holder` has a non-null value pointer
+    explicit operator bool() const { return value_ptr() != nullptr; }
+
+    template <typename H>
+    H &holder() const {
+        return reinterpret_cast<H &>(vh[1]);
+    }
+    bool holder_constructed() const {
+        return inst->simple_layout
+                   ? inst->simple_holder_constructed
+                   : (inst->nonsimple.status[index] & instance::status_holder_constructed) != 0u;
+    }
+    // NOLINTNEXTLINE(readability-make-member-function-const)
+    void set_holder_constructed(bool v = true) {
+        if (inst->simple_layout) {
+            inst->simple_holder_constructed = v;
+        } else if (v) {
+            inst->nonsimple.status[index] |= instance::status_holder_constructed;
+        } else {
+            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_holder_constructed;
+        }
+    }
+    bool instance_registered() const {
+        return inst->simple_layout
+                   ? inst->simple_instance_registered
+                   : ((inst->nonsimple.status[index] & instance::status_instance_registered) != 0);
+    }
+    // NOLINTNEXTLINE(readability-make-member-function-const)
+    void set_instance_registered(bool v = true) {
+        if (inst->simple_layout) {
+            inst->simple_instance_registered = v;
+        } else if (v) {
+            inst->nonsimple.status[index] |= instance::status_instance_registered;
+        } else {
+            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_instance_registered;
+        }
+    }
+};
+
 // Container for accessing and iterating over an instance's values/holders
 struct values_and_holders {
 private:
@@ -432,7 +493,7 @@ PYBIND11_NOINLINE void instance::allocate_layout() {
 // NOLINTNEXTLINE(readability-make-member-function-const)
 PYBIND11_NOINLINE void instance::deallocate_layout() {
     if (!simple_layout) {
-        PyMem_Free(reinterpret_cast<void *>(nonsimple.values_and_holders));
+        PyMem_Free(nonsimple.values_and_holders);
     }
 }
 
@@ -445,17 +506,16 @@ PYBIND11_NOINLINE bool isinstance_generic(handle obj, const std::type_info &tp)
 }
 
 PYBIND11_NOINLINE handle get_object_handle(const void *ptr, const detail::type_info *type) {
-    return with_instance_map(ptr, [&](instance_map &instances) {
-        auto range = instances.equal_range(ptr);
-        for (auto it = range.first; it != range.second; ++it) {
-            for (const auto &vh : values_and_holders(it->second)) {
-                if (vh.type == type) {
-                    return handle((PyObject *) it->second);
-                }
+    auto &instances = get_internals().registered_instances;
+    auto range = instances.equal_range(ptr);
+    for (auto it = range.first; it != range.second; ++it) {
+        for (const auto &vh : values_and_holders(it->second)) {
+            if (vh.type == type) {
+                return handle((PyObject *) it->second);
             }
         }
-        return handle();
-    });
+    }
+    return handle();
 }
 
 inline PyThreadState *get_thread_state_unchecked() {
@@ -614,13 +674,6 @@ public:
         }
         return false;
     }
-    bool try_cpp_conduit(handle src) {
-        value = try_raw_pointer_ephemeral_from_cpp_conduit(src, cpptype);
-        if (value != nullptr) {
-            return true;
-        }
-        return false;
-    }
     void check_holder_compat() {}
 
     PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
@@ -752,10 +805,6 @@ public:
             return true;
         }
 
-        if (convert && cpptype && this_.try_cpp_conduit(src)) {
-            return true;
-        }
-
         return false;
     }
 
@@ -783,32 +832,6 @@ public:
     void *value = nullptr;
 };
 
-inline object cpp_conduit_method(handle self,
-                                 const bytes &pybind11_platform_abi_id,
-                                 const capsule &cpp_type_info_capsule,
-                                 const bytes &pointer_kind) {
-#ifdef PYBIND11_HAS_STRING_VIEW
-    using cpp_str = std::string_view;
-#else
-    using cpp_str = std::string;
-#endif
-    if (cpp_str(pybind11_platform_abi_id) != PYBIND11_PLATFORM_ABI_ID) {
-        return none();
-    }
-    if (std::strcmp(cpp_type_info_capsule.name(), typeid(std::type_info).name()) != 0) {
-        return none();
-    }
-    if (cpp_str(pointer_kind) != "raw_pointer_ephemeral") {
-        throw std::runtime_error("Invalid pointer_kind: \"" + std::string(pointer_kind) + "\"");
-    }
-    const auto *cpp_type_info = cpp_type_info_capsule.get_pointer<const std::type_info>();
-    type_caster_generic caster(*cpp_type_info);
-    if (!caster.load(self, false)) {
-        return none();
-    }
-    return capsule(caster.value, cpp_type_info->name());
-}
-
 /**
  * Determine suitable casting operator for pointer-or-lvalue-casting type casters.  The type caster
  * needs to provide `operator T*()` and `operator T&()` operators.
@@ -1088,11 +1111,11 @@ public:
             || policy == return_value_policy::automatic_reference) {
             policy = return_value_policy::copy;
         }
-        return cast(std::addressof(src), policy, parent);
+        return cast(&src, policy, parent);
     }
 
     static handle cast(itype &&src, return_value_policy, handle parent) {
-        return cast(std::addressof(src), return_value_policy::move, parent);
+        return cast(&src, return_value_policy::move, parent);
     }
 
     // Returns a (pointer, type_info) pair taking care of necessary type lookup for a

include/pybind11/detail/value_and_holder.h

@@ -1,77 +0,0 @@
-// Copyright (c) 2016-2024 The Pybind Development Team.
-// All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#pragma once
-
-#include "common.h"
-
-#include <cstddef>
-#include <typeinfo>
-
-PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
-PYBIND11_NAMESPACE_BEGIN(detail)
-
-struct value_and_holder {
-    instance *inst = nullptr;
-    size_t index = 0u;
-    const detail::type_info *type = nullptr;
-    void **vh = nullptr;
-
-    // Main constructor for a found value/holder:
-    value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index)
-        : inst{i}, index{index}, type{type},
-          vh{inst->simple_layout ? inst->simple_value_holder
-                                 : &inst->nonsimple.values_and_holders[vpos]} {}
-
-    // Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
-    value_and_holder() = default;
-
-    // Used for past-the-end iterator
-    explicit value_and_holder(size_t index) : index{index} {}
-
-    template <typename V = void>
-    V *&value_ptr() const {
-        return reinterpret_cast<V *&>(vh[0]);
-    }
-    // True if this `value_and_holder` has a non-null value pointer
-    explicit operator bool() const { return value_ptr() != nullptr; }
-
-    template <typename H>
-    H &holder() const {
-        return reinterpret_cast<H &>(vh[1]);
-    }
-    bool holder_constructed() const {
-        return inst->simple_layout
-                   ? inst->simple_holder_constructed
-                   : (inst->nonsimple.status[index] & instance::status_holder_constructed) != 0u;
-    }
-    // NOLINTNEXTLINE(readability-make-member-function-const)
-    void set_holder_constructed(bool v = true) {
-        if (inst->simple_layout) {
-            inst->simple_holder_constructed = v;
-        } else if (v) {
-            inst->nonsimple.status[index] |= instance::status_holder_constructed;
-        } else {
-            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_holder_constructed;
-        }
-    }
-    bool instance_registered() const {
-        return inst->simple_layout
-                   ? inst->simple_instance_registered
-                   : ((inst->nonsimple.status[index] & instance::status_instance_registered) != 0);
-    }
-    // NOLINTNEXTLINE(readability-make-member-function-const)
-    void set_instance_registered(bool v = true) {
-        if (inst->simple_layout) {
-            inst->simple_instance_registered = v;
-        } else if (v) {
-            inst->nonsimple.status[index] |= instance::status_instance_registered;
-        } else {
-            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_instance_registered;
-        }
-    }
-};
-
-PYBIND11_NAMESPACE_END(detail)
-PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/eigen/matrix.h

@@ -9,8 +9,7 @@
 
 #pragma once
 
-#include <pybind11/numpy.h>
-
+#include "../numpy.h"
 #include "common.h"
 
 /* HINT: To suppress warnings originating from the Eigen headers, use -isystem.

include/pybind11/eigen/tensor.h

@@ -7,8 +7,7 @@
 
 #pragma once
 
-#include <pybind11/numpy.h>
-
+#include "../numpy.h"
 #include "common.h"
 
 #if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER)
@@ -470,6 +469,9 @@ struct type_caster<Eigen::TensorMap<Type, Options>,
                 parent_object = reinterpret_borrow<object>(parent);
                 break;
 
+            case return_value_policy::take_ownership:
+                delete src;
+                // fallthrough
             default:
                 // move, take_ownership don't make any sense for a ref/map:
                 pybind11_fail("Invalid return_value_policy for Eigen Map type, must be either "

include/pybind11/embed.h

@@ -103,6 +103,19 @@ inline void initialize_interpreter_pre_pyconfig(bool init_signal_handlers,
                                                 bool add_program_dir_to_path) {
     detail::precheck_interpreter();
     Py_InitializeEx(init_signal_handlers ? 1 : 0);
+#    if defined(WITH_THREAD) && PY_VERSION_HEX < 0x03070000
+    PyEval_InitThreads();
+#    endif
+
+    // Before it was special-cased in python 3.8, passing an empty or null argv
+    // caused a segfault, so we have to reimplement the special case ourselves.
+    bool special_case = (argv == nullptr || argc <= 0);
+
+    const char *const empty_argv[]{"\0"};
+    const char *const *safe_argv = special_case ? empty_argv : argv;
+    if (special_case) {
+        argc = 1;
+    }
 
     auto argv_size = static_cast<size_t>(argc);
     // SetArgv* on python 3 takes wchar_t, so we have to convert.
@@ -110,7 +123,7 @@ inline void initialize_interpreter_pre_pyconfig(bool init_signal_handlers,
     std::vector<std::unique_ptr<wchar_t[], detail::wide_char_arg_deleter>> widened_argv_entries;
     widened_argv_entries.reserve(argv_size);
     for (size_t ii = 0; ii < argv_size; ++ii) {
-        widened_argv_entries.emplace_back(detail::widen_chars(argv[ii]));
+        widened_argv_entries.emplace_back(detail::widen_chars(safe_argv[ii]));
         if (!widened_argv_entries.back()) {
             // A null here indicates a character-encoding failure or the python
             // interpreter out of memory. Give up.

include/pybind11/eval.h

@@ -19,7 +19,7 @@ PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 inline void ensure_builtins_in_globals(object &global) {
-#if defined(PYPY_VERSION)
+#if defined(PYPY_VERSION) || PY_VERSION_HEX < 0x03080000
     // Running exec and eval adds `builtins` module under `__builtins__` key to
     // globals if not yet present.  Python 3.8 made PyRun_String behave
     // similarly. Let's also do that for older versions, for consistency. This

include/pybind11/functional.h

@@ -9,55 +9,12 @@
 
 #pragma once
 
-#define PYBIND11_HAS_TYPE_CASTER_STD_FUNCTION_SPECIALIZATIONS
-
 #include "pybind11.h"
 
 #include <functional>
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
-PYBIND11_NAMESPACE_BEGIN(type_caster_std_function_specializations)
-
-// ensure GIL is held during functor destruction
-struct func_handle {
-    function f;
-#if !(defined(_MSC_VER) && _MSC_VER == 1916 && defined(PYBIND11_CPP17))
-    // This triggers a syntax error under very special conditions (very weird indeed).
-    explicit
-#endif
-        func_handle(function &&f_) noexcept
-        : f(std::move(f_)) {
-    }
-    func_handle(const func_handle &f_) { operator=(f_); }
-    func_handle &operator=(const func_handle &f_) {
-        gil_scoped_acquire acq;
-        f = f_.f;
-        return *this;
-    }
-    ~func_handle() {
-        gil_scoped_acquire acq;
-        function kill_f(std::move(f));
-    }
-};
-
-// to emulate 'move initialization capture' in C++11
-struct func_wrapper_base {
-    func_handle hfunc;
-    explicit func_wrapper_base(func_handle &&hf) noexcept : hfunc(hf) {}
-};
-
-template <typename Return, typename... Args>
-struct func_wrapper : func_wrapper_base {
-    using func_wrapper_base::func_wrapper_base;
-    Return operator()(Args... args) const {
-        gil_scoped_acquire acq;
-        // casts the returned object as a rvalue to the return type
-        return hfunc.f(std::forward<Args>(args)...).template cast<Return>();
-    }
-};
-
-PYBIND11_NAMESPACE_END(type_caster_std_function_specializations)
 
 template <typename Return, typename... Args>
 struct type_caster<std::function<Return(Args...)>> {
@@ -120,8 +77,40 @@ public:
             // See PR #1413 for full details
         }
 
-        value = type_caster_std_function_specializations::func_wrapper<Return, Args...>(
-            type_caster_std_function_specializations::func_handle(std::move(func)));
+        // ensure GIL is held during functor destruction
+        struct func_handle {
+            function f;
+#if !(defined(_MSC_VER) && _MSC_VER == 1916 && defined(PYBIND11_CPP17))
+            // This triggers a syntax error under very special conditions (very weird indeed).
+            explicit
+#endif
+                func_handle(function &&f_) noexcept
+                : f(std::move(f_)) {
+            }
+            func_handle(const func_handle &f_) { operator=(f_); }
+            func_handle &operator=(const func_handle &f_) {
+                gil_scoped_acquire acq;
+                f = f_.f;
+                return *this;
+            }
+            ~func_handle() {
+                gil_scoped_acquire acq;
+                function kill_f(std::move(f));
+            }
+        };
+
+        // to emulate 'move initialization capture' in C++11
+        struct func_wrapper {
+            func_handle hfunc;
+            explicit func_wrapper(func_handle &&hf) noexcept : hfunc(std::move(hf)) {}
+            Return operator()(Args... args) const {
+                gil_scoped_acquire acq;
+                // casts the returned object as a rvalue to the return type
+                return hfunc.f(std::forward<Args>(args)...).template cast<Return>();
+            }
+        };
+
+        value = func_wrapper(func_handle(std::move(func)));
         return true;
     }
 

include/pybind11/gil.h

@@ -13,7 +13,7 @@
 
 #include <cassert>
 
-#if !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
+#if defined(WITH_THREAD) && !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
 #    include "detail/internals.h"
 #endif
 
@@ -26,7 +26,9 @@ PyThreadState *get_thread_state_unchecked();
 
 PYBIND11_NAMESPACE_END(detail)
 
-#if !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
+#if defined(WITH_THREAD)
+
+#    if !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
 
 /* The functions below essentially reproduce the PyGILState_* API using a RAII
  * pattern, but there are a few important differences:
@@ -67,11 +69,11 @@ public:
 
         if (!tstate) {
             tstate = PyThreadState_New(internals.istate);
-#    if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
+#        if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
             if (!tstate) {
                 pybind11_fail("scoped_acquire: could not create thread state!");
             }
-#    endif
+#        endif
             tstate->gilstate_counter = 0;
             PYBIND11_TLS_REPLACE_VALUE(internals.tstate, tstate);
         } else {
@@ -92,20 +94,20 @@ public:
 
     PYBIND11_NOINLINE void dec_ref() {
         --tstate->gilstate_counter;
-#    if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
+#        if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
         if (detail::get_thread_state_unchecked() != tstate) {
             pybind11_fail("scoped_acquire::dec_ref(): thread state must be current!");
         }
         if (tstate->gilstate_counter < 0) {
             pybind11_fail("scoped_acquire::dec_ref(): reference count underflow!");
         }
-#    endif
+#        endif
         if (tstate->gilstate_counter == 0) {
-#    if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
+#        if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
             if (!release) {
                 pybind11_fail("scoped_acquire::dec_ref(): internal error!");
             }
-#    endif
+#        endif
             PyThreadState_Clear(tstate);
             if (active) {
                 PyThreadState_DeleteCurrent();
@@ -147,7 +149,9 @@ public:
         // NOLINTNEXTLINE(cppcoreguidelines-prefer-member-initializer)
         tstate = PyEval_SaveThread();
         if (disassoc) {
-            auto key = internals.tstate; // NOLINT(readability-qualified-auto)
+            // Python >= 3.7 can remove this, it's an int before 3.7
+            // NOLINTNEXTLINE(readability-qualified-auto)
+            auto key = internals.tstate;
             PYBIND11_TLS_DELETE_VALUE(key);
         }
     }
@@ -171,7 +175,9 @@ public:
             PyEval_RestoreThread(tstate);
         }
         if (disassoc) {
-            auto key = detail::get_internals().tstate; // NOLINT(readability-qualified-auto)
+            // Python >= 3.7 can remove this, it's an int before 3.7
+            // NOLINTNEXTLINE(readability-qualified-auto)
+            auto key = detail::get_internals().tstate;
             PYBIND11_TLS_REPLACE_VALUE(key, tstate);
         }
     }
@@ -182,7 +188,7 @@ private:
     bool active = true;
 };
 
-#else // PYBIND11_SIMPLE_GIL_MANAGEMENT
+#    else // PYBIND11_SIMPLE_GIL_MANAGEMENT
 
 class gil_scoped_acquire {
     PyGILState_STATE state;
@@ -210,6 +216,32 @@ public:
     void disarm() {}
 };
 
-#endif // PYBIND11_SIMPLE_GIL_MANAGEMENT
+#    endif // PYBIND11_SIMPLE_GIL_MANAGEMENT
+
+#else // WITH_THREAD
+
+class gil_scoped_acquire {
+public:
+    gil_scoped_acquire() {
+        // Trick to suppress `unused variable` error messages (at call sites).
+        (void) (this != (this + 1));
+    }
+    gil_scoped_acquire(const gil_scoped_acquire &) = delete;
+    gil_scoped_acquire &operator=(const gil_scoped_acquire &) = delete;
+    void disarm() {}
+};
+
+class gil_scoped_release {
+public:
+    gil_scoped_release() {
+        // Trick to suppress `unused variable` error messages (at call sites).
+        (void) (this != (this + 1));
+    }
+    gil_scoped_release(const gil_scoped_release &) = delete;
+    gil_scoped_release &operator=(const gil_scoped_release &) = delete;
+    void disarm() {}
+};
+
+#endif // WITH_THREAD
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/gil_safe_call_once.h

@@ -8,10 +8,6 @@
 #include <cassert>
 #include <mutex>
 
-#ifdef Py_GIL_DISABLED
-#    include <atomic>
-#endif
-
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 // Use the `gil_safe_call_once_and_store` class below instead of the naive
@@ -86,12 +82,7 @@ public:
 private:
     alignas(T) char storage_[sizeof(T)] = {};
     std::once_flag once_flag_ = {};
-#ifdef Py_GIL_DISABLED
-    std::atomic_bool
-#else
-    bool
-#endif
-        is_initialized_{false};
+    bool is_initialized_ = false;
     // The `is_initialized_`-`storage_` pair is very similar to `std::optional`,
     // but the latter does not have the triviality properties of former,
     // therefore `std::optional` is not a viable alternative here.

include/pybind11/numpy.h

@@ -901,11 +901,7 @@ public:
 
     template <typename T>
     array(ShapeContainer shape, StridesContainer strides, const T *ptr, handle base = handle())
-        : array(pybind11::dtype::of<T>(),
-                std::move(shape),
-                std::move(strides),
-                reinterpret_cast<const void *>(ptr),
-                base) {}
+        : array(pybind11::dtype::of<T>(), std::move(shape), std::move(strides), ptr, base) {}
 
     template <typename T>
     array(ShapeContainer shape, const T *ptr, handle base = handle())
@@ -1557,9 +1553,7 @@ PYBIND11_NOINLINE void register_structured_dtype(any_container<field_descriptor>
 
     auto tindex = std::type_index(tinfo);
     numpy_internals.registered_dtypes[tindex] = {dtype_ptr, std::move(format_str)};
-    with_internals([tindex, &direct_converter](internals &internals) {
-        internals.direct_conversions[tindex].push_back(direct_converter);
-    });
+    get_internals().direct_conversions[tindex].push_back(direct_converter);
 }
 
 template <typename T, typename SFINAE>
@@ -1990,7 +1984,7 @@ private:
         // Pointers to values the function was called with; the vectorized ones set here will start
         // out as array_t<T> pointers, but they will be changed them to T pointers before we make
         // call the wrapped function.  Non-vectorized pointers are left as-is.
-        std::array<void *, N> params{{reinterpret_cast<void *>(&args)...}};
+        std::array<void *, N> params{{&args...}};
 
         // The array of `buffer_info`s of vectorized arguments:
         std::array<buffer_info, NVectorized> buffers{

include/pybind11/pybind11.h

@@ -9,8 +9,8 @@
 */
 
 #pragma once
+
 #include "detail/class.h"
-#include "detail/exception_translation.h"
 #include "detail/init.h"
 #include "attr.h"
 #include "gil.h"
@@ -95,6 +95,24 @@ inline std::string replace_newlines_and_squash(const char *text) {
     return result.substr(str_begin, str_range);
 }
 
+// Apply all the extensions translators from a list
+// Return true if one of the translators completed without raising an exception
+// itself. Return of false indicates that if there are other translators
+// available, they should be tried.
+inline bool apply_exception_translators(std::forward_list<ExceptionTranslator> &translators) {
+    auto last_exception = std::current_exception();
+
+    for (auto &translator : translators) {
+        try {
+            translator(last_exception);
+            return true;
+        } catch (...) {
+            last_exception = std::current_exception();
+        }
+    }
+    return false;
+}
+
 #if defined(_MSC_VER)
 #    define PYBIND11_COMPAT_STRDUP _strdup
 #else
@@ -592,8 +610,7 @@ protected:
         int index = 0;
         /* Create a nice pydoc rec including all signatures and
            docstrings of the functions in the overload chain */
-        if (chain && options::show_function_signatures()
-            && std::strcmp(rec->name, "_pybind11_conduit_v1_") != 0) {
+        if (chain && options::show_function_signatures()) {
             // First a generic signature
             signatures += rec->name;
             signatures += "(*args, **kwargs)\n";
@@ -602,8 +619,7 @@ protected:
         // Then specific overload signatures
         bool first_user_def = true;
         for (auto *it = chain_start; it != nullptr; it = it->next) {
-            if (options::show_function_signatures()
-                && std::strcmp(rec->name, "_pybind11_conduit_v1_") != 0) {
+            if (options::show_function_signatures()) {
                 if (index > 0) {
                     signatures += '\n';
                 }
@@ -1022,7 +1038,33 @@ protected:
             throw;
 #endif
         } catch (...) {
-            try_translate_exceptions();
+            /* When an exception is caught, give each registered exception
+               translator a chance to translate it to a Python exception. First
+               all module-local translators will be tried in reverse order of
+               registration. If none of the module-locale translators handle
+               the exception (or there are no module-locale translators) then
+               the global translators will be tried, also in reverse order of
+               registration.
+
+               A translator may choose to do one of the following:
+
+                - catch the exception and call py::set_error()
+                  to set a standard (or custom) Python exception, or
+                - do nothing and let the exception fall through to the next translator, or
+                - delegate translation to the next translator by throwing a new type of exception.
+             */
+
+            auto &local_exception_translators
+                = get_local_internals().registered_exception_translators;
+            if (detail::apply_exception_translators(local_exception_translators)) {
+                return nullptr;
+            }
+            auto &exception_translators = get_internals().registered_exception_translators;
+            if (detail::apply_exception_translators(exception_translators)) {
+                return nullptr;
+            }
+
+            set_error(PyExc_SystemError, "Exception escaped from default exception translator!");
             return nullptr;
         }
 
@@ -1157,16 +1199,6 @@ struct handle_type_name<cpp_function> {
 
 PYBIND11_NAMESPACE_END(detail)
 
-// Use to activate Py_MOD_GIL_NOT_USED.
-class mod_gil_not_used {
-public:
-    explicit mod_gil_not_used(bool flag = true) : flag_(flag) {}
-    bool flag() const { return flag_; }
-
-private:
-    bool flag_;
-};
-
 /// Wrapper for Python extension modules
 class module_ : public object {
 public:
@@ -1267,11 +1299,7 @@ public:
 
         ``def`` should point to a statically allocated module_def.
     \endrst */
-    static module_ create_extension_module(const char *name,
-                                           const char *doc,
-                                           module_def *def,
-                                           mod_gil_not_used gil_not_used
-                                           = mod_gil_not_used(false)) {
+    static module_ create_extension_module(const char *name, const char *doc, module_def *def) {
         // module_def is PyModuleDef
         // Placement new (not an allocation).
         def = new (def)
@@ -1291,11 +1319,6 @@ public:
             }
             pybind11_fail("Internal error in module_::create_extension_module()");
         }
-        if (gil_not_used.flag()) {
-#ifdef Py_GIL_DISABLED
-            PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
-#endif
-        }
         // TODO: Should be reinterpret_steal for Python 3, but Python also steals it again when
         //       returned from PyInit_...
         //       For Python 2, reinterpret_borrow was correct.
@@ -1374,26 +1397,15 @@ protected:
         tinfo->default_holder = rec.default_holder;
         tinfo->module_local = rec.module_local;
 
-        with_internals([&](internals &internals) {
-            auto tindex = std::type_index(*rec.type);
-            tinfo->direct_conversions = &internals.direct_conversions[tindex];
-            if (rec.module_local) {
-                get_local_internals().registered_types_cpp[tindex] = tinfo;
-            } else {
-                internals.registered_types_cpp[tindex] = tinfo;
-            }
-
-            PYBIND11_WARNING_PUSH
-#if defined(__GNUC__) && __GNUC__ == 12
-            // When using GCC 12 these warnings are disabled as they trigger
-            // false positive warnings.  Discussed here:
-            // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115824.
-            PYBIND11_WARNING_DISABLE_GCC("-Warray-bounds")
-            PYBIND11_WARNING_DISABLE_GCC("-Wstringop-overread")
-#endif
-            internals.registered_types_py[(PyTypeObject *) m_ptr] = {tinfo};
-            PYBIND11_WARNING_POP
-        });
+        auto &internals = get_internals();
+        auto tindex = std::type_index(*rec.type);
+        tinfo->direct_conversions = &internals.direct_conversions[tindex];
+        if (rec.module_local) {
+            get_local_internals().registered_types_cpp[tindex] = tinfo;
+        } else {
+            internals.registered_types_cpp[tindex] = tinfo;
+        }
+        internals.registered_types_py[(PyTypeObject *) m_ptr] = {tinfo};
 
         if (rec.bases.size() > 1 || rec.multiple_inheritance) {
             mark_parents_nonsimple(tinfo->type);
@@ -1606,14 +1618,11 @@ public:
         generic_type::initialize(record);
 
         if (has_alias) {
-            with_internals([&](internals &internals) {
-                auto &instances = record.module_local ? get_local_internals().registered_types_cpp
-                                                      : internals.registered_types_cpp;
-                instances[std::type_index(typeid(type_alias))]
-                    = instances[std::type_index(typeid(type))];
-            });
+            auto &instances = record.module_local ? get_local_internals().registered_types_cpp
+                                                  : get_internals().registered_types_cpp;
+            instances[std::type_index(typeid(type_alias))]
+                = instances[std::type_index(typeid(type))];
         }
-        def("_pybind11_conduit_v1_", cpp_conduit_method);
     }
 
     template <typename Base, detail::enable_if_t<is_base<Base>::value, int> = 0>
@@ -2327,32 +2336,28 @@ keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret) {
 
 inline std::pair<decltype(internals::registered_types_py)::iterator, bool>
 all_type_info_get_cache(PyTypeObject *type) {
-    auto res = with_internals([type](internals &internals) {
-        return internals
-            .registered_types_py
+    auto res = get_internals()
+                   .registered_types_py
 #ifdef __cpp_lib_unordered_map_try_emplace
-            .try_emplace(type);
+                   .try_emplace(type);
 #else
-            .emplace(type, std::vector<detail::type_info *>());
+                   .emplace(type, std::vector<detail::type_info *>());
 #endif
-    });
     if (res.second) {
         // New cache entry created; set up a weak reference to automatically remove it if the type
         // gets destroyed:
         weakref((PyObject *) type, cpp_function([type](handle wr) {
-                    with_internals([type](internals &internals) {
-                        internals.registered_types_py.erase(type);
+                    get_internals().registered_types_py.erase(type);
 
-                        // TODO consolidate the erasure code in pybind11_meta_dealloc() in class.h
-                        auto &cache = internals.inactive_override_cache;
-                        for (auto it = cache.begin(), last = cache.end(); it != last;) {
-                            if (it->first == reinterpret_cast<PyObject *>(type)) {
-                                it = cache.erase(it);
-                            } else {
-                                ++it;
-                            }
+                    // TODO consolidate the erasure code in pybind11_meta_dealloc() in class.h
+                    auto &cache = get_internals().inactive_override_cache;
+                    for (auto it = cache.begin(), last = cache.end(); it != last;) {
+                        if (it->first == reinterpret_cast<PyObject *>(type)) {
+                            it = cache.erase(it);
+                        } else {
+                            ++it;
                         }
-                    });
+                    }
 
                     wr.dec_ref();
                 }))
@@ -2557,11 +2562,7 @@ void implicitly_convertible() {
         ~set_flag() { flag = false; }
     };
     auto implicit_caster = [](PyObject *obj, PyTypeObject *type) -> PyObject * {
-#ifdef Py_GIL_DISABLED
-        thread_local bool currently_used = false;
-#else
         static bool currently_used = false;
-#endif
         if (currently_used) { // implicit conversions are non-reentrant
             return nullptr;
         }
@@ -2586,12 +2587,8 @@ void implicitly_convertible() {
 }
 
 inline void register_exception_translator(ExceptionTranslator &&translator) {
-    detail::with_exception_translators(
-        [&](std::forward_list<ExceptionTranslator> &exception_translators,
-            std::forward_list<ExceptionTranslator> &local_exception_translators) {
-            (void) local_exception_translators;
-            exception_translators.push_front(std::forward<ExceptionTranslator>(translator));
-        });
+    detail::get_internals().registered_exception_translators.push_front(
+        std::forward<ExceptionTranslator>(translator));
 }
 
 /**
@@ -2601,12 +2598,8 @@ inline void register_exception_translator(ExceptionTranslator &&translator) {
  * the exception.
  */
 inline void register_local_exception_translator(ExceptionTranslator &&translator) {
-    detail::with_exception_translators(
-        [&](std::forward_list<ExceptionTranslator> &exception_translators,
-            std::forward_list<ExceptionTranslator> &local_exception_translators) {
-            (void) exception_translators;
-            local_exception_translators.push_front(std::forward<ExceptionTranslator>(translator));
-        });
+    detail::get_local_internals().registered_exception_translators.push_front(
+        std::forward<ExceptionTranslator>(translator));
 }
 
 /**
@@ -2763,19 +2756,14 @@ get_type_override(const void *this_ptr, const type_info *this_type, const char *
 
     /* Cache functions that aren't overridden in Python to avoid
        many costly Python dictionary lookups below */
-    bool not_overridden = with_internals([&key](internals &internals) {
-        auto &cache = internals.inactive_override_cache;
-        return cache.find(key) != cache.end();
-    });
-    if (not_overridden) {
+    auto &cache = get_internals().inactive_override_cache;
+    if (cache.find(key) != cache.end()) {
         return function();
     }
 
     function override = getattr(self, name, function());
     if (override.is_cpp_function()) {
-        with_internals([&](internals &internals) {
-            internals.inactive_override_cache.insert(std::move(key));
-        });
+        cache.insert(std::move(key));
         return function();
     }
 

include/pybind11/pytypes.h

@@ -980,23 +980,6 @@ inline PyObject *dict_getitem(PyObject *v, PyObject *key) {
     return rv;
 }
 
-inline PyObject *dict_getitemstringref(PyObject *v, const char *key) {
-#if PY_VERSION_HEX >= 0x030D0000
-    PyObject *rv;
-    if (PyDict_GetItemStringRef(v, key, &rv) < 0) {
-        throw error_already_set();
-    }
-    return rv;
-#else
-    PyObject *rv = dict_getitemstring(v, key);
-    if (rv == nullptr && PyErr_Occurred()) {
-        throw error_already_set();
-    }
-    Py_XINCREF(rv);
-    return rv;
-#endif
-}
-
 // Helper aliases/functions to support implicit casting of values given to python
 // accessors/methods. When given a pyobject, this simply returns the pyobject as-is; for other C++
 // type, the value goes through pybind11::cast(obj) to convert it to an `object`.
@@ -1259,7 +1242,6 @@ protected:
     using pointer = arrow_proxy<const handle>;
 
     sequence_fast_readonly(handle obj, ssize_t n) : ptr(PySequence_Fast_ITEMS(obj.ptr()) + n) {}
-    sequence_fast_readonly() = default;
 
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference dereference() const { return *ptr; }
@@ -1282,7 +1264,6 @@ protected:
     using pointer = arrow_proxy<const sequence_accessor>;
 
     sequence_slow_readwrite(handle obj, ssize_t index) : obj(obj), index(index) {}
-    sequence_slow_readwrite() = default;
 
     reference dereference() const { return {obj, static_cast<size_t>(index)}; }
     void increment() { ++index; }

include/pybind11/stl.h

@@ -11,14 +11,10 @@
 
 #include "pybind11.h"
 #include "detail/common.h"
-#include "detail/descr.h"
-#include "detail/type_caster_base.h"
 
 #include <deque>
-#include <initializer_list>
 #include <list>
 #include <map>
-#include <memory>
 #include <ostream>
 #include <set>
 #include <unordered_map>
@@ -39,89 +35,6 @@
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
 
-//
-// Begin: Equivalent of
-//        https://github.com/google/clif/blob/ae4eee1de07cdf115c0c9bf9fec9ff28efce6f6c/clif/python/runtime.cc#L388-L438
-/*
-The three `PyObjectTypeIsConvertibleTo*()` functions below are
-the result of converging the behaviors of pybind11 and PyCLIF
-(http://github.com/google/clif).
-
-Originally PyCLIF was extremely far on the permissive side of the spectrum,
-while pybind11 was very far on the strict side. Originally PyCLIF accepted any
-Python iterable as input for a C++ `vector`/`set`/`map` argument, as long as
-the elements were convertible. The obvious (in hindsight) problem was that
-any empty Python iterable could be passed to any of these C++ types, e.g. `{}`
-was accepted for C++ `vector`/`set` arguments, or `[]` for C++ `map` arguments.
-
-The functions below strike a practical permissive-vs-strict compromise,
-informed by tens of thousands of use cases in the wild. A main objective is
-to prevent accidents and improve readability:
-
-- Python literals must match the C++ types.
-
-- For C++ `set`: The potentially reducing conversion from a Python sequence
-  (e.g. Python `list` or `tuple`) to a C++ `set` must be explicit, by going
-  through a Python `set`.
-
-- However, a Python `set` can still be passed to a C++ `vector`. The rationale
-  is that this conversion is not reducing. Implicit conversions of this kind
-  are also fairly commonly used, therefore enforcing explicit conversions
-  would have an unfavorable cost : benefit ratio; more sloppily speaking,
-  such an enforcement would be more annoying than helpful.
-*/
-
-inline bool PyObjectIsInstanceWithOneOfTpNames(PyObject *obj,
-                                               std::initializer_list<const char *> tp_names) {
-    if (PyType_Check(obj)) {
-        return false;
-    }
-    const char *obj_tp_name = Py_TYPE(obj)->tp_name;
-    for (const auto *tp_name : tp_names) {
-        if (std::strcmp(obj_tp_name, tp_name) == 0) {
-            return true;
-        }
-    }
-    return false;
-}
-
-inline bool PyObjectTypeIsConvertibleToStdVector(PyObject *obj) {
-    if (PySequence_Check(obj) != 0) {
-        return !PyUnicode_Check(obj) && !PyBytes_Check(obj);
-    }
-    return (PyGen_Check(obj) != 0) || (PyAnySet_Check(obj) != 0)
-           || PyObjectIsInstanceWithOneOfTpNames(
-               obj, {"dict_keys", "dict_values", "dict_items", "map", "zip"});
-}
-
-inline bool PyObjectTypeIsConvertibleToStdSet(PyObject *obj) {
-    return (PyAnySet_Check(obj) != 0) || PyObjectIsInstanceWithOneOfTpNames(obj, {"dict_keys"});
-}
-
-inline bool PyObjectTypeIsConvertibleToStdMap(PyObject *obj) {
-    if (PyDict_Check(obj)) {
-        return true;
-    }
-    // Implicit requirement in the conditions below:
-    // A type with `.__getitem__()` & `.items()` methods must implement these
-    // to be compatible with https://docs.python.org/3/c-api/mapping.html
-    if (PyMapping_Check(obj) == 0) {
-        return false;
-    }
-    PyObject *items = PyObject_GetAttrString(obj, "items");
-    if (items == nullptr) {
-        PyErr_Clear();
-        return false;
-    }
-    bool is_convertible = (PyCallable_Check(items) != 0);
-    Py_DECREF(items);
-    return is_convertible;
-}
-
-//
-// End: Equivalent of clif/python/runtime.cc
-//
-
 /// Extracts an const lvalue reference or rvalue reference for U based on the type of T (e.g. for
 /// forwarding a container element).  Typically used indirect via forwarded_type(), below.
 template <typename T, typename U>
@@ -153,10 +66,17 @@ private:
     }
     void reserve_maybe(const anyset &, void *) {}
 
-    bool convert_iterable(const iterable &itbl, bool convert) {
-        for (const auto &it : itbl) {
+public:
+    bool load(handle src, bool convert) {
+        if (!isinstance<anyset>(src)) {
+            return false;
+        }
+        auto s = reinterpret_borrow<anyset>(src);
+        value.clear();
+        reserve_maybe(s, &value);
+        for (auto entry : s) {
             key_conv conv;
-            if (!conv.load(it, convert)) {
+            if (!conv.load(entry, convert)) {
                 return false;
             }
             value.insert(cast_op<Key &&>(std::move(conv)));
@@ -164,29 +84,6 @@ private:
         return true;
     }
 
-    bool convert_anyset(anyset s, bool convert) {
-        value.clear();
-        reserve_maybe(s, &value);
-        return convert_iterable(s, convert);
-    }
-
-public:
-    bool load(handle src, bool convert) {
-        if (!PyObjectTypeIsConvertibleToStdSet(src.ptr())) {
-            return false;
-        }
-        if (isinstance<anyset>(src)) {
-            value.clear();
-            return convert_anyset(reinterpret_borrow<anyset>(src), convert);
-        }
-        if (!convert) {
-            return false;
-        }
-        assert(isinstance<iterable>(src));
-        value.clear();
-        return convert_iterable(reinterpret_borrow<iterable>(src), convert);
-    }
-
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
         if (!std::is_lvalue_reference<T>::value) {
@@ -218,10 +115,15 @@ private:
     }
     void reserve_maybe(const dict &, void *) {}
 
-    bool convert_elements(const dict &d, bool convert) {
+public:
+    bool load(handle src, bool convert) {
+        if (!isinstance<dict>(src)) {
+            return false;
+        }
+        auto d = reinterpret_borrow<dict>(src);
         value.clear();
         reserve_maybe(d, &value);
-        for (const auto &it : d) {
+        for (auto it : d) {
             key_conv kconv;
             value_conv vconv;
             if (!kconv.load(it.first.ptr(), convert) || !vconv.load(it.second.ptr(), convert)) {
@@ -232,25 +134,6 @@ private:
         return true;
     }
 
-public:
-    bool load(handle src, bool convert) {
-        if (!PyObjectTypeIsConvertibleToStdMap(src.ptr())) {
-            return false;
-        }
-        if (isinstance<dict>(src)) {
-            return convert_elements(reinterpret_borrow<dict>(src), convert);
-        }
-        if (!convert) {
-            return false;
-        }
-        auto items = reinterpret_steal<object>(PyMapping_Items(src.ptr()));
-        if (!items) {
-            throw error_already_set();
-        }
-        assert(isinstance<iterable>(items));
-        return convert_elements(dict(reinterpret_borrow<iterable>(items)), convert);
-    }
-
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
         dict d;
@@ -283,35 +166,13 @@ struct list_caster {
     using value_conv = make_caster<Value>;
 
     bool load(handle src, bool convert) {
-        if (!PyObjectTypeIsConvertibleToStdVector(src.ptr())) {
+        if (!isinstance<sequence>(src) || isinstance<bytes>(src) || isinstance<str>(src)) {
             return false;
         }
-        if (isinstance<sequence>(src)) {
-            return convert_elements(src, convert);
-        }
-        if (!convert) {
-            return false;
-        }
-        // Designed to be behavior-equivalent to passing tuple(src) from Python:
-        // The conversion to a tuple will first exhaust the generator object, to ensure that
-        // the generator is not left in an unpredictable (to the caller) partially-consumed
-        // state.
-        assert(isinstance<iterable>(src));
-        return convert_elements(tuple(reinterpret_borrow<iterable>(src)), convert);
-    }
-
-private:
-    template <typename T = Type, enable_if_t<has_reserve_method<T>::value, int> = 0>
-    void reserve_maybe(const sequence &s, Type *) {
-        value.reserve(s.size());
-    }
-    void reserve_maybe(const sequence &, void *) {}
-
-    bool convert_elements(handle seq, bool convert) {
-        auto s = reinterpret_borrow<sequence>(seq);
+        auto s = reinterpret_borrow<sequence>(src);
         value.clear();
         reserve_maybe(s, &value);
-        for (const auto &it : seq) {
+        for (const auto &it : s) {
             value_conv conv;
             if (!conv.load(it, convert)) {
                 return false;
@@ -321,6 +182,13 @@ private:
         return true;
     }
 
+private:
+    template <typename T = Type, enable_if_t<has_reserve_method<T>::value, int> = 0>
+    void reserve_maybe(const sequence &s, Type *) {
+        value.reserve(s.size());
+    }
+    void reserve_maybe(const sequence &, void *) {}
+
 public:
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
@@ -352,87 +220,43 @@ struct type_caster<std::deque<Type, Alloc>> : list_caster<std::deque<Type, Alloc
 template <typename Type, typename Alloc>
 struct type_caster<std::list<Type, Alloc>> : list_caster<std::list<Type, Alloc>, Type> {};
 
-template <typename ArrayType, typename V, size_t... I>
-ArrayType vector_to_array_impl(V &&v, index_sequence<I...>) {
-    return {{std::move(v[I])...}};
-}
-
-// Based on https://en.cppreference.com/w/cpp/container/array/to_array
-template <typename ArrayType, size_t N, typename V>
-ArrayType vector_to_array(V &&v) {
-    return vector_to_array_impl<ArrayType, V>(std::forward<V>(v), make_index_sequence<N>{});
-}
-
 template <typename ArrayType, typename Value, bool Resizable, size_t Size = 0>
 struct array_caster {
     using value_conv = make_caster<Value>;
 
 private:
-    std::unique_ptr<ArrayType> value;
+    template <bool R = Resizable>
+    bool require_size(enable_if_t<R, size_t> size) {
+        if (value.size() != size) {
+            value.resize(size);
+        }
+        return true;
+    }
+    template <bool R = Resizable>
+    bool require_size(enable_if_t<!R, size_t> size) {
+        return size == Size;
+    }
 
-    template <bool R = Resizable, enable_if_t<R, int> = 0>
-    bool convert_elements(handle seq, bool convert) {
-        auto l = reinterpret_borrow<sequence>(seq);
-        value.reset(new ArrayType{});
-        // Using `resize` to preserve the behavior exactly as it was before PR #5305
-        // For the `resize` to work, `Value` must be default constructible.
-        // For `std::valarray`, this is a requirement:
-        // https://en.cppreference.com/w/cpp/named_req/NumericType
-        value->resize(l.size());
+public:
+    bool load(handle src, bool convert) {
+        if (!isinstance<sequence>(src)) {
+            return false;
+        }
+        auto l = reinterpret_borrow<sequence>(src);
+        if (!require_size(l.size())) {
+            return false;
+        }
         size_t ctr = 0;
         for (const auto &it : l) {
             value_conv conv;
             if (!conv.load(it, convert)) {
                 return false;
             }
-            (*value)[ctr++] = cast_op<Value &&>(std::move(conv));
+            value[ctr++] = cast_op<Value &&>(std::move(conv));
         }
         return true;
     }
 
-    template <bool R = Resizable, enable_if_t<!R, int> = 0>
-    bool convert_elements(handle seq, bool convert) {
-        auto l = reinterpret_borrow<sequence>(seq);
-        if (l.size() != Size) {
-            return false;
-        }
-        // The `temp` storage is needed to support `Value` types that are not
-        // default-constructible.
-        // Deliberate choice: no template specializations, for simplicity, and
-        // because the compile time overhead for the specializations is deemed
-        // more significant than the runtime overhead for the `temp` storage.
-        std::vector<Value> temp;
-        temp.reserve(l.size());
-        for (auto it : l) {
-            value_conv conv;
-            if (!conv.load(it, convert)) {
-                return false;
-            }
-            temp.emplace_back(cast_op<Value &&>(std::move(conv)));
-        }
-        value.reset(new ArrayType(vector_to_array<ArrayType, Size>(std::move(temp))));
-        return true;
-    }
-
-public:
-    bool load(handle src, bool convert) {
-        if (!PyObjectTypeIsConvertibleToStdVector(src.ptr())) {
-            return false;
-        }
-        if (isinstance<sequence>(src)) {
-            return convert_elements(src, convert);
-        }
-        if (!convert) {
-            return false;
-        }
-        // Designed to be behavior-equivalent to passing tuple(src) from Python:
-        // The conversion to a tuple will first exhaust the generator object, to ensure that
-        // the generator is not left in an unpredictable (to the caller) partially-consumed
-        // state.
-        assert(isinstance<iterable>(src));
-        return convert_elements(tuple(reinterpret_borrow<iterable>(src)), convert);
-    }
-
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
         list l(src.size());
@@ -448,36 +272,12 @@ public:
         return l.release();
     }
 
-    // Code copied from PYBIND11_TYPE_CASTER macro.
-    // Intentionally preserving the behavior exactly as it was before PR #5305
-    template <typename T_, enable_if_t<std::is_same<ArrayType, remove_cv_t<T_>>::value, int> = 0>
-    static handle cast(T_ *src, return_value_policy policy, handle parent) {
-        if (!src) {
-            return none().release();
-        }
-        if (policy == return_value_policy::take_ownership) {
-            auto h = cast(std::move(*src), policy, parent);
-            delete src; // WARNING: Assumes `src` was allocated with `new`.
-            return h;
-        }
-        return cast(*src, policy, parent);
-    }
-
-    // NOLINTNEXTLINE(google-explicit-constructor)
-    operator ArrayType *() { return &(*value); }
-    // NOLINTNEXTLINE(google-explicit-constructor)
-    operator ArrayType &() { return *value; }
-    // NOLINTNEXTLINE(google-explicit-constructor)
-    operator ArrayType &&() && { return std::move(*value); }
-
-    template <typename T_>
-    using cast_op_type = movable_cast_op_type<T_>;
-
-    static constexpr auto name
-        = const_name<Resizable>(const_name(""), const_name("Annotated[")) + const_name("list[")
-          + value_conv::name + const_name("]")
-          + const_name<Resizable>(
-              const_name(""), const_name(", FixedSize(") + const_name<Size>() + const_name(")]"));
+    PYBIND11_TYPE_CASTER(ArrayType,
+                         const_name<Resizable>(const_name(""), const_name("Annotated["))
+                             + const_name("list[") + value_conv::name + const_name("]")
+                             + const_name<Resizable>(const_name(""),
+                                                     const_name(", FixedSize(")
+                                                         + const_name<Size>() + const_name(")]")));
 };
 
 template <typename Type, size_t Size>

include/pybind11/stl/filesystem.h

@@ -4,17 +4,18 @@
 
 #pragma once
 
-#include <pybind11/cast.h>
-#include <pybind11/detail/common.h>
-#include <pybind11/detail/descr.h>
-#include <pybind11/pybind11.h>
-#include <pybind11/pytypes.h>
+#include "../pybind11.h"
+#include "../detail/common.h"
+#include "../detail/descr.h"
+#include "../cast.h"
+#include "../pytypes.h"
 
 #include <string>
 
 #ifdef __has_include
 #    if defined(PYBIND11_CPP17)
-#        if __has_include(<filesystem>)
+#        if __has_include(<filesystem>) && \
+          PY_VERSION_HEX >= 0x03060000
 #            include <filesystem>
 #            define PYBIND11_HAS_FILESYSTEM 1
 #        elif __has_include(<experimental/filesystem>)
@@ -33,13 +34,6 @@
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
 
-#ifdef PYPY_VERSION
-#    define PYBIND11_REINTERPRET_CAST_VOID_PTR_IF_NOT_PYPY(...) (__VA_ARGS__)
-#else
-#    define PYBIND11_REINTERPRET_CAST_VOID_PTR_IF_NOT_PYPY(...)                                   \
-        (reinterpret_cast<void *>(__VA_ARGS__))
-#endif
-
 #if defined(PYBIND11_HAS_FILESYSTEM) || defined(PYBIND11_HAS_EXPERIMENTAL_FILESYSTEM)
 template <typename T>
 struct path_caster {
@@ -79,8 +73,7 @@ public:
         }
         PyObject *native = nullptr;
         if constexpr (std::is_same_v<typename T::value_type, char>) {
-            if (PyUnicode_FSConverter(buf, PYBIND11_REINTERPRET_CAST_VOID_PTR_IF_NOT_PYPY(&native))
-                != 0) {
+            if (PyUnicode_FSConverter(buf, &native) != 0) {
                 if (auto *c_str = PyBytes_AsString(native)) {
                     // AsString returns a pointer to the internal buffer, which
                     // must not be free'd.
@@ -88,8 +81,7 @@ public:
                 }
             }
         } else if constexpr (std::is_same_v<typename T::value_type, wchar_t>) {
-            if (PyUnicode_FSDecoder(buf, PYBIND11_REINTERPRET_CAST_VOID_PTR_IF_NOT_PYPY(&native))
-                != 0) {
+            if (PyUnicode_FSDecoder(buf, &native) != 0) {
                 if (auto *c_str = PyUnicode_AsWideCharString(native, nullptr)) {
                     // AsWideCharString returns a new string that must be free'd.
                     value = c_str; // Copies the string.

include/pybind11/stl_bind.h

@@ -180,7 +180,7 @@ void vector_modifiers(
                         v.end());
                 try {
                     v.shrink_to_fit();
-                } catch (const std::exception &) { // NOLINT(bugprone-empty-catch)
+                } catch (const std::exception &) {
                     // Do nothing
                 }
                 throw;

include/pybind11/typing.h

@@ -14,8 +14,6 @@
 #include "cast.h"
 #include "pytypes.h"
 
-#include <algorithm>
-
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(typing)
 
@@ -65,63 +63,6 @@ class Callable<Return(Args...)> : public function {
     using function::function;
 };
 
-template <typename T>
-class Type : public type {
-    using type::type;
-};
-
-template <typename... Types>
-class Union : public object {
-    PYBIND11_OBJECT_DEFAULT(Union, object, PyObject_Type)
-    using object::object;
-};
-
-template <typename T>
-class Optional : public object {
-    PYBIND11_OBJECT_DEFAULT(Optional, object, PyObject_Type)
-    using object::object;
-};
-
-template <typename T>
-class TypeGuard : public bool_ {
-    using bool_::bool_;
-};
-
-template <typename T>
-class TypeIs : public bool_ {
-    using bool_::bool_;
-};
-
-class NoReturn : public none {
-    using none::none;
-};
-
-class Never : public none {
-    using none::none;
-};
-
-#if defined(__cpp_nontype_template_args) && __cpp_nontype_template_args >= 201911L
-#    define PYBIND11_TYPING_H_HAS_STRING_LITERAL
-template <size_t N>
-struct StringLiteral {
-    constexpr StringLiteral(const char (&str)[N]) { std::copy_n(str, N, name); }
-    char name[N];
-};
-
-template <StringLiteral... StrLits>
-class Literal : public object {
-    PYBIND11_OBJECT_DEFAULT(Literal, object, PyObject_Type)
-};
-
-// Example syntax for creating a TypeVar.
-// typedef typing::TypeVar<"T"> TypeVarT;
-template <StringLiteral>
-class TypeVar : public object {
-    PYBIND11_OBJECT_DEFAULT(TypeVar, object, PyObject_Type)
-    using object::object;
-};
-#endif
-
 PYBIND11_NAMESPACE_END(typing)
 
 PYBIND11_NAMESPACE_BEGIN(detail)
@@ -180,63 +121,5 @@ struct handle_type_name<typing::Callable<Return(Args...)>> {
           + const_name("], ") + make_caster<retval_type>::name + const_name("]");
 };
 
-template <typename Return>
-struct handle_type_name<typing::Callable<Return(ellipsis)>> {
-    // PEP 484 specifies this syntax for defining only return types of callables
-    using retval_type = conditional_t<std::is_same<Return, void>::value, void_type, Return>;
-    static constexpr auto name
-        = const_name("Callable[..., ") + make_caster<retval_type>::name + const_name("]");
-};
-
-template <typename T>
-struct handle_type_name<typing::Type<T>> {
-    static constexpr auto name = const_name("type[") + make_caster<T>::name + const_name("]");
-};
-
-template <typename... Types>
-struct handle_type_name<typing::Union<Types...>> {
-    static constexpr auto name = const_name("Union[")
-                                 + ::pybind11::detail::concat(make_caster<Types>::name...)
-                                 + const_name("]");
-};
-
-template <typename T>
-struct handle_type_name<typing::Optional<T>> {
-    static constexpr auto name = const_name("Optional[") + make_caster<T>::name + const_name("]");
-};
-
-template <typename T>
-struct handle_type_name<typing::TypeGuard<T>> {
-    static constexpr auto name = const_name("TypeGuard[") + make_caster<T>::name + const_name("]");
-};
-
-template <typename T>
-struct handle_type_name<typing::TypeIs<T>> {
-    static constexpr auto name = const_name("TypeIs[") + make_caster<T>::name + const_name("]");
-};
-
-template <>
-struct handle_type_name<typing::NoReturn> {
-    static constexpr auto name = const_name("NoReturn");
-};
-
-template <>
-struct handle_type_name<typing::Never> {
-    static constexpr auto name = const_name("Never");
-};
-
-#if defined(PYBIND11_TYPING_H_HAS_STRING_LITERAL)
-template <typing::StringLiteral... Literals>
-struct handle_type_name<typing::Literal<Literals...>> {
-    static constexpr auto name = const_name("Literal[")
-                                 + pybind11::detail::concat(const_name(Literals.name)...)
-                                 + const_name("]");
-};
-template <typing::StringLiteral StrLit>
-struct handle_type_name<typing::TypeVar<StrLit>> {
-    static constexpr auto name = const_name(StrLit.name);
-};
-#endif
-
 PYBIND11_NAMESPACE_END(detail)
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/warnings.h

@@ -1,75 +0,0 @@
-/*
-    pybind11/warnings.h: Python warnings wrappers.
-
-    Copyright (c) 2024 Jan Iwaszkiewicz <jiwaszkiewicz6@gmail.com>
-
-    All rights reserved. Use of this source code is governed by a
-    BSD-style license that can be found in the LICENSE file.
-*/
-
-#pragma once
-
-#include "pybind11.h"
-#include "detail/common.h"
-
-PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
-
-PYBIND11_NAMESPACE_BEGIN(detail)
-
-inline bool PyWarning_Check(PyObject *obj) {
-    int result = PyObject_IsSubclass(obj, PyExc_Warning);
-    if (result == 1) {
-        return true;
-    }
-    if (result == -1) {
-        raise_from(PyExc_SystemError,
-                   "pybind11::detail::PyWarning_Check(): PyObject_IsSubclass() call failed.");
-        throw error_already_set();
-    }
-    return false;
-}
-
-PYBIND11_NAMESPACE_END(detail)
-
-PYBIND11_NAMESPACE_BEGIN(warnings)
-
-inline object
-new_warning_type(handle scope, const char *name, handle base = PyExc_RuntimeWarning) {
-    if (!detail::PyWarning_Check(base.ptr())) {
-        pybind11_fail("pybind11::warnings::new_warning_type(): cannot create custom warning, base "
-                      "must be a subclass of "
-                      "PyExc_Warning!");
-    }
-    if (hasattr(scope, name)) {
-        pybind11_fail("pybind11::warnings::new_warning_type(): an attribute with name \""
-                      + std::string(name) + "\" exists already.");
-    }
-    std::string full_name = scope.attr("__name__").cast<std::string>() + std::string(".") + name;
-    handle h(PyErr_NewException(full_name.c_str(), base.ptr(), nullptr));
-    if (!h) {
-        raise_from(PyExc_SystemError,
-                   "pybind11::warnings::new_warning_type(): PyErr_NewException() call failed.");
-        throw error_already_set();
-    }
-    auto obj = reinterpret_steal<object>(h);
-    scope.attr(name) = obj;
-    return obj;
-}
-
-// Similar to Python `warnings.warn()`
-inline void
-warn(const char *message, handle category = PyExc_RuntimeWarning, int stack_level = 2) {
-    if (!detail::PyWarning_Check(category.ptr())) {
-        pybind11_fail(
-            "pybind11::warnings::warn(): cannot raise warning, category must be a subclass of "
-            "PyExc_Warning!");
-    }
-
-    if (PyErr_WarnEx(category.ptr(), message, stack_level) == -1) {
-        throw error_already_set();
-    }
-}
-
-PYBIND11_NAMESPACE_END(warnings)
-
-PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

noxfile.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import argparse
 
 import nox
@@ -45,7 +43,7 @@ def tests_packaging(session: nox.Session) -> None:
     Run the packaging tests.
     """
 
-    session.install("-r", "tests/requirements.txt", "pip")
+    session.install("-r", "tests/requirements.txt")
     session.run("pytest", "tests/extra_python_package", *session.posargs)
 
 

pybind11/__init__.py

@@ -1,9 +1,7 @@
-from __future__ import annotations
-
 import sys
 
-if sys.version_info < (3, 8):  # noqa: UP036
-    msg = "pybind11 does not support Python < 3.8. v2.13 was the last release supporting Python 3.7."
+if sys.version_info < (3, 6):  # noqa: UP036
+    msg = "pybind11 does not support Python < 3.6. 2.9 was the last release supporting Python 2.7 and 3.5."
     raise ImportError(msg)
 
 

pybind11/__main__.py

@@ -1,36 +1,12 @@
 # pylint: disable=missing-function-docstring
-from __future__ import annotations
 
 import argparse
-import re
 import sys
 import sysconfig
 
 from ._version import __version__
 from .commands import get_cmake_dir, get_include, get_pkgconfig_dir
 
-# This is the conditional used for os.path being posixpath
-if "posix" in sys.builtin_module_names:
-    from shlex import quote
-elif "nt" in sys.builtin_module_names:
-    # See https://github.com/mesonbuild/meson/blob/db22551ed9d2dd7889abea01cc1c7bba02bf1c75/mesonbuild/utils/universal.py#L1092-L1121
-    # and the original documents:
-    # https://docs.microsoft.com/en-us/cpp/c-language/parsing-c-command-line-arguments and
-    # https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
-    UNSAFE = re.compile("[ \t\n\r]")
-
-    def quote(s: str) -> str:
-        if s and not UNSAFE.search(s):
-            return s
-
-        # Paths cannot contain a '"' on Windows, so we don't need to worry
-        # about nuanced counting here.
-        return f'"{s}\\"' if s.endswith("\\") else f'"{s}"'
-else:
-
-    def quote(s: str) -> str:
-        return s
-
 
 def print_includes() -> None:
     dirs = [
@@ -45,7 +21,7 @@ def print_includes() -> None:
         if d and d not in unique_dirs:
             unique_dirs.append(d)
 
-    print(" ".join(quote(f"-I{d}") for d in unique_dirs))
+    print(" ".join("-I" + d for d in unique_dirs))
 
 
 def main() -> None:
@@ -77,9 +53,9 @@ def main() -> None:
     if args.includes:
         print_includes()
     if args.cmakedir:
-        print(quote(get_cmake_dir()))
+        print(get_cmake_dir())
     if args.pkgconfigdir:
-        print(quote(get_pkgconfig_dir()))
+        print(get_pkgconfig_dir())
 
 
 if __name__ == "__main__":

pybind11/_version.py

@@ -1,12 +1,12 @@
-from __future__ import annotations
+from typing import Union
 
 
-def _to_int(s: str) -> int | str:
+def _to_int(s: str) -> Union[int, str]:
     try:
         return int(s)
     except ValueError:
         return s
 
 
-__version__ = "2.14.0.dev1"
+__version__ = "2.13.0.dev1"
 version_info = tuple(_to_int(s) for s in __version__.split("."))

pybind11/commands.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import os
 
 DIR = os.path.abspath(os.path.dirname(__file__))

pybind11/setup_helpers.py

@@ -36,7 +36,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 # If you copy this file in, you don't
 # need the .pyi file; it's just an interface file for static type checkers.
-from __future__ import annotations
 
 import contextlib
 import os
@@ -53,6 +52,7 @@ from pathlib import Path
 from typing import (
     Any,
     Callable,
+    Dict,
     Iterable,
     Iterator,
     List,
@@ -113,10 +113,10 @@ class Pybind11Extension(_Extension):
     # flags are prepended, so that they can be further overridden, e.g. by
     # ``extra_compile_args=["-g"]``.
 
-    def _add_cflags(self, flags: list[str]) -> None:
+    def _add_cflags(self, flags: List[str]) -> None:
         self.extra_compile_args[:0] = flags
 
-    def _add_ldflags(self, flags: list[str]) -> None:
+    def _add_ldflags(self, flags: List[str]) -> None:
         self.extra_link_args[:0] = flags
 
     def __init__(self, *args: Any, **kwargs: Any) -> None:
@@ -249,8 +249,8 @@ def has_flag(compiler: Any, flag: str) -> bool:
 cpp_flag_cache = None
 
 
-@lru_cache
-def auto_cpp_level(compiler: Any) -> str | int:
+@lru_cache()
+def auto_cpp_level(compiler: Any) -> Union[str, int]:
     """
     Return the max supported C++ std level (17, 14, or 11). Returns latest on Windows.
     """
@@ -288,8 +288,8 @@ class build_ext(_build_ext):  # noqa: N801
 
 
 def intree_extensions(
-    paths: Iterable[str], package_dir: dict[str, str] | None = None
-) -> list[Pybind11Extension]:
+    paths: Iterable[str], package_dir: Optional[Dict[str, str]] = None
+) -> List[Pybind11Extension]:
     """
     Generate Pybind11Extensions from source files directly located in a Python
     source tree.
@@ -409,7 +409,7 @@ class ParallelCompile:
 
     def __init__(
         self,
-        envvar: str | None = None,
+        envvar: Optional[str] = None,
         default: int = 0,
         max: int = 0,  # pylint: disable=redefined-builtin
         needs_recompile: Callable[[str, str], bool] = no_recompile,
@@ -418,7 +418,7 @@ class ParallelCompile:
         self.default = default
         self.max = max
         self.needs_recompile = needs_recompile
-        self._old: list[CCompilerMethod] = []
+        self._old: List[CCompilerMethod] = []
 
     def function(self) -> CCompilerMethod:
         """
@@ -427,14 +427,14 @@ class ParallelCompile:
 
         def compile_function(
             compiler: distutils.ccompiler.CCompiler,
-            sources: list[str],
-            output_dir: str | None = None,
-            macros: list[tuple[str] | tuple[str, str | None]] | None = None,
-            include_dirs: list[str] | None = None,
+            sources: List[str],
+            output_dir: Optional[str] = None,
+            macros: Optional[List[Union[Tuple[str], Tuple[str, Optional[str]]]]] = None,
+            include_dirs: Optional[List[str]] = None,
             debug: bool = False,
-            extra_preargs: list[str] | None = None,
-            extra_postargs: list[str] | None = None,
-            depends: list[str] | None = None,
+            extra_preargs: Optional[List[str]] = None,
+            extra_postargs: Optional[List[str]] = None,
+            depends: Optional[List[str]] = None,
         ) -> Any:
             # These lines are directly from distutils.ccompiler.CCompiler
             macros, objects, extra_postargs, pp_opts, build = compiler._setup_compile(  # type: ignore[attr-defined]

pyproject.toml

@@ -30,7 +30,7 @@ ignore_missing_imports = true
 
 
 [tool.pylint]
-master.py-version = "3.8"
+master.py-version = "3.6"
 reports.output-format = "colorized"
 messages_control.disable = [
   "design",
@@ -45,7 +45,7 @@ messages_control.disable = [
 ]
 
 [tool.ruff]
-target-version = "py38"
+target-version = "py37"
 src = ["src"]
 
 [tool.ruff.lint]
@@ -76,8 +76,6 @@ ignore = [
 ]
 unfixable = ["T20"]
 isort.known-first-party = ["env", "pybind11_cross_module_tests", "pybind11_tests"]
-isort.required-imports = ["from __future__ import annotations"]
-
 
 [tool.ruff.lint.per-file-ignores]
 "tests/**" = ["EM", "N", "E721"]

setup.cfg

@@ -14,12 +14,13 @@ classifiers =
     Topic :: Utilities
     Programming Language :: C++
     Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
     Programming Language :: Python :: 3.12
-    Programming Language :: Python :: 3.13
     License :: OSI Approved :: BSD License
     Programming Language :: Python :: Implementation :: PyPy
     Programming Language :: Python :: Implementation :: CPython
@@ -38,5 +39,5 @@ project_urls =
     Chat = https://gitter.im/pybind/Lobby
 
 [options]
-python_requires = >=3.8
+python_requires = >=3.6
 zip_safe = False

setup.py

@@ -1,7 +1,6 @@
 #!/usr/bin/env python3
 
 # Setup script for PyPI; use CMakeFile.txt to build extension modules
-from __future__ import annotations
 
 import contextlib
 import os
@@ -10,9 +9,9 @@ import shutil
 import string
 import subprocess
 import sys
-from collections.abc import Generator
 from pathlib import Path
 from tempfile import TemporaryDirectory
+from typing import Dict, Iterator, List, Union
 
 import setuptools.command.sdist
 
@@ -24,7 +23,7 @@ VERSION_FILE = Path("pybind11/_version.py")
 COMMON_FILE = Path("include/pybind11/detail/common.h")
 
 
-def build_expected_version_hex(matches: dict[str, str]) -> str:
+def build_expected_version_hex(matches: Dict[str, str]) -> str:
     patch_level_serial = matches["PATCH"]
     serial = None
     major = int(matches["MAJOR"])
@@ -65,7 +64,7 @@ to_src = (
 
 
 # Read the listed version
-loc: dict[str, str] = {}
+loc: Dict[str, str] = {}
 code = compile(VERSION_FILE.read_text(encoding="utf-8"), "pybind11/_version.py", "exec")
 exec(code, loc)
 version = loc["__version__"]
@@ -85,7 +84,9 @@ if version_hex != exp_version_hex:
 
 
 # TODO: use literals & overload (typing extensions or Python 3.8)
-def get_and_replace(filename: Path, binary: bool = False, **opts: str) -> bytes | str:
+def get_and_replace(
+    filename: Path, binary: bool = False, **opts: str
+) -> Union[bytes, str]:
     if binary:
         contents = filename.read_bytes()
         return string.Template(contents.decode()).substitute(opts).encode()
@@ -96,7 +97,7 @@ def get_and_replace(filename: Path, binary: bool = False, **opts: str) -> bytes
 # Use our input files instead when making the SDist (and anything that depends
 # on it, like a wheel)
 class SDist(setuptools.command.sdist.sdist):
-    def make_release_tree(self, base_dir: str, files: list[str]) -> None:
+    def make_release_tree(self, base_dir: str, files: List[str]) -> None:
         super().make_release_tree(base_dir, files)
 
         for to, src in to_src:
@@ -111,7 +112,7 @@ class SDist(setuptools.command.sdist.sdist):
 
 # Remove the CMake install directory when done
 @contextlib.contextmanager
-def remove_output(*sources: str) -> Generator[None, None, None]:
+def remove_output(*sources: str) -> Iterator[None]:
     try:
         yield
     finally:

tests/CMakeLists.txt

@@ -5,7 +5,16 @@
 # All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 # Filter out items; print an optional message if any items filtered. This ignores extensions.
 #
@@ -67,8 +76,8 @@ project(pybind11_tests CXX)
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/../tools")
 
 option(PYBIND11_WERROR "Report all warnings as errors" OFF)
-option(DOWNLOAD_EIGEN "Download EIGEN" OFF)
-option(PYBIND11_CUDA_TESTS "Enable building CUDA tests" OFF)
+option(DOWNLOAD_EIGEN "Download EIGEN (requires CMake 3.11+)" OFF)
+option(PYBIND11_CUDA_TESTS "Enable building CUDA tests (requires CMake 3.12+)" OFF)
 set(PYBIND11_TEST_OVERRIDE
     ""
     CACHE STRING "Tests from ;-separated list of *.cpp files will be built instead of all tests")
@@ -79,12 +88,7 @@ set(PYBIND11_TEST_FILTER
 if(CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
   # We're being loaded directly, i.e. not via add_subdirectory, so make this
   # work as its own project and load the pybind11Config to get the tools we need
-
-  if(SKBUILD)
-    add_subdirectory(.. pybind11_src)
-  else()
-    find_package(pybind11 REQUIRED CONFIG)
-  endif()
+  find_package(pybind11 REQUIRED CONFIG)
 endif()
 
 if(NOT CMAKE_BUILD_TYPE AND NOT DEFINED CMAKE_CONFIGURATION_TYPES)
@@ -118,7 +122,6 @@ set(PYBIND11_TEST_FILES
     test_const_name
     test_constants_and_functions
     test_copy_move
-    test_cpp_conduit
     test_custom_type_casters
     test_custom_type_setup
     test_docstring_options
@@ -150,13 +153,11 @@ set(PYBIND11_TEST_FILES
     test_tagbased_polymorphic
     test_thread
     test_type_caster_pyobject_ptr
-    test_type_caster_std_function_specializations
     test_union
     test_unnamed_namespace_a
     test_unnamed_namespace_b
     test_vector_unique_ptr_member
-    test_virtual_functions
-    test_warnings)
+    test_virtual_functions)
 
 # Invoking cmake with something like:
 #     cmake -DPYBIND11_TEST_OVERRIDE="test_callbacks.cpp;test_pickling.cpp" ..
@@ -219,8 +220,6 @@ tests_extra_targets("test_exceptions.py;test_local_bindings.py;test_stl.py;test_
 # And add additional targets for other tests.
 tests_extra_targets("test_exceptions.py" "cross_module_interleaved_error_already_set")
 tests_extra_targets("test_gil_scoped.py" "cross_module_gil_utils")
-tests_extra_targets("test_cpp_conduit.py"
-                    "exo_planet_pybind11;exo_planet_c_api;home_planet_very_lonely_traveler")
 
 set(PYBIND11_EIGEN_REPO
     "https://gitlab.com/libeigen/eigen.git"
@@ -244,21 +243,25 @@ endif()
 if(PYBIND11_TEST_FILES_EIGEN_I GREATER -1)
   # Try loading via newer Eigen's Eigen3Config first (bypassing tools/FindEigen3.cmake).
   # Eigen 3.3.1+ exports a cmake 3.0+ target for handling dependency requirements, but also
+  # produces a fatal error if loaded from a pre-3.0 cmake.
   if(DOWNLOAD_EIGEN)
-    if(CMAKE_VERSION VERSION_LESS 3.18)
-      set(_opts)
-    else()
-      set(_opts SOURCE_SUBDIR no-cmake-build)
+    if(CMAKE_VERSION VERSION_LESS 3.11)
+      message(FATAL_ERROR "CMake 3.11+ required when using DOWNLOAD_EIGEN")
     endif()
+
     include(FetchContent)
     FetchContent_Declare(
       eigen
       GIT_REPOSITORY "${PYBIND11_EIGEN_REPO}"
-      GIT_TAG "${PYBIND11_EIGEN_VERSION_HASH}"
-      ${_opts})
-    FetchContent_MakeAvailable(eigen)
-    if(NOT CMAKE_VERSION VERSION_LESS 3.18)
-      set(EIGEN3_INCLUDE_DIR "${eigen_SOURCE_DIR}")
+      GIT_TAG "${PYBIND11_EIGEN_VERSION_HASH}")
+
+    FetchContent_GetProperties(eigen)
+    if(NOT eigen_POPULATED)
+      message(
+        STATUS
+          "Downloading Eigen ${PYBIND11_EIGEN_VERSION_STRING} (${PYBIND11_EIGEN_VERSION_HASH}) from ${PYBIND11_EIGEN_REPO}"
+      )
+      FetchContent_Populate(eigen)
     endif()
 
     set(EIGEN3_INCLUDE_DIR ${eigen_SOURCE_DIR})
@@ -306,7 +309,8 @@ if(PYBIND11_TEST_FILES_EIGEN_I GREATER -1)
     if(PYBIND11_TEST_FILES_EIGEN_I GREATER -1)
       list(REMOVE_AT PYBIND11_TEST_FILES ${PYBIND11_TEST_FILES_EIGEN_I})
     endif()
-    message(STATUS "Building tests WITHOUT Eigen, use -DDOWNLOAD_EIGEN=ON to download")
+    message(
+      STATUS "Building tests WITHOUT Eigen, use -DDOWNLOAD_EIGEN=ON on CMake 3.11+ to download")
   endif()
 endif()
 
@@ -386,9 +390,6 @@ function(pybind11_enable_warnings target_name)
               -Wdeprecated
               -Wundef
               -Wnon-virtual-dtor)
-    if(DEFINED CMAKE_CXX_STANDARD AND NOT CMAKE_CXX_STANDARD VERSION_LESS 20)
-      target_compile_options(${target_name} PRIVATE -Wpedantic)
-    endif()
   endif()
 
   if(PYBIND11_WERROR)
@@ -488,16 +489,15 @@ foreach(target ${test_targets})
       endforeach()
     endif()
   endif()
-  if(SKBUILD)
-    install(TARGETS ${target} LIBRARY DESTINATION .)
-  endif()
 endforeach()
 
 # Provide nice organisation in IDEs
-source_group(
-  TREE "${CMAKE_CURRENT_SOURCE_DIR}/../include"
-  PREFIX "Header Files"
-  FILES ${PYBIND11_HEADERS})
+if(NOT CMAKE_VERSION VERSION_LESS 3.8)
+  source_group(
+    TREE "${CMAKE_CURRENT_SOURCE_DIR}/../include"
+    PREFIX "Header Files"
+    FILES ${PYBIND11_HEADERS})
+endif()
 
 # Make sure pytest is found or produce a warning
 pybind11_find_import(pytest VERSION 3.1)

tests/conftest.py

@@ -4,8 +4,6 @@ Extends output capture as needed by pybind11: ignore constructors, optional unor
 Adds docstring and exceptions message sanitizers.
 """
 
-from __future__ import annotations
-
 import contextlib
 import difflib
 import gc
@@ -136,7 +134,7 @@ class Capture:
         return Output(self.err)
 
 
-@pytest.fixture
+@pytest.fixture()
 def capture(capsys):
     """Extended `capsys` with context manager and custom equality operators"""
     return Capture(capsys)
@@ -172,7 +170,7 @@ def _sanitize_docstring(thing):
     return _sanitize_general(s)
 
 
-@pytest.fixture
+@pytest.fixture()
 def doc():
     """Sanitize docstrings and add custom failure explanation"""
     return SanitizedString(_sanitize_docstring)
@@ -184,7 +182,7 @@ def _sanitize_message(thing):
     return _hexadecimal.sub("0", s)
 
 
-@pytest.fixture
+@pytest.fixture()
 def msg():
     """Sanitize messages and add custom failure explanation"""
     return SanitizedString(_sanitize_message)

tests/constructor_stats.h

@@ -190,7 +190,7 @@ public:
                     t1 = &p.first;
                 }
             }
-        } catch (const std::out_of_range &) { // NOLINT(bugprone-empty-catch)
+        } catch (const std::out_of_range &) {
         }
         if (!t1) {
             throw std::runtime_error("Unknown class passed to ConstructorStats::get()");

tests/cross_module_gil_utils.cpp

@@ -92,9 +92,6 @@ extern "C" PYBIND11_EXPORT PyObject *PyInit_cross_module_gil_utils() {
     if (m != nullptr) {
         static_assert(sizeof(&gil_acquire) == sizeof(void *),
                       "Function pointer must have the same size as void*");
-#ifdef Py_GIL_DISABLED
-        PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
-#endif
         ADD_FUNCTION("gil_acquire_funcaddr", gil_acquire)
         ADD_FUNCTION("gil_multi_acquire_release_funcaddr", gil_multi_acquire_release)
         ADD_FUNCTION("gil_acquire_inner_custom_funcaddr",

tests/cross_module_interleaved_error_already_set.cpp

@@ -42,9 +42,6 @@ extern "C" PYBIND11_EXPORT PyObject *PyInit_cross_module_interleaved_error_alrea
     if (m != nullptr) {
         static_assert(sizeof(&interleaved_error_already_set) == sizeof(void *),
                       "Function pointer must have the same size as void *");
-#ifdef Py_GIL_DISABLED
-        PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
-#endif
         PyModule_AddObject(
             m,
             "funcaddr",

tests/custom_exceptions.py

@@ -1,10 +0,0 @@
-from __future__ import annotations
-
-
-class PythonMyException7(Exception):
-    def __init__(self, message):
-        self.message = message
-        super().__init__(message)
-
-    def __str__(self):
-        return "[PythonMyException7]: " + self.message.a

tests/eigen_tensor_avoid_stl_array.cpp

@@ -11,6 +11,4 @@
 
 #include "test_eigen_tensor.inl"
 
-PYBIND11_MODULE(eigen_tensor_avoid_stl_array, m, pybind11::mod_gil_not_used()) {
-    eigen_tensor_test::test_module(m);
-}
+PYBIND11_MODULE(eigen_tensor_avoid_stl_array, m) { eigen_tensor_test::test_module(m); }

tests/env.py

@@ -1,8 +1,5 @@
-from __future__ import annotations
-
 import platform
 import sys
-import sysconfig
 
 import pytest
 
@@ -12,7 +9,6 @@ WIN = sys.platform.startswith("win32") or sys.platform.startswith("cygwin")
 
 CPYTHON = platform.python_implementation() == "CPython"
 PYPY = platform.python_implementation() == "PyPy"
-PY_GIL_DISABLED = bool(sysconfig.get_config_var("Py_GIL_DISABLED"))
 
 
 def deprecated_call():

tests/exo_planet_c_api.cpp

@@ -1,103 +0,0 @@
-// Copyright (c) 2024 The pybind Community.
-
-// THIS MUST STAY AT THE TOP!
-#include <pybind11/pybind11.h> // EXCLUSIVELY for PYBIND11_PLATFORM_ABI_ID
-// Potential future direction to maximize reusability:
-// (e.g. for use from SWIG, Cython, PyCLIF, nanobind):
-//     #include <pybind11/compat/platform_abi_id.h>
-// This would only depend on:
-//     1. A C++ compiler, WITHOUT requiring -fexceptions.
-//     2. Python.h
-
-#include "test_cpp_conduit_traveler_types.h"
-
-#include <Python.h>
-#include <typeinfo>
-
-namespace {
-
-void *get_cpp_conduit_void_ptr(PyObject *py_obj, const std::type_info *cpp_type_info) {
-    PyObject *cpp_type_info_capsule
-        = PyCapsule_New(const_cast<void *>(static_cast<const void *>(cpp_type_info)),
-                        typeid(std::type_info).name(),
-                        nullptr);
-    if (cpp_type_info_capsule == nullptr) {
-        return nullptr;
-    }
-    PyObject *cpp_conduit = PyObject_CallMethod(py_obj,
-                                                "_pybind11_conduit_v1_",
-                                                "yOy",
-                                                PYBIND11_PLATFORM_ABI_ID,
-                                                cpp_type_info_capsule,
-                                                "raw_pointer_ephemeral");
-    Py_DECREF(cpp_type_info_capsule);
-    if (cpp_conduit == nullptr) {
-        return nullptr;
-    }
-    void *void_ptr = PyCapsule_GetPointer(cpp_conduit, cpp_type_info->name());
-    Py_DECREF(cpp_conduit);
-    if (PyErr_Occurred()) {
-        return nullptr;
-    }
-    return void_ptr;
-}
-
-template <typename T>
-T *get_cpp_conduit_type_ptr(PyObject *py_obj) {
-    void *void_ptr = get_cpp_conduit_void_ptr(py_obj, &typeid(T));
-    if (void_ptr == nullptr) {
-        return nullptr;
-    }
-    return static_cast<T *>(void_ptr);
-}
-
-extern "C" PyObject *wrapGetLuggage(PyObject * /*self*/, PyObject *traveler) {
-    const auto *cpp_traveler
-        = get_cpp_conduit_type_ptr<pybind11_tests::test_cpp_conduit::Traveler>(traveler);
-    if (cpp_traveler == nullptr) {
-        return nullptr;
-    }
-    return PyUnicode_FromString(cpp_traveler->luggage.c_str());
-}
-
-extern "C" PyObject *wrapGetPoints(PyObject * /*self*/, PyObject *premium_traveler) {
-    const auto *cpp_premium_traveler
-        = get_cpp_conduit_type_ptr<pybind11_tests::test_cpp_conduit::PremiumTraveler>(
-            premium_traveler);
-    if (cpp_premium_traveler == nullptr) {
-        return nullptr;
-    }
-    return PyLong_FromLong(static_cast<long>(cpp_premium_traveler->points));
-}
-
-PyMethodDef ThisMethodDef[] = {{"GetLuggage", wrapGetLuggage, METH_O, nullptr},
-                               {"GetPoints", wrapGetPoints, METH_O, nullptr},
-                               {nullptr, nullptr, 0, nullptr}};
-
-struct PyModuleDef ThisModuleDef = {
-    PyModuleDef_HEAD_INIT, // m_base
-    "exo_planet_c_api",    // m_name
-    nullptr,               // m_doc
-    -1,                    // m_size
-    ThisMethodDef,         // m_methods
-    nullptr,               // m_slots
-    nullptr,               // m_traverse
-    nullptr,               // m_clear
-    nullptr                // m_free
-};
-
-} // namespace
-
-#if defined(WIN32) || defined(_WIN32)
-#    define EXO_PLANET_C_API_EXPORT __declspec(dllexport)
-#else
-#    define EXO_PLANET_C_API_EXPORT __attribute__((visibility("default")))
-#endif
-
-extern "C" EXO_PLANET_C_API_EXPORT PyObject *PyInit_exo_planet_c_api() {
-    PyObject *m = PyModule_Create(&ThisModuleDef);
-    if (m == nullptr) {
-        return nullptr;
-    }
-    return m;
-}

tests/exo_planet_pybind11.cpp

@@ -1,19 +0,0 @@
-// Copyright (c) 2024 The pybind Community.
-
-#if defined(PYBIND11_INTERNALS_VERSION)
-#    undef PYBIND11_INTERNALS_VERSION
-#endif
-#define PYBIND11_INTERNALS_VERSION 900000001
-
-#include "test_cpp_conduit_traveler_bindings.h"
-
-namespace pybind11_tests {
-namespace test_cpp_conduit {
-
-PYBIND11_MODULE(exo_planet_pybind11, m) {
-    wrap_traveler(m);
-    m.def("wrap_very_lonely_traveler", [m]() { wrap_very_lonely_traveler(m); });
-}
-
-} // namespace test_cpp_conduit
-} // namespace pybind11_tests

tests/extra_python_package/test_files.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import contextlib
 import os
 import string
@@ -9,6 +7,7 @@ import tarfile
 import zipfile
 
 # These tests must be run explicitly
+# They require CMake 3.15+ (--install)
 
 DIR = os.path.abspath(os.path.dirname(__file__))
 MAIN_DIR = os.path.dirname(os.path.dirname(DIR))
@@ -47,20 +46,16 @@ main_headers = {
     "include/pybind11/stl_bind.h",
     "include/pybind11/type_caster_pyobject_ptr.h",
     "include/pybind11/typing.h",
-    "include/pybind11/warnings.h",
 }
 
 detail_headers = {
     "include/pybind11/detail/class.h",
     "include/pybind11/detail/common.h",
-    "include/pybind11/detail/cpp_conduit.h",
     "include/pybind11/detail/descr.h",
     "include/pybind11/detail/init.h",
     "include/pybind11/detail/internals.h",
     "include/pybind11/detail/type_caster_base.h",
     "include/pybind11/detail/typeid.h",
-    "include/pybind11/detail/value_and_holder.h",
-    "include/pybind11/detail/exception_translation.h",
 }
 
 eigen_headers = {

tests/extra_setuptools/test_setuphelper.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import os
 import subprocess
 import sys

tests/home_planet_very_lonely_traveler.cpp

@@ -1,13 +0,0 @@
-// Copyright (c) 2024 The pybind Community.
-
-#include "test_cpp_conduit_traveler_bindings.h"
-
-namespace pybind11_tests {
-namespace test_cpp_conduit {
-
-PYBIND11_MODULE(home_planet_very_lonely_traveler, m) {
-    m.def("wrap_very_lonely_traveler", [m]() { wrap_very_lonely_traveler(m); });
-}
-
-} // namespace test_cpp_conduit
-} // namespace pybind11_tests

tests/local_bindings.h

@@ -56,13 +56,13 @@ private:
     std::string message = "";
 };
 
-PYBIND11_MAKE_OPAQUE(LocalVec)
-PYBIND11_MAKE_OPAQUE(LocalVec2)
-PYBIND11_MAKE_OPAQUE(LocalMap)
-PYBIND11_MAKE_OPAQUE(NonLocalVec)
-// PYBIND11_MAKE_OPAQUE(NonLocalVec2) // same type as LocalVec2
-PYBIND11_MAKE_OPAQUE(NonLocalMap)
-PYBIND11_MAKE_OPAQUE(NonLocalMap2)
+PYBIND11_MAKE_OPAQUE(LocalVec);
+PYBIND11_MAKE_OPAQUE(LocalVec2);
+PYBIND11_MAKE_OPAQUE(LocalMap);
+PYBIND11_MAKE_OPAQUE(NonLocalVec);
+// PYBIND11_MAKE_OPAQUE(NonLocalVec2); // same type as LocalVec2
+PYBIND11_MAKE_OPAQUE(NonLocalMap);
+PYBIND11_MAKE_OPAQUE(NonLocalMap2);
 
 // Simple bindings (used with the above):
 template <typename T, int Adjust = 0, typename... Args>
@@ -70,7 +70,7 @@ py::class_<T> bind_local(Args &&...args) {
     return py::class_<T>(std::forward<Args>(args)...).def(py::init<int>()).def("get", [](T &i) {
         return i.i + Adjust;
     });
-}
+};
 
 // Simulate a foreign library base class (to match the example in the docs):
 namespace pets {

tests/pybind11_cross_module_tests.cpp

@@ -16,7 +16,7 @@
 #include <numeric>
 #include <utility>
 
-PYBIND11_MODULE(pybind11_cross_module_tests, m, py::mod_gil_not_used()) {
+PYBIND11_MODULE(pybind11_cross_module_tests, m) {
     m.doc() = "pybind11 cross-module test module";
 
     // test_local_bindings.py tests:

tests/pybind11_tests.cpp

@@ -58,7 +58,7 @@ void bind_ConstructorStats(py::module_ &m) {
         // registered instances to allow instance cleanup checks (invokes a GC first)
         .def_static("detail_reg_inst", []() {
             ConstructorStats::gc();
-            return py::detail::num_registered_instances();
+            return py::detail::get_internals().registered_instances.size();
         });
 }
 
@@ -75,7 +75,7 @@ const char *cpp_std() {
 #endif
 }
 
-PYBIND11_MODULE(pybind11_tests, m, py::mod_gil_not_used()) {
+PYBIND11_MODULE(pybind11_tests, m) {
     m.doc() = "pybind11 test module";
 
     // Intentionally kept minimal to not create a maintenance chore

tests/pybind11_tests.h

@@ -3,8 +3,6 @@
 #include <pybind11/eval.h>
 #include <pybind11/pybind11.h>
 
-#include <memory>
-
 namespace py = pybind11;
 using namespace pybind11::literals;
 
@@ -54,17 +52,6 @@ union IntFloat {
     float f;
 };
 
-class UnusualOpRef {
-public:
-    using NonTrivialType = std::shared_ptr<int>; // Almost any non-trivial type will do.
-    // Overriding operator& should not break pybind11.
-    NonTrivialType operator&() { return non_trivial_member; }
-    NonTrivialType operator&() const { return non_trivial_member; }
-
-private:
-    NonTrivialType non_trivial_member;
-};
-
 /// Custom cast-only type that casts to a string "rvalue" or "lvalue" depending on the cast
 /// context. Used to test recursive casters (e.g. std::tuple, stl containers).
 struct RValueCaster {};

tests/pyproject.toml

@@ -1,17 +0,0 @@
-# Warning: this is currently used for pyodide, and is not a general out-of-tree
-# builder for the tests (yet). Specifically, wheels can't be built from SDists.
-
-[build-system]
-requires = ["scikit-build-core"]
-build-backend = "scikit_build_core.build"
-
-[project]
-name = "pybind11_tests"
-version = "0.0.1"
-dependencies = ["pytest", "pytest-timeout", "numpy", "scipy"]
-
-[tool.scikit-build.cmake.define]
-PYBIND11_FINDPYTHON = true
-
-[tool.cibuildwheel]
-test-command = "pytest -o timeout=0 -p no:cacheprovider {project}/tests/test_*.py"

tests/requirements.txt

@@ -1,12 +1,15 @@
 --only-binary=:all:
-build~=1.0; python_version>="3.8"
+build~=0.9; python_version=="3.6"
+build~=1.0; python_version>="3.7"
+numpy~=1.20.0; python_version=="3.7" and platform_python_implementation=="PyPy"
 numpy~=1.23.0; python_version=="3.8" and platform_python_implementation=="PyPy"
 numpy~=1.25.0; python_version=="3.9" and platform_python_implementation=='PyPy'
-numpy~=1.21.5; platform_python_implementation!="PyPy" and python_version>="3.8" and python_version<"3.10"
+numpy~=1.19.3; platform_python_implementation!="PyPy" and python_version=="3.6"
+numpy~=1.21.5; platform_python_implementation!="PyPy" and python_version>="3.7" and python_version<"3.10"
 numpy~=1.22.2; platform_python_implementation!="PyPy" and python_version=="3.10"
 numpy~=1.26.0; platform_python_implementation!="PyPy" and python_version>="3.11" and python_version<"3.13"
 pytest~=7.0
 pytest-timeout
 scipy~=1.5.4; platform_python_implementation!="PyPy" and python_version<"3.10"
-scipy~=1.8.0; platform_python_implementation!="PyPy" and python_version=="3.10" and sys_platform!='win32'
-scipy~=1.11.1; platform_python_implementation!="PyPy" and python_version>="3.11" and python_version<"3.13" and sys_platform!='win32'
+scipy~=1.8.0; platform_python_implementation!="PyPy" and python_version=="3.10"
+scipy~=1.11.1; platform_python_implementation!="PyPy" and python_version>="3.11" and python_version<"3.13"

tests/test_async.py

@@ -1,17 +1,10 @@
-from __future__ import annotations
-
-import sys
-
 import pytest
 
 asyncio = pytest.importorskip("asyncio")
 m = pytest.importorskip("pybind11_tests.async_module")
 
-if sys.platform.startswith("emscripten"):
-    pytest.skip("Can't run a new event_loop in pyodide", allow_module_level=True)
 
-
-@pytest.fixture
+@pytest.fixture()
 def event_loop():
     loop = asyncio.new_event_loop()
     yield loop

tests/test_buffers.cpp

@@ -167,18 +167,6 @@ TEST_SUBMODULE(buffers, m) {
                  sizeof(float)});
         });
 
-    class BrokenMatrix : public Matrix {
-    public:
-        BrokenMatrix(py::ssize_t rows, py::ssize_t cols) : Matrix(rows, cols) {}
-        void throw_runtime_error() { throw std::runtime_error("See PR #5324 for context."); }
-    };
-    py::class_<BrokenMatrix>(m, "BrokenMatrix", py::buffer_protocol())
-        .def(py::init<py::ssize_t, py::ssize_t>())
-        .def_buffer([](BrokenMatrix &m) {
-            m.throw_runtime_error();
-            return py::buffer_info();
-        });
-
     // test_inherited_protocol
     class SquareMatrix : public Matrix {
     public:

tests/test_buffers.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import ctypes
 import io
 import struct
@@ -228,10 +226,3 @@ def test_buffer_docstring():
         m.get_buffer_info.__doc__.strip()
         == "get_buffer_info(arg0: Buffer) -> pybind11_tests.buffers.buffer_info"
     )
-
-
-def test_buffer_exception():
-    with pytest.raises(BufferError, match="Error getting buffer") as excinfo:
-        memoryview(m.BrokenMatrix(1, 1))
-    assert isinstance(excinfo.value.__cause__, RuntimeError)
-    assert "for context" in str(excinfo.value.__cause__)

tests/test_builtin_casters.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import sys
 
 import pytest
@@ -297,7 +295,7 @@ def test_int_convert():
     cant_convert(3.14159)
     # TODO: Avoid DeprecationWarning in `PyLong_AsLong` (and similar)
     # TODO: PyPy 3.8 does not behave like CPython 3.8 here yet (7.3.7)
-    if sys.version_info < (3, 10) and env.CPYTHON:
+    if (3, 8) <= sys.version_info < (3, 10) and env.CPYTHON:
         with env.deprecated_call():
             assert convert(Int()) == 42
     else:
@@ -368,8 +366,6 @@ def test_tuple(doc):
     """
     )
 
-    assert doc(m.empty_tuple) == """empty_tuple() -> tuple[()]"""
-
     assert m.rvalue_pair() == ("rvalue", "rvalue")
     assert m.lvalue_pair() == ("lvalue", "lvalue")
     assert m.rvalue_tuple() == ("rvalue", "rvalue", "rvalue")

tests/test_call_policies.cpp

@@ -95,7 +95,7 @@ TEST_SUBMODULE(call_policies, m) {
         },
         py::call_guard<DependentGuard, CustomGuard>());
 
-#if !defined(PYPY_VERSION)
+#if defined(WITH_THREAD) && !defined(PYPY_VERSION)
     // `py::call_guard<py::gil_scoped_release>()` should work in PyPy as well,
     // but it's unclear how to test it without `PyGILState_GetThisThreadState`.
     auto report_gil_status = []() {

tests/test_call_policies.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import pytest
 
 import env  # noqa: F401

tests/test_callbacks.cpp

@@ -148,7 +148,7 @@ TEST_SUBMODULE(callbacks, m) {
     m.def("dummy_function2", [](int i, int j) { return i + j; });
     m.def(
         "roundtrip",
-        [](std::function<int(int)> f, bool expect_none) {
+        [](std::function<int(int)> f, bool expect_none = false) {
             if (expect_none && f) {
                 throw std::runtime_error("Expected None to be converted to empty std::function");
             }

tests/test_callbacks.py

@@ -1,6 +1,3 @@
-from __future__ import annotations
-
-import sys
 import time
 from threading import Thread
 
@@ -154,7 +151,6 @@ def test_python_builtins():
     assert m.test_sum_builtin(sum, []) == 0
 
 
-@pytest.mark.skipif(sys.platform.startswith("emscripten"), reason="Requires threads")
 def test_async_callbacks():
     # serves as state for async callback
     class Item:
@@ -178,7 +174,6 @@ def test_async_callbacks():
     assert sum(res) == sum(x + 3 for x in work)
 
 
-@pytest.mark.skipif(sys.platform.startswith("emscripten"), reason="Requires threads")
 def test_async_async_callbacks():
     t = Thread(target=test_async_callbacks)
     t.start()

tests/test_chrono.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import datetime
 
 import pytest

tests/test_class.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 from unittest import mock
 
 import pytest

tests/test_cmake_build/installed_embed/CMakeLists.txt

@@ -1,4 +1,13 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_installed_embed CXX)
 

tests/test_cmake_build/installed_function/CMakeLists.txt

@@ -1,4 +1,14 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+project(test_installed_module CXX)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_installed_function CXX)
 

tests/test_cmake_build/installed_target/CMakeLists.txt

@@ -1,4 +1,13 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_installed_target CXX)
 

tests/test_cmake_build/main.cpp

@@ -1,6 +1,6 @@
 #include <pybind11/pybind11.h>
 namespace py = pybind11;
 
-PYBIND11_MODULE(test_cmake_build, m, py::mod_gil_not_used()) {
+PYBIND11_MODULE(test_cmake_build, m) {
     m.def("add", [](int i, int j) { return i + j; });
 }

tests/test_cmake_build/subdirectory_embed/CMakeLists.txt

@@ -1,4 +1,13 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_subdirectory_embed CXX)
 

tests/test_cmake_build/subdirectory_function/CMakeLists.txt

@@ -1,4 +1,13 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_subdirectory_function CXX)
 

tests/test_cmake_build/subdirectory_target/CMakeLists.txt

@@ -1,4 +1,13 @@
-cmake_minimum_required(VERSION 3.15...3.30)
+cmake_minimum_required(VERSION 3.5)
+
+# The `cmake_minimum_required(VERSION 3.5...3.29)` syntax does not work with
+# some versions of VS that have a patched CMake 3.11. This forces us to emulate
+# the behavior using the following workaround:
+if(${CMAKE_VERSION} VERSION_LESS 3.29)
+  cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
+else()
+  cmake_policy(VERSION 3.29)
+endif()
 
 project(test_subdirectory_target CXX)
 

tests/test_cmake_build/test.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import sys
 
 import test_cmake_build

tests/test_const_name.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import pytest
 
 from pybind11_tests import const_name as m

tests/test_constants_and_functions.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import pytest
 
 m = pytest.importorskip("pybind11_tests.constants_and_functions")

tests/test_copy_move.cpp

@@ -157,13 +157,6 @@ public:
 PYBIND11_NAMESPACE_END(detail)
 PYBIND11_NAMESPACE_END(pybind11)
 
-namespace {
-
-py::object CastUnusualOpRefConstRef(const UnusualOpRef &cref) { return py::cast(cref); }
-py::object CastUnusualOpRefMovable(UnusualOpRef &&mvbl) { return py::cast(std::move(mvbl)); }
-
-} // namespace
-
 TEST_SUBMODULE(copy_move_policies, m) {
     // test_lacking_copy_ctor
     py::class_<lacking_copy_ctor>(m, "lacking_copy_ctor")
@@ -300,11 +293,6 @@ TEST_SUBMODULE(copy_move_policies, m) {
 
     // Make sure that cast from pytype rvalue to other pytype works
     m.def("get_pytype_rvalue_castissue", [](double i) { return py::float_(i).cast<py::int_>(); });
-
-    py::class_<UnusualOpRef>(m, "UnusualOpRef");
-    m.def("CallCastUnusualOpRefConstRef",
-          []() { return CastUnusualOpRefConstRef(UnusualOpRef()); });
-    m.def("CallCastUnusualOpRefMovable", []() { return CastUnusualOpRefMovable(UnusualOpRef()); });
 }
 
 /*

tests/test_copy_move.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import pytest
 
 from pybind11_tests import copy_move_policies as m
@@ -132,9 +130,3 @@ def test_pytype_rvalue_cast():
 
     value = m.get_pytype_rvalue_castissue(1.0)
     assert value == 1
-
-
-def test_unusual_op_ref():
-    # Merely to test that this still exists and built successfully.
-    assert m.CallCastUnusualOpRefConstRef().__class__.__name__ == "UnusualOpRef"
-    assert m.CallCastUnusualOpRefMovable().__class__.__name__ == "UnusualOpRef"

tests/test_cpp_conduit.cpp

@@ -1,22 +0,0 @@
-// Copyright (c) 2024 The pybind Community.
-
-#include "pybind11_tests.h"
-#include "test_cpp_conduit_traveler_bindings.h"
-
-#include <typeinfo>
-
-namespace pybind11_tests {
-namespace test_cpp_conduit {
-
-TEST_SUBMODULE(cpp_conduit, m) {
-    m.attr("PYBIND11_PLATFORM_ABI_ID") = py::bytes(PYBIND11_PLATFORM_ABI_ID);
-    m.attr("cpp_type_info_capsule_Traveler")
-        = py::capsule(&typeid(Traveler), typeid(std::type_info).name());
-    m.attr("cpp_type_info_capsule_int") = py::capsule(&typeid(int), typeid(std::type_info).name());
-
-    wrap_traveler(m);
-    wrap_lonely_traveler(m);
-}
-
-} // namespace test_cpp_conduit
-} // namespace pybind11_tests