Multi-step, slightly messy merge of v2.10.0 (aa304c9)

# Conflicts:
#	.clang-format
#	.clang-tidy
#	.github/CONTRIBUTING.md
#	.github/workflows/ci.yml
#	.github/workflows/configure.yml
#	.github/workflows/upstream.yml
#	.pre-commit-config.yaml
#	docs/Doxyfile
#	docs/advanced/cast/overview.rst
#	docs/advanced/exceptions.rst
#	docs/advanced/functions.rst
#	docs/advanced/pycpp/numpy.rst
#	docs/benchmark.py
#	docs/changelog.rst
#	docs/classes.rst
#	docs/compiling.rst
#	docs/requirements.txt
#	docs/upgrade.rst
#	include/pybind11/attr.h
#	include/pybind11/buffer_info.h
#	include/pybind11/cast.h
#	include/pybind11/chrono.h
#	include/pybind11/detail/class.h
#	include/pybind11/detail/common.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/eigen.h
#	include/pybind11/embed.h
#	include/pybind11/eval.h
#	include/pybind11/functional.h
#	include/pybind11/gil.h
#	include/pybind11/iostream.h
#	include/pybind11/numpy.h
#	include/pybind11/operators.h
#	include/pybind11/pybind11.h
#	include/pybind11/pytypes.h
#	include/pybind11/stl.h
#	include/pybind11/stl/filesystem.h
#	include/pybind11/stl_bind.h
#	noxfile.py
#	pybind11/__init__.py
#	pybind11/_version.py
#	pybind11/_version.pyi
#	pybind11/setup_helpers.py
#	pybind11/setup_helpers.pyi
#	pyproject.toml
#	setup.cfg
#	setup.py
#	tests/CMakeLists.txt
#	tests/env.py
#	tests/extra_python_package/test_files.py
#	tests/extra_setuptools/test_setuphelper.py
#	tests/local_bindings.h
#	tests/object.h
#	tests/pybind11_cross_module_tests.cpp
#	tests/pybind11_tests.h
#	tests/requirements.txt
#	tests/test_buffers.cpp
#	tests/test_buffers.py
#	tests/test_builtin_casters.cpp
#	tests/test_builtin_casters.py
#	tests/test_call_policies.cpp
#	tests/test_callbacks.cpp
#	tests/test_callbacks.py
#	tests/test_chrono.py
#	tests/test_class.cpp
#	tests/test_cmake_build/test.py
#	tests/test_constants_and_functions.cpp
#	tests/test_copy_move.cpp
#	tests/test_custom_type_casters.cpp
#	tests/test_custom_type_setup.py
#	tests/test_eigen.cpp
#	tests/test_eigen.py
#	tests/test_embed/test_interpreter.cpp
#	tests/test_embed/test_interpreter.py
#	tests/test_embed/test_trampoline.py
#	tests/test_enum.cpp
#	tests/test_enum.py
#	tests/test_eval.cpp
#	tests/test_exceptions.cpp
#	tests/test_exceptions.h
#	tests/test_exceptions.py
#	tests/test_factory_constructors.cpp
#	tests/test_factory_constructors.py
#	tests/test_gil_scoped.cpp
#	tests/test_iostream.py
#	tests/test_kwargs_and_defaults.cpp
#	tests/test_kwargs_and_defaults.py
#	tests/test_local_bindings.cpp
#	tests/test_methods_and_attributes.cpp
#	tests/test_methods_and_attributes.py
#	tests/test_modules.cpp
#	tests/test_modules.py
#	tests/test_multiple_inheritance.cpp
#	tests/test_multiple_inheritance.py
#	tests/test_numpy_array.cpp
#	tests/test_numpy_dtypes.cpp
#	tests/test_numpy_dtypes.py
#	tests/test_numpy_vectorize.cpp
#	tests/test_opaque_types.cpp
#	tests/test_operator_overloading.cpp
#	tests/test_ownership_transfer.cpp
#	tests/test_pickling.cpp
#	tests/test_pytypes.cpp
#	tests/test_pytypes.py
#	tests/test_sequences_and_iterators.cpp
#	tests/test_sequences_and_iterators.py
#	tests/test_smart_ptr.cpp
#	tests/test_stl.cpp
#	tests/test_stl_binders.py
#	tests/test_tagbased_polymorphic.cpp
#	tests/test_thread.cpp
#	tests/test_thread.py
#	tests/test_virtual_functions.cpp
#	tests/test_virtual_functions.py
#	tools/libsize.py
#	tools/pybind11NewTools.cmake
#	tools/pybind11Tools.cmake

.appveyor.yml

@@ -1,6 +1,6 @@
 version: 1.0.{build}
 image:
-- Visual Studio 2015
+- Visual Studio 2017
 test: off
 skip_branch_with_pr: true
 build:
@@ -11,11 +11,9 @@ environment:
   matrix:
   - PYTHON: 36
     CONFIG: Debug
-  - PYTHON: 27
-    CONFIG: Debug
 install:
 - ps: |
-    $env:CMAKE_GENERATOR = "Visual Studio 14 2015"
+    $env:CMAKE_GENERATOR = "Visual Studio 15 2017"
     if ($env:PLATFORM -eq "x64") { $env:PYTHON = "$env:PYTHON-x64" }
     $env:PATH = "C:\Python$env:PYTHON\;C:\Python$env:PYTHON\Scripts\;$env:PATH"
     python -W ignore -m pip install --upgrade pip wheel

.clang-format

@@ -3,17 +3,36 @@
 # clang-format --style=llvm --dump-config
 BasedOnStyle: LLVM
 AccessModifierOffset: -4
+AllowShortLambdasOnASingleLine: true
 AlwaysBreakTemplateDeclarations: Yes
 BinPackArguments: false
 BinPackParameters: false
 BreakBeforeBinaryOperators: All
 BreakConstructorInitializers: BeforeColon
 ColumnLimit: 99
+CommentPragmas: 'NOLINT:.*|^ IWYU pragma:'
+IncludeBlocks: Regroup
 IndentCaseLabels: true
 IndentPPDirectives: AfterHash
 IndentWidth: 4
 Language: Cpp
 SpaceAfterCStyleCast: true
 Standard: Cpp11
+StatementMacros: ['PyObject_HEAD']
 TabWidth: 4
+IncludeCategories:
+  - Regex:           '<pybind11/.*'
+    Priority:        -1
+  - Regex:           'pybind11.h"$'
+    Priority:        1
+  - Regex:           '^".*/?detail/'
+    Priority:        1
+    SortPriority:    2
+  - Regex:           '^"'
+    Priority:        1
+    SortPriority:    3
+  - Regex:           '<[[:alnum:]._]+>'
+    Priority:        4
+  - Regex:           '.*'
+    Priority:        5
 ...

.clang-tidy

@@ -1,65 +1,75 @@
 FormatStyle: file
 
-Checks: '
-*bugprone*,
-cppcoreguidelines-init-variables,
-cppcoreguidelines-slicing,
-clang-analyzer-optin.cplusplus.VirtualCall,
-google-explicit-constructor,
-llvm-namespace-comment,
-misc-misplaced-const,
-misc-non-copyable-objects,
-misc-static-assert,
-misc-throw-by-value-catch-by-reference,
-misc-uniqueptr-reset-release,
-misc-unused-parameters,
-modernize-avoid-bind,
-modernize-make-shared,
-modernize-redundant-void-arg,
-modernize-replace-auto-ptr,
-modernize-replace-disallow-copy-and-assign-macro,
-modernize-replace-random-shuffle,
-modernize-shrink-to-fit,
-modernize-use-auto,
-modernize-use-bool-literals,
-modernize-use-equals-default,
-modernize-use-equals-delete,
-modernize-use-default-member-init,
-modernize-use-noexcept,
-modernize-use-emplace,
-modernize-use-override,
-modernize-use-using,
-*performance*,
-readability-avoid-const-params-in-decls,
-readability-const-return-type,
-readability-container-size-empty,
-readability-delete-null-pointer,
-readability-else-after-return,
-readability-implicit-bool-conversion,
-readability-make-member-function-const,
-readability-misplaced-array-index,
-readability-non-const-parameter,
-readability-redundant-function-ptr-dereference,
-readability-redundant-smartptr-get,
-readability-redundant-string-cstr,
-readability-simplify-subscript-expr,
-readability-static-accessed-through-instance,
-readability-static-definition-in-anonymous-namespace,
-readability-string-compare,
-readability-uniqueptr-delete-release,
--bugprone-exception-escape,
--bugprone-reserved-identifier,
--bugprone-unused-raii,
-'
+Checks: |
+  *bugprone*,
+  *performance*,
+  clang-analyzer-optin.cplusplus.VirtualCall,
+  clang-analyzer-optin.performance.Padding,
+  cppcoreguidelines-init-variables,
+  cppcoreguidelines-prefer-member-initializer,
+  cppcoreguidelines-pro-type-static-cast-downcast,
+  cppcoreguidelines-slicing,
+  google-explicit-constructor,
+  llvm-namespace-comment,
+  misc-definitions-in-headers,
+  misc-misplaced-const,
+  misc-non-copyable-objects,
+  misc-static-assert,
+  misc-throw-by-value-catch-by-reference,
+  misc-uniqueptr-reset-release,
+  misc-unused-parameters,
+  modernize-avoid-bind,
+  modernize-loop-convert,
+  modernize-make-shared,
+  modernize-redundant-void-arg,
+  modernize-replace-auto-ptr,
+  modernize-replace-disallow-copy-and-assign-macro,
+  modernize-replace-random-shuffle,
+  modernize-shrink-to-fit,
+  modernize-use-auto,
+  modernize-use-bool-literals,
+  modernize-use-default-member-init,
+  modernize-use-emplace,
+  modernize-use-equals-default,
+  modernize-use-equals-delete,
+  modernize-use-noexcept,
+  modernize-use-nullptr,
+  modernize-use-override,
+  modernize-use-using,
+  readability-avoid-const-params-in-decls,
+  readability-braces-around-statements,
+  readability-const-return-type,
+  readability-container-size-empty,
+  readability-delete-null-pointer,
+  readability-else-after-return,
+  readability-implicit-bool-conversion,
+  readability-inconsistent-declaration-parameter-name,
+  readability-make-member-function-const,
+  readability-misplaced-array-index,
+  readability-non-const-parameter,
+  readability-qualified-auto,
+  readability-redundant-function-ptr-dereference,
+  readability-redundant-smartptr-get,
+  readability-redundant-string-cstr,
+  readability-simplify-subscript-expr,
+  readability-static-accessed-through-instance,
+  readability-static-definition-in-anonymous-namespace,
+  readability-string-compare,
+  readability-suspicious-call-argument,
+  readability-uniqueptr-delete-release,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-exception-escape,
+  -bugprone-reserved-identifier,
+  -bugprone-unused-raii,
 
 CheckOptions:
 - key:             performance-for-range-copy.WarnOnAllAutoCopies
   value:           true
+- key:             performance-inefficient-string-concatenation.StrictMode
+  value:           true
 - key:             performance-unnecessary-value-param.AllowedTypes
   value:           'exception_ptr$;'
 - key:             readability-implicit-bool-conversion.AllowPointerConditions
   value:           true
 
 HeaderFilterRegex: 'pybind11/.*h'
-
-WarningsAsErrors: '*'

.gitattributes

@@ -0,0 +1 @@
+docs/*.svg binary

.github/CONTRIBUTING.md

@@ -93,19 +93,18 @@ cmake --build build -j4
 
 Tips:
 
-* You can use `virtualenv` (from PyPI) instead of `venv` (which is Python 3
-  only).
+* 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 3.14+, just add “cmake” to the pip install command.
+* 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`.
 
 ### Configuration options
 
-In CMake, configuration options are given with “-D”. Options are stored in the
+In CMake, configuration options are given with "-D". Options are stored in the
 build directory, in the `CMakeCache.txt` file, so they are remembered for each
 build directory. Two selections are special - the generator, given with `-G`,
 and the compiler, which is selected based on environment variables `CXX` and
@@ -115,12 +114,12 @@ after the initial run.
 The valid options are:
 
 * `-DCMAKE_BUILD_TYPE`: Release, Debug, MinSizeRel, RelWithDebInfo
-* `-DPYBIND11_FINDPYTHON=ON`: Use CMake 3.12+’s FindPython instead of the
+* `-DPYBIND11_FINDPYTHON=ON`: Use CMake 3.12+'s FindPython instead of the
   classic, deprecated, custom FindPythonLibs
 * `-DPYBIND11_NOPYTHON=ON`: Disable all Python searching (disables tests)
 * `-DBUILD_TESTING=ON`: Enable the tests
 * `-DDOWNLOAD_CATCH=ON`: Download catch to build the C++ tests
-* `-DOWNLOAD_EIGEN=ON`: Download Eigen for the NumPy tests
+* `-DDOWNLOAD_EIGEN=ON`: Download Eigen for the NumPy tests
 * `-DPYBIND11_INSTALL=ON/OFF`: Enable the install target (on by default for the
   master project)
 * `-DUSE_PYTHON_INSTALL_DIR=ON`: Try to install into the python dir
@@ -159,8 +158,9 @@ tests with these targets:
 * `test_cmake_build`: Install / subdirectory tests
 
 If you want to build just a subset of tests, use
-`-DPYBIND11_TEST_OVERRIDE="test_callbacks.cpp;test_pickling.cpp"`. If this is
-empty, all tests will be built.
+`-DPYBIND11_TEST_OVERRIDE="test_callbacks;test_pickling"`. If this is
+empty, all tests will be built. Tests are specified without an extension if they need both a .py and
+.cpp file.
 
 You may also pass flags to the `pytest` target by editing `tests/pytest.ini` or
 by using the `PYTEST_ADDOPTS` environment variable
@@ -235,12 +235,14 @@ directory inside your pybind11 git clone. Files will be modified in place,
 so you can use git to monitor the changes.
 
 ```bash
-docker run --rm -v $PWD:/mounted_pybind11 -it silkeh/clang:12
+docker run --rm -v $PWD:/mounted_pybind11 -it silkeh/clang:13
 apt-get update && apt-get install -y python3-dev python3-pytest
-cmake -S /mounted_pybind11/ -B build -DCMAKE_CXX_CLANG_TIDY="$(which clang-tidy);-fix" -DDOWNLOAD_EIGEN=ON -DDOWNLOAD_CATCH=ON -DCMAKE_CXX_STANDARD=17
-cmake --build build -j 2 -- --keep-going
+cmake -S /mounted_pybind11/ -B build -DCMAKE_CXX_CLANG_TIDY="$(which clang-tidy);--use-color" -DDOWNLOAD_EIGEN=ON -DDOWNLOAD_CATCH=ON -DCMAKE_CXX_STANDARD=17
+cmake --build build -j 2
 ```
 
+You can add `--fix` to the options list if you want.
+
 ### Include what you use
 
 To run include what you use, install (`brew install include-what-you-use` on
@@ -256,7 +258,7 @@ The report is sent to stderr; you can pipe it into a file if you wish.
 ### Build recipes
 
 This builds with the Intel compiler (assuming it is in your path, along with a
-recent CMake and Python 3):
+recent CMake and Python):
 
 ```bash
 python3 -m venv venv

.github/matchers/pylint.json

@@ -0,0 +1,32 @@
+{
+  "problemMatcher": [
+    {
+      "severity": "warning",
+      "pattern": [
+        {
+          "regexp": "^([^:]+):(\\d+):(\\d+): ([A-DF-Z]\\d+): \\033\\[[\\d;]+m([^\\033]+).*$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "code": 4,
+          "message": 5
+        }
+      ],
+      "owner": "pylint-warning"
+    },
+    {
+      "severity": "error",
+      "pattern": [
+        {
+          "regexp": "^([^:]+):(\\d+):(\\d+): (E\\d+): \\033\\[[\\d;]+m([^\\033]+).*$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "code": 4,
+          "message": 5
+        }
+      ],
+      "owner": "pylint-error"
+    }
+  ]
+}