Merge branch 'master' into sh_merge_master

.github/dependabot.yml

@@ -5,7 +5,3 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
-    ignore:
-      # Official actions have moving tags like v1
-      - dependency-name: "actions/*"
-        update-types: ["version-update:semver-minor", "version-update:semver-patch"]

.github/workflows/ci.yml

@@ -31,6 +31,7 @@ jobs:
         - '3.6'
         - '3.9'
         - '3.10'
+        - '3.11-dev'
         - 'pypy-3.7'
         - 'pypy-3.8'
         - 'pypy-3.9'
@@ -66,7 +67,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python ${{ matrix.python }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python }}
 
@@ -186,8 +187,8 @@ jobs:
         - python-version: "3.9"
           python-debug: true
           valgrind: true
-      # - python-version: "3.11-dev"
+        - python-version: "3.11-dev"
-      #   python-debug: false
+          python-debug: false
 
     name: "🐍 ${{ matrix.python-version }}${{ matrix.python-debug && '-dbg' || '' }} (deadsnakes)${{ matrix.valgrind && ' • Valgrind' || '' }} • x64"
     runs-on: ubuntu-latest
@@ -687,7 +688,9 @@ jobs:
     steps:
     - uses: actions/checkout@v3
 
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v4
+      with:
+        python-version: "3.x"
 
     - name: Install Doxygen
       run: sudo apt-get install -y doxygen librsvg2-bin # Changed to rsvg-convert in 20.04
@@ -735,7 +738,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python ${{ matrix.python }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python }}
         architecture: x86
@@ -788,7 +791,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python ${{ matrix.python }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python }}
         architecture: x86
@@ -836,7 +839,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python ${{ matrix.python }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python }}
 

.github/workflows/configure.yml

@@ -41,7 +41,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python 3.7
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: 3.7
         architecture: ${{ matrix.arch }}

.github/workflows/format.yml

@@ -22,7 +22,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v4
+      with:
+        python-version: "3.x"
     - name: Add matchers
       run: echo "::add-matcher::$GITHUB_WORKSPACE/.github/matchers/pylint.json"
     - uses: pre-commit/action@v3.0.0

.github/workflows/pip.yml

@@ -28,7 +28,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup 🐍 3.6
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: 3.6
 
@@ -50,7 +50,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup 🐍 3.8
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: 3.8
 
@@ -91,7 +91,9 @@ jobs:
     needs: [packaging]
 
     steps:
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v4
+      with:
+        python-version: "3.x"
 
     # Downloads all to directories matching the artifact names
     - uses: actions/download-artifact@v3

.github/workflows/upstream.yml

@@ -14,7 +14,7 @@ env:
 
 jobs:
   standard:
-    name: "🐍 3.11 dev • ubuntu-latest • x64"
+    name: "🐍 3.11 latest internals • ubuntu-latest • x64"
     runs-on: ubuntu-latest
     if: "contains(github.event.pull_request.labels.*.name, 'python dev')"
 
@@ -22,7 +22,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup Python 3.11
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: "3.11-dev"
 

.pre-commit-config.yaml

@@ -46,7 +46,7 @@ repos:
 
 # Black, the code formatter, natively supports pre-commit
 - repo: https://github.com/psf/black
-  rev: "22.3.0" # Keep in sync with blacken-docs
+  rev: "22.6.0" # Keep in sync with blacken-docs
   hooks:
   - id: black
 
@@ -56,11 +56,11 @@ repos:
   hooks:
   - id: blacken-docs
     additional_dependencies:
-    - black==22.3.0 # keep in sync with black hook
+    - black==22.6.0 # keep in sync with black hook
 
 # Changes tabs to spaces
 - repo: https://github.com/Lucas-C/pre-commit-hooks
-  rev: "v1.2.0"
+  rev: "v1.3.0"
   hooks:
   - id: remove-tabs
     exclude: (^docs/.*|\.patch)?$
@@ -110,7 +110,7 @@ repos:
 
 # PyLint has native support - not always usable, but works for us
 - repo: https://github.com/PyCQA/pylint
-  rev: "v2.14.3"
+  rev: "v2.14.4"
   hooks:
   - id: pylint
     files: ^pybind11
@@ -167,7 +167,7 @@ repos:
 
 # Clang format the codebase automatically
 - repo: https://github.com/pre-commit/mirrors-clang-format
-  rev: "v14.0.5"
+  rev: "v14.0.6"
   hooks:
   - id: clang-format
     types_or: [c++, c, cuda]

docs/changelog.rst

@@ -14,44 +14,164 @@ IN DEVELOPMENT
 
 Removed support for Python 2.7, Python 3.5, and MSVC 2015. Support for MSVC
 2017 is limited due to availability of CI runners; we highly recommend MSVC
-2019 or 2022 be used.
+2019 or 2022 be used. Initial support added for Python 3.11.
+
 
 New features:
 
+* ``py::anyset`` & ``py::frozenset`` were added, with copying (cast) to
+  ``std::set`` (similar to ``set``).
+  `#3901 <https://github.com/pybind/pybind11/pull/3901>`_
+
+* Support bytearray casting to string.
+  `#3707 <https://github.com/pybind/pybind11/pull/3707>`_
+
 * ``type_caster<std::monostate>`` was added. ``std::monostate`` is a tag type
   that allows ``std::variant`` to act as an optional, or allows default
   construction of a ``std::variant`` holding a non-default constructible type.
   `#3818 <https://github.com/pybind/pybind11/pull/3818>`_
 
-* Support bytearray casting to string.
+* ``pybind11::capsule::set_name`` added to mutate the name of the capsule instance.
-  `#3707 <https://github.com/pybind/pybind11/pull/3707>`_
+  `#3866 <https://github.com/pybind/pybind11/pull/3866>`_
+
+* NumPy: dtype constructor from type number added, accessors corresponding to
+  Python API ``dtype.num``, ``dtype.byteorder``, ``dtype.flags`` and
+  ``dtype.alignment`` added.
+  `#3868 <https://github.com/pybind/pybind11/pull/3868>`_
+
 
 Changes:
 
-* Python 2 support was removed completely.
+* Python 3.6 is now the minimum supported version.
   `#3688 <https://github.com/pybind/pybind11/pull/3688>`_
+  `#3719 <https://github.com/pybind/pybind11/pull/3719>`_
 
 * The minimum version for MSVC is now 2017.
   `#3722 <https://github.com/pybind/pybind11/pull/3722>`_
 
+* Fix issues with CPython 3.11 betas and add to supported test matrix.
+  `#3923 <https://github.com/pybind/pybind11/pull/3923>`_
+
+* ``error_already_set`` is now safer and more performant, especially for
+  exceptions with long tracebacks, by delaying computation.
+  `#1895 <https://github.com/pybind/pybind11/pull/1895>`_
+
 * Improve exception handling in python ``str`` bindings.
   `#3826 <https://github.com/pybind/pybind11/pull/3826>`_
 
 * The bindings for capsules now have more consistent exception handling.
   `#3825 <https://github.com/pybind/pybind11/pull/3825>`_
 
-* Fix exception handling when ``pybind11::weakref()`` fails.
+* ``PYBIND11_OBJECT_CVT`` and ``PYBIND11_OBJECT_CVT_DEFAULT`` macro can now be
-  `#3739 <https://github.com/pybind/pybind11/pull/3739>`_
+  used to define classes in namespaces other than pybind11.
+  `#3797 <https://github.com/pybind/pybind11/pull/3797>`_
+
+* Error printing code now uses ``PYBIND11_DETAILED_ERROR_MESSAGES`` instead of
+  requiring ``NDEBUG``, allowing use with release builds if desired.
+  `#3913 <https://github.com/pybind/pybind11/pull/3913>`_
 
 
 Bug fixes:
 
-* ``PYBIND11_OBJECT_CVT`` and ``PYBIND11_OBJECT_CVT_DEFAULT`` macro can be used
+* Fix exception handling when ``pybind11::weakref()`` fails.
-  to define classes in namespaces other than pybind11.
+  `#3739 <https://github.com/pybind/pybind11/pull/3739>`_
-  `#3797 <https://github.com/pybind/pybind11/pull/3797>`_
+
+* ``module_::def_submodule`` was missing proper error handling. This is fixed now.
+  `#3973 <https://github.com/pybind/pybind11/pull/3973>`_
+
+* The behavior or ``error_already_set`` was made safer and the highly opaque
+  "Unknown internal error occurred" message was replaced with a more helpful
+  message.
+  `#3982 <https://github.com/pybind/pybind11/pull/3982>`_
+
+* ``error_already_set::what()`` now handles non-normalized exceptions correctly.
+  `#3971 <https://github.com/pybind/pybind11/pull/3971>`_
+
+* Support older C++ compilers where filesystem is not yet part of the standard
+  library and is instead included in ``std::experimental::filesystem``.
+  `#3840 <https://github.com/pybind/pybind11/pull/3840>`_
+
+* Fix ``-Wfree-nonheap-object`` warnings produced by GCC by avoiding returning
+  pointers to static objects with ``return_value_policy::take_ownership``.
+  `#3946 <https://github.com/pybind/pybind11/pull/3946>`_
+
+* Fix cast from pytype rvalue to another pytype.
+  `#3949 <https://github.com/pybind/pybind11/pull/3949>`_
+
+* ``pybind11::detail::get_internals()`` is now resilient to in-flight Python
+  exceptions.
+  `#3981 <https://github.com/pybind/pybind11/pull/3981>`_
+
+* Arrays with a dimension of size 0 are now properly converted to dynamic Eigen
+  matrices (more common in NumPy 1.23).
+  `#4038 <https://github.com/pybind/pybind11/pull/4038>`_
+
+* Avoid catching unrelated errors when importing NumPy.
+  `#3974 <https://github.com/pybind/pybind11/pull/3974>`_
+
+Performance and style:
+
+* Added an accessor overload of ``(object &&key)`` to reference steal the
+  object when using python types as keys. This prevents unnecessary reference
+  count overhead for attr, dictionary, tuple, and sequence look ups. Added
+  additional regression tests. Fixed a performance bug the caused accessor
+  assignments to potentially perform unnecessary copies.
+  `#3970 <https://github.com/pybind/pybind11/pull/3970>`_
+
+* Perfect forward all args of ``make_iterator``.
+  `#3980 <https://github.com/pybind/pybind11/pull/3980>`_
+
+* Avoid potential bug in pycapsule destructor by adding an ``error_guard`` to
+  one of the dtors.
+  `#3958 <https://github.com/pybind/pybind11/pull/3958>`_
+
+* Optimize dictionary access in ``strip_padding`` for numpy.
+  `#3994 <https://github.com/pybind/pybind11/pull/3994>`_
+
+* ``stl_bind.h`` bindings now take slice args as a const-ref.
+  `#3852 <https://github.com/pybind/pybind11/pull/3852>`_
+
+* Made slice constructor more consistent, and improve performance of some
+  casters by allowing reference stealing.
+  `#3845 <https://github.com/pybind/pybind11/pull/3845>`_
+
+* Change numpy dtype from_args method to use const ref.
+  `#3878 <https://github.com/pybind/pybind11/pull/3878>`_
+
+* Follow rule of three to ensure ``PyErr_Restore`` is called only once.
+  `#3872 <https://github.com/pybind/pybind11/pull/3872>`_
+
+* Added missing perfect forwarding for ``make_iterator`` functions.
+  `#3860 <https://github.com/pybind/pybind11/pull/3860>`_
+
+* Optimize c++ to python function casting by using the rvalue caster.
+  `#3966 <https://github.com/pybind/pybind11/pull/3966>`_
+
+* Avoid potential implicit copy/assignment constructors causing double free in
+  ``strdup_gaurd``.
+  `#3905 <https://github.com/pybind/pybind11/pull/3905>`_
+
+* Enable clang-tidy checks ``misc-definitions-in-headers``,
+  ``modernize-loop-convert``, and ``modernize-use-nullptr``.
+  `#3881 <https://github.com/pybind/pybind11/pull/3881>`_
+  `#3988 <https://github.com/pybind/pybind11/pull/3988>`_
+
 
 Build system improvements:
 
+* CMake: Fix file extension on Windows with cp36 and cp37 using FindPython.
+  `#3919 <https://github.com/pybind/pybind11/pull/3919>`_
+
+* CMake: Support multiple Python targets (such as on vcpkg).
+  `#3948 <https://github.com/pybind/pybind11/pull/3948>`_
+
+* CMake: Fix issue with NVCC on Windows.
+  `#3947 <https://github.com/pybind/pybind11/pull/3947>`_
+
+* CMake: Drop the bitness check on cross compiles (like targeting WebAssembly
+  via Emscripten).
+  `#3959 <https://github.com/pybind/pybind11/pull/3959>`_
+
 * Add MSVC builds in debug mode to CI.
   `#3784 <https://github.com/pybind/pybind11/pull/3784>`_
 
@@ -59,15 +179,20 @@ Build system improvements:
   `#3732 <https://github.com/pybind/pybind11/pull/3732>`_,
   `#3741 <https://github.com/pybind/pybind11/pull/3741>`_
 
-* Avoid ``setup.py <command>`` usage in internal tests.
-  `#3734 <https://github.com/pybind/pybind11/pull/3734>`_
-
 
 Backend and tidying up:
 
-* Remove idioms in code comments.  Use inclusive language.
+* Remove idioms in code comments.  Use more inclusive language.
   `#3809 <https://github.com/pybind/pybind11/pull/3809>`_
 
+* ``#include <iostream>`` was removed from the ``pybind11/stl.h`` header. Your
+  project may break if it has a transitive dependency on this include. The fix
+  is to "Include What You Use".
+  `#3928 <https://github.com/pybind/pybind11/pull/3928>`_
+
+* Avoid ``setup.py <command>`` usage in internal tests.
+  `#3734 <https://github.com/pybind/pybind11/pull/3734>`_
+
 
 Version 2.9.2 (Mar 29, 2022)
 ----------------------------

docs/classes.rst

@@ -482,7 +482,7 @@ The binding code for this example looks as follows:
         .value("Cat", Pet::Kind::Cat)
         .export_values();
 
-    py::class_<Pet::Attributes> attributes(pet, "Attributes")
+    py::class_<Pet::Attributes>(pet, "Attributes")
         .def(py::init<>())
         .def_readwrite("age", &Pet::Attributes::age);
 

include/pybind11/attr.h

@@ -345,9 +345,11 @@ struct type_record {
 
         bases.append((PyObject *) base_info->type);
 
-        if (base_info->type->tp_dictoffset != 0) {
+#if PY_VERSION_HEX < 0x030B0000
-            dynamic_attr = true;
+        dynamic_attr |= base_info->type->tp_dictoffset != 0;
-        }
+#else
+        dynamic_attr |= (base_info->type->tp_flags & Py_TPFLAGS_MANAGED_DICT) != 0;
+#endif
 
         if (caster) {
             base_info->implicit_casts.emplace_back(type, caster);

include/pybind11/cast.h

@@ -871,7 +871,7 @@ struct always_construct_holder {
 
 /// Create a specialization for custom holder types (silently ignores std::shared_ptr)
 #define PYBIND11_DECLARE_HOLDER_TYPE(type, holder_type, ...)                                      \
-    namespace pybind11 {                                                                          \
+    PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)                                                  \
     namespace detail {                                                                            \
     template <typename type>                                                                      \
     struct always_construct_holder<holder_type> : always_construct_holder<void, ##__VA_ARGS__> {  \
@@ -880,7 +880,7 @@ struct always_construct_holder {
     class type_caster<holder_type, enable_if_t<!is_shared_ptr<holder_type>::value>>               \
         : public type_caster_holder<type, holder_type> {};                                        \
     }                                                                                             \
-    }
+    PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
 // PYBIND11_DECLARE_HOLDER_TYPE holder types:
 template <typename base, typename holder>
@@ -1680,12 +1680,12 @@ handle type::handle_of() {
 }
 
 #define PYBIND11_MAKE_OPAQUE(...)                                                                 \
-    namespace pybind11 {                                                                          \
+    PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)                                                  \
     namespace detail {                                                                            \
     template <>                                                                                   \
     class type_caster<__VA_ARGS__> : public type_caster_for_class_<__VA_ARGS__> {};               \
     }                                                                                             \
-    }
+    PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
 /// Lets you pass a type containing a `,` through a macro parameter without needing a separate
 /// typedef, e.g.:

include/pybind11/detail/class.h

@@ -533,6 +533,10 @@ extern "C" inline int pybind11_set_dict(PyObject *self, PyObject *new_dict, void
 extern "C" inline int pybind11_traverse(PyObject *self, visitproc visit, void *arg) {
     PyObject *&dict = *_PyObject_GetDictPtr(self);
     Py_VISIT(dict);
+// https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_traverse
+#if PY_VERSION_HEX >= 0x03090000
+    Py_VISIT(Py_TYPE(self));
+#endif
     return 0;
 }
 
@@ -547,8 +551,12 @@ extern "C" inline int pybind11_clear(PyObject *self) {
 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     auto *type = &heap_type->ht_type;
     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
+#if PY_VERSION_HEX < 0x030B0000
     type->tp_dictoffset = type->tp_basicsize;           // place dict at the end
     type->tp_basicsize += (ssize_t) sizeof(PyObject *); // and allocate enough space for it
+#else
+    type->tp_flags |= Py_TPFLAGS_MANAGED_DICT;
+#endif
     type->tp_traverse = pybind11_traverse;
     type->tp_clear = pybind11_clear;
 

include/pybind11/detail/common.h

@@ -38,6 +38,7 @@
 #            define PYBIND11_CPP17
 #            if __cplusplus >= 202002L
 #                define PYBIND11_CPP20
+// Please update tests/pybind11_tests.cpp `cpp_std()` when adding a macro here.
 #            endif
 #        endif
 #    endif

include/pybind11/detail/init.h

@@ -498,4 +498,4 @@ struct pickle_factory<Get, Set, RetState(Self), NewInstance(ArgState)> {
 
 PYBIND11_NAMESPACE_END(initimpl)
 PYBIND11_NAMESPACE_END(detail)
-PYBIND11_NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/detail/typeid.h

@@ -20,6 +20,7 @@
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(detail)
+
 /// Erase all occurrences of a substring
 inline void erase_all(std::string &string, const std::string &search) {
     for (size_t pos = 0;;) {
@@ -46,14 +47,19 @@ PYBIND11_NOINLINE void clean_type_id(std::string &name) {
 #endif
     detail::erase_all(name, "pybind11::");
 }
+
+inline std::string clean_type_id(const char *typeid_name) {
+    std::string name(typeid_name);
+    detail::clean_type_id(name);
+    return name;
+}
+
 PYBIND11_NAMESPACE_END(detail)
 
 /// Return a string representation of a C++ type
 template <typename T>
 static std::string type_id() {
-    std::string name(typeid(T).name());
+    return detail::clean_type_id(typeid(T).name());
-    detail::clean_type_id(name);
-    return name;
 }
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

include/pybind11/eigen.h

@@ -111,9 +111,15 @@ struct EigenConformable {
     bool stride_compatible() const {
         // To have compatible strides, we need (on both dimensions) one of fully dynamic strides,
         // matching strides, or a dimension size of 1 (in which case the stride value is
-        // irrelevant)
+        // irrelevant). Alternatively, if any dimension size is 0, the strides are not relevant
-        return !negativestrides
+        // (and numpy ≥ 1.23 sets the strides to 0 in that case, so we need to check explicitly).
-               && (props::inner_stride == Eigen::Dynamic || props::inner_stride == stride.inner()
+        if (negativestrides) {
+            return false;
+        }
+        if (rows == 0 || cols == 0) {
+            return true;
+        }
+        return (props::inner_stride == Eigen::Dynamic || props::inner_stride == stride.inner()
                 || (EigenRowMajor ? cols : rows) == 1)
                && (props::outer_stride == Eigen::Dynamic || props::outer_stride == stride.outer()
                    || (EigenRowMajor ? rows : cols) == 1);

include/pybind11/embed.h

@@ -86,37 +86,6 @@ inline wchar_t *widen_chars(const char *safe_arg) {
     return widened_arg;
 }
 
-/// Python 2.x/3.x-compatible version of `PySys_SetArgv`
-inline void set_interpreter_argv(int argc, const char *const *argv, bool add_program_dir_to_path) {
-    // 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.
-    std::unique_ptr<wchar_t *[]> widened_argv(new wchar_t *[argv_size]);
-    std::vector<std::unique_ptr<wchar_t[], 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(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.
-            return;
-        }
-        widened_argv[ii] = widened_argv_entries.back().get();
-    }
-
-    auto *pysys_argv = widened_argv.get();
-    PySys_SetArgvEx(argc, pysys_argv, static_cast<int>(add_program_dir_to_path));
-}
-
 PYBIND11_NAMESPACE_END(detail)
 
 /** \rst
@@ -146,9 +115,64 @@ inline void initialize_interpreter(bool init_signal_handlers = true,
         pybind11_fail("The interpreter is already running");
     }
 
+#if PY_VERSION_HEX < 0x030B0000
+
     Py_InitializeEx(init_signal_handlers ? 1 : 0);
 
-    detail::set_interpreter_argv(argc, argv, add_program_dir_to_path);
+    // 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.
+    std::unique_ptr<wchar_t *[]> widened_argv(new wchar_t *[argv_size]);
+    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(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.
+            return;
+        }
+        widened_argv[ii] = widened_argv_entries.back().get();
+    }
+
+    auto *pysys_argv = widened_argv.get();
+
+    PySys_SetArgvEx(argc, pysys_argv, static_cast<int>(add_program_dir_to_path));
+#else
+    PyConfig config;
+    PyConfig_InitIsolatedConfig(&config);
+    config.install_signal_handlers = init_signal_handlers ? 1 : 0;
+
+    PyStatus status = PyConfig_SetBytesArgv(&config, argc, const_cast<char *const *>(argv));
+    if (PyStatus_Exception(status)) {
+        // A failure here indicates a character-encoding failure or the python
+        // interpreter out of memory. Give up.
+        PyConfig_Clear(&config);
+        throw std::runtime_error(PyStatus_IsError(status) ? status.err_msg
+                                                          : "Failed to prepare CPython");
+    }
+    status = Py_InitializeFromConfig(&config);
+    PyConfig_Clear(&config);
+    if (PyStatus_Exception(status)) {
+        throw std::runtime_error(PyStatus_IsError(status) ? status.err_msg
+                                                          : "Failed to init CPython");
+    }
+    if (add_program_dir_to_path) {
+        PyRun_SimpleString("import sys, os.path; "
+                           "sys.path.insert(0, "
+                           "os.path.abspath(os.path.dirname(sys.argv[0])) "
+                           "if sys.argv and os.path.exists(sys.argv[0]) else '')");
+    }
+#endif
 }
 
 /** \rst

setup.cfg

@@ -19,6 +19,7 @@ classifiers =
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
     License :: OSI Approved :: BSD License
     Programming Language :: Python :: Implementation :: PyPy
     Programming Language :: Python :: Implementation :: CPython

tests/conftest.py

@@ -13,7 +13,7 @@ import textwrap
 import pytest
 
 # Early diagnostic for failed imports
-import pybind11_tests  # noqa: F401
+import pybind11_tests
 
 _long_marker = re.compile(r"([0-9])L")
 _hexadecimal = re.compile(r"0x[0-9a-fA-F]+")
@@ -198,3 +198,16 @@ def gc_collect():
 def pytest_configure():
     pytest.suppress = suppress
     pytest.gc_collect = gc_collect
+
+
+def pytest_report_header(config):
+    del config  # Unused.
+    assert (
+        pybind11_tests.compiler_info is not None
+    ), "Please update pybind11_tests.cpp if this assert fails."
+    return (
+        "C++ Info:"
+        f" {pybind11_tests.compiler_info}"
+        f" {pybind11_tests.cpp_std}"
+        f" {pybind11_tests.PYBIND11_INTERNALS_ID}"
+    )

tests/pybind11_tests.cpp

@@ -62,9 +62,34 @@ void bind_ConstructorStats(py::module_ &m) {
         });
 }
 
+const char *cpp_std() {
+    return
+#if defined(PYBIND11_CPP20)
+        "C++20";
+#elif defined(PYBIND11_CPP17)
+        "C++17";
+#elif defined(PYBIND11_CPP14)
+        "C++14";
+#else
+        "C++11";
+#endif
+}
+
 PYBIND11_MODULE(pybind11_tests, m) {
     m.doc() = "pybind11 test module";
 
+    // Intentionally kept minimal to not create a maintenance chore
+    // ("just enough" to be conclusive).
+#if defined(_MSC_FULL_VER)
+    m.attr("compiler_info") = "MSVC " PYBIND11_TOSTRING(_MSC_FULL_VER);
+#elif defined(__VERSION__)
+    m.attr("compiler_info") = __VERSION__;
+#else
+    m.attr("compiler_info") = py::none();
+#endif
+    m.attr("cpp_std") = cpp_std();
+    m.attr("PYBIND11_INTERNALS_ID") = PYBIND11_INTERNALS_ID;
+
     bind_ConstructorStats(m);
 
 #if defined(PYBIND11_DETAILED_ERROR_MESSAGES)

tests/requirements.txt

@@ -1,4 +1,4 @@
-build==0.7.0
+build==0.8.0
 numpy==1.21.5; platform_python_implementation=="PyPy" and sys_platform=="linux" and python_version=="3.7"
 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"

tests/test_eigen.cpp

@@ -345,10 +345,13 @@ TEST_SUBMODULE(eigen, m) {
         },
         py::arg{}.noconvert());
 
-    // test_issue738
+    // test_issue738, test_zero_length
-    // Issue #738: 1xN or Nx1 2D matrices were neither accepted nor properly copied with an
+    // Issue #738: 1×N or N×1 2D matrices were neither accepted nor properly copied with an
     // incompatible stride value on the length-1 dimension--but that should be allowed (without
     // requiring a copy!) because the stride value can be safely ignored on a size-1 dimension.
+    // Similarly, 0×N or N×0 matrices were not accepted--again, these should be allowed since
+    // they contain no data. This particularly affects numpy ≥ 1.23, which sets the strides to
+    // 0 if any dimension size is 0.
     m.def("iss738_f1",
           &adjust_matrix<const Eigen::Ref<const Eigen::MatrixXd> &>,
           py::arg{}.noconvert());

tests/test_eigen.py

@@ -744,6 +744,13 @@ def test_issue738():
     )
 
 
+@pytest.mark.parametrize("func", [m.iss738_f1, m.iss738_f2])
+@pytest.mark.parametrize("sizes", [(0, 2), (2, 0)])
+def test_zero_length(func, sizes):
+    """Ignore strides on a length-0 dimension (even if they would be incompatible length > 1)"""
+    assert np.all(func(np.zeros(sizes)) == np.zeros(sizes))
+
+
 def test_issue1105():
     """Issue 1105: 1xN or Nx1 input arrays weren't accepted for eigen
     compile-time row vectors or column vector"""

tests/test_methods_and_attributes.py

@@ -1,9 +1,21 @@
+import sys
+
 import pytest
 
 import env  # noqa: F401
 from pybind11_tests import ConstructorStats
 from pybind11_tests import methods_and_attributes as m
 
+NO_GETTER_MSG = (
+    "unreadable attribute" if sys.version_info < (3, 11) else "object has no getter"
+)
+NO_SETTER_MSG = (
+    "can't set attribute" if sys.version_info < (3, 11) else "object has no setter"
+)
+NO_DELETER_MSG = (
+    "can't delete attribute" if sys.version_info < (3, 11) else "object has no deleter"
+)
+
 
 def test_methods_and_attributes():
     instance1 = m.ExampleMandA()
@@ -102,32 +114,32 @@ def test_properties():
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_writeonly  # unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     instance.def_property_writeonly = 4
     assert instance.def_property_readonly == 4
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_impossible  # noqa: F841 unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     with pytest.raises(AttributeError) as excinfo:
         instance.def_property_impossible = 5
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
 
 def test_static_properties():
     assert m.TestProperties.def_readonly_static == 1
     with pytest.raises(AttributeError) as excinfo:
         m.TestProperties.def_readonly_static = 2
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_readwrite_static = 2
     assert m.TestProperties.def_readwrite_static == 2
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = m.TestProperties.def_writeonly_static  # unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_writeonly_static = 3
     assert m.TestProperties.def_readonly_static == 3
@@ -135,14 +147,14 @@ def test_static_properties():
     assert m.TestProperties.def_property_readonly_static == 3
     with pytest.raises(AttributeError) as excinfo:
         m.TestProperties.def_property_readonly_static = 99
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_property_static = 4
     assert m.TestProperties.def_property_static == 4
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = m.TestProperties.def_property_writeonly_static
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_property_writeonly_static = 5
     assert m.TestProperties.def_property_static == 5
@@ -160,7 +172,7 @@ def test_static_properties():
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_writeonly_static  # noqa: F841 unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     instance.def_property_writeonly_static = 4
     assert instance.def_property_static == 4
@@ -180,7 +192,7 @@ def test_static_properties():
     properties_override = m.TestPropertiesOverride()
     with pytest.raises(AttributeError) as excinfo:
         del properties_override.def_readonly
-    assert "can't delete attribute" in str(excinfo.value)
+    assert NO_DELETER_MSG in str(excinfo.value)
 
 
 def test_static_cls():