EIC code displayed by LXR master/​jana2/​src/​python/​externals/​pybind11-2.10.3/​include/​pybind11/​pybind11.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2025-01-18 10:17:49

 /*
     pybind11/pybind11.h: Main header file of the C++11 python
     binding generator library
 
     Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
 
     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 "detail/class.h"
 #include "detail/init.h"
 #include "attr.h"
 #include "gil.h"
 #include "options.h"
 
 #include <cstdlib>
 #include <cstring>
 #include <memory>
 #include <new>
 #include <string>
 #include <utility>
 #include <vector>
 
 #if defined(__cpp_lib_launder) && !(defined(_MSC_VER) && (_MSC_VER < 1914))
 #    define PYBIND11_STD_LAUNDER std::launder
 #    define PYBIND11_HAS_STD_LAUNDER 1
 #else
 #    define PYBIND11_STD_LAUNDER
 #    define PYBIND11_HAS_STD_LAUNDER 0
 #endif
 #if defined(__GNUG__) && !defined(__clang__)
 #    include <cxxabi.h>
 #endif
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 /* https://stackoverflow.com/questions/46798456/handling-gccs-noexcept-type-warning
    This warning is about ABI compatibility, not code health.
    It is only actually needed in a couple places, but apparently GCC 7 "generates this warning if
    and only if the first template instantiation ... involves noexcept" [stackoverflow], therefore
    it could get triggered from seemingly random places, depending on user code.
    No other GCC version generates this warning.
  */
 #if defined(__GNUC__) && __GNUC__ == 7
 PYBIND11_WARNING_DISABLE_GCC("-Wnoexcept-type")
 #endif
 
 PYBIND11_WARNING_DISABLE_MSVC(4127)
 
 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;
 }
 
 #if defined(_MSC_VER)
 #    define PYBIND11_COMPAT_STRDUP _strdup
 #else
 #    define PYBIND11_COMPAT_STRDUP strdup
 #endif
 
 PYBIND11_NAMESPACE_END(detail)
 
 /// Wraps an arbitrary C++ function/method/lambda function/.. into a callable Python object
 class cpp_function : public function {
 public:
     cpp_function() = default;
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(std::nullptr_t) {}
 
     /// Construct a cpp_function from a vanilla function pointer
     template <typename Return, typename... Args, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (*f)(Args...), const Extra &...extra) {
         initialize(f, f, extra...);
     }
 
     /// Construct a cpp_function from a lambda function (possibly with internal state)
     template <typename Func,
               typename... Extra,
               typename = detail::enable_if_t<detail::is_lambda<Func>::value>>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Func &&f, const Extra &...extra) {
         initialize(
             std::forward<Func>(f), (detail::function_signature_t<Func> *) nullptr, extra...);
     }
 
     /// Construct a cpp_function from a class method (non-const, no ref-qualifier)
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...), const Extra &...extra) {
         initialize(
             [f](Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
             (Return(*)(Class *, Arg...)) nullptr,
             extra...);
     }
 
     /// Construct a cpp_function from a class method (non-const, lvalue ref-qualifier)
     /// A copy of the overload for non-const functions without explicit ref-qualifier
     /// but with an added `&`.
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...) &, const Extra &...extra) {
         initialize(
             [f](Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
             (Return(*)(Class *, Arg...)) nullptr,
             extra...);
     }
 
     /// Construct a cpp_function from a class method (const, no ref-qualifier)
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...) const, const Extra &...extra) {
         initialize([f](const Class *c,
                        Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
                    (Return(*)(const Class *, Arg...)) nullptr,
                    extra...);
     }
 
     /// Construct a cpp_function from a class method (const, lvalue ref-qualifier)
     /// A copy of the overload for const functions without explicit ref-qualifier
     /// but with an added `&`.
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...) const &, const Extra &...extra) {
         initialize([f](const Class *c,
                        Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
                    (Return(*)(const Class *, Arg...)) nullptr,
                    extra...);
     }
 
     /// Return the function name
     object name() const { return attr("__name__"); }
 
 protected:
     struct InitializingFunctionRecordDeleter {
         // `destruct(function_record, false)`: `initialize_generic` copies strings and
         // takes care of cleaning up in case of exceptions. So pass `false` to `free_strings`.
         void operator()(detail::function_record *rec) { destruct(rec, false); }
     };
     using unique_function_record
         = std::unique_ptr<detail::function_record, InitializingFunctionRecordDeleter>;
 
     /// Space optimization: don't inline this frequently instantiated fragment
     PYBIND11_NOINLINE unique_function_record make_function_record() {
         return unique_function_record(new detail::function_record());
     }
 
     /// Special internal constructor for functors, lambda functions, etc.
     template <typename Func, typename Return, typename... Args, typename... Extra>
     void initialize(Func &&f, Return (*)(Args...), const Extra &...extra) {
         using namespace detail;
         struct capture {
             remove_reference_t<Func> f;
         };
 
         /* Store the function including any extra state it might have (e.g. a lambda capture
          * object) */
         // The unique_ptr makes sure nothing is leaked in case of an exception.
         auto unique_rec = make_function_record();
         auto *rec = unique_rec.get();
 
         /* Store the capture object directly in the function record if there is enough space */
         if (sizeof(capture) <= sizeof(rec->data)) {
             /* Without these pragmas, GCC warns that there might not be
                enough space to use the placement new operator. However, the
                'if' statement above ensures that this is the case. */
             PYBIND11_WARNING_PUSH
 
 #if defined(__GNUG__) && __GNUC__ >= 6
             PYBIND11_WARNING_DISABLE_GCC("-Wplacement-new")
 #endif
 
             new ((capture *) &rec->data) capture{std::forward<Func>(f)};
 
 #if !PYBIND11_HAS_STD_LAUNDER
             PYBIND11_WARNING_DISABLE_GCC("-Wstrict-aliasing")
 #endif
 
             // UB without std::launder, but without breaking ABI and/or
             // a significant refactoring it's "impossible" to solve.
             if (!std::is_trivially_destructible<capture>::value) {
                 rec->free_data = [](function_record *r) {
                     auto data = PYBIND11_STD_LAUNDER((capture *) &r->data);
                     (void) data;
                     data->~capture();
                 };
             }
             PYBIND11_WARNING_POP
         } else {
             rec->data[0] = new capture{std::forward<Func>(f)};
             rec->free_data = [](function_record *r) { delete ((capture *) r->data[0]); };
         }
 
         /* Type casters for the function arguments and return value */
         using cast_in = argument_loader<Args...>;
         using cast_out
             = make_caster<conditional_t<std::is_void<Return>::value, void_type, Return>>;
 
         static_assert(
             expected_num_args<Extra...>(
                 sizeof...(Args), cast_in::args_pos >= 0, cast_in::has_kwargs),
             "The number of argument annotations does not match the number of function arguments");
 
         /* Dispatch code which converts function arguments and performs the actual function call */
         rec->impl = [](function_call &call) -> handle {
             cast_in args_converter;
 
             /* Try to cast the function arguments into the C++ domain */
             if (!args_converter.load_args(call)) {
                 return PYBIND11_TRY_NEXT_OVERLOAD;
             }
 
             /* Invoke call policy pre-call hook */
             process_attributes<Extra...>::precall(call);
 
             /* Get a pointer to the capture object */
             const auto *data = (sizeof(capture) <= sizeof(call.func.data) ? &call.func.data
                                                                           : call.func.data[0]);
             auto *cap = const_cast<capture *>(reinterpret_cast<const capture *>(data));
 
             /* Override policy for rvalues -- usually to enforce rvp::move on an rvalue */
             return_value_policy policy
                 = return_value_policy_override<Return>::policy(call.func.policy);
 
             /* Function scope guard -- defaults to the compile-to-nothing `void_type` */
             using Guard = extract_guard_t<Extra...>;
 
             /* Perform the function call */
             handle result
                 = cast_out::cast(std::move(args_converter).template call<Return, Guard>(cap->f),
                                  policy,
                                  call.parent);
 
             /* Invoke call policy post-call hook */
             process_attributes<Extra...>::postcall(call, result);
 
             return result;
         };
 
         rec->nargs_pos = cast_in::args_pos >= 0
                              ? static_cast<std::uint16_t>(cast_in::args_pos)
                              : sizeof...(Args) - cast_in::has_kwargs; // Will get reduced more if
                                                                       // we have a kw_only
         rec->has_args = cast_in::args_pos >= 0;
         rec->has_kwargs = cast_in::has_kwargs;
 
         /* Process any user-provided function attributes */
         process_attributes<Extra...>::init(extra..., rec);
 
         {
             constexpr bool has_kw_only_args = any_of<std::is_same<kw_only, Extra>...>::value,
                            has_pos_only_args = any_of<std::is_same<pos_only, Extra>...>::value,
                            has_arg_annotations = any_of<is_keyword<Extra>...>::value;
             static_assert(has_arg_annotations || !has_kw_only_args,
                           "py::kw_only requires the use of argument annotations");
             static_assert(has_arg_annotations || !has_pos_only_args,
                           "py::pos_only requires the use of argument annotations (for docstrings "
                           "and aligning the annotations to the argument)");
 
             static_assert(constexpr_sum(is_kw_only<Extra>::value...) <= 1,
                           "py::kw_only may be specified only once");
             static_assert(constexpr_sum(is_pos_only<Extra>::value...) <= 1,
                           "py::pos_only may be specified only once");
             constexpr auto kw_only_pos = constexpr_first<is_kw_only, Extra...>();
             constexpr auto pos_only_pos = constexpr_first<is_pos_only, Extra...>();
             static_assert(!(has_kw_only_args && has_pos_only_args) || pos_only_pos < kw_only_pos,
                           "py::pos_only must come before py::kw_only");
         }
 
         /* Generate a readable signature describing the function's arguments and return
            value types */
         static constexpr auto signature
             = const_name("(") + cast_in::arg_names + const_name(") -> ") + cast_out::name;
         PYBIND11_DESCR_CONSTEXPR auto types = decltype(signature)::types();
 
         /* Register the function with Python from generic (non-templated) code */
         // Pass on the ownership over the `unique_rec` to `initialize_generic`. `rec` stays valid.
         initialize_generic(std::move(unique_rec), signature.text, types.data(), sizeof...(Args));
 
         /* Stash some additional information used by an important optimization in 'functional.h' */
         using FunctionType = Return (*)(Args...);
         constexpr bool is_function_ptr
             = std::is_convertible<Func, FunctionType>::value && sizeof(capture) == sizeof(void *);
         if (is_function_ptr) {
             rec->is_stateless = true;
             rec->data[1]
                 = const_cast<void *>(reinterpret_cast<const void *>(&typeid(FunctionType)));
         }
     }
 
     // Utility class that keeps track of all duplicated strings, and cleans them up in its
     // destructor, unless they are released. Basically a RAII-solution to deal with exceptions
     // along the way.
     class strdup_guard {
     public:
         strdup_guard() = default;
         strdup_guard(const strdup_guard &) = delete;
         strdup_guard &operator=(const strdup_guard &) = delete;
 
         ~strdup_guard() {
             for (auto *s : strings) {
                 std::free(s);
             }
         }
         char *operator()(const char *s) {
             auto *t = PYBIND11_COMPAT_STRDUP(s);
             strings.push_back(t);
             return t;
         }
         void release() { strings.clear(); }
 
     private:
         std::vector<char *> strings;
     };
 
     /// Register a function call with Python (generic non-templated code goes here)
     void initialize_generic(unique_function_record &&unique_rec,
                             const char *text,
                             const std::type_info *const *types,
                             size_t args) {
         // Do NOT receive `unique_rec` by value. If this function fails to move out the unique_ptr,
         // we do not want this to destruct the pointer. `initialize` (the caller) still relies on
         // the pointee being alive after this call. Only move out if a `capsule` is going to keep
         // it alive.
         auto *rec = unique_rec.get();
 
         // Keep track of strdup'ed strings, and clean them up as long as the function's capsule
         // has not taken ownership yet (when `unique_rec.release()` is called).
         // Note: This cannot easily be fixed by a `unique_ptr` with custom deleter, because the
         // strings are only referenced before strdup'ing. So only *after* the following block could
         // `destruct` safely be called, but even then, `repr` could still throw in the middle of
         // copying all strings.
         strdup_guard guarded_strdup;
 
         /* Create copies of all referenced C-style strings */
         rec->name = guarded_strdup(rec->name ? rec->name : "");
         if (rec->doc) {
             rec->doc = guarded_strdup(rec->doc);
         }
         for (auto &a : rec->args) {
             if (a.name) {
                 a.name = guarded_strdup(a.name);
             }
             if (a.descr) {
                 a.descr = guarded_strdup(a.descr);
             } else if (a.value) {
                 a.descr = guarded_strdup(repr(a.value).cast<std::string>().c_str());
             }
         }
 
         rec->is_constructor = (std::strcmp(rec->name, "__init__") == 0)
                               || (std::strcmp(rec->name, "__setstate__") == 0);
 
 #if defined(PYBIND11_DETAILED_ERROR_MESSAGES) && !defined(PYBIND11_DISABLE_NEW_STYLE_INIT_WARNING)
         if (rec->is_constructor && !rec->is_new_style_constructor) {
             const auto class_name
                 = detail::get_fully_qualified_tp_name((PyTypeObject *) rec->scope.ptr());
             const auto func_name = std::string(rec->name);
             PyErr_WarnEx(PyExc_FutureWarning,
                          ("pybind11-bound class '" + class_name
                           + "' is using an old-style "
                             "placement-new '"
                           + func_name
                           + "' which has been deprecated. See "
                             "the upgrade guide in pybind11's docs. This message is only visible "
                             "when compiled in debug mode.")
                              .c_str(),
                          0);
         }
 #endif
 
         /* Generate a proper function signature */
         std::string signature;
         size_t type_index = 0, arg_index = 0;
         bool is_starred = false;
         for (const auto *pc = text; *pc != '\0'; ++pc) {
             const auto c = *pc;
 
             if (c == '{') {
                 // Write arg name for everything except *args and **kwargs.
                 is_starred = *(pc + 1) == '*';
                 if (is_starred) {
                     continue;
                 }
                 // Separator for keyword-only arguments, placed before the kw
                 // arguments start (unless we are already putting an *args)
                 if (!rec->has_args && arg_index == rec->nargs_pos) {
                     signature += "*, ";
                 }
                 if (arg_index < rec->args.size() && rec->args[arg_index].name) {
                     signature += rec->args[arg_index].name;
                 } else if (arg_index == 0 && rec->is_method) {
                     signature += "self";
                 } else {
                     signature += "arg" + std::to_string(arg_index - (rec->is_method ? 1 : 0));
                 }
                 signature += ": ";
             } else if (c == '}') {
                 // Write default value if available.
                 if (!is_starred && arg_index < rec->args.size() && rec->args[arg_index].descr) {
                     signature += " = ";
                     signature += rec->args[arg_index].descr;
                 }
                 // Separator for positional-only arguments (placed after the
                 // argument, rather than before like *
                 if (rec->nargs_pos_only > 0 && (arg_index + 1) == rec->nargs_pos_only) {
                     signature += ", /";
                 }
                 if (!is_starred) {
                     arg_index++;
                 }
             } else if (c == '%') {
                 const std::type_info *t = types[type_index++];
                 if (!t) {
                     pybind11_fail("Internal error while parsing type signature (1)");
                 }
                 if (auto *tinfo = detail::get_type_info(*t)) {
                     handle th((PyObject *) tinfo->type);
                     signature += th.attr("__module__").cast<std::string>() + "."
                                  + th.attr("__qualname__").cast<std::string>();
                 } else if (rec->is_new_style_constructor && arg_index == 0) {
                     // A new-style `__init__` takes `self` as `value_and_holder`.
                     // Rewrite it to the proper class type.
                     signature += rec->scope.attr("__module__").cast<std::string>() + "."
                                  + rec->scope.attr("__qualname__").cast<std::string>();
                 } else {
                     std::string tname(t->name());
                     detail::clean_type_id(tname);
                     signature += tname;
                 }
             } else {
                 signature += c;
             }
         }
 
         if (arg_index != args - rec->has_args - rec->has_kwargs || types[type_index] != nullptr) {
             pybind11_fail("Internal error while parsing type signature (2)");
         }
 
         rec->signature = guarded_strdup(signature.c_str());
         rec->args.shrink_to_fit();
         rec->nargs = (std::uint16_t) args;
 
         if (rec->sibling && PYBIND11_INSTANCE_METHOD_CHECK(rec->sibling.ptr())) {
             rec->sibling = PYBIND11_INSTANCE_METHOD_GET_FUNCTION(rec->sibling.ptr());
         }
 
         detail::function_record *chain = nullptr, *chain_start = rec;
         if (rec->sibling) {
             if (PyCFunction_Check(rec->sibling.ptr())) {
                 auto *self = PyCFunction_GET_SELF(rec->sibling.ptr());
                 if (!isinstance<capsule>(self)) {
                     chain = nullptr;
                 } else {
                     auto rec_capsule = reinterpret_borrow<capsule>(self);
                     if (detail::is_function_record_capsule(rec_capsule)) {
                         chain = rec_capsule.get_pointer<detail::function_record>();
                         /* Never append a method to an overload chain of a parent class;
                            instead, hide the parent's overloads in this case */
                         if (!chain->scope.is(rec->scope)) {
                             chain = nullptr;
                         }
                     } else {
                         chain = nullptr;
                     }
                 }
             }
             // Don't trigger for things like the default __init__, which are wrapper_descriptors
             // that we are intentionally replacing
             else if (!rec->sibling.is_none() && rec->name[0] != '_') {
                 pybind11_fail("Cannot overload existing non-function object \""
                               + std::string(rec->name) + "\" with a function of the same name");
             }
         }
 
         if (!chain) {
             /* No existing overload was found, create a new function object */
             rec->def = new PyMethodDef();
             std::memset(rec->def, 0, sizeof(PyMethodDef));
             rec->def->ml_name = rec->name;
             rec->def->ml_meth
                 = reinterpret_cast<PyCFunction>(reinterpret_cast<void (*)()>(dispatcher));
             rec->def->ml_flags = METH_VARARGS | METH_KEYWORDS;
 
             capsule rec_capsule(unique_rec.release(),
                                 [](void *ptr) { destruct((detail::function_record *) ptr); });
             rec_capsule.set_name(detail::get_function_record_capsule_name());
             guarded_strdup.release();
 
             object scope_module;
             if (rec->scope) {
                 if (hasattr(rec->scope, "__module__")) {
                     scope_module = rec->scope.attr("__module__");
                 } else if (hasattr(rec->scope, "__name__")) {
                     scope_module = rec->scope.attr("__name__");
                 }
             }
 
             m_ptr = PyCFunction_NewEx(rec->def, rec_capsule.ptr(), scope_module.ptr());
             if (!m_ptr) {
                 pybind11_fail("cpp_function::cpp_function(): Could not allocate function object");
             }
         } else {
             /* Append at the beginning or end of the overload chain */
             m_ptr = rec->sibling.ptr();
             inc_ref();
             if (chain->is_method != rec->is_method) {
                 pybind11_fail(
                     "overloading a method with both static and instance methods is not supported; "
 #if !defined(PYBIND11_DETAILED_ERROR_MESSAGES)
                     "#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for more "
                     "details"
 #else
                     "error while attempting to bind "
                     + std::string(rec->is_method ? "instance" : "static") + " method "
                     + std::string(pybind11::str(rec->scope.attr("__name__"))) + "."
                     + std::string(rec->name) + signature
 #endif
                 );
             }
 
             if (rec->prepend) {
                 // Beginning of chain; we need to replace the capsule's current head-of-the-chain
                 // pointer with this one, then make this one point to the previous head of the
                 // chain.
                 chain_start = rec;
                 rec->next = chain;
                 auto rec_capsule
                     = reinterpret_borrow<capsule>(((PyCFunctionObject *) m_ptr)->m_self);
                 rec_capsule.set_pointer(unique_rec.release());
                 guarded_strdup.release();
             } else {
                 // Or end of chain (normal behavior)
                 chain_start = chain;
                 while (chain->next) {
                     chain = chain->next;
                 }
                 chain->next = unique_rec.release();
                 guarded_strdup.release();
             }
         }
 
         std::string signatures;
         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()) {
             // First a generic signature
             signatures += rec->name;
             signatures += "(*args, **kwargs)\n";
             signatures += "Overloaded function.\n\n";
         }
         // Then specific overload signatures
         bool first_user_def = true;
         for (auto *it = chain_start; it != nullptr; it = it->next) {
             if (options::show_function_signatures()) {
                 if (index > 0) {
                     signatures += '\n';
                 }
                 if (chain) {
                     signatures += std::to_string(++index) + ". ";
                 }
                 signatures += rec->name;
                 signatures += it->signature;
                 signatures += '\n';
             }
             if (it->doc && it->doc[0] != '\0' && options::show_user_defined_docstrings()) {
                 // If we're appending another docstring, and aren't printing function signatures,
                 // we need to append a newline first:
                 if (!options::show_function_signatures()) {
                     if (first_user_def) {
                         first_user_def = false;
                     } else {
                         signatures += '\n';
                     }
                 }
                 if (options::show_function_signatures()) {
                     signatures += '\n';
                 }
                 signatures += it->doc;
                 if (options::show_function_signatures()) {
                     signatures += '\n';
                 }
             }
         }
 
         /* Install docstring */
         auto *func = (PyCFunctionObject *) m_ptr;
         std::free(const_cast<char *>(func->m_ml->ml_doc));
         // Install docstring if it's non-empty (when at least one option is enabled)
         func->m_ml->ml_doc
             = signatures.empty() ? nullptr : PYBIND11_COMPAT_STRDUP(signatures.c_str());
 
         if (rec->is_method) {
             m_ptr = PYBIND11_INSTANCE_METHOD_NEW(m_ptr, rec->scope.ptr());
             if (!m_ptr) {
                 pybind11_fail(
                     "cpp_function::cpp_function(): Could not allocate instance method object");
             }
             Py_DECREF(func);
         }
     }
 
     /// When a cpp_function is GCed, release any memory allocated by pybind11
     static void destruct(detail::function_record *rec, bool free_strings = true) {
 // If on Python 3.9, check the interpreter "MICRO" (patch) version.
 // If this is running on 3.9.0, we have to work around a bug.
 #if !defined(PYPY_VERSION) && PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION == 9
         static bool is_zero = Py_GetVersion()[4] == '0';
 #endif
 
         while (rec) {
             detail::function_record *next = rec->next;
             if (rec->free_data) {
                 rec->free_data(rec);
             }
             // During initialization, these strings might not have been copied yet,
             // so they cannot be freed. Once the function has been created, they can.
             // Check `make_function_record` for more details.
             if (free_strings) {
                 std::free((char *) rec->name);
                 std::free((char *) rec->doc);
                 std::free((char *) rec->signature);
                 for (auto &arg : rec->args) {
                     std::free(const_cast<char *>(arg.name));
                     std::free(const_cast<char *>(arg.descr));
                 }
             }
             for (auto &arg : rec->args) {
                 arg.value.dec_ref();
             }
             if (rec->def) {
                 std::free(const_cast<char *>(rec->def->ml_doc));
 // Python 3.9.0 decref's these in the wrong order; rec->def
 // If loaded on 3.9.0, let these leak (use Python 3.9.1 at runtime to fix)
 // See https://github.com/python/cpython/pull/22670
 #if !defined(PYPY_VERSION) && PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION == 9
                 if (!is_zero) {
                     delete rec->def;
                 }
 #else
                 delete rec->def;
 #endif
             }
             delete rec;
             rec = next;
         }
     }
 
     /// Main dispatch logic for calls to functions bound using pybind11
     static PyObject *dispatcher(PyObject *self, PyObject *args_in, PyObject *kwargs_in) {
         using namespace detail;
         assert(isinstance<capsule>(self));
 
         /* Iterator over the list of potentially admissible overloads */
         const function_record *overloads = reinterpret_cast<function_record *>(
                                   PyCapsule_GetPointer(self, get_function_record_capsule_name())),
                               *it = overloads;
         assert(overloads != nullptr);
 
         /* Need to know how many arguments + keyword arguments there are to pick the right
            overload */
         const auto n_args_in = (size_t) PyTuple_GET_SIZE(args_in);
 
         handle parent = n_args_in > 0 ? PyTuple_GET_ITEM(args_in, 0) : nullptr,
                result = PYBIND11_TRY_NEXT_OVERLOAD;
 
         auto self_value_and_holder = value_and_holder();
         if (overloads->is_constructor) {
             if (!parent
                 || !PyObject_TypeCheck(parent.ptr(), (PyTypeObject *) overloads->scope.ptr())) {
                 PyErr_SetString(
                     PyExc_TypeError,
                     "__init__(self, ...) called with invalid or missing `self` argument");
                 return nullptr;
             }
 
             auto *const tinfo = get_type_info((PyTypeObject *) overloads->scope.ptr());
             auto *const pi = reinterpret_cast<instance *>(parent.ptr());
             self_value_and_holder = pi->get_value_and_holder(tinfo, true);
 
             // If this value is already registered it must mean __init__ is invoked multiple times;
             // we really can't support that in C++, so just ignore the second __init__.
             if (self_value_and_holder.instance_registered()) {
                 return none().release().ptr();
             }
         }
 
         try {
             // We do this in two passes: in the first pass, we load arguments with `convert=false`;
             // in the second, we allow conversion (except for arguments with an explicit
             // py::arg().noconvert()).  This lets us prefer calls without conversion, with
             // conversion as a fallback.
             std::vector<function_call> second_pass;
 
             // However, if there are no overloads, we can just skip the no-convert pass entirely
             const bool overloaded = it != nullptr && it->next != nullptr;
 
             for (; it != nullptr; it = it->next) {
 
                 /* For each overload:
                    1. Copy all positional arguments we were given, also checking to make sure that
                       named positional arguments weren't *also* specified via kwarg.
                    2. If we weren't given enough, try to make up the omitted ones by checking
                       whether they were provided by a kwarg matching the `py::arg("name")` name. If
                       so, use it (and remove it from kwargs); if not, see if the function binding
                       provided a default that we can use.
                    3. Ensure that either all keyword arguments were "consumed", or that the
                    function takes a kwargs argument to accept unconsumed kwargs.
                    4. Any positional arguments still left get put into a tuple (for args), and any
                       leftover kwargs get put into a dict.
                    5. Pack everything into a vector; if we have py::args or py::kwargs, they are an
                       extra tuple or dict at the end of the positional arguments.
                    6. Call the function call dispatcher (function_record::impl)
 
                    If one of these fail, move on to the next overload and keep trying until we get
                    a result other than PYBIND11_TRY_NEXT_OVERLOAD.
                  */
 
                 const function_record &func = *it;
                 size_t num_args = func.nargs; // Number of positional arguments that we need
                 if (func.has_args) {
                     --num_args; // (but don't count py::args
                 }
                 if (func.has_kwargs) {
                     --num_args; //  or py::kwargs)
                 }
                 size_t pos_args = func.nargs_pos;
 
                 if (!func.has_args && n_args_in > pos_args) {
                     continue; // Too many positional arguments for this overload
                 }
 
                 if (n_args_in < pos_args && func.args.size() < pos_args) {
                     continue; // Not enough positional arguments given, and not enough defaults to
                               // fill in the blanks
                 }
 
                 function_call call(func, parent);
 
                 // Protect std::min with parentheses
                 size_t args_to_copy = (std::min)(pos_args, n_args_in);
                 size_t args_copied = 0;
 
                 // 0. Inject new-style `self` argument
                 if (func.is_new_style_constructor) {
                     // The `value` may have been preallocated by an old-style `__init__`
                     // if it was a preceding candidate for overload resolution.
                     if (self_value_and_holder) {
                         self_value_and_holder.type->dealloc(self_value_and_holder);
                     }
 
                     call.init_self = PyTuple_GET_ITEM(args_in, 0);
                     call.args.emplace_back(reinterpret_cast<PyObject *>(&self_value_and_holder));
                     call.args_convert.push_back(false);
                     ++args_copied;
                 }
 
                 // 1. Copy any position arguments given.
                 bool bad_arg = false;
                 for (; args_copied < args_to_copy; ++args_copied) {
                     const argument_record *arg_rec
                         = args_copied < func.args.size() ? &func.args[args_copied] : nullptr;
                     if (kwargs_in && arg_rec && arg_rec->name
                         && dict_getitemstring(kwargs_in, arg_rec->name)) {
                         bad_arg = true;
                         break;
                     }
 
                     handle arg(PyTuple_GET_ITEM(args_in, args_copied));
                     if (arg_rec && !arg_rec->none && arg.is_none()) {
                         bad_arg = true;
                         break;
                     }
                     call.args.push_back(arg);
                     call.args_convert.push_back(arg_rec ? arg_rec->convert : true);
                 }
                 if (bad_arg) {
                     continue; // Maybe it was meant for another overload (issue #688)
                 }
 
                 // Keep track of how many position args we copied out in case we need to come back
                 // to copy the rest into a py::args argument.
                 size_t positional_args_copied = args_copied;
 
                 // We'll need to copy this if we steal some kwargs for defaults
                 dict kwargs = reinterpret_borrow<dict>(kwargs_in);
 
                 // 1.5. Fill in any missing pos_only args from defaults if they exist
                 if (args_copied < func.nargs_pos_only) {
                     for (; args_copied < func.nargs_pos_only; ++args_copied) {
                         const auto &arg_rec = func.args[args_copied];
                         handle value;
 
                         if (arg_rec.value) {
                             value = arg_rec.value;
                         }
                         if (value) {
                             call.args.push_back(value);
                             call.args_convert.push_back(arg_rec.convert);
                         } else {
                             break;
                         }
                     }
 
                     if (args_copied < func.nargs_pos_only) {
                         continue; // Not enough defaults to fill the positional arguments
                     }
                 }
 
                 // 2. Check kwargs and, failing that, defaults that may help complete the list
                 if (args_copied < num_args) {
                     bool copied_kwargs = false;
 
                     for (; args_copied < num_args; ++args_copied) {
                         const auto &arg_rec = func.args[args_copied];
 
                         handle value;
                         if (kwargs_in && arg_rec.name) {
                             value = dict_getitemstring(kwargs.ptr(), arg_rec.name);
                         }
 
                         if (value) {
                             // Consume a kwargs value
                             if (!copied_kwargs) {
                                 kwargs = reinterpret_steal<dict>(PyDict_Copy(kwargs.ptr()));
                                 copied_kwargs = true;
                             }
                             if (PyDict_DelItemString(kwargs.ptr(), arg_rec.name) == -1) {
                                 throw error_already_set();
                             }
                         } else if (arg_rec.value) {
                             value = arg_rec.value;
                         }
 
                         if (!arg_rec.none && value.is_none()) {
                             break;
                         }
 
                         if (value) {
                             // If we're at the py::args index then first insert a stub for it to be
                             // replaced later
                             if (func.has_args && call.args.size() == func.nargs_pos) {
                                 call.args.push_back(none());
                             }
 
                             call.args.push_back(value);
                             call.args_convert.push_back(arg_rec.convert);
                         } else {
                             break;
                         }
                     }
 
                     if (args_copied < num_args) {
                         continue; // Not enough arguments, defaults, or kwargs to fill the
                                   // positional arguments
                     }
                 }
 
                 // 3. Check everything was consumed (unless we have a kwargs arg)
                 if (kwargs && !kwargs.empty() && !func.has_kwargs) {
                     continue; // Unconsumed kwargs, but no py::kwargs argument to accept them
                 }
 
                 // 4a. If we have a py::args argument, create a new tuple with leftovers
                 if (func.has_args) {
                     tuple extra_args;
                     if (args_to_copy == 0) {
                         // We didn't copy out any position arguments from the args_in tuple, so we
                         // can reuse it directly without copying:
                         extra_args = reinterpret_borrow<tuple>(args_in);
                     } else if (positional_args_copied >= n_args_in) {
                         extra_args = tuple(0);
                     } else {
                         size_t args_size = n_args_in - positional_args_copied;
                         extra_args = tuple(args_size);
                         for (size_t i = 0; i < args_size; ++i) {
                             extra_args[i] = PyTuple_GET_ITEM(args_in, positional_args_copied + i);
                         }
                     }
                     if (call.args.size() <= func.nargs_pos) {
                         call.args.push_back(extra_args);
                     } else {
                         call.args[func.nargs_pos] = extra_args;
                     }
                     call.args_convert.push_back(false);
                     call.args_ref = std::move(extra_args);
                 }
 
                 // 4b. If we have a py::kwargs, pass on any remaining kwargs
                 if (func.has_kwargs) {
                     if (!kwargs.ptr()) {
                         kwargs = dict(); // If we didn't get one, send an empty one
                     }
                     call.args.push_back(kwargs);
                     call.args_convert.push_back(false);
                     call.kwargs_ref = std::move(kwargs);
                 }
 
 // 5. Put everything in a vector.  Not technically step 5, we've been building it
 // in `call.args` all along.
 #if defined(PYBIND11_DETAILED_ERROR_MESSAGES)
                 if (call.args.size() != func.nargs || call.args_convert.size() != func.nargs) {
                     pybind11_fail("Internal error: function call dispatcher inserted wrong number "
                                   "of arguments!");
                 }
 #endif
 
                 std::vector<bool> second_pass_convert;
                 if (overloaded) {
                     // We're in the first no-convert pass, so swap out the conversion flags for a
                     // set of all-false flags.  If the call fails, we'll swap the flags back in for
                     // the conversion-allowed call below.
                     second_pass_convert.resize(func.nargs, false);
                     call.args_convert.swap(second_pass_convert);
                 }
 
                 // 6. Call the function.
                 try {
                     loader_life_support guard{};
                     result = func.impl(call);
                 } catch (reference_cast_error &) {
                     result = PYBIND11_TRY_NEXT_OVERLOAD;
                 }
 
                 if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD) {
                     break;
                 }
 
                 if (overloaded) {
                     // The (overloaded) call failed; if the call has at least one argument that
                     // permits conversion (i.e. it hasn't been explicitly specified `.noconvert()`)
                     // then add this call to the list of second pass overloads to try.
                     for (size_t i = func.is_method ? 1 : 0; i < pos_args; i++) {
                         if (second_pass_convert[i]) {
                             // Found one: swap the converting flags back in and store the call for
                             // the second pass.
                             call.args_convert.swap(second_pass_convert);
                             second_pass.push_back(std::move(call));
                             break;
                         }
                     }
                 }
             }
 
             if (overloaded && !second_pass.empty() && result.ptr() == PYBIND11_TRY_NEXT_OVERLOAD) {
                 // The no-conversion pass finished without success, try again with conversion
                 // allowed
                 for (auto &call : second_pass) {
                     try {
                         loader_life_support guard{};
                         result = call.func.impl(call);
                     } catch (reference_cast_error &) {
                         result = PYBIND11_TRY_NEXT_OVERLOAD;
                     }
 
                     if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD) {
                         // The error reporting logic below expects 'it' to be valid, as it would be
                         // if we'd encountered this failure in the first-pass loop.
                         if (!result) {
                             it = &call.func;
                         }
                         break;
                     }
                 }
             }
         } catch (error_already_set &e) {
             e.restore();
             return nullptr;
 #ifdef __GLIBCXX__
         } catch (abi::__forced_unwind &) {
             throw;
 #endif
         } catch (...) {
             /* 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 PyErr_SetString or PyErr_SetObject
                   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;
             }
 
             PyErr_SetString(PyExc_SystemError,
                             "Exception escaped from default exception translator!");
             return nullptr;
         }
 
         auto append_note_if_missing_header_is_suspected = [](std::string &msg) {
             if (msg.find("std::") != std::string::npos) {
                 msg += "\n\n"
                        "Did you forget to `#include <pybind11/stl.h>`? Or <pybind11/complex.h>,\n"
                        "<pybind11/functional.h>, <pybind11/chrono.h>, etc. Some automatic\n"
                        "conversions are optional and require extra headers to be included\n"
                        "when compiling your pybind11 module.";
             }
         };
 
         if (result.ptr() == PYBIND11_TRY_NEXT_OVERLOAD) {
             if (overloads->is_operator) {
                 return handle(Py_NotImplemented).inc_ref().ptr();
             }
 
             std::string msg = std::string(overloads->name) + "(): incompatible "
                               + std::string(overloads->is_constructor ? "constructor" : "function")
                               + " arguments. The following argument types are supported:\n";
 
             int ctr = 0;
             for (const function_record *it2 = overloads; it2 != nullptr; it2 = it2->next) {
                 msg += "    " + std::to_string(++ctr) + ". ";
 
                 bool wrote_sig = false;
                 if (overloads->is_constructor) {
                     // For a constructor, rewrite `(self: Object, arg0, ...) -> NoneType` as
                     // `Object(arg0, ...)`
                     std::string sig = it2->signature;
                     size_t start = sig.find('(') + 7; // skip "(self: "
                     if (start < sig.size()) {
                         // End at the , for the next argument
                         size_t end = sig.find(", "), next = end + 2;
                         size_t ret = sig.rfind(" -> ");
                         // Or the ), if there is no comma:
                         if (end >= sig.size()) {
                             next = end = sig.find(')');
                         }
                         if (start < end && next < sig.size()) {
                             msg.append(sig, start, end - start);
                             msg += '(';
                             msg.append(sig, next, ret - next);
                             wrote_sig = true;
                         }
                     }
                 }
                 if (!wrote_sig) {
                     msg += it2->signature;
                 }
 
                 msg += '\n';
             }
             msg += "\nInvoked with: ";
             auto args_ = reinterpret_borrow<tuple>(args_in);
             bool some_args = false;
             for (size_t ti = overloads->is_constructor ? 1 : 0; ti < args_.size(); ++ti) {
                 if (!some_args) {
                     some_args = true;
                 } else {
                     msg += ", ";
                 }
                 try {
                     msg += pybind11::repr(args_[ti]);
                 } catch (const error_already_set &) {
                     msg += "<repr raised Error>";
                 }
             }
             if (kwargs_in) {
                 auto kwargs = reinterpret_borrow<dict>(kwargs_in);
                 if (!kwargs.empty()) {
                     if (some_args) {
                         msg += "; ";
                     }
                     msg += "kwargs: ";
                     bool first = true;
                     for (auto kwarg : kwargs) {
                         if (first) {
                             first = false;
                         } else {
                             msg += ", ";
                         }
                         msg += pybind11::str("{}=").format(kwarg.first);
                         try {
                             msg += pybind11::repr(kwarg.second);
                         } catch (const error_already_set &) {
                             msg += "<repr raised Error>";
                         }
                     }
                 }
             }
 
             append_note_if_missing_header_is_suspected(msg);
             // Attach additional error info to the exception if supported
             if (PyErr_Occurred()) {
                 // #HelpAppreciated: unit test coverage for this branch.
                 raise_from(PyExc_TypeError, msg.c_str());
                 return nullptr;
             }
             PyErr_SetString(PyExc_TypeError, msg.c_str());
             return nullptr;
         }
         if (!result) {
             std::string msg = "Unable to convert function return value to a "
                               "Python type! The signature was\n\t";
             msg += it->signature;
             append_note_if_missing_header_is_suspected(msg);
             // Attach additional error info to the exception if supported
             if (PyErr_Occurred()) {
                 raise_from(PyExc_TypeError, msg.c_str());
                 return nullptr;
             }
             PyErr_SetString(PyExc_TypeError, msg.c_str());
             return nullptr;
         }
         if (overloads->is_constructor && !self_value_and_holder.holder_constructed()) {
             auto *pi = reinterpret_cast<instance *>(parent.ptr());
             self_value_and_holder.type->init_instance(pi, nullptr);
         }
         return result.ptr();
     }
 };
 
 /// Wrapper for Python extension modules
 class module_ : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(module_, object, PyModule_Check)
 
     /// Create a new top-level Python module with the given name and docstring
     PYBIND11_DEPRECATED("Use PYBIND11_MODULE or module_::create_extension_module instead")
     explicit module_(const char *name, const char *doc = nullptr) {
         *this = create_extension_module(name, doc, new PyModuleDef());
     }
 
     /** \rst
         Create Python binding for a new function within the module scope. ``Func``
         can be a plain C++ function, a function pointer, or a lambda function. For
         details on the ``Extra&& ... extra`` argument, see section :ref:`extras`.
     \endrst */
     template <typename Func, typename... Extra>
     module_ &def(const char *name_, Func &&f, const Extra &...extra) {
         cpp_function func(std::forward<Func>(f),
                           name(name_),
                           scope(*this),
                           sibling(getattr(*this, name_, none())),
                           extra...);
         // NB: allow overwriting here because cpp_function sets up a chain with the intention of
         // overwriting (and has already checked internally that it isn't overwriting
         // non-functions).
         add_object(name_, func, true /* overwrite */);
         return *this;
     }
 
     /** \rst
         Create and return a new Python submodule with the given name and docstring.
         This also works recursively, i.e.
 
         .. code-block:: cpp
 
             py::module_ m("example", "pybind11 example plugin");
             py::module_ m2 = m.def_submodule("sub", "A submodule of 'example'");
             py::module_ m3 = m2.def_submodule("subsub", "A submodule of 'example.sub'");
     \endrst */
     module_ def_submodule(const char *name, const char *doc = nullptr) {
         const char *this_name = PyModule_GetName(m_ptr);
         if (this_name == nullptr) {
             throw error_already_set();
         }
         std::string full_name = std::string(this_name) + '.' + name;
         handle submodule = PyImport_AddModule(full_name.c_str());
         if (!submodule) {
             throw error_already_set();
         }
         auto result = reinterpret_borrow<module_>(submodule);
         if (doc && options::show_user_defined_docstrings()) {
             result.attr("__doc__") = pybind11::str(doc);
         }
         attr(name) = result;
         return result;
     }
 
     /// Import and return a module or throws `error_already_set`.
     static module_ import(const char *name) {
         PyObject *obj = PyImport_ImportModule(name);
         if (!obj) {
             throw error_already_set();
         }
         return reinterpret_steal<module_>(obj);
     }
 
     /// Reload the module or throws `error_already_set`.
     void reload() {
         PyObject *obj = PyImport_ReloadModule(ptr());
         if (!obj) {
             throw error_already_set();
         }
         *this = reinterpret_steal<module_>(obj);
     }
 
     /** \rst
         Adds an object to the module using the given name.  Throws if an object with the given name
         already exists.
 
         ``overwrite`` should almost always be false: attempting to overwrite objects that pybind11
         has established will, in most cases, break things.
     \endrst */
     PYBIND11_NOINLINE void add_object(const char *name, handle obj, bool overwrite = false) {
         if (!overwrite && hasattr(*this, name)) {
             pybind11_fail(
                 "Error during initialization: multiple incompatible definitions with name \""
                 + std::string(name) + "\"");
         }
 
         PyModule_AddObject(ptr(), name, obj.inc_ref().ptr() /* steals a reference */);
     }
 
     using module_def = PyModuleDef; // TODO: Can this be removed (it was needed only for Python 2)?
 
     /** \rst
         Create a new top-level module that can be used as the main module of a C extension.
 
         ``def`` should point to a statically allocated module_def.
     \endrst */
     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)
             PyModuleDef{/* m_base */ PyModuleDef_HEAD_INIT,
                         /* m_name */ name,
                         /* m_doc */ options::show_user_defined_docstrings() ? doc : nullptr,
                         /* m_size */ -1,
                         /* m_methods */ nullptr,
                         /* m_slots */ nullptr,
                         /* m_traverse */ nullptr,
                         /* m_clear */ nullptr,
                         /* m_free */ nullptr};
         auto *m = PyModule_Create(def);
         if (m == nullptr) {
             if (PyErr_Occurred()) {
                 throw error_already_set();
             }
             pybind11_fail("Internal error in module_::create_extension_module()");
         }
         // 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.
         return reinterpret_borrow<module_>(m);
     }
 };
 
 // When inside a namespace (or anywhere as long as it's not the first item on a line),
 // C++20 allows "module" to be used. This is provided for backward compatibility, and for
 // simplicity, if someone wants to use py::module for example, that is perfectly safe.
 using module = module_;
 
 /// \ingroup python_builtins
 /// Return a dictionary representing the global variables in the current execution frame,
 /// or ``__main__.__dict__`` if there is no frame (usually when the interpreter is embedded).
 inline dict globals() {
     PyObject *p = PyEval_GetGlobals();
     return reinterpret_borrow<dict>(p ? p : module_::import("__main__").attr("__dict__").ptr());
 }
 
 template <typename... Args, typename = detail::enable_if_t<args_are_all_keyword_or_ds<Args...>()>>
 PYBIND11_DEPRECATED("make_simple_namespace should be replaced with "
                     "py::module_::import(\"types\").attr(\"SimpleNamespace\") ")
 object make_simple_namespace(Args &&...args_) {
     return module_::import("types").attr("SimpleNamespace")(std::forward<Args>(args_)...);
 }
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 /// Generic support for creating new Python heap types
 class generic_type : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(generic_type, object, PyType_Check)
 protected:
     void initialize(const type_record &rec) {
         if (rec.scope && hasattr(rec.scope, "__dict__")
             && rec.scope.attr("__dict__").contains(rec.name)) {
             pybind11_fail("generic_type: cannot initialize type \"" + std::string(rec.name)
                           + "\": an object with that name is already defined");
         }
 
         if ((rec.module_local ? get_local_type_info(*rec.type) : get_global_type_info(*rec.type))
             != nullptr) {
             pybind11_fail("generic_type: type \"" + std::string(rec.name)
                           + "\" is already registered!");
         }
 
         m_ptr = make_new_python_type(rec);
 
         /* Register supplemental type information in C++ dict */
         auto *tinfo = new detail::type_info();
         tinfo->type = (PyTypeObject *) m_ptr;
         tinfo->cpptype = rec.type;
         tinfo->type_size = rec.type_size;
         tinfo->type_align = rec.type_align;
         tinfo->operator_new = rec.operator_new;
         tinfo->holder_size_in_ptrs = size_in_ptrs(rec.holder_size);
         tinfo->init_instance = rec.init_instance;
         tinfo->dealloc = rec.dealloc;
         tinfo->simple_type = true;
         tinfo->simple_ancestors = true;
         tinfo->default_holder = rec.default_holder;
         tinfo->module_local = rec.module_local;
 
         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);
             tinfo->simple_ancestors = false;
         } else if (rec.bases.size() == 1) {
             auto *parent_tinfo = get_type_info((PyTypeObject *) rec.bases[0].ptr());
             assert(parent_tinfo != nullptr);
             bool parent_simple_ancestors = parent_tinfo->simple_ancestors;
             tinfo->simple_ancestors = parent_simple_ancestors;
             // The parent can no longer be a simple type if it has MI and has a child
             parent_tinfo->simple_type = parent_tinfo->simple_type && parent_simple_ancestors;
         }
 
         if (rec.module_local) {
             // Stash the local typeinfo and loader so that external modules can access it.
             tinfo->module_local_load = &type_caster_generic::local_load;
             setattr(m_ptr, PYBIND11_MODULE_LOCAL_ID, capsule(tinfo));
         }
     }
 
     /// Helper function which tags all parents of a type using mult. inheritance
     void mark_parents_nonsimple(PyTypeObject *value) {
         auto t = reinterpret_borrow<tuple>(value->tp_bases);
         for (handle h : t) {
             auto *tinfo2 = get_type_info((PyTypeObject *) h.ptr());
             if (tinfo2) {
                 tinfo2->simple_type = false;
             }
             mark_parents_nonsimple((PyTypeObject *) h.ptr());
         }
     }
 
     void install_buffer_funcs(buffer_info *(*get_buffer)(PyObject *, void *),
                               void *get_buffer_data) {
         auto *type = (PyHeapTypeObject *) m_ptr;
         auto *tinfo = detail::get_type_info(&type->ht_type);
 
         if (!type->ht_type.tp_as_buffer) {
             pybind11_fail("To be able to register buffer protocol support for the type '"
                           + get_fully_qualified_tp_name(tinfo->type)
                           + "' the associated class<>(..) invocation must "
                             "include the pybind11::buffer_protocol() annotation!");
         }
 
         tinfo->get_buffer = get_buffer;
         tinfo->get_buffer_data = get_buffer_data;
     }
 
     // rec_func must be set for either fget or fset.
     void def_property_static_impl(const char *name,
                                   handle fget,
                                   handle fset,
                                   detail::function_record *rec_func) {
         const auto is_static = (rec_func != nullptr) && !(rec_func->is_method && rec_func->scope);
         const auto has_doc = (rec_func != nullptr) && (rec_func->doc != nullptr)
                              && pybind11::options::show_user_defined_docstrings();
         auto property = handle(
             (PyObject *) (is_static ? get_internals().static_property_type : &PyProperty_Type));
         attr(name) = property(fget.ptr() ? fget : none(),
                               fset.ptr() ? fset : none(),
                               /*deleter*/ none(),
                               pybind11::str(has_doc ? rec_func->doc : ""));
     }
 };
 
 /// Set the pointer to operator new if it exists. The cast is needed because it can be overloaded.
 template <typename T,
           typename = void_t<decltype(static_cast<void *(*) (size_t)>(T::operator new))>>
 void set_operator_new(type_record *r) {
     r->operator_new = &T::operator new;
 }
 
 template <typename>
 void set_operator_new(...) {}
 
 template <typename T, typename SFINAE = void>
 struct has_operator_delete : std::false_type {};
 template <typename T>
 struct has_operator_delete<T, void_t<decltype(static_cast<void (*)(void *)>(T::operator delete))>>
     : std::true_type {};
 template <typename T, typename SFINAE = void>
 struct has_operator_delete_size : std::false_type {};
 template <typename T>
 struct has_operator_delete_size<
     T,
     void_t<decltype(static_cast<void (*)(void *, size_t)>(T::operator delete))>> : std::true_type {
 };
 /// Call class-specific delete if it exists or global otherwise. Can also be an overload set.
 template <typename T, enable_if_t<has_operator_delete<T>::value, int> = 0>
 void call_operator_delete(T *p, size_t, size_t) {
     T::operator delete(p);
 }
 template <typename T,
           enable_if_t<!has_operator_delete<T>::value && has_operator_delete_size<T>::value, int>
           = 0>
 void call_operator_delete(T *p, size_t s, size_t) {
     T::operator delete(p, s);
 }
 
 inline void call_operator_delete(void *p, size_t s, size_t a) {
     (void) s;
     (void) a;
 #if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
     if (a > __STDCPP_DEFAULT_NEW_ALIGNMENT__) {
 #    ifdef __cpp_sized_deallocation
         ::operator delete(p, s, std::align_val_t(a));
 #    else
         ::operator delete(p, std::align_val_t(a));
 #    endif
         return;
     }
 #endif
 #ifdef __cpp_sized_deallocation
     ::operator delete(p, s);
 #else
     ::operator delete(p);
 #endif
 }
 
 inline void add_class_method(object &cls, const char *name_, const cpp_function &cf) {
     cls.attr(cf.name()) = cf;
     if (std::strcmp(name_, "__eq__") == 0 && !cls.attr("__dict__").contains("__hash__")) {
         cls.attr("__hash__") = none();
     }
 }
 
 PYBIND11_NAMESPACE_END(detail)
 
 /// Given a pointer to a member function, cast it to its `Derived` version.
 /// Forward everything else unchanged.
 template <typename /*Derived*/, typename F>
 auto method_adaptor(F &&f) -> decltype(std::forward<F>(f)) {
     return std::forward<F>(f);
 }
 
 template <typename Derived, typename Return, typename Class, typename... Args>
 auto method_adaptor(Return (Class::*pmf)(Args...)) -> Return (Derived::*)(Args...) {
     static_assert(
         detail::is_accessible_base_of<Class, Derived>::value,
         "Cannot bind an inaccessible base class method; use a lambda definition instead");
     return pmf;
 }
 
 template <typename Derived, typename Return, typename Class, typename... Args>
 auto method_adaptor(Return (Class::*pmf)(Args...) const) -> Return (Derived::*)(Args...) const {
     static_assert(
         detail::is_accessible_base_of<Class, Derived>::value,
         "Cannot bind an inaccessible base class method; use a lambda definition instead");
     return pmf;
 }
 
 template <typename type_, typename... options>
 class class_ : public detail::generic_type {
     template <typename T>
     using is_holder = detail::is_holder_type<type_, T>;
     template <typename T>
     using is_subtype = detail::is_strict_base_of<type_, T>;
     template <typename T>
     using is_base = detail::is_strict_base_of<T, type_>;
     // struct instead of using here to help MSVC:
     template <typename T>
     struct is_valid_class_option : detail::any_of<is_holder<T>, is_subtype<T>, is_base<T>> {};
 
 public:
     using type = type_;
     using type_alias = detail::exactly_one_t<is_subtype, void, options...>;
     constexpr static bool has_alias = !std::is_void<type_alias>::value;
     using holder_type = detail::exactly_one_t<is_holder, std::unique_ptr<type>, options...>;
 
     static_assert(detail::all_of<is_valid_class_option<options>...>::value,
                   "Unknown/invalid class_ template parameters provided");
 
     static_assert(!has_alias || std::is_polymorphic<type>::value,
                   "Cannot use an alias class with a non-polymorphic type");
 
     PYBIND11_OBJECT(class_, generic_type, PyType_Check)
 
     template <typename... Extra>
     class_(handle scope, const char *name, const Extra &...extra) {
         using namespace detail;
 
         // MI can only be specified via class_ template options, not constructor parameters
         static_assert(
             none_of<is_pyobject<Extra>...>::value || // no base class arguments, or:
                 (constexpr_sum(is_pyobject<Extra>::value...) == 1 && // Exactly one base
                  constexpr_sum(is_base<options>::value...) == 0 &&   // no template option bases
                  // no multiple_inheritance attr
                  none_of<std::is_same<multiple_inheritance, Extra>...>::value),
             "Error: multiple inheritance bases must be specified via class_ template options");
 
         type_record record;
         record.scope = scope;
         record.name = name;
         record.type = &typeid(type);
         record.type_size = sizeof(conditional_t<has_alias, type_alias, type>);
         record.type_align = alignof(conditional_t<has_alias, type_alias, type> &);
         record.holder_size = sizeof(holder_type);
         record.init_instance = init_instance;
         record.dealloc = dealloc;
         record.default_holder = detail::is_instantiation<std::unique_ptr, holder_type>::value;
 
         set_operator_new<type>(&record);
 
         /* Register base classes specified via template arguments to class_, if any */
         PYBIND11_EXPAND_SIDE_EFFECTS(add_base<options>(record));
 
         /* Process optional arguments, if any */
         process_attributes<Extra...>::init(extra..., &record);
 
         generic_type::initialize(record);
 
         if (has_alias) {
             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))];
         }
     }
 
     template <typename Base, detail::enable_if_t<is_base<Base>::value, int> = 0>
     static void add_base(detail::type_record &rec) {
         rec.add_base(typeid(Base), [](void *src) -> void * {
             return static_cast<Base *>(reinterpret_cast<type *>(src));
         });
     }
 
     template <typename Base, detail::enable_if_t<!is_base<Base>::value, int> = 0>
     static void add_base(detail::type_record &) {}
 
     template <typename Func, typename... Extra>
     class_ &def(const char *name_, Func &&f, const Extra &...extra) {
         cpp_function cf(method_adaptor<type>(std::forward<Func>(f)),
                         name(name_),
                         is_method(*this),
                         sibling(getattr(*this, name_, none())),
                         extra...);
         add_class_method(*this, name_, cf);
         return *this;
     }
 
     template <typename Func, typename... Extra>
     class_ &def_static(const char *name_, Func &&f, const Extra &...extra) {
         static_assert(!std::is_member_function_pointer<Func>::value,
                       "def_static(...) called with a non-static member function pointer");
         cpp_function cf(std::forward<Func>(f),
                         name(name_),
                         scope(*this),
                         sibling(getattr(*this, name_, none())),
                         extra...);
         auto cf_name = cf.name();
         attr(std::move(cf_name)) = staticmethod(std::move(cf));
         return *this;
     }
 
     template <typename T, typename... Extra, detail::enable_if_t<T::op_enable_if_hook, int> = 0>
     class_ &def(const T &op, const Extra &...extra) {
         op.execute(*this, extra...);
         return *this;
     }
 
     template <typename T, typename... Extra, detail::enable_if_t<T::op_enable_if_hook, int> = 0>
     class_ &def_cast(const T &op, const Extra &...extra) {
         op.execute_cast(*this, extra...);
         return *this;
     }
 
     template <typename... Args, typename... Extra>
     class_ &def(const detail::initimpl::constructor<Args...> &init, const Extra &...extra) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(init);
         init.execute(*this, extra...);
         return *this;
     }
 
     template <typename... Args, typename... Extra>
     class_ &def(const detail::initimpl::alias_constructor<Args...> &init, const Extra &...extra) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(init);
         init.execute(*this, extra...);
         return *this;
     }
 
     template <typename... Args, typename... Extra>
     class_ &def(detail::initimpl::factory<Args...> &&init, const Extra &...extra) {
         std::move(init).execute(*this, extra...);
         return *this;
     }
 
     template <typename... Args, typename... Extra>
     class_ &def(detail::initimpl::pickle_factory<Args...> &&pf, const Extra &...extra) {
         std::move(pf).execute(*this, extra...);
         return *this;
     }
 
     template <typename Func>
     class_ &def_buffer(Func &&func) {
         struct capture {
             Func func;
         };
         auto *ptr = new capture{std::forward<Func>(func)};
         install_buffer_funcs(
             [](PyObject *obj, void *ptr) -> buffer_info * {
                 detail::make_caster<type> caster;
                 if (!caster.load(obj, false)) {
                     return nullptr;
                 }
                 return new buffer_info(((capture *) ptr)->func(std::move(caster)));
             },
             ptr);
         weakref(m_ptr, cpp_function([ptr](handle wr) {
                     delete ptr;
                     wr.dec_ref();
                 }))
             .release();
         return *this;
     }
 
     template <typename Return, typename Class, typename... Args>
     class_ &def_buffer(Return (Class::*func)(Args...)) {
         return def_buffer([func](type &obj) { return (obj.*func)(); });
     }
 
     template <typename Return, typename Class, typename... Args>
     class_ &def_buffer(Return (Class::*func)(Args...) const) {
         return def_buffer([func](const type &obj) { return (obj.*func)(); });
     }
 
     template <typename C, typename D, typename... Extra>
     class_ &def_readwrite(const char *name, D C::*pm, const Extra &...extra) {
         static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value,
                       "def_readwrite() requires a class member (or base class member)");
         cpp_function fget([pm](const type &c) -> const D & { return c.*pm; }, is_method(*this)),
             fset([pm](type &c, const D &value) { c.*pm = value; }, is_method(*this));
         def_property(name, fget, fset, return_value_policy::reference_internal, extra...);
         return *this;
     }
 
     template <typename C, typename D, typename... Extra>
     class_ &def_readonly(const char *name, const D C::*pm, const Extra &...extra) {
         static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value,
                       "def_readonly() requires a class member (or base class member)");
         cpp_function fget([pm](const type &c) -> const D & { return c.*pm; }, is_method(*this));
         def_property_readonly(name, fget, return_value_policy::reference_internal, extra...);
         return *this;
     }
 
     template <typename D, typename... Extra>
     class_ &def_readwrite_static(const char *name, D *pm, const Extra &...extra) {
         cpp_function fget([pm](const object &) -> const D & { return *pm; }, scope(*this)),
             fset([pm](const object &, const D &value) { *pm = value; }, scope(*this));
         def_property_static(name, fget, fset, return_value_policy::reference, extra...);
         return *this;
     }
 
     template <typename D, typename... Extra>
     class_ &def_readonly_static(const char *name, const D *pm, const Extra &...extra) {
         cpp_function fget([pm](const object &) -> const D & { return *pm; }, scope(*this));
         def_property_readonly_static(name, fget, return_value_policy::reference, extra...);
         return *this;
     }
 
     /// Uses return_value_policy::reference_internal by default
     template <typename Getter, typename... Extra>
     class_ &def_property_readonly(const char *name, const Getter &fget, const Extra &...extra) {
         return def_property_readonly(name,
                                      cpp_function(method_adaptor<type>(fget)),
                                      return_value_policy::reference_internal,
                                      extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &
     def_property_readonly(const char *name, const cpp_function &fget, const Extra &...extra) {
         return def_property(name, fget, nullptr, extra...);
     }
 
     /// Uses return_value_policy::reference by default
     template <typename Getter, typename... Extra>
     class_ &
     def_property_readonly_static(const char *name, const Getter &fget, const Extra &...extra) {
         return def_property_readonly_static(
             name, cpp_function(fget), return_value_policy::reference, extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property_readonly_static(const char *name,
                                          const cpp_function &fget,
                                          const Extra &...extra) {
         return def_property_static(name, fget, nullptr, extra...);
     }
 
     /// Uses return_value_policy::reference_internal by default
     template <typename Getter, typename Setter, typename... Extra>
     class_ &
     def_property(const char *name, const Getter &fget, const Setter &fset, const Extra &...extra) {
         return def_property(name, fget, cpp_function(method_adaptor<type>(fset)), extra...);
     }
     template <typename Getter, typename... Extra>
     class_ &def_property(const char *name,
                          const Getter &fget,
                          const cpp_function &fset,
                          const Extra &...extra) {
         return def_property(name,
                             cpp_function(method_adaptor<type>(fget)),
                             fset,
                             return_value_policy::reference_internal,
                             extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property(const char *name,
                          const cpp_function &fget,
                          const cpp_function &fset,
                          const Extra &...extra) {
         return def_property_static(name, fget, fset, is_method(*this), extra...);
     }
 
     /// Uses return_value_policy::reference by default
     template <typename Getter, typename... Extra>
     class_ &def_property_static(const char *name,
                                 const Getter &fget,
                                 const cpp_function &fset,
                                 const Extra &...extra) {
         return def_property_static(
             name, cpp_function(fget), fset, return_value_policy::reference, extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property_static(const char *name,
                                 const cpp_function &fget,
                                 const cpp_function &fset,
                                 const Extra &...extra) {
         static_assert(0 == detail::constexpr_sum(std::is_base_of<arg, Extra>::value...),
                       "Argument annotations are not allowed for properties");
         auto rec_fget = get_function_record(fget), rec_fset = get_function_record(fset);
         auto *rec_active = rec_fget;
         if (rec_fget) {
             char *doc_prev = rec_fget->doc; /* 'extra' field may include a property-specific
                                                documentation string */
             detail::process_attributes<Extra...>::init(extra..., rec_fget);
             if (rec_fget->doc && rec_fget->doc != doc_prev) {
                 std::free(doc_prev);
                 rec_fget->doc = PYBIND11_COMPAT_STRDUP(rec_fget->doc);
             }
         }
         if (rec_fset) {
             char *doc_prev = rec_fset->doc;
             detail::process_attributes<Extra...>::init(extra..., rec_fset);
             if (rec_fset->doc && rec_fset->doc != doc_prev) {
                 std::free(doc_prev);
                 rec_fset->doc = PYBIND11_COMPAT_STRDUP(rec_fset->doc);
             }
             if (!rec_active) {
                 rec_active = rec_fset;
             }
         }
         def_property_static_impl(name, fget, fset, rec_active);
         return *this;
     }
 
 private:
     /// Initialize holder object, variant 1: object derives from enable_shared_from_this
     template <typename T>
     static void init_holder(detail::instance *inst,
                             detail::value_and_holder &v_h,
                             const holder_type * /* unused */,
                             const std::enable_shared_from_this<T> * /* dummy */) {
 
         auto sh = std::dynamic_pointer_cast<typename holder_type::element_type>(
             detail::try_get_shared_from_this(v_h.value_ptr<type>()));
         if (sh) {
             new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(sh));
             v_h.set_holder_constructed();
         }
 
         if (!v_h.holder_constructed() && inst->owned) {
             new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
             v_h.set_holder_constructed();
         }
     }
 
     static void init_holder_from_existing(const detail::value_and_holder &v_h,
                                           const holder_type *holder_ptr,
                                           std::true_type /*is_copy_constructible*/) {
         new (std::addressof(v_h.holder<holder_type>()))
             holder_type(*reinterpret_cast<const holder_type *>(holder_ptr));
     }
 
     static void init_holder_from_existing(const detail::value_and_holder &v_h,
                                           const holder_type *holder_ptr,
                                           std::false_type /*is_copy_constructible*/) {
         new (std::addressof(v_h.holder<holder_type>()))
             holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
     }
 
     /// Initialize holder object, variant 2: try to construct from existing holder object, if
     /// possible
     static void init_holder(detail::instance *inst,
                             detail::value_and_holder &v_h,
                             const holder_type *holder_ptr,
                             const void * /* dummy -- not enable_shared_from_this<T>) */) {
         if (holder_ptr) {
             init_holder_from_existing(v_h, holder_ptr, std::is_copy_constructible<holder_type>());
             v_h.set_holder_constructed();
         } else if (detail::always_construct_holder<holder_type>::value || inst->owned) {
             new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
             v_h.set_holder_constructed();
         }
     }
 
     /// Performs instance initialization including constructing a holder and registering the known
     /// instance.  Should be called as soon as the `type` value_ptr is set for an instance.  Takes
     /// an optional pointer to an existing holder to use; if not specified and the instance is
     /// `.owned`, a new holder will be constructed to manage the value pointer.
     static void init_instance(detail::instance *inst, const void *holder_ptr) {
         auto v_h = inst->get_value_and_holder(detail::get_type_info(typeid(type)));
         if (!v_h.instance_registered()) {
             register_instance(inst, v_h.value_ptr(), v_h.type);
             v_h.set_instance_registered();
         }
         init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());
     }
 
     /// Deallocates an instance; via holder, if constructed; otherwise via operator delete.
     static void dealloc(detail::value_and_holder &v_h) {
         // We could be deallocating because we are cleaning up after a Python exception.
         // If so, the Python error indicator will be set. We need to clear that before
         // running the destructor, in case the destructor code calls more Python.
         // If we don't, the Python API will exit with an exception, and pybind11 will
         // throw error_already_set from the C++ destructor which is forbidden and triggers
         // std::terminate().
         error_scope scope;
         if (v_h.holder_constructed()) {
             v_h.holder<holder_type>().~holder_type();
             v_h.set_holder_constructed(false);
         } else {
             detail::call_operator_delete(
                 v_h.value_ptr<type>(), v_h.type->type_size, v_h.type->type_align);
         }
         v_h.value_ptr() = nullptr;
     }
 
     static detail::function_record *get_function_record(handle h) {
         h = detail::get_function(h);
         if (!h) {
             return nullptr;
         }
 
         handle func_self = PyCFunction_GET_SELF(h.ptr());
         if (!func_self) {
             throw error_already_set();
         }
         if (!isinstance<capsule>(func_self)) {
             return nullptr;
         }
         auto cap = reinterpret_borrow<capsule>(func_self);
         if (!detail::is_function_record_capsule(cap)) {
             return nullptr;
         }
         return cap.get_pointer<detail::function_record>();
     }
 };
 
 /// Binds an existing constructor taking arguments Args...
 template <typename... Args>
 detail::initimpl::constructor<Args...> init() {
     return {};
 }
 /// Like `init<Args...>()`, but the instance is always constructed through the alias class (even
 /// when not inheriting on the Python side).
 template <typename... Args>
 detail::initimpl::alias_constructor<Args...> init_alias() {
     return {};
 }
 
 /// Binds a factory function as a constructor
 template <typename Func, typename Ret = detail::initimpl::factory<Func>>
 Ret init(Func &&f) {
     return {std::forward<Func>(f)};
 }
 
 /// Dual-argument factory function: the first function is called when no alias is needed, the
 /// second when an alias is needed (i.e. due to python-side inheritance).  Arguments must be
 /// identical.
 template <typename CFunc, typename AFunc, typename Ret = detail::initimpl::factory<CFunc, AFunc>>
 Ret init(CFunc &&c, AFunc &&a) {
     return {std::forward<CFunc>(c), std::forward<AFunc>(a)};
 }
 
 /// Binds pickling functions `__getstate__` and `__setstate__` and ensures that the type
 /// returned by `__getstate__` is the same as the argument accepted by `__setstate__`.
 template <typename GetState, typename SetState>
 detail::initimpl::pickle_factory<GetState, SetState> pickle(GetState &&g, SetState &&s) {
     return {std::forward<GetState>(g), std::forward<SetState>(s)};
 }
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 inline str enum_name(handle arg) {
     dict entries = arg.get_type().attr("__entries");
     for (auto kv : entries) {
         if (handle(kv.second[int_(0)]).equal(arg)) {
             return pybind11::str(kv.first);
         }
     }
     return "???";
 }
 
 struct enum_base {
     enum_base(const handle &base, const handle &parent) : m_base(base), m_parent(parent) {}
 
     PYBIND11_NOINLINE void init(bool is_arithmetic, bool is_convertible) {
         m_base.attr("__entries") = dict();
         auto property = handle((PyObject *) &PyProperty_Type);
         auto static_property = handle((PyObject *) get_internals().static_property_type);
 
         m_base.attr("__repr__") = cpp_function(
             [](const object &arg) -> str {
                 handle type = type::handle_of(arg);
                 object type_name = type.attr("__name__");
                 return pybind11::str("<{}.{}: {}>")
                     .format(std::move(type_name), enum_name(arg), int_(arg));
             },
             name("__repr__"),
             is_method(m_base));
 
         m_base.attr("name") = property(cpp_function(&enum_name, name("name"), is_method(m_base)));
 
         m_base.attr("__str__") = cpp_function(
             [](handle arg) -> str {
                 object type_name = type::handle_of(arg).attr("__name__");
                 return pybind11::str("{}.{}").format(std::move(type_name), enum_name(arg));
             },
             name("name"),
             is_method(m_base));
 
         if (options::show_enum_members_docstring()) {
             m_base.attr("__doc__") = static_property(
                 cpp_function(
                     [](handle arg) -> std::string {
                         std::string docstring;
                         dict entries = arg.attr("__entries");
                         if (((PyTypeObject *) arg.ptr())->tp_doc) {
                             docstring += std::string(
                                 reinterpret_cast<PyTypeObject *>(arg.ptr())->tp_doc);
                             docstring += "\n\n";
                         }
                         docstring += "Members:";
                         for (auto kv : entries) {
                             auto key = std::string(pybind11::str(kv.first));
                             auto comment = kv.second[int_(1)];
                             docstring += "\n\n  ";
                             docstring += key;
                             if (!comment.is_none()) {
                                 docstring += " : ";
                                 docstring += pybind11::str(comment).cast<std::string>();
                             }
                         }
                         return docstring;
                     },
                     name("__doc__")),
                 none(),
                 none(),
                 "");
         }
 
         m_base.attr("__members__") = static_property(cpp_function(
                                                          [](handle arg) -> dict {
                                                              dict entries = arg.attr("__entries"),
                                                                   m;
                                                              for (auto kv : entries) {
                                                                  m[kv.first] = kv.second[int_(0)];
                                                              }
                                                              return m;
                                                          },
                                                          name("__members__")),
                                                      none(),
                                                      none(),
                                                      "");
 
 #define PYBIND11_ENUM_OP_STRICT(op, expr, strict_behavior)                                        \
     m_base.attr(op) = cpp_function(                                                               \
         [](const object &a, const object &b) {                                                    \
             if (!type::handle_of(a).is(type::handle_of(b)))                                       \
                 strict_behavior; /* NOLINT(bugprone-macro-parentheses) */                         \
             return expr;                                                                          \
         },                                                                                        \
         name(op),                                                                                 \
         is_method(m_base),                                                                        \
         arg("other"))
 
 #define PYBIND11_ENUM_OP_CONV(op, expr)                                                           \
     m_base.attr(op) = cpp_function(                                                               \
         [](const object &a_, const object &b_) {                                                  \
             int_ a(a_), b(b_);                                                                    \
             return expr;                                                                          \
         },                                                                                        \
         name(op),                                                                                 \
         is_method(m_base),                                                                        \
         arg("other"))
 
 #define PYBIND11_ENUM_OP_CONV_LHS(op, expr)                                                       \
     m_base.attr(op) = cpp_function(                                                               \
         [](const object &a_, const object &b) {                                                   \
             int_ a(a_);                                                                           \
             return expr;                                                                          \
         },                                                                                        \
         name(op),                                                                                 \
         is_method(m_base),                                                                        \
         arg("other"))
 
         if (is_convertible) {
             PYBIND11_ENUM_OP_CONV_LHS("__eq__", !b.is_none() && a.equal(b));
             PYBIND11_ENUM_OP_CONV_LHS("__ne__", b.is_none() || !a.equal(b));
 
             if (is_arithmetic) {
                 PYBIND11_ENUM_OP_CONV("__lt__", a < b);
                 PYBIND11_ENUM_OP_CONV("__gt__", a > b);
                 PYBIND11_ENUM_OP_CONV("__le__", a <= b);
                 PYBIND11_ENUM_OP_CONV("__ge__", a >= b);
                 PYBIND11_ENUM_OP_CONV("__and__", a & b);
                 PYBIND11_ENUM_OP_CONV("__rand__", a & b);
                 PYBIND11_ENUM_OP_CONV("__or__", a | b);
                 PYBIND11_ENUM_OP_CONV("__ror__", a | b);
                 PYBIND11_ENUM_OP_CONV("__xor__", a ^ b);
                 PYBIND11_ENUM_OP_CONV("__rxor__", a ^ b);
                 m_base.attr("__invert__")
                     = cpp_function([](const object &arg) { return ~(int_(arg)); },
                                    name("__invert__"),
                                    is_method(m_base));
             }
         } else {
             PYBIND11_ENUM_OP_STRICT("__eq__", int_(a).equal(int_(b)), return false);
             PYBIND11_ENUM_OP_STRICT("__ne__", !int_(a).equal(int_(b)), return true);
 
             if (is_arithmetic) {
 #define PYBIND11_THROW throw type_error("Expected an enumeration of matching type!");
                 PYBIND11_ENUM_OP_STRICT("__lt__", int_(a) < int_(b), PYBIND11_THROW);
                 PYBIND11_ENUM_OP_STRICT("__gt__", int_(a) > int_(b), PYBIND11_THROW);
                 PYBIND11_ENUM_OP_STRICT("__le__", int_(a) <= int_(b), PYBIND11_THROW);
                 PYBIND11_ENUM_OP_STRICT("__ge__", int_(a) >= int_(b), PYBIND11_THROW);
 #undef PYBIND11_THROW
             }
         }
 
 #undef PYBIND11_ENUM_OP_CONV_LHS
 #undef PYBIND11_ENUM_OP_CONV
 #undef PYBIND11_ENUM_OP_STRICT
 
         m_base.attr("__getstate__") = cpp_function(
             [](const object &arg) { return int_(arg); }, name("__getstate__"), is_method(m_base));
 
         m_base.attr("__hash__") = cpp_function(
             [](const object &arg) { return int_(arg); }, name("__hash__"), is_method(m_base));
     }
 
     PYBIND11_NOINLINE void value(char const *name_, object value, const char *doc = nullptr) {
         dict entries = m_base.attr("__entries");
         str name(name_);
         if (entries.contains(name)) {
             std::string type_name = (std::string) str(m_base.attr("__name__"));
             throw value_error(std::move(type_name) + ": element \"" + std::string(name_)
                               + "\" already exists!");
         }
 
         entries[name] = pybind11::make_tuple(value, doc);
         m_base.attr(std::move(name)) = std::move(value);
     }
 
     PYBIND11_NOINLINE void export_values() {
         dict entries = m_base.attr("__entries");
         for (auto kv : entries) {
             m_parent.attr(kv.first) = kv.second[int_(0)];
         }
     }
 
     handle m_base;
     handle m_parent;
 };
 
 template <bool is_signed, size_t length>
 struct equivalent_integer {};
 template <>
 struct equivalent_integer<true, 1> {
     using type = int8_t;
 };
 template <>
 struct equivalent_integer<false, 1> {
     using type = uint8_t;
 };
 template <>
 struct equivalent_integer<true, 2> {
     using type = int16_t;
 };
 template <>
 struct equivalent_integer<false, 2> {
     using type = uint16_t;
 };
 template <>
 struct equivalent_integer<true, 4> {
     using type = int32_t;
 };
 template <>
 struct equivalent_integer<false, 4> {
     using type = uint32_t;
 };
 template <>
 struct equivalent_integer<true, 8> {
     using type = int64_t;
 };
 template <>
 struct equivalent_integer<false, 8> {
     using type = uint64_t;
 };
 
 template <typename IntLike>
 using equivalent_integer_t =
     typename equivalent_integer<std::is_signed<IntLike>::value, sizeof(IntLike)>::type;
 
 PYBIND11_NAMESPACE_END(detail)
 
 /// Binds C++ enumerations and enumeration classes to Python
 template <typename Type>
 class enum_ : public class_<Type> {
 public:
     using Base = class_<Type>;
     using Base::attr;
     using Base::def;
     using Base::def_property_readonly;
     using Base::def_property_readonly_static;
     using Underlying = typename std::underlying_type<Type>::type;
     // Scalar is the integer representation of underlying type
     using Scalar = detail::conditional_t<detail::any_of<detail::is_std_char_type<Underlying>,
                                                         std::is_same<Underlying, bool>>::value,
                                          detail::equivalent_integer_t<Underlying>,
                                          Underlying>;
 
     template <typename... Extra>
     enum_(const handle &scope, const char *name, const Extra &...extra)
         : class_<Type>(scope, name, extra...), m_base(*this, scope) {
         constexpr bool is_arithmetic = detail::any_of<std::is_same<arithmetic, Extra>...>::value;
         constexpr bool is_convertible = std::is_convertible<Type, Underlying>::value;
         m_base.init(is_arithmetic, is_convertible);
 
         def(init([](Scalar i) { return static_cast<Type>(i); }), arg("value"));
         def_property_readonly("value", [](Type value) { return (Scalar) value; });
         def("__int__", [](Type value) { return (Scalar) value; });
         def("__index__", [](Type value) { return (Scalar) value; });
         attr("__setstate__") = cpp_function(
             [](detail::value_and_holder &v_h, Scalar arg) {
                 detail::initimpl::setstate<Base>(
                     v_h, static_cast<Type>(arg), Py_TYPE(v_h.inst) != v_h.type->type);
             },
             detail::is_new_style_constructor(),
             pybind11::name("__setstate__"),
             is_method(*this),
             arg("state"));
     }
 
     /// Export enumeration entries into the parent scope
     enum_ &export_values() {
         m_base.export_values();
         return *this;
     }
 
     /// Add an enumeration entry
     enum_ &value(char const *name, Type value, const char *doc = nullptr) {
         m_base.value(name, pybind11::cast(value, return_value_policy::copy), doc);
         return *this;
     }
 
 private:
     detail::enum_base m_base;
 };
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 PYBIND11_NOINLINE void keep_alive_impl(handle nurse, handle patient) {
     if (!nurse || !patient) {
         pybind11_fail("Could not activate keep_alive!");
     }
 
     if (patient.is_none() || nurse.is_none()) {
         return; /* Nothing to keep alive or nothing to be kept alive by */
     }
 
     auto tinfo = all_type_info(Py_TYPE(nurse.ptr()));
     if (!tinfo.empty()) {
         /* It's a pybind-registered type, so we can store the patient in the
          * internal list. */
         add_patient(nurse.ptr(), patient.ptr());
     } else {
         /* Fall back to clever approach based on weak references taken from
          * Boost.Python. This is not used for pybind-registered types because
          * the objects can be destroyed out-of-order in a GC pass. */
         cpp_function disable_lifesupport([patient](handle weakref) {
             patient.dec_ref();
             weakref.dec_ref();
         });
 
         weakref wr(nurse, disable_lifesupport);
 
         patient.inc_ref(); /* reference patient and leak the weak reference */
         (void) wr.release();
     }
 }
 
 PYBIND11_NOINLINE void
 keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret) {
     auto get_arg = [&](size_t n) {
         if (n == 0) {
             return ret;
         }
         if (n == 1 && call.init_self) {
             return call.init_self;
         }
         if (n <= call.args.size()) {
             return call.args[n - 1];
         }
         return handle();
     };
 
     keep_alive_impl(get_arg(Nurse), get_arg(Patient));
 }
 
 inline std::pair<decltype(internals::registered_types_py)::iterator, bool>
 all_type_info_get_cache(PyTypeObject *type) {
     auto res = get_internals()
                    .registered_types_py
 #ifdef __cpp_lib_unordered_map_try_emplace
                    .try_emplace(type);
 #else
                    .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) {
                     get_internals().registered_types_py.erase(type);
 
                     // 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();
                 }))
             .release();
     }
 
     return res;
 }
 
 /* There are a large number of apparently unused template arguments because
  * each combination requires a separate py::class_ registration.
  */
 template <typename Access,
           return_value_policy Policy,
           typename Iterator,
           typename Sentinel,
           typename ValueType,
           typename... Extra>
 struct iterator_state {
     Iterator it;
     Sentinel end;
     bool first_or_done;
 };
 
 // Note: these helpers take the iterator by non-const reference because some
 // iterators in the wild can't be dereferenced when const. The & after Iterator
 // is required for MSVC < 16.9. SFINAE cannot be reused for result_type due to
 // bugs in ICC, NVCC, and PGI compilers. See PR #3293.
 template <typename Iterator, typename SFINAE = decltype(*std::declval<Iterator &>())>
 struct iterator_access {
     using result_type = decltype(*std::declval<Iterator &>());
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     result_type operator()(Iterator &it) const { return *it; }
 };
 
 template <typename Iterator, typename SFINAE = decltype((*std::declval<Iterator &>()).first)>
 class iterator_key_access {
 private:
     using pair_type = decltype(*std::declval<Iterator &>());
 
 public:
     /* If either the pair itself or the element of the pair is a reference, we
      * want to return a reference, otherwise a value. When the decltype
      * expression is parenthesized it is based on the value category of the
      * expression; otherwise it is the declared type of the pair member.
      * The use of declval<pair_type> in the second branch rather than directly
      * using *std::declval<Iterator &>() is a workaround for nvcc
      * (it's not used in the first branch because going via decltype and back
      * through declval does not perfectly preserve references).
      */
     using result_type
         = conditional_t<std::is_reference<decltype(*std::declval<Iterator &>())>::value,
                         decltype(((*std::declval<Iterator &>()).first)),
                         decltype(std::declval<pair_type>().first)>;
     result_type operator()(Iterator &it) const { return (*it).first; }
 };
 
 template <typename Iterator, typename SFINAE = decltype((*std::declval<Iterator &>()).second)>
 class iterator_value_access {
 private:
     using pair_type = decltype(*std::declval<Iterator &>());
 
 public:
     using result_type
         = conditional_t<std::is_reference<decltype(*std::declval<Iterator &>())>::value,
                         decltype(((*std::declval<Iterator &>()).second)),
                         decltype(std::declval<pair_type>().second)>;
     result_type operator()(Iterator &it) const { return (*it).second; }
 };
 
 template <typename Access,
           return_value_policy Policy,
           typename Iterator,
           typename Sentinel,
           typename ValueType,
           typename... Extra>
 iterator make_iterator_impl(Iterator first, Sentinel last, Extra &&...extra) {
     using state = detail::iterator_state<Access, Policy, Iterator, Sentinel, ValueType, Extra...>;
     // TODO: state captures only the types of Extra, not the values
 
     if (!detail::get_type_info(typeid(state), false)) {
         class_<state>(handle(), "iterator", pybind11::module_local())
             .def("__iter__", [](state &s) -> state & { return s; })
             .def(
                 "__next__",
                 [](state &s) -> ValueType {
                     if (!s.first_or_done) {
                         ++s.it;
                     } else {
                         s.first_or_done = false;
                     }
                     if (s.it == s.end) {
                         s.first_or_done = true;
                         throw stop_iteration();
                     }
                     return Access()(s.it);
                     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
                 },
                 std::forward<Extra>(extra)...,
                 Policy);
     }
 
     return cast(state{first, last, true});
 }
 
 PYBIND11_NAMESPACE_END(detail)
 
 /// Makes a python iterator from a first and past-the-end C++ InputIterator.
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Iterator,
           typename Sentinel,
           typename ValueType = typename detail::iterator_access<Iterator>::result_type,
           typename... Extra>
 iterator make_iterator(Iterator first, Sentinel last, Extra &&...extra) {
     return detail::make_iterator_impl<detail::iterator_access<Iterator>,
                                       Policy,
                                       Iterator,
                                       Sentinel,
                                       ValueType,
                                       Extra...>(first, last, std::forward<Extra>(extra)...);
 }
 
 /// Makes a python iterator over the keys (`.first`) of a iterator over pairs from a
 /// first and past-the-end InputIterator.
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Iterator,
           typename Sentinel,
           typename KeyType = typename detail::iterator_key_access<Iterator>::result_type,
           typename... Extra>
 iterator make_key_iterator(Iterator first, Sentinel last, Extra &&...extra) {
     return detail::make_iterator_impl<detail::iterator_key_access<Iterator>,
                                       Policy,
                                       Iterator,
                                       Sentinel,
                                       KeyType,
                                       Extra...>(first, last, std::forward<Extra>(extra)...);
 }
 
 /// Makes a python iterator over the values (`.second`) of a iterator over pairs from a
 /// first and past-the-end InputIterator.
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Iterator,
           typename Sentinel,
           typename ValueType = typename detail::iterator_value_access<Iterator>::result_type,
           typename... Extra>
 iterator make_value_iterator(Iterator first, Sentinel last, Extra &&...extra) {
     return detail::make_iterator_impl<detail::iterator_value_access<Iterator>,
                                       Policy,
                                       Iterator,
                                       Sentinel,
                                       ValueType,
                                       Extra...>(first, last, std::forward<Extra>(extra)...);
 }
 
 /// Makes an iterator over values of an stl container or other container supporting
 /// `std::begin()`/`std::end()`
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Type,
           typename... Extra>
 iterator make_iterator(Type &value, Extra &&...extra) {
     return make_iterator<Policy>(
         std::begin(value), std::end(value), std::forward<Extra>(extra)...);
 }
 
 /// Makes an iterator over the keys (`.first`) of a stl map-like container supporting
 /// `std::begin()`/`std::end()`
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Type,
           typename... Extra>
 iterator make_key_iterator(Type &value, Extra &&...extra) {
     return make_key_iterator<Policy>(
         std::begin(value), std::end(value), std::forward<Extra>(extra)...);
 }
 
 /// Makes an iterator over the values (`.second`) of a stl map-like container supporting
 /// `std::begin()`/`std::end()`
 template <return_value_policy Policy = return_value_policy::reference_internal,
           typename Type,
           typename... Extra>
 iterator make_value_iterator(Type &value, Extra &&...extra) {
     return make_value_iterator<Policy>(
         std::begin(value), std::end(value), std::forward<Extra>(extra)...);
 }
 
 template <typename InputType, typename OutputType>
 void implicitly_convertible() {
     struct set_flag {
         bool &flag;
         explicit set_flag(bool &flag_) : flag(flag_) { flag_ = true; }
         ~set_flag() { flag = false; }
     };
     auto implicit_caster = [](PyObject *obj, PyTypeObject *type) -> PyObject * {
         static bool currently_used = false;
         if (currently_used) { // implicit conversions are non-reentrant
             return nullptr;
         }
         set_flag flag_helper(currently_used);
         if (!detail::make_caster<InputType>().load(obj, false)) {
             return nullptr;
         }
         tuple args(1);
         args[0] = obj;
         PyObject *result = PyObject_Call((PyObject *) type, args.ptr(), nullptr);
         if (result == nullptr) {
             PyErr_Clear();
         }
         return result;
     };
 
     if (auto *tinfo = detail::get_type_info(typeid(OutputType))) {
         tinfo->implicit_conversions.emplace_back(std::move(implicit_caster));
     } else {
         pybind11_fail("implicitly_convertible: Unable to find type " + type_id<OutputType>());
     }
 }
 
 inline void register_exception_translator(ExceptionTranslator &&translator) {
     detail::get_internals().registered_exception_translators.push_front(
         std::forward<ExceptionTranslator>(translator));
 }
 
 /**
  * Add a new module-local exception translator. Locally registered functions
  * will be tried before any globally registered exception translators, which
  * will only be invoked if the module-local handlers do not deal with
  * the exception.
  */
 inline void register_local_exception_translator(ExceptionTranslator &&translator) {
     detail::get_local_internals().registered_exception_translators.push_front(
         std::forward<ExceptionTranslator>(translator));
 }
 
 /**
  * Wrapper to generate a new Python exception type.
  *
  * This should only be used with PyErr_SetString for now.
  * It is not (yet) possible to use as a py::base.
  * Template type argument is reserved for future use.
  */
 template <typename type>
 class exception : public object {
 public:
     exception() = default;
     exception(handle scope, const char *name, handle base = PyExc_Exception) {
         std::string full_name
             = scope.attr("__name__").cast<std::string>() + std::string(".") + name;
         m_ptr = PyErr_NewException(const_cast<char *>(full_name.c_str()), base.ptr(), nullptr);
         if (hasattr(scope, "__dict__") && scope.attr("__dict__").contains(name)) {
             pybind11_fail("Error during initialization: multiple incompatible "
                           "definitions with name \""
                           + std::string(name) + "\"");
         }
         scope.attr(name) = *this;
     }
 
     // Sets the current python exception to this exception object with the given message
     void operator()(const char *message) { PyErr_SetString(m_ptr, message); }
 };
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 // Returns a reference to a function-local static exception object used in the simple
 // register_exception approach below.  (It would be simpler to have the static local variable
 // directly in register_exception, but that makes clang <3.5 segfault - issue #1349).
 template <typename CppException>
 exception<CppException> &get_exception_object() {
     static exception<CppException> ex;
     return ex;
 }
 
 // Helper function for register_exception and register_local_exception
 template <typename CppException>
 exception<CppException> &
 register_exception_impl(handle scope, const char *name, handle base, bool isLocal) {
     auto &ex = detail::get_exception_object<CppException>();
     if (!ex) {
         ex = exception<CppException>(scope, name, base);
     }
 
     auto register_func
         = isLocal ? &register_local_exception_translator : &register_exception_translator;
 
     register_func([](std::exception_ptr p) {
         if (!p) {
             return;
         }
         try {
             std::rethrow_exception(p);
         } catch (const CppException &e) {
             detail::get_exception_object<CppException>()(e.what());
         }
     });
     return ex;
 }
 
 PYBIND11_NAMESPACE_END(detail)
 
 /**
  * Registers a Python exception in `m` of the given `name` and installs a translator to
  * translate the C++ exception to the created Python exception using the what() method.
  * This is intended for simple exception translations; for more complex translation, register the
  * exception object and translator directly.
  */
 template <typename CppException>
 exception<CppException> &
 register_exception(handle scope, const char *name, handle base = PyExc_Exception) {
     return detail::register_exception_impl<CppException>(scope, name, base, false /* isLocal */);
 }
 
 /**
  * Registers a Python exception in `m` of the given `name` and installs a translator to
  * translate the C++ exception to the created Python exception using the what() method.
  * This translator will only be used for exceptions that are thrown in this module and will be
  * tried before global exception translators, including those registered with register_exception.
  * This is intended for simple exception translations; for more complex translation, register the
  * exception object and translator directly.
  */
 template <typename CppException>
 exception<CppException> &
 register_local_exception(handle scope, const char *name, handle base = PyExc_Exception) {
     return detail::register_exception_impl<CppException>(scope, name, base, true /* isLocal */);
 }
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 PYBIND11_NOINLINE void print(const tuple &args, const dict &kwargs) {
     auto strings = tuple(args.size());
     for (size_t i = 0; i < args.size(); ++i) {
         strings[i] = str(args[i]);
     }
     auto sep = kwargs.contains("sep") ? kwargs["sep"] : str(" ");
     auto line = sep.attr("join")(std::move(strings));
 
     object file;
     if (kwargs.contains("file")) {
         file = kwargs["file"].cast<object>();
     } else {
         try {
             file = module_::import("sys").attr("stdout");
         } catch (const error_already_set &) {
             /* If print() is called from code that is executed as
                part of garbage collection during interpreter shutdown,
                importing 'sys' can fail. Give up rather than crashing the
                interpreter in this case. */
             return;
         }
     }
 
     auto write = file.attr("write");
     write(std::move(line));
     write(kwargs.contains("end") ? kwargs["end"] : str("\n"));
 
     if (kwargs.contains("flush") && kwargs["flush"].cast<bool>()) {
         file.attr("flush")();
     }
 }
 PYBIND11_NAMESPACE_END(detail)
 
 template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
 void print(Args &&...args) {
     auto c = detail::collect_arguments<policy>(std::forward<Args>(args)...);
     detail::print(c.args(), c.kwargs());
 }
 
 inline void
 error_already_set::m_fetched_error_deleter(detail::error_fetch_and_normalize *raw_ptr) {
     gil_scoped_acquire gil;
     error_scope scope;
     delete raw_ptr;
 }
 
 inline const char *error_already_set::what() const noexcept {
     gil_scoped_acquire gil;
     error_scope scope;
     return m_fetched_error->error_string().c_str();
 }
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 inline function
 get_type_override(const void *this_ptr, const type_info *this_type, const char *name) {
     handle self = get_object_handle(this_ptr, this_type);
     if (!self) {
         return function();
     }
     handle type = type::handle_of(self);
     auto key = std::make_pair(type.ptr(), name);
 
     /* Cache functions that aren't overridden in Python to avoid
        many costly Python dictionary lookups below */
     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()) {
         cache.insert(std::move(key));
         return function();
     }
 
     /* Don't call dispatch code if invoked from overridden function.
        Unfortunately this doesn't work on PyPy. */
 #if !defined(PYPY_VERSION)
 #    if PY_VERSION_HEX >= 0x03090000
     PyFrameObject *frame = PyThreadState_GetFrame(PyThreadState_Get());
     if (frame != nullptr) {
         PyCodeObject *f_code = PyFrame_GetCode(frame);
         // f_code is guaranteed to not be NULL
         if ((std::string) str(f_code->co_name) == name && f_code->co_argcount > 0) {
             PyObject *locals = PyEval_GetLocals();
             if (locals != nullptr) {
                 PyObject *co_varnames = PyObject_GetAttrString((PyObject *) f_code, "co_varnames");
                 PyObject *self_arg = PyTuple_GET_ITEM(co_varnames, 0);
                 Py_DECREF(co_varnames);
                 PyObject *self_caller = dict_getitem(locals, self_arg);
                 if (self_caller == self.ptr()) {
                     Py_DECREF(f_code);
                     Py_DECREF(frame);
                     return function();
                 }
             }
         }
         Py_DECREF(f_code);
         Py_DECREF(frame);
     }
 #    else
     PyFrameObject *frame = PyThreadState_Get()->frame;
     if (frame != nullptr && (std::string) str(frame->f_code->co_name) == name
         && frame->f_code->co_argcount > 0) {
         PyFrame_FastToLocals(frame);
         PyObject *self_caller
             = dict_getitem(frame->f_locals, PyTuple_GET_ITEM(frame->f_code->co_varnames, 0));
         if (self_caller == self.ptr()) {
             return function();
         }
     }
 #    endif
 
 #else
     /* PyPy currently doesn't provide a detailed cpyext emulation of
        frame objects, so we have to emulate this using Python. This
        is going to be slow..*/
     dict d;
     d["self"] = self;
     d["name"] = pybind11::str(name);
     PyObject *result
         = PyRun_String("import inspect\n"
                        "frame = inspect.currentframe()\n"
                        "if frame is not None:\n"
                        "    frame = frame.f_back\n"
                        "    if frame is not None and str(frame.f_code.co_name) == name and "
                        "frame.f_code.co_argcount > 0:\n"
                        "        self_caller = frame.f_locals[frame.f_code.co_varnames[0]]\n"
                        "        if self_caller == self:\n"
                        "            self = None\n",
                        Py_file_input,
                        d.ptr(),
                        d.ptr());
     if (result == nullptr)
         throw error_already_set();
     Py_DECREF(result);
     if (d["self"].is_none())
         return function();
 #endif
 
     return override;
 }
 PYBIND11_NAMESPACE_END(detail)
 
 /** \rst
   Try to retrieve a python method by the provided name from the instance pointed to by the
   this_ptr.
 
   :this_ptr: The pointer to the object the overridden method should be retrieved for. This should
              be the first non-trampoline class encountered in the inheritance chain.
   :name: The name of the overridden Python method to retrieve.
   :return: The Python method by this name from the object or an empty function wrapper.
  \endrst */
 template <class T>
 function get_override(const T *this_ptr, const char *name) {
     auto *tinfo = detail::get_type_info(typeid(T));
     return tinfo ? detail::get_type_override(this_ptr, tinfo, name) : function();
 }
 
 #define PYBIND11_OVERRIDE_IMPL(ret_type, cname, name, ...)                                        \
     do {                                                                                          \
         pybind11::gil_scoped_acquire gil;                                                         \
         pybind11::function override                                                               \
             = pybind11::get_override(static_cast<const cname *>(this), name);                     \
         if (override) {                                                                           \
             auto o = override(__VA_ARGS__);                                                       \
             if (pybind11::detail::cast_is_temporary_value_reference<ret_type>::value) {           \
                 static pybind11::detail::override_caster_t<ret_type> caster;                      \
                 return pybind11::detail::cast_ref<ret_type>(std::move(o), caster);                \
             }                                                                                     \
             return pybind11::detail::cast_safe<ret_type>(std::move(o));                           \
         }                                                                                         \
     } while (false)
 
 /** \rst
     Macro to populate the virtual method in the trampoline class. This macro tries to look up a
     method named 'fn' from the Python side, deals with the :ref:`gil` and necessary argument
     conversions to call this method and return the appropriate type.
     See :ref:`overriding_virtuals` for more information. This macro should be used when the method
     name in C is not the same as the method name in Python. For example with `__str__`.
 
     .. code-block:: cpp
 
       std::string toString() override {
         PYBIND11_OVERRIDE_NAME(
             std::string, // Return type (ret_type)
             Animal,      // Parent class (cname)
             "__str__",   // Name of method in Python (name)
             toString,    // Name of function in C++ (fn)
         );
       }
 \endrst */
 #define PYBIND11_OVERRIDE_NAME(ret_type, cname, name, fn, ...)                                    \
     do {                                                                                          \
         PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__); \
         return cname::fn(__VA_ARGS__);                                                            \
     } while (false)
 
 /** \rst
     Macro for pure virtual functions, this function is identical to
     :c:macro:`PYBIND11_OVERRIDE_NAME`, except that it throws if no override can be found.
 \endrst */
 #define PYBIND11_OVERRIDE_PURE_NAME(ret_type, cname, name, fn, ...)                               \
     do {                                                                                          \
         PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__); \
         pybind11::pybind11_fail(                                                                  \
             "Tried to call pure virtual function \"" PYBIND11_STRINGIFY(cname) "::" name "\"");   \
     } while (false)
 
 /** \rst
     Macro to populate the virtual method in the trampoline class. This macro tries to look up the
     method from the Python side, deals with the :ref:`gil` and necessary argument conversions to
     call this method and return the appropriate type. This macro should be used if the method name
     in C and in Python are identical.
     See :ref:`overriding_virtuals` for more information.
 
     .. code-block:: cpp
 
       class PyAnimal : public Animal {
       public:
           // Inherit the constructors
           using Animal::Animal;
 
           // Trampoline (need one for each virtual function)
           std::string go(int n_times) override {
               PYBIND11_OVERRIDE_PURE(
                   std::string, // Return type (ret_type)
                   Animal,      // Parent class (cname)
                   go,          // Name of function in C++ (must match Python name) (fn)
                   n_times      // Argument(s) (...)
               );
           }
       };
 \endrst */
 #define PYBIND11_OVERRIDE(ret_type, cname, fn, ...)                                               \
     PYBIND11_OVERRIDE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), #fn, fn, __VA_ARGS__)
 
 /** \rst
     Macro for pure virtual functions, this function is identical to :c:macro:`PYBIND11_OVERRIDE`,
     except that it throws if no override can be found.
 \endrst */
 #define PYBIND11_OVERRIDE_PURE(ret_type, cname, fn, ...)                                          \
     PYBIND11_OVERRIDE_PURE_NAME(                                                                  \
         PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), #fn, fn, __VA_ARGS__)
 
 // Deprecated versions
 
 PYBIND11_DEPRECATED("get_type_overload has been deprecated")
 inline function
 get_type_overload(const void *this_ptr, const detail::type_info *this_type, const char *name) {
     return detail::get_type_override(this_ptr, this_type, name);
 }
 
 template <class T>
 inline function get_overload(const T *this_ptr, const char *name) {
     return get_override(this_ptr, name);
 }
 
 #define PYBIND11_OVERLOAD_INT(ret_type, cname, name, ...)                                         \
     PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__)
 #define PYBIND11_OVERLOAD_NAME(ret_type, cname, name, fn, ...)                                    \
     PYBIND11_OVERRIDE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, fn, __VA_ARGS__)
 #define PYBIND11_OVERLOAD_PURE_NAME(ret_type, cname, name, fn, ...)                               \
     PYBIND11_OVERRIDE_PURE_NAME(                                                                  \
         PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, fn, __VA_ARGS__);
 #define PYBIND11_OVERLOAD(ret_type, cname, fn, ...)                                               \
     PYBIND11_OVERRIDE(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), fn, __VA_ARGS__)
 #define PYBIND11_OVERLOAD_PURE(ret_type, cname, fn, ...)                                          \
     PYBIND11_OVERRIDE_PURE(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), fn, __VA_ARGS__);
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)