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diff --git a/3rdparty/pybind11/tests/constructor_stats.h b/3rdparty/pybind11/tests/constructor_stats.h
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+#pragma once
+/*
+    tests/constructor_stats.h -- framework for printing and tracking object
+    instance lifetimes in example/test code.
+
+    Copyright (c) 2016 Jason Rhinelander <jason@imaginary.ca>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+
+This header provides a few useful tools for writing examples or tests that want to check and/or
+display object instance lifetimes.  It requires that you include this header and add the following
+function calls to constructors:
+
+    class MyClass {
+        MyClass() { ...; print_default_created(this); }
+        ~MyClass() { ...; print_destroyed(this); }
+        MyClass(const MyClass &c) { ...; print_copy_created(this); }
+        MyClass(MyClass &&c) { ...; print_move_created(this); }
+        MyClass(int a, int b) { ...; print_created(this, a, b); }
+        MyClass &operator=(const MyClass &c) { ...; print_copy_assigned(this); }
+        MyClass &operator=(MyClass &&c) { ...; print_move_assigned(this); }
+
+        ...
+    }
+
+You can find various examples of these in several of the existing testing .cpp files.  (Of course
+you don't need to add any of the above constructors/operators that you don't actually have, except
+for the destructor).
+
+Each of these will print an appropriate message such as:
+
+    ### MyClass @ 0x2801910 created via default constructor
+    ### MyClass @ 0x27fa780 created 100 200
+    ### MyClass @ 0x2801910 destroyed
+    ### MyClass @ 0x27fa780 destroyed
+
+You can also include extra arguments (such as the 100, 200 in the output above, coming from the
+value constructor) for all of the above methods which will be included in the output.
+
+For testing, each of these also keeps track the created instances and allows you to check how many
+of the various constructors have been invoked from the Python side via code such as:
+
+    from pybind11_tests import ConstructorStats
+    cstats = ConstructorStats.get(MyClass)
+    print(cstats.alive())
+    print(cstats.default_constructions)
+
+Note that `.alive()` should usually be the first thing you call as it invokes Python's garbage
+collector to actually destroy objects that aren't yet referenced.
+
+For everything except copy and move constructors and destructors, any extra values given to the
+print_...() function is stored in a class-specific values list which you can retrieve and inspect
+from the ConstructorStats instance `.values()` method.
+
+In some cases, when you need to track instances of a C++ class not registered with pybind11, you
+need to add a function returning the ConstructorStats for the C++ class; this can be done with:
+
+    m.def("get_special_cstats", &ConstructorStats::get<SpecialClass>, py::return_value_policy::reference)
+
+Finally, you can suppress the output messages, but keep the constructor tracking (for
+inspection/testing in python) by using the functions with `print_` replaced with `track_` (e.g.
+`track_copy_created(this)`).
+
+*/
+
+#include "pybind11_tests.h"
+#include <unordered_map>
+#include <list>
+#include <typeindex>
+#include <sstream>
+
+class ConstructorStats {
+protected:
+    std::unordered_map<void*, int> _instances; // Need a map rather than set because members can shared address with parents
+    std::list<std::string> _values; // Used to track values (e.g. of value constructors)
+public:
+    int default_constructions = 0;
+    int copy_constructions = 0;
+    int move_constructions = 0;
+    int copy_assignments = 0;
+    int move_assignments = 0;
+
+    void copy_created(void *inst) {
+        created(inst);
+        copy_constructions++;
+    }
+
+    void move_created(void *inst) {
+        created(inst);
+        move_constructions++;
+    }
+
+    void default_created(void *inst) {
+        created(inst);
+        default_constructions++;
+    }
+
+    void created(void *inst) {
+        ++_instances[inst];
+    }
+
+    void destroyed(void *inst) {
+        if (--_instances[inst] < 0)
+            throw std::runtime_error("cstats.destroyed() called with unknown "
+                                     "instance; potential double-destruction "
+                                     "or a missing cstats.created()");
+    }
+
+    static void gc() {
+        // Force garbage collection to ensure any pending destructors are invoked:
+#if defined(PYPY_VERSION)
+        PyObject *globals = PyEval_GetGlobals();
+        PyObject *result = PyRun_String(
+            "import gc\n"
+            "for i in range(2):"
+            "    gc.collect()\n",
+            Py_file_input, globals, globals);
+        if (result == nullptr)
+            throw py::error_already_set();
+        Py_DECREF(result);
+#else
+        py::module::import("gc").attr("collect")();
+#endif
+    }
+
+    int alive() {
+        gc();
+        int total = 0;
+        for (const auto &p : _instances)
+            if (p.second > 0)
+                total += p.second;
+        return total;
+    }
+
+    void value() {} // Recursion terminator
+    // Takes one or more values, converts them to strings, then stores them.
+    template <typename T, typename... Tmore> void value(const T &v, Tmore &&...args) {
+        std::ostringstream oss;
+        oss << v;
+        _values.push_back(oss.str());
+        value(std::forward<Tmore>(args)...);
+    }
+
+    // Move out stored values
+    py::list values() {
+        py::list l;
+        for (const auto &v : _values) l.append(py::cast(v));
+        _values.clear();
+        return l;
+    }
+
+    // Gets constructor stats from a C++ type index
+    static ConstructorStats& get(std::type_index type) {
+        static std::unordered_map<std::type_index, ConstructorStats> all_cstats;
+        return all_cstats[type];
+    }
+
+    // Gets constructor stats from a C++ type
+    template <typename T> static ConstructorStats& get() {
+#if defined(PYPY_VERSION)
+        gc();
+#endif
+        return get(typeid(T));
+    }
+
+    // Gets constructor stats from a Python class
+    static ConstructorStats& get(py::object class_) {
+        auto &internals = py::detail::get_internals();
+        const std::type_index *t1 = nullptr, *t2 = nullptr;
+        try {
+            auto *type_info = internals.registered_types_py.at((PyTypeObject *) class_.ptr()).at(0);
+            for (auto &p : internals.registered_types_cpp) {
+                if (p.second == type_info) {
+                    if (t1) {
+                        t2 = &p.first;
+                        break;
+                    }
+                    t1 = &p.first;
+                }
+            }
+        }
+        catch (const std::out_of_range&) {}
+        if (!t1) throw std::runtime_error("Unknown class passed to ConstructorStats::get()");
+        auto &cs1 = get(*t1);
+        // If we have both a t1 and t2 match, one is probably the trampoline class; return whichever
+        // has more constructions (typically one or the other will be 0)
+        if (t2) {
+            auto &cs2 = get(*t2);
+            int cs1_total = cs1.default_constructions + cs1.copy_constructions + cs1.move_constructions + (int) cs1._values.size();
+            int cs2_total = cs2.default_constructions + cs2.copy_constructions + cs2.move_constructions + (int) cs2._values.size();
+            if (cs2_total > cs1_total) return cs2;
+        }
+        return cs1;
+    }
+};
+
+// To track construction/destruction, you need to call these methods from the various
+// constructors/operators.  The ones that take extra values record the given values in the
+// constructor stats values for later inspection.
+template <class T> void track_copy_created(T *inst) { ConstructorStats::get<T>().copy_created(inst); }
+template <class T> void track_move_created(T *inst) { ConstructorStats::get<T>().move_created(inst); }
+template <class T, typename... Values> void track_copy_assigned(T *, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.copy_assignments++;
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_move_assigned(T *, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.move_assignments++;
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_default_created(T *inst, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.default_created(inst);
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_created(T *inst, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.created(inst);
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_destroyed(T *inst) {
+    ConstructorStats::get<T>().destroyed(inst);
+}
+template <class T, typename... Values> void track_values(T *, Values &&...values) {
+    ConstructorStats::get<T>().value(std::forward<Values>(values)...);
+}
+
+/// Don't cast pointers to Python, print them as strings
+inline const char *format_ptrs(const char *p) { return p; }
+template <typename T>
+py::str format_ptrs(T *p) { return "{:#x}"_s.format(reinterpret_cast<std::uintptr_t>(p)); }
+template <typename T>
+auto format_ptrs(T &&x) -> decltype(std::forward<T>(x)) { return std::forward<T>(x); }
+
+template <class T, typename... Output>
+void print_constr_details(T *inst, const std::string &action, Output &&...output) {
+    py::print("###", py::type_id<T>(), "@", format_ptrs(inst), action,
+              format_ptrs(std::forward<Output>(output))...);
+}
+
+// Verbose versions of the above:
+template <class T, typename... Values> void print_copy_created(T *inst, Values &&...values) { // NB: this prints, but doesn't store, given values
+    print_constr_details(inst, "created via copy constructor", values...);
+    track_copy_created(inst);
+}
+template <class T, typename... Values> void print_move_created(T *inst, Values &&...values) { // NB: this prints, but doesn't store, given values
+    print_constr_details(inst, "created via move constructor", values...);
+    track_move_created(inst);
+}
+template <class T, typename... Values> void print_copy_assigned(T *inst, Values &&...values) {
+    print_constr_details(inst, "assigned via copy assignment", values...);
+    track_copy_assigned(inst, values...);
+}
+template <class T, typename... Values> void print_move_assigned(T *inst, Values &&...values) {
+    print_constr_details(inst, "assigned via move assignment", values...);
+    track_move_assigned(inst, values...);
+}
+template <class T, typename... Values> void print_default_created(T *inst, Values &&...values) {
+    print_constr_details(inst, "created via default constructor", values...);
+    track_default_created(inst, values...);
+}
+template <class T, typename... Values> void print_created(T *inst, Values &&...values) {
+    print_constr_details(inst, "created", values...);
+    track_created(inst, values...);
+}
+template <class T, typename... Values> void print_destroyed(T *inst, Values &&...values) { // Prints but doesn't store given values
+    print_constr_details(inst, "destroyed", values...);
+    track_destroyed(inst);
+}
+template <class T, typename... Values> void print_values(T *inst, Values &&...values) {
+    print_constr_details(inst, ":", values...);
+    track_values(inst, values...);
+}
+