diff --git a/.gitmodules b/.gitmodules
index ae3fc556..5e187288 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -34,3 +34,6 @@
 [submodule "modules/flat.hpp"]
 	path = modules/flat.hpp
 	url = https://github.com/BlackMATov/flat.hpp
+[submodule "modules/variant"]
+	path = modules/variant
+	url = https://github.com/mpark/variant
diff --git a/headers/3rdparty/flat.hpp/detail/is_transparent.hpp b/headers/3rdparty/flat.hpp/detail/is_transparent.hpp
new file mode 100644
index 00000000..2f6ec110
--- /dev/null
+++ b/headers/3rdparty/flat.hpp/detail/is_transparent.hpp
@@ -0,0 +1,23 @@
+/*******************************************************************************
+ * This file is part of the "https://github.com/blackmatov/flat.hpp"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2019, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#pragma once
+
+#include <type_traits>
+
+namespace flat_hpp::detail
+{
+    template < typename T, typename U, typename = void >
+    struct is_transparent
+    : std::false_type {};
+
+    template < typename T, typename U >
+    struct is_transparent<T, U, std::void_t<typename T::is_transparent>>
+    : std::true_type {};
+
+    template < typename T, typename U >
+    inline constexpr bool is_transparent_v = is_transparent<T, U>::value;
+}
diff --git a/headers/3rdparty/flat.hpp/detail/pair_compare.hpp b/headers/3rdparty/flat.hpp/detail/pair_compare.hpp
new file mode 100644
index 00000000..3d90c44c
--- /dev/null
+++ b/headers/3rdparty/flat.hpp/detail/pair_compare.hpp
@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * This file is part of the "https://github.com/blackmatov/flat.hpp"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2019, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#pragma once
+
+#include "is_transparent.hpp"
+
+namespace flat_hpp::detail
+{
+    template < typename Pair, typename Compare >
+    class pair_compare : public Compare {
+    public:
+        pair_compare() = default;
+
+        pair_compare(const Compare& compare)
+        : Compare(compare) {}
+
+        bool operator()(
+            const typename Pair::first_type& l,
+            const typename Pair::first_type& r) const
+        {
+            return Compare::operator()(l, r);
+        }
+
+        bool operator()(const Pair& l, const Pair& r) const {
+            return Compare::operator()(l.first, r.first);
+        }
+
+        bool operator()(
+            const typename Pair::first_type& l,
+            const Pair& r) const
+        {
+            return Compare::operator()(l, r.first);
+        }
+
+        bool operator()(
+            const Pair& l,
+            const typename Pair::first_type& r) const
+        {
+            return Compare::operator()(l.first, r);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            is_transparent_v<Compare, K>,
+            bool>
+        operator()(const K& l, const Pair& r) const {
+            return Compare::operator()(l, r.first);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            is_transparent_v<Compare, K>,
+            bool>
+        operator()(const Pair& l, const K& r) const {
+            return Compare::operator()(l.first, r);
+        }
+    };
+}
diff --git a/headers/3rdparty/flat.hpp/flat_map.hpp b/headers/3rdparty/flat.hpp/flat_map.hpp
index 54baa505..fef0b961 100644
--- a/headers/3rdparty/flat.hpp/flat_map.hpp
+++ b/headers/3rdparty/flat.hpp/flat_map.hpp
@@ -15,55 +15,21 @@
 #include <type_traits>
 #include <initializer_list>
 
+#include "detail/pair_compare.hpp"
+#include "detail/is_transparent.hpp"
+
 namespace flat_hpp
 {
-    namespace detail
-    {
-        template < typename Value, typename Compare >
-        class flat_map_compare : public Compare {
-        public:
-            flat_map_compare() = default;
-
-            flat_map_compare(const Compare& compare)
-            : Compare(compare) {}
-
-            bool operator()(
-                const typename Value::first_type& l,
-                const typename Value::first_type& r) const
-            {
-                return Compare::operator()(l, r);
-            }
-
-            bool operator()(
-                const typename Value::first_type& l,
-                const Value& r) const
-            {
-                return Compare::operator()(l, r.first);
-            }
-
-            bool operator()(
-                const Value& l,
-                const typename Value::first_type& r) const
-            {
-                return Compare::operator()(l.first, r);
-            }
-
-            bool operator()(const Value& l, const Value& r) const {
-                return Compare::operator()(l.first, r.first);
-            }
-        };
-    }
-
     template < typename Key
              , typename Value
              , typename Compare = std::less<Key>
              , typename Container = std::vector<std::pair<Key, Value>> >
     class flat_map
-        : private detail::flat_map_compare<
+        : private detail::pair_compare<
             typename Container::value_type,
             Compare>
     {
-        using base_type = detail::flat_map_compare<
+        using base_type = detail::pair_compare<
             typename Container::value_type,
             Compare>;
     public:
@@ -299,6 +265,30 @@ namespace flat_hpp
             throw std::out_of_range("flat_map::at: key not found");
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            mapped_type&>
+        at(const K& key) {
+            const iterator iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_map::at: key not found");
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const mapped_type&>
+        at(const K& key) const {
+            const const_iterator iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_map::at: key not found");
+        }
+
         std::pair<iterator, bool> insert(value_type&& value) {
             const iterator iter = lower_bound(value.first);
             return iter == end() || this->operator()(value, *iter)
@@ -362,7 +352,7 @@ namespace flat_hpp
         }
 
         size_type erase(const key_type& key) {
-            const iterator iter = find(key);
+            const const_iterator iter = find(key);
             return iter != end()
                 ? (erase(iter), 1)
                 : 0;
@@ -384,16 +374,47 @@ namespace flat_hpp
             return iter != end() ? 1 : 0;
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            size_type>
+        count(const K& key) const {
+            const const_iterator iter = find(key);
+            return iter != end() ? 1 : 0;
+        }
+
         iterator find(const key_type& key) {
             const iterator iter = lower_bound(key);
-            return iter != end() && !this->operator()(key, iter->first)
+            return iter != end() && !this->operator()(key, *iter)
                 ? iter
                 : end();
         }
 
         const_iterator find(const key_type& key) const {
             const const_iterator iter = lower_bound(key);
-            return iter != end() && !this->operator()(key, iter->first)
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        find(const K& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        find(const K& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
                 ? iter
                 : end();
         }
@@ -408,6 +429,24 @@ namespace flat_hpp
             return std::equal_range(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<iterator, iterator>>
+        equal_range(const K& key) {
+            const base_type& comp = *this;
+            return std::equal_range(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<const_iterator, const_iterator>>
+        equal_range(const K& key) const {
+            const base_type& comp = *this;
+            return std::equal_range(begin(), end(), key, comp);
+        }
+
         iterator lower_bound(const key_type& key) {
             const base_type& comp = *this;
             return std::lower_bound(begin(), end(), key, comp);
@@ -418,6 +457,24 @@ namespace flat_hpp
             return std::lower_bound(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        lower_bound(const K& key) {
+            const base_type& comp = *this;
+            return std::lower_bound(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        lower_bound(const K& key) const {
+            const base_type& comp = *this;
+            return std::lower_bound(begin(), end(), key, comp);
+        }
+
         iterator upper_bound(const key_type& key) {
             const base_type& comp = *this;
             return std::upper_bound(begin(), end(), key, comp);
@@ -428,6 +485,24 @@ namespace flat_hpp
             return std::upper_bound(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        upper_bound(const K& key) {
+            const base_type& comp = *this;
+            return std::upper_bound(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        upper_bound(const K& key) const {
+            const base_type& comp = *this;
+            return std::upper_bound(begin(), end(), key, comp);
+        }
+
         key_compare key_comp() const {
             return *this;
         }
diff --git a/headers/3rdparty/flat.hpp/flat_multimap.hpp b/headers/3rdparty/flat.hpp/flat_multimap.hpp
index c20d395a..2977061b 100644
--- a/headers/3rdparty/flat.hpp/flat_multimap.hpp
+++ b/headers/3rdparty/flat.hpp/flat_multimap.hpp
@@ -15,55 +15,21 @@
 #include <type_traits>
 #include <initializer_list>
 
+#include "detail/pair_compare.hpp"
+#include "detail/is_transparent.hpp"
+
 namespace flat_hpp
 {
-    namespace detail
-    {
-        template < typename Value, typename Compare >
-        class flat_multimap_compare : public Compare {
-        public:
-            flat_multimap_compare() = default;
-
-            flat_multimap_compare(const Compare& compare)
-            : Compare(compare) {}
-
-            bool operator()(
-                const typename Value::first_type& l,
-                const typename Value::first_type& r) const
-            {
-                return Compare::operator()(l, r);
-            }
-
-            bool operator()(
-                const typename Value::first_type& l,
-                const Value& r) const
-            {
-                return Compare::operator()(l, r.first);
-            }
-
-            bool operator()(
-                const Value& l,
-                const typename Value::first_type& r) const
-            {
-                return Compare::operator()(l.first, r);
-            }
-
-            bool operator()(const Value& l, const Value& r) const {
-                return Compare::operator()(l.first, r.first);
-            }
-        };
-    }
-
     template < typename Key
              , typename Value
              , typename Compare = std::less<Key>
              , typename Container = std::vector<std::pair<Key, Value>> >
     class flat_multimap
-        : private detail::flat_multimap_compare<
+        : private detail::pair_compare<
             typename Container::value_type,
             Compare>
     {
-        using base_type = detail::flat_multimap_compare<
+        using base_type = detail::pair_compare<
             typename Container::value_type,
             Compare>;
     public:
@@ -299,6 +265,30 @@ namespace flat_hpp
             throw std::out_of_range("flat_multimap::at: key not found");
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            mapped_type&>
+        at(const K& key) {
+            const iterator iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_multimap::at: key not found");
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const mapped_type&>
+        at(const K& key) const {
+            const const_iterator iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_multimap::at: key not found");
+        }
+
         iterator insert(value_type&& value) {
             const iterator iter = upper_bound(value.first);
             return data_.insert(iter, std::move(value));
@@ -380,16 +370,47 @@ namespace flat_hpp
             return std::distance(p.first, p.second);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            size_type>
+        count(const K& key) const {
+            const auto p = equal_range(key);
+            return std::distance(p.first, p.second);
+        }
+
         iterator find(const key_type& key) {
             const iterator iter = lower_bound(key);
-            return iter != end() && !this->operator()(key, iter->first)
+            return iter != end() && !this->operator()(key, *iter)
                 ? iter
                 : end();
         }
 
         const_iterator find(const key_type& key) const {
             const const_iterator iter = lower_bound(key);
-            return iter != end() && !this->operator()(key, iter->first)
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        find(const K& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        find(const K& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
                 ? iter
                 : end();
         }
@@ -404,6 +425,24 @@ namespace flat_hpp
             return std::equal_range(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<iterator, iterator>>
+        equal_range(const K& key) {
+            const base_type& comp = *this;
+            return std::equal_range(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<const_iterator, const_iterator>>
+        equal_range(const K& key) const {
+            const base_type& comp = *this;
+            return std::equal_range(begin(), end(), key, comp);
+        }
+
         iterator lower_bound(const key_type& key) {
             const base_type& comp = *this;
             return std::lower_bound(begin(), end(), key, comp);
@@ -414,6 +453,24 @@ namespace flat_hpp
             return std::lower_bound(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        lower_bound(const K& key) {
+            const base_type& comp = *this;
+            return std::lower_bound(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        lower_bound(const K& key) const {
+            const base_type& comp = *this;
+            return std::lower_bound(begin(), end(), key, comp);
+        }
+
         iterator upper_bound(const key_type& key) {
             const base_type& comp = *this;
             return std::upper_bound(begin(), end(), key, comp);
@@ -424,6 +481,24 @@ namespace flat_hpp
             return std::upper_bound(begin(), end(), key, comp);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        upper_bound(const K& key) {
+            const base_type& comp = *this;
+            return std::upper_bound(begin(), end(), key, comp);
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        upper_bound(const K& key) const {
+            const base_type& comp = *this;
+            return std::upper_bound(begin(), end(), key, comp);
+        }
+
         key_compare key_comp() const {
             return *this;
         }
diff --git a/headers/3rdparty/flat.hpp/flat_multiset.hpp b/headers/3rdparty/flat.hpp/flat_multiset.hpp
index e6e91117..52f25317 100644
--- a/headers/3rdparty/flat.hpp/flat_multiset.hpp
+++ b/headers/3rdparty/flat.hpp/flat_multiset.hpp
@@ -15,6 +15,8 @@
 #include <type_traits>
 #include <initializer_list>
 
+#include "detail/is_transparent.hpp"
+
 namespace flat_hpp
 {
     template < typename Key
@@ -295,6 +297,15 @@ namespace flat_hpp
             return std::distance(p.first, p.second);
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            size_type>
+        count(const K& key) const {
+            const auto p = equal_range(key);
+            return std::distance(p.first, p.second);
+        }
+
         iterator find(const key_type& key) {
             const iterator iter = lower_bound(key);
             return iter != end() && !this->operator()(key, *iter)
@@ -309,6 +320,28 @@ namespace flat_hpp
                 : end();
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        find(const K& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        find(const K& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
         std::pair<iterator, iterator> equal_range(const key_type& key) {
             return std::equal_range(begin(), end(), key, key_comp());
         }
@@ -317,6 +350,22 @@ namespace flat_hpp
             return std::equal_range(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<iterator, iterator>>
+        equal_range(const K& key) {
+            return std::equal_range(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<const_iterator, const_iterator>>
+        equal_range(const K& key) const {
+            return std::equal_range(begin(), end(), key, key_comp());
+        }
+
         iterator lower_bound(const key_type& key) {
             return std::lower_bound(begin(), end(), key, key_comp());
         }
@@ -325,6 +374,22 @@ namespace flat_hpp
             return std::lower_bound(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        lower_bound(const K& key) {
+            return std::lower_bound(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        lower_bound(const K& key) const {
+            return std::lower_bound(begin(), end(), key, key_comp());
+        }
+
         iterator upper_bound(const key_type& key) {
             return std::upper_bound(begin(), end(), key, key_comp());
         }
@@ -333,6 +398,22 @@ namespace flat_hpp
             return std::upper_bound(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        upper_bound(const K& key) {
+            return std::upper_bound(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        upper_bound(const K& key) const {
+            return std::upper_bound(begin(), end(), key, key_comp());
+        }
+
         key_compare key_comp() const {
             return *this;
         }
diff --git a/headers/3rdparty/flat.hpp/flat_set.hpp b/headers/3rdparty/flat.hpp/flat_set.hpp
index d5cf454a..aacd2e93 100644
--- a/headers/3rdparty/flat.hpp/flat_set.hpp
+++ b/headers/3rdparty/flat.hpp/flat_set.hpp
@@ -15,6 +15,8 @@
 #include <type_traits>
 #include <initializer_list>
 
+#include "detail/is_transparent.hpp"
+
 namespace flat_hpp
 {
     template < typename Key
@@ -277,7 +279,7 @@ namespace flat_hpp
         }
 
         size_type erase(const key_type& key) {
-            const iterator iter = find(key);
+            const const_iterator iter = find(key);
             return iter != end()
                 ? (erase(iter), 1)
                 : 0;
@@ -299,6 +301,15 @@ namespace flat_hpp
             return iter != end() ? 1 : 0;
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            size_type>
+        count(const K& key) const {
+            const const_iterator iter = find(key);
+            return iter != end() ? 1 : 0;
+        }
+
         iterator find(const key_type& key) {
             const iterator iter = lower_bound(key);
             return iter != end() && !this->operator()(key, *iter)
@@ -313,6 +324,28 @@ namespace flat_hpp
                 : end();
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        find(const K& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        find(const K& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !this->operator()(key, *iter)
+                ? iter
+                : end();
+        }
+
         std::pair<iterator, iterator> equal_range(const key_type& key) {
             return std::equal_range(begin(), end(), key, key_comp());
         }
@@ -321,6 +354,22 @@ namespace flat_hpp
             return std::equal_range(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<iterator, iterator>>
+        equal_range(const K& key) {
+            return std::equal_range(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            std::pair<const_iterator, const_iterator>>
+        equal_range(const K& key) const {
+            return std::equal_range(begin(), end(), key, key_comp());
+        }
+
         iterator lower_bound(const key_type& key) {
             return std::lower_bound(begin(), end(), key, key_comp());
         }
@@ -329,6 +378,22 @@ namespace flat_hpp
             return std::lower_bound(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        lower_bound(const K& key) {
+            return std::lower_bound(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        lower_bound(const K& key) const {
+            return std::lower_bound(begin(), end(), key, key_comp());
+        }
+
         iterator upper_bound(const key_type& key) {
             return std::upper_bound(begin(), end(), key, key_comp());
         }
@@ -337,6 +402,22 @@ namespace flat_hpp
             return std::upper_bound(begin(), end(), key, key_comp());
         }
 
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            iterator>
+        upper_bound(const K& key) {
+            return std::upper_bound(begin(), end(), key, key_comp());
+        }
+
+        template < typename K >
+        std::enable_if_t<
+            detail::is_transparent_v<Compare, K>,
+            const_iterator>
+        upper_bound(const K& key) const {
+            return std::upper_bound(begin(), end(), key, key_comp());
+        }
+
         key_compare key_comp() const {
             return *this;
         }
diff --git a/headers/3rdparty/variant/config.hpp b/headers/3rdparty/variant/config.hpp
new file mode 100644
index 00000000..e411d687
--- /dev/null
+++ b/headers/3rdparty/variant/config.hpp
@@ -0,0 +1,96 @@
+// MPark.Variant
+//
+// Copyright Michael Park, 2015-2017
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#ifndef MPARK_CONFIG_HPP
+#define MPARK_CONFIG_HPP
+
+// MSVC 2015 Update 3.
+#if __cplusplus < 201103L && (!defined(_MSC_VER) || _MSC_FULL_VER < 190024210)
+#error "MPark.Variant requires C++11 support."
+#endif
+
+#ifndef __has_attribute
+#define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef __has_include
+#define __has_include(x) 0
+#endif
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#if __has_attribute(always_inline) || defined(__GNUC__)
+#define MPARK_ALWAYS_INLINE __attribute__((__always_inline__)) inline
+#elif defined(_MSC_VER)
+#define MPARK_ALWAYS_INLINE __forceinline
+#else
+#define MPARK_ALWAYS_INLINE inline
+#endif
+
+#if __has_builtin(__builtin_addressof) || \
+    (defined(__GNUC__) && __GNUC__ >= 7) || defined(_MSC_VER)
+#define MPARK_BUILTIN_ADDRESSOF
+#endif
+
+#if __has_builtin(__builtin_unreachable) || defined(__GNUC__)
+#define MPARK_BUILTIN_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+#define MPARK_BUILTIN_UNREACHABLE __assume(false)
+#else
+#define MPARK_BUILTIN_UNREACHABLE
+#endif
+
+#if __has_builtin(__type_pack_element)
+#define MPARK_TYPE_PACK_ELEMENT
+#endif
+
+#if defined(__cpp_constexpr) && __cpp_constexpr >= 200704 && \
+    !(defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ == 9)
+#define MPARK_CPP11_CONSTEXPR
+#endif
+
+#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304
+#define MPARK_CPP14_CONSTEXPR
+#endif
+
+#if __has_feature(cxx_exceptions) || defined(__cpp_exceptions) || \
+    (defined(_MSC_VER) && defined(_CPPUNWIND))
+#define MPARK_EXCEPTIONS
+#endif
+
+#if defined(__cpp_generic_lambdas) || defined(_MSC_VER)
+#define MPARK_GENERIC_LAMBDAS
+#endif
+
+#if defined(__cpp_lib_integer_sequence)
+#define MPARK_INTEGER_SEQUENCE
+#endif
+
+#if defined(__cpp_return_type_deduction) || defined(_MSC_VER)
+#define MPARK_RETURN_TYPE_DEDUCTION
+#endif
+
+#if defined(__cpp_lib_transparent_operators) || defined(_MSC_VER)
+#define MPARK_TRANSPARENT_OPERATORS
+#endif
+
+#if defined(__cpp_variable_templates) || defined(_MSC_VER)
+#define MPARK_VARIABLE_TEMPLATES
+#endif
+
+#if !defined(__GLIBCXX__) || __has_include(<codecvt>)  // >= libstdc++-5
+#define MPARK_TRIVIALITY_TYPE_TRAITS
+#define MPARK_INCOMPLETE_TYPE_TRAITS
+#endif
+
+#endif  // MPARK_CONFIG_HPP
diff --git a/headers/3rdparty/variant/in_place.hpp b/headers/3rdparty/variant/in_place.hpp
new file mode 100644
index 00000000..56cae131
--- /dev/null
+++ b/headers/3rdparty/variant/in_place.hpp
@@ -0,0 +1,35 @@
+// MPark.Variant
+//
+// Copyright Michael Park, 2015-2017
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#ifndef MPARK_IN_PLACE_HPP
+#define MPARK_IN_PLACE_HPP
+
+#include <cstddef>
+
+#include "config.hpp"
+
+namespace mpark {
+
+  struct in_place_t { explicit in_place_t() = default; };
+
+  template <std::size_t I>
+  struct in_place_index_t { explicit in_place_index_t() = default; };
+
+  template <typename T>
+  struct in_place_type_t { explicit in_place_type_t() = default; };
+
+#ifdef MPARK_VARIABLE_TEMPLATES
+  constexpr in_place_t in_place{};
+
+  template <std::size_t I> constexpr in_place_index_t<I> in_place_index{};
+
+  template <typename T> constexpr in_place_type_t<T> in_place_type{};
+#endif
+
+}  // namespace mpark
+
+#endif  // MPARK_IN_PLACE_HPP
diff --git a/headers/3rdparty/variant/lib.hpp b/headers/3rdparty/variant/lib.hpp
new file mode 100644
index 00000000..42256686
--- /dev/null
+++ b/headers/3rdparty/variant/lib.hpp
@@ -0,0 +1,499 @@
+// MPark.Variant
+//
+// Copyright Michael Park, 2015-2017
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#ifndef MPARK_LIB_HPP
+#define MPARK_LIB_HPP
+
+#include <memory>
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+#include "config.hpp"
+
+#define MPARK_RETURN(...) \
+  noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__) { return __VA_ARGS__; }
+
+namespace mpark {
+  namespace lib {
+    template <typename T>
+    struct identity { using type = T; };
+
+    inline namespace cpp14 {
+      template <typename T, std::size_t N>
+      struct array {
+        constexpr const T &operator[](std::size_t index) const {
+          return data[index];
+        }
+
+        T data[N == 0 ? 1 : N];
+      };
+
+      template <typename T>
+      using add_pointer_t = typename std::add_pointer<T>::type;
+
+      template <typename... Ts>
+      using common_type_t = typename std::common_type<Ts...>::type;
+
+      template <typename T>
+      using decay_t = typename std::decay<T>::type;
+
+      template <bool B, typename T = void>
+      using enable_if_t = typename std::enable_if<B, T>::type;
+
+      template <typename T>
+      using remove_const_t = typename std::remove_const<T>::type;
+
+      template <typename T>
+      using remove_reference_t = typename std::remove_reference<T>::type;
+
+      template <typename T>
+      inline constexpr T &&forward(remove_reference_t<T> &t) noexcept {
+        return static_cast<T &&>(t);
+      }
+
+      template <typename T>
+      inline constexpr T &&forward(remove_reference_t<T> &&t) noexcept {
+        static_assert(!std::is_lvalue_reference<T>::value,
+                      "can not forward an rvalue as an lvalue");
+        return static_cast<T &&>(t);
+      }
+
+      template <typename T>
+      inline constexpr remove_reference_t<T> &&move(T &&t) noexcept {
+        return static_cast<remove_reference_t<T> &&>(t);
+      }
+
+#ifdef MPARK_INTEGER_SEQUENCE
+      using std::integer_sequence;
+      using std::index_sequence;
+      using std::make_index_sequence;
+      using std::index_sequence_for;
+#else
+      template <typename T, T... Is>
+      struct integer_sequence {
+        using value_type = T;
+        static constexpr std::size_t size() noexcept { return sizeof...(Is); }
+      };
+
+      template <std::size_t... Is>
+      using index_sequence = integer_sequence<std::size_t, Is...>;
+
+      template <typename Lhs, typename Rhs>
+      struct make_index_sequence_concat;
+
+      template <std::size_t... Lhs, std::size_t... Rhs>
+      struct make_index_sequence_concat<index_sequence<Lhs...>,
+                                        index_sequence<Rhs...>>
+          : identity<index_sequence<Lhs..., (sizeof...(Lhs) + Rhs)...>> {};
+
+      template <std::size_t N>
+      struct make_index_sequence_impl;
+
+      template <std::size_t N>
+      using make_index_sequence = typename make_index_sequence_impl<N>::type;
+
+      template <std::size_t N>
+      struct make_index_sequence_impl
+          : make_index_sequence_concat<make_index_sequence<N / 2>,
+                                       make_index_sequence<N - (N / 2)>> {};
+
+      template <>
+      struct make_index_sequence_impl<0> : identity<index_sequence<>> {};
+
+      template <>
+      struct make_index_sequence_impl<1> : identity<index_sequence<0>> {};
+
+      template <typename... Ts>
+      using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
+#endif
+
+      // <functional>
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using equal_to = std::equal_to<>;
+#else
+      struct equal_to {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) == lib::forward<Rhs>(rhs))
+      };
+#endif
+
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using not_equal_to = std::not_equal_to<>;
+#else
+      struct not_equal_to {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) != lib::forward<Rhs>(rhs))
+      };
+#endif
+
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using less = std::less<>;
+#else
+      struct less {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) < lib::forward<Rhs>(rhs))
+      };
+#endif
+
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using greater = std::greater<>;
+#else
+      struct greater {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) > lib::forward<Rhs>(rhs))
+      };
+#endif
+
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using less_equal = std::less_equal<>;
+#else
+      struct less_equal {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) <= lib::forward<Rhs>(rhs))
+      };
+#endif
+
+#ifdef MPARK_TRANSPARENT_OPERATORS
+      using greater_equal = std::greater_equal<>;
+#else
+      struct greater_equal {
+        template <typename Lhs, typename Rhs>
+        inline constexpr auto operator()(Lhs &&lhs, Rhs &&rhs) const
+          MPARK_RETURN(lib::forward<Lhs>(lhs) >= lib::forward<Rhs>(rhs))
+      };
+#endif
+    }  // namespace cpp14
+
+    inline namespace cpp17 {
+
+      // <type_traits>
+      template <bool B>
+      using bool_constant = std::integral_constant<bool, B>;
+
+      template <typename...>
+      struct voider : identity<void> {};
+
+      template <typename... Ts>
+      using void_t = typename voider<Ts...>::type;
+
+      namespace detail {
+        namespace swappable {
+
+          using std::swap;
+
+          template <typename T>
+          struct is_swappable {
+            private:
+            template <typename U,
+                      typename = decltype(swap(std::declval<U &>(),
+                                               std::declval<U &>()))>
+            inline static std::true_type test(int);
+
+            template <typename U>
+            inline static std::false_type test(...);
+
+            public:
+            static constexpr bool value = decltype(test<T>(0))::value;
+          };
+
+          template <bool IsSwappable, typename T>
+          struct is_nothrow_swappable {
+            static constexpr bool value =
+                noexcept(swap(std::declval<T &>(), std::declval<T &>()));
+          };
+
+          template <typename T>
+          struct is_nothrow_swappable<false, T> : std::false_type {};
+
+        }  // namespace swappable
+      }  // namespace detail
+
+      using detail::swappable::is_swappable;
+
+      template <typename T>
+      using is_nothrow_swappable =
+          detail::swappable::is_nothrow_swappable<is_swappable<T>::value, T>;
+
+      // <functional>
+      namespace detail {
+
+        template <typename T>
+        struct is_reference_wrapper : std::false_type {};
+
+        template <typename T>
+        struct is_reference_wrapper<std::reference_wrapper<T>>
+            : std::true_type {};
+
+        template <bool, int>
+        struct Invoke;
+
+        template <>
+        struct Invoke<true /* pmf */, 0 /* is_base_of */> {
+          template <typename R, typename T, typename Arg, typename... Args>
+          inline static constexpr auto invoke(R T::*pmf, Arg &&arg, Args &&... args)
+            MPARK_RETURN((lib::forward<Arg>(arg).*pmf)(lib::forward<Args>(args)...))
+        };
+
+        template <>
+        struct Invoke<true /* pmf */, 1 /* is_reference_wrapper */> {
+          template <typename R, typename T, typename Arg, typename... Args>
+          inline static constexpr auto invoke(R T::*pmf, Arg &&arg, Args &&... args)
+            MPARK_RETURN((lib::forward<Arg>(arg).get().*pmf)(lib::forward<Args>(args)...))
+        };
+
+        template <>
+        struct Invoke<true /* pmf */, 2 /* otherwise */> {
+          template <typename R, typename T, typename Arg, typename... Args>
+          inline static constexpr auto invoke(R T::*pmf, Arg &&arg, Args &&... args)
+            MPARK_RETURN(((*lib::forward<Arg>(arg)).*pmf)(lib::forward<Args>(args)...))
+        };
+
+        template <>
+        struct Invoke<false /* pmo */, 0 /* is_base_of */> {
+          template <typename R, typename T, typename Arg>
+          inline static constexpr auto invoke(R T::*pmo, Arg &&arg)
+            MPARK_RETURN(lib::forward<Arg>(arg).*pmo)
+        };
+
+        template <>
+        struct Invoke<false /* pmo */, 1 /* is_reference_wrapper */> {
+          template <typename R, typename T, typename Arg>
+          inline static constexpr auto invoke(R T::*pmo, Arg &&arg)
+            MPARK_RETURN(lib::forward<Arg>(arg).get().*pmo)
+        };
+
+        template <>
+        struct Invoke<false /* pmo */, 2 /* otherwise */> {
+          template <typename R, typename T, typename Arg>
+          inline static constexpr auto invoke(R T::*pmo, Arg &&arg)
+              MPARK_RETURN((*lib::forward<Arg>(arg)).*pmo)
+        };
+
+        template <typename R, typename T, typename Arg, typename... Args>
+        inline constexpr auto invoke(R T::*f, Arg &&arg, Args &&... args)
+          MPARK_RETURN(
+              Invoke<std::is_function<R>::value,
+                     (std::is_base_of<T, lib::decay_t<Arg>>::value
+                          ? 0
+                          : is_reference_wrapper<lib::decay_t<Arg>>::value
+                                ? 1
+                                : 2)>::invoke(f,
+                                              lib::forward<Arg>(arg),
+                                              lib::forward<Args>(args)...))
+
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4100)
+#endif
+        template <typename F, typename... Args>
+        inline constexpr auto invoke(F &&f, Args &&... args)
+          MPARK_RETURN(lib::forward<F>(f)(lib::forward<Args>(args)...))
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+      }  // namespace detail
+
+      template <typename F, typename... Args>
+      inline constexpr auto invoke(F &&f, Args &&... args)
+        MPARK_RETURN(detail::invoke(lib::forward<F>(f),
+                                    lib::forward<Args>(args)...))
+
+      namespace detail {
+
+        template <typename Void, typename, typename...>
+        struct invoke_result {};
+
+        template <typename F, typename... Args>
+        struct invoke_result<void_t<decltype(lib::invoke(
+                                 std::declval<F>(), std::declval<Args>()...))>,
+                             F,
+                             Args...>
+            : identity<decltype(
+                  lib::invoke(std::declval<F>(), std::declval<Args>()...))> {};
+
+      }  // namespace detail
+
+      template <typename F, typename... Args>
+      using invoke_result = detail::invoke_result<void, F, Args...>;
+
+      template <typename F, typename... Args>
+      using invoke_result_t = typename invoke_result<F, Args...>::type;
+
+      namespace detail {
+
+        template <typename Void, typename, typename...>
+        struct is_invocable : std::false_type {};
+
+        template <typename F, typename... Args>
+        struct is_invocable<void_t<invoke_result_t<F, Args...>>, F, Args...>
+            : std::true_type {};
+
+        template <typename Void, typename, typename, typename...>
+        struct is_invocable_r : std::false_type {};
+
+        template <typename R, typename F, typename... Args>
+        struct is_invocable_r<void_t<invoke_result_t<F, Args...>>,
+                              R,
+                              F,
+                              Args...>
+            : std::is_convertible<invoke_result_t<F, Args...>, R> {};
+
+      }  // namespace detail
+
+      template <typename F, typename... Args>
+      using is_invocable = detail::is_invocable<void, F, Args...>;
+
+      template <typename R, typename F, typename... Args>
+      using is_invocable_r = detail::is_invocable_r<void, R, F, Args...>;
+
+      // <memory>
+#ifdef MPARK_BUILTIN_ADDRESSOF
+      template <typename T>
+      inline constexpr T *addressof(T &arg) noexcept {
+        return __builtin_addressof(arg);
+      }
+#else
+      namespace detail {
+
+        namespace has_addressof_impl {
+
+          struct fail;
+
+          template <typename T>
+          inline fail operator&(T &&);
+
+          template <typename T>
+          inline static constexpr bool impl() {
+            return (std::is_class<T>::value || std::is_union<T>::value) &&
+                   !std::is_same<decltype(&std::declval<T &>()), fail>::value;
+          }
+
+        }  // namespace has_addressof_impl
+
+        template <typename T>
+        using has_addressof = bool_constant<has_addressof_impl::impl<T>()>;
+
+        template <typename T>
+        inline constexpr T *addressof(T &arg, std::true_type) noexcept {
+          return std::addressof(arg);
+        }
+
+        template <typename T>
+        inline constexpr T *addressof(T &arg, std::false_type) noexcept {
+          return &arg;
+        }
+
+      }  // namespace detail
+
+      template <typename T>
+      inline constexpr T *addressof(T &arg) noexcept {
+        return detail::addressof(arg, detail::has_addressof<T>{});
+      }
+#endif
+
+      template <typename T>
+      inline constexpr T *addressof(const T &&) = delete;
+
+    }  // namespace cpp17
+
+    template <typename T>
+    struct remove_all_extents : identity<T> {};
+
+    template <typename T, std::size_t N>
+    struct remove_all_extents<array<T, N>> : remove_all_extents<T> {};
+
+    template <typename T>
+    using remove_all_extents_t = typename remove_all_extents<T>::type;
+
+    template <std::size_t N>
+    using size_constant = std::integral_constant<std::size_t, N>;
+
+    template <std::size_t I, typename T>
+    struct indexed_type : size_constant<I> { using type = T; };
+
+    template <bool... Bs>
+    using all = std::is_same<integer_sequence<bool, true, Bs...>,
+                             integer_sequence<bool, Bs..., true>>;
+
+#ifdef MPARK_TYPE_PACK_ELEMENT
+    template <std::size_t I, typename... Ts>
+    using type_pack_element_t = __type_pack_element<I, Ts...>;
+#else
+    template <std::size_t I, typename... Ts>
+    struct type_pack_element_impl {
+      private:
+      template <typename>
+      struct set;
+
+      template <std::size_t... Is>
+      struct set<index_sequence<Is...>> : indexed_type<Is, Ts>... {};
+
+      template <typename T>
+      inline static std::enable_if<true, T> impl(indexed_type<I, T>);
+
+      inline static std::enable_if<false> impl(...);
+
+      public:
+      using type = decltype(impl(set<index_sequence_for<Ts...>>{}));
+    };
+
+    template <std::size_t I, typename... Ts>
+    using type_pack_element = typename type_pack_element_impl<I, Ts...>::type;
+
+    template <std::size_t I, typename... Ts>
+    using type_pack_element_t = typename type_pack_element<I, Ts...>::type;
+#endif
+
+#ifdef MPARK_TRIVIALITY_TYPE_TRAITS
+    using std::is_trivially_copy_constructible;
+    using std::is_trivially_move_constructible;
+    using std::is_trivially_copy_assignable;
+    using std::is_trivially_move_assignable;
+#else
+    template <typename T>
+    struct is_trivially_copy_constructible
+        : bool_constant<
+              std::is_copy_constructible<T>::value && __has_trivial_copy(T)> {};
+
+    template <typename T>
+    struct is_trivially_move_constructible : bool_constant<__is_trivial(T)> {};
+
+    template <typename T>
+    struct is_trivially_copy_assignable
+        : bool_constant<
+              std::is_copy_assignable<T>::value && __has_trivial_assign(T)> {};
+
+    template <typename T>
+    struct is_trivially_move_assignable : bool_constant<__is_trivial(T)> {};
+#endif
+
+    template <typename T, bool>
+    struct dependent_type : T {};
+
+    template <typename Is, std::size_t J>
+    struct push_back;
+
+    template <typename Is, std::size_t J>
+    using push_back_t = typename push_back<Is, J>::type;
+
+    template <std::size_t... Is, std::size_t J>
+    struct push_back<index_sequence<Is...>, J> {
+      using type = index_sequence<Is..., J>;
+    };
+
+  }  // namespace lib
+}  // namespace mpark
+
+#undef MPARK_RETURN
+
+#endif  // MPARK_LIB_HPP
diff --git a/headers/3rdparty/variant/variant.hpp b/headers/3rdparty/variant/variant.hpp
new file mode 100644
index 00000000..1fc0b219
--- /dev/null
+++ b/headers/3rdparty/variant/variant.hpp
@@ -0,0 +1,2156 @@
+// MPark.Variant
+//
+// Copyright Michael Park, 2015-2017
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#ifndef MPARK_VARIANT_HPP
+#define MPARK_VARIANT_HPP
+
+/*
+   variant synopsis
+
+namespace std {
+
+  // 20.7.2, class template variant
+  template <class... Types>
+  class variant {
+  public:
+
+    // 20.7.2.1, constructors
+    constexpr variant() noexcept(see below);
+    variant(const variant&);
+    variant(variant&&) noexcept(see below);
+
+    template <class T> constexpr variant(T&&) noexcept(see below);
+
+    template <class T, class... Args>
+    constexpr explicit variant(in_place_type_t<T>, Args&&...);
+
+    template <class T, class U, class... Args>
+    constexpr explicit variant(
+        in_place_type_t<T>, initializer_list<U>, Args&&...);
+
+    template <size_t I, class... Args>
+    constexpr explicit variant(in_place_index_t<I>, Args&&...);
+
+    template <size_t I, class U, class... Args>
+    constexpr explicit variant(
+        in_place_index_t<I>, initializer_list<U>, Args&&...);
+
+    // 20.7.2.2, destructor
+    ~variant();
+
+    // 20.7.2.3, assignment
+    variant& operator=(const variant&);
+    variant& operator=(variant&&) noexcept(see below);
+
+    template <class T> variant& operator=(T&&) noexcept(see below);
+
+    // 20.7.2.4, modifiers
+    template <class T, class... Args>
+    T& emplace(Args&&...);
+
+    template <class T, class U, class... Args>
+    T& emplace(initializer_list<U>, Args&&...);
+
+    template <size_t I, class... Args>
+    variant_alternative<I, variant>& emplace(Args&&...);
+
+    template <size_t I, class U, class...  Args>
+    variant_alternative<I, variant>& emplace(initializer_list<U>, Args&&...);
+
+    // 20.7.2.5, value status
+    constexpr bool valueless_by_exception() const noexcept;
+    constexpr size_t index() const noexcept;
+
+    // 20.7.2.6, swap
+    void swap(variant&) noexcept(see below);
+  };
+
+  // 20.7.3, variant helper classes
+  template <class T> struct variant_size; // undefined
+
+  template <class T>
+  constexpr size_t variant_size_v = variant_size<T>::value;
+
+  template <class T> struct variant_size<const T>;
+  template <class T> struct variant_size<volatile T>;
+  template <class T> struct variant_size<const volatile T>;
+
+  template <class... Types>
+  struct variant_size<variant<Types...>>;
+
+  template <size_t I, class T> struct variant_alternative; // undefined
+
+  template <size_t I, class T>
+  using variant_alternative_t = typename variant_alternative<I, T>::type;
+
+  template <size_t I, class T> struct variant_alternative<I, const T>;
+  template <size_t I, class T> struct variant_alternative<I, volatile T>;
+  template <size_t I, class T> struct variant_alternative<I, const volatile T>;
+
+  template <size_t I, class... Types>
+  struct variant_alternative<I, variant<Types...>>;
+
+  constexpr size_t variant_npos = -1;
+
+  // 20.7.4, value access
+  template <class T, class... Types>
+  constexpr bool holds_alternative(const variant<Types...>&) noexcept;
+
+  template <size_t I, class... Types>
+  constexpr variant_alternative_t<I, variant<Types...>>&
+  get(variant<Types...>&);
+
+  template <size_t I, class... Types>
+  constexpr variant_alternative_t<I, variant<Types...>>&&
+  get(variant<Types...>&&);
+
+  template <size_t I, class... Types>
+  constexpr variant_alternative_t<I, variant<Types...>> const&
+  get(const variant<Types...>&);
+
+  template <size_t I, class... Types>
+  constexpr variant_alternative_t<I, variant<Types...>> const&&
+  get(const variant<Types...>&&);
+
+  template <class T, class...  Types>
+  constexpr T& get(variant<Types...>&);
+
+  template <class T, class... Types>
+  constexpr T&& get(variant<Types...>&&);
+
+  template <class T, class... Types>
+  constexpr const T& get(const variant<Types...>&);
+
+  template <class T, class... Types>
+  constexpr const T&& get(const variant<Types...>&&);
+
+  template <size_t I, class... Types>
+  constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
+  get_if(variant<Types...>*) noexcept;
+
+  template <size_t I, class... Types>
+  constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
+  get_if(const variant<Types...>*) noexcept;
+
+  template <class T, class... Types>
+  constexpr add_pointer_t<T>
+  get_if(variant<Types...>*) noexcept;
+
+  template <class T, class... Types>
+  constexpr add_pointer_t<const T>
+  get_if(const variant<Types...>*) noexcept;
+
+  // 20.7.5, relational operators
+  template <class... Types>
+  constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
+
+  template <class... Types>
+  constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
+
+  template <class... Types>
+  constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
+
+  template <class... Types>
+  constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
+
+  template <class... Types>
+  constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
+
+  template <class... Types>
+  constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
+
+  // 20.7.6, visitation
+  template <class Visitor, class... Variants>
+  constexpr see below visit(Visitor&&, Variants&&...);
+
+  // 20.7.7, class monostate
+  struct monostate;
+
+  // 20.7.8, monostate relational operators
+  constexpr bool operator<(monostate, monostate) noexcept;
+  constexpr bool operator>(monostate, monostate) noexcept;
+  constexpr bool operator<=(monostate, monostate) noexcept;
+  constexpr bool operator>=(monostate, monostate) noexcept;
+  constexpr bool operator==(monostate, monostate) noexcept;
+  constexpr bool operator!=(monostate, monostate) noexcept;
+
+  // 20.7.9, specialized algorithms
+  template <class... Types>
+  void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
+
+  // 20.7.10, class bad_variant_access
+  class bad_variant_access;
+
+  // 20.7.11, hash support
+  template <class T> struct hash;
+  template <class... Types> struct hash<variant<Types...>>;
+  template <> struct hash<monostate>;
+
+} // namespace std
+
+*/
+
+#include <cstddef>
+#include <exception>
+#include <functional>
+#include <initializer_list>
+#include <limits>
+#include <new>
+#include <type_traits>
+#include <utility>
+
+#include "config.hpp"
+#include "in_place.hpp"
+#include "lib.hpp"
+
+namespace mpark {
+
+#ifdef MPARK_RETURN_TYPE_DEDUCTION
+
+#define AUTO auto
+#define AUTO_RETURN(...) { return __VA_ARGS__; }
+
+#define AUTO_REFREF auto &&
+#define AUTO_REFREF_RETURN(...) { return __VA_ARGS__; }
+
+#define DECLTYPE_AUTO decltype(auto)
+#define DECLTYPE_AUTO_RETURN(...) { return __VA_ARGS__; }
+
+#else
+
+#define AUTO auto
+#define AUTO_RETURN(...) \
+  -> lib::decay_t<decltype(__VA_ARGS__)> { return __VA_ARGS__; }
+
+#define AUTO_REFREF auto
+#define AUTO_REFREF_RETURN(...)                                           \
+  -> decltype((__VA_ARGS__)) {                                            \
+    static_assert(std::is_reference<decltype((__VA_ARGS__))>::value, ""); \
+    return __VA_ARGS__;                                                   \
+  }
+
+#define DECLTYPE_AUTO auto
+#define DECLTYPE_AUTO_RETURN(...) \
+  -> decltype(__VA_ARGS__) { return __VA_ARGS__; }
+
+#endif
+
+  class bad_variant_access : public std::exception {
+    public:
+    virtual const char *what() const noexcept override { return "bad_variant_access"; }
+  };
+
+  [[noreturn]] inline void throw_bad_variant_access() {
+#ifdef MPARK_EXCEPTIONS
+    throw bad_variant_access{};
+#else
+    std::terminate();
+    MPARK_BUILTIN_UNREACHABLE;
+#endif
+  }
+
+  template <typename... Ts>
+  class variant;
+
+  template <typename T>
+  struct variant_size;
+
+#ifdef MPARK_VARIABLE_TEMPLATES
+  template <typename T>
+  constexpr std::size_t variant_size_v = variant_size<T>::value;
+#endif
+
+  template <typename T>
+  struct variant_size<const T> : variant_size<T> {};
+
+  template <typename T>
+  struct variant_size<volatile T> : variant_size<T> {};
+
+  template <typename T>
+  struct variant_size<const volatile T> : variant_size<T> {};
+
+  template <typename... Ts>
+  struct variant_size<variant<Ts...>> : lib::size_constant<sizeof...(Ts)> {};
+
+  template <std::size_t I, typename T>
+  struct variant_alternative;
+
+  template <std::size_t I, typename T>
+  using variant_alternative_t = typename variant_alternative<I, T>::type;
+
+  template <std::size_t I, typename T>
+  struct variant_alternative<I, const T>
+      : std::add_const<variant_alternative_t<I, T>> {};
+
+  template <std::size_t I, typename T>
+  struct variant_alternative<I, volatile T>
+      : std::add_volatile<variant_alternative_t<I, T>> {};
+
+  template <std::size_t I, typename T>
+  struct variant_alternative<I, const volatile T>
+      : std::add_cv<variant_alternative_t<I, T>> {};
+
+  template <std::size_t I, typename... Ts>
+  struct variant_alternative<I, variant<Ts...>> {
+    static_assert(I < sizeof...(Ts),
+                  "index out of bounds in `std::variant_alternative<>`");
+    using type = lib::type_pack_element_t<I, Ts...>;
+  };
+
+  constexpr std::size_t variant_npos = static_cast<std::size_t>(-1);
+
+  namespace detail {
+
+    constexpr std::size_t not_found = static_cast<std::size_t>(-1);
+    constexpr std::size_t ambiguous = static_cast<std::size_t>(-2);
+
+#ifdef MPARK_CPP14_CONSTEXPR
+    template <typename T, typename... Ts>
+    inline constexpr std::size_t find_index() {
+      constexpr lib::array<bool, sizeof...(Ts)> matches = {
+          {std::is_same<T, Ts>::value...}
+      };
+      std::size_t result = not_found;
+      for (std::size_t i = 0; i < sizeof...(Ts); ++i) {
+        if (matches[i]) {
+          if (result != not_found) {
+            return ambiguous;
+          }
+          result = i;
+        }
+      }
+      return result;
+    }
+#else
+    inline constexpr std::size_t find_index_impl(std::size_t result,
+                                                 std::size_t) {
+      return result;
+    }
+
+    template <typename... Bs>
+    inline constexpr std::size_t find_index_impl(std::size_t result,
+                                                 std::size_t idx,
+                                                 bool b,
+                                                 Bs... bs) {
+      return b ? (result != not_found ? ambiguous
+                                      : find_index_impl(idx, idx + 1, bs...))
+               : find_index_impl(result, idx + 1, bs...);
+    }
+
+    template <typename T, typename... Ts>
+    inline constexpr std::size_t find_index() {
+      return find_index_impl(not_found, 0, std::is_same<T, Ts>::value...);
+    }
+#endif
+
+    template <std::size_t I>
+    using find_index_sfinae_impl =
+        lib::enable_if_t<I != not_found && I != ambiguous,
+                         lib::size_constant<I>>;
+
+    template <typename T, typename... Ts>
+    using find_index_sfinae = find_index_sfinae_impl<find_index<T, Ts...>()>;
+
+    template <std::size_t I>
+    struct find_index_checked_impl : lib::size_constant<I> {
+      static_assert(I != not_found, "the specified type is not found.");
+      static_assert(I != ambiguous, "the specified type is ambiguous.");
+    };
+
+    template <typename T, typename... Ts>
+    using find_index_checked = find_index_checked_impl<find_index<T, Ts...>()>;
+
+    struct valueless_t {};
+
+    enum class Trait { TriviallyAvailable, Available, Unavailable };
+
+    template <typename T,
+              template <typename> class IsTriviallyAvailable,
+              template <typename> class IsAvailable>
+    inline constexpr Trait trait() {
+      return IsTriviallyAvailable<T>::value
+                 ? Trait::TriviallyAvailable
+                 : IsAvailable<T>::value ? Trait::Available
+                                         : Trait::Unavailable;
+    }
+
+#ifdef MPARK_CPP14_CONSTEXPR
+    template <typename... Traits>
+    inline constexpr Trait common_trait(Traits... traits_) {
+      Trait result = Trait::TriviallyAvailable;
+      lib::array<Trait, sizeof...(Traits)> traits = {{traits_...}};
+      for (std::size_t i = 0; i < sizeof...(Traits); ++i) {
+        Trait t = traits[i];
+        if (static_cast<int>(t) > static_cast<int>(result)) {
+          result = t;
+        }
+      }
+      return result;
+    }
+#else
+    inline constexpr Trait common_trait_impl(Trait result) { return result; }
+
+    template <typename... Traits>
+    inline constexpr Trait common_trait_impl(Trait result,
+                                             Trait t,
+                                             Traits... ts) {
+      return static_cast<int>(t) > static_cast<int>(result)
+                 ? common_trait_impl(t, ts...)
+                 : common_trait_impl(result, ts...);
+    }
+
+    template <typename... Traits>
+    inline constexpr Trait common_trait(Traits... ts) {
+      return common_trait_impl(Trait::TriviallyAvailable, ts...);
+    }
+#endif
+
+    template <typename... Ts>
+    struct traits {
+      static constexpr Trait copy_constructible_trait =
+          common_trait(trait<Ts,
+                             lib::is_trivially_copy_constructible,
+                             std::is_copy_constructible>()...);
+
+      static constexpr Trait move_constructible_trait =
+          common_trait(trait<Ts,
+                             lib::is_trivially_move_constructible,
+                             std::is_move_constructible>()...);
+
+      static constexpr Trait copy_assignable_trait =
+          common_trait(copy_constructible_trait,
+                       trait<Ts,
+                             lib::is_trivially_copy_assignable,
+                             std::is_copy_assignable>()...);
+
+      static constexpr Trait move_assignable_trait =
+          common_trait(move_constructible_trait,
+                       trait<Ts,
+                             lib::is_trivially_move_assignable,
+                             std::is_move_assignable>()...);
+
+      static constexpr Trait destructible_trait =
+          common_trait(trait<Ts,
+                             std::is_trivially_destructible,
+                             std::is_destructible>()...);
+    };
+
+    namespace access {
+
+      struct recursive_union {
+#ifdef MPARK_RETURN_TYPE_DEDUCTION
+        template <typename V>
+        inline static constexpr auto &&get_alt(V &&v, in_place_index_t<0>) {
+          return lib::forward<V>(v).head_;
+        }
+
+        template <typename V, std::size_t I>
+        inline static constexpr auto &&get_alt(V &&v, in_place_index_t<I>) {
+          return get_alt(lib::forward<V>(v).tail_, in_place_index_t<I - 1>{});
+        }
+#else
+        template <std::size_t I, bool Dummy = true>
+        struct get_alt_impl {
+          template <typename V>
+          inline constexpr AUTO_REFREF operator()(V &&v) const
+            AUTO_REFREF_RETURN(get_alt_impl<I - 1>{}(lib::forward<V>(v).tail_))
+        };
+
+        template <bool Dummy>
+        struct get_alt_impl<0, Dummy> {
+          template <typename V>
+          inline constexpr AUTO_REFREF operator()(V &&v) const
+            AUTO_REFREF_RETURN(lib::forward<V>(v).head_)
+        };
+
+        template <typename V, std::size_t I>
+        inline static constexpr AUTO_REFREF get_alt(V &&v, in_place_index_t<I>)
+          AUTO_REFREF_RETURN(get_alt_impl<I>{}(lib::forward<V>(v)))
+#endif
+      };
+
+      struct base {
+        template <std::size_t I, typename V>
+        inline static constexpr AUTO_REFREF get_alt(V &&v)
+#ifdef _MSC_VER
+          AUTO_REFREF_RETURN(recursive_union::get_alt(
+              lib::forward<V>(v).data_, in_place_index_t<I>{}))
+#else
+          AUTO_REFREF_RETURN(recursive_union::get_alt(
+              data(lib::forward<V>(v)), in_place_index_t<I>{}))
+#endif
+      };
+
+      struct variant {
+        template <std::size_t I, typename V>
+        inline static constexpr AUTO_REFREF get_alt(V &&v)
+          AUTO_REFREF_RETURN(base::get_alt<I>(lib::forward<V>(v).impl_))
+      };
+
+    }  // namespace access
+
+    namespace visitation {
+
+#if defined(MPARK_CPP14_CONSTEXPR) && !defined(_MSC_VER)
+#define MPARK_VARIANT_SWITCH_VISIT
+#endif
+
+      struct base {
+        template <typename Visitor, typename... Vs>
+        using dispatch_result_t = decltype(
+            lib::invoke(std::declval<Visitor>(),
+                        access::base::get_alt<0>(std::declval<Vs>())...));
+
+        template <typename Expected>
+        struct expected {
+          template <typename Actual>
+          inline static constexpr bool but_got() {
+            return std::is_same<Expected, Actual>::value;
+          }
+        };
+
+        template <typename Expected, typename Actual>
+        struct visit_return_type_check {
+          static_assert(
+              expected<Expected>::template but_got<Actual>(),
+              "`visit` requires the visitor to have a single return type");
+
+          template <typename Visitor, typename... Alts>
+          inline static constexpr DECLTYPE_AUTO invoke(Visitor &&visitor,
+                                                       Alts &&... alts)
+            DECLTYPE_AUTO_RETURN(lib::invoke(lib::forward<Visitor>(visitor),
+                                             lib::forward<Alts>(alts)...))
+        };
+
+#ifdef MPARK_VARIANT_SWITCH_VISIT
+        template <bool B, typename R, typename... ITs>
+        struct dispatcher;
+
+        template <typename R, typename... ITs>
+        struct dispatcher<false, R, ITs...> {
+          template <std::size_t B, typename F, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch(
+              F &&, typename ITs::type &&..., Vs &&...) {
+            MPARK_BUILTIN_UNREACHABLE;
+          }
+
+          template <std::size_t I, typename F, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch_case(F &&, Vs &&...) {
+            MPARK_BUILTIN_UNREACHABLE;
+          }
+
+          template <std::size_t B, typename F, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch_at(std::size_t,
+                                                             F &&,
+                                                             Vs &&...) {
+            MPARK_BUILTIN_UNREACHABLE;
+          }
+        };
+
+        template <typename R, typename... ITs>
+        struct dispatcher<true, R, ITs...> {
+          template <std::size_t B, typename F>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch(
+              F &&f, typename ITs::type &&... visited_vs) {
+            using Expected = R;
+            using Actual = decltype(lib::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<ITs::value>(
+                    lib::forward<typename ITs::type>(visited_vs))...));
+            return visit_return_type_check<Expected, Actual>::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<ITs::value>(
+                    lib::forward<typename ITs::type>(visited_vs))...);
+          }
+
+          template <std::size_t B, typename F, typename V, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch(
+              F &&f, typename ITs::type &&... visited_vs, V &&v, Vs &&... vs) {
+#define MPARK_DISPATCH(I)                                                   \
+  dispatcher<(I < lib::decay_t<V>::size()),                                 \
+             R,                                                             \
+             ITs...,                                                        \
+             lib::indexed_type<I, V>>::                                     \
+      template dispatch<0>(lib::forward<F>(f),                              \
+                           lib::forward<typename ITs::type>(visited_vs)..., \
+                           lib::forward<V>(v),                              \
+                           lib::forward<Vs>(vs)...)
+
+#define MPARK_DEFAULT(I)                                                      \
+  dispatcher<(I < lib::decay_t<V>::size()), R, ITs...>::template dispatch<I>( \
+      lib::forward<F>(f),                                                     \
+      lib::forward<typename ITs::type>(visited_vs)...,                        \
+      lib::forward<V>(v),                                                     \
+      lib::forward<Vs>(vs)...)
+
+            switch (v.index()) {
+              case B + 0: return MPARK_DISPATCH(B + 0);
+              case B + 1: return MPARK_DISPATCH(B + 1);
+              case B + 2: return MPARK_DISPATCH(B + 2);
+              case B + 3: return MPARK_DISPATCH(B + 3);
+              case B + 4: return MPARK_DISPATCH(B + 4);
+              case B + 5: return MPARK_DISPATCH(B + 5);
+              case B + 6: return MPARK_DISPATCH(B + 6);
+              case B + 7: return MPARK_DISPATCH(B + 7);
+              case B + 8: return MPARK_DISPATCH(B + 8);
+              case B + 9: return MPARK_DISPATCH(B + 9);
+              case B + 10: return MPARK_DISPATCH(B + 10);
+              case B + 11: return MPARK_DISPATCH(B + 11);
+              case B + 12: return MPARK_DISPATCH(B + 12);
+              case B + 13: return MPARK_DISPATCH(B + 13);
+              case B + 14: return MPARK_DISPATCH(B + 14);
+              case B + 15: return MPARK_DISPATCH(B + 15);
+              case B + 16: return MPARK_DISPATCH(B + 16);
+              case B + 17: return MPARK_DISPATCH(B + 17);
+              case B + 18: return MPARK_DISPATCH(B + 18);
+              case B + 19: return MPARK_DISPATCH(B + 19);
+              case B + 20: return MPARK_DISPATCH(B + 20);
+              case B + 21: return MPARK_DISPATCH(B + 21);
+              case B + 22: return MPARK_DISPATCH(B + 22);
+              case B + 23: return MPARK_DISPATCH(B + 23);
+              case B + 24: return MPARK_DISPATCH(B + 24);
+              case B + 25: return MPARK_DISPATCH(B + 25);
+              case B + 26: return MPARK_DISPATCH(B + 26);
+              case B + 27: return MPARK_DISPATCH(B + 27);
+              case B + 28: return MPARK_DISPATCH(B + 28);
+              case B + 29: return MPARK_DISPATCH(B + 29);
+              case B + 30: return MPARK_DISPATCH(B + 30);
+              case B + 31: return MPARK_DISPATCH(B + 31);
+              default: return MPARK_DEFAULT(B + 32);
+            }
+
+#undef MPARK_DEFAULT
+#undef MPARK_DISPATCH
+          }
+
+          template <std::size_t I, typename F, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch_case(F &&f,
+                                                               Vs &&... vs) {
+            using Expected = R;
+            using Actual = decltype(
+                lib::invoke(lib::forward<F>(f),
+                            access::base::get_alt<I>(lib::forward<Vs>(vs))...));
+            return visit_return_type_check<Expected, Actual>::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<I>(lib::forward<Vs>(vs))...);
+          }
+
+          template <std::size_t B, typename F, typename V, typename... Vs>
+          MPARK_ALWAYS_INLINE static constexpr R dispatch_at(std::size_t index,
+                                                             F &&f,
+                                                             V &&v,
+                                                             Vs &&... vs) {
+            static_assert(lib::all<(lib::decay_t<V>::size() ==
+                                    lib::decay_t<Vs>::size())...>::value,
+                          "all of the variants must be the same size.");
+#define MPARK_DISPATCH_AT(I)                                               \
+  dispatcher<(I < lib::decay_t<V>::size()), R>::template dispatch_case<I>( \
+      lib::forward<F>(f), lib::forward<V>(v), lib::forward<Vs>(vs)...)
+
+#define MPARK_DEFAULT(I)                                                 \
+  dispatcher<(I < lib::decay_t<V>::size()), R>::template dispatch_at<I>( \
+      index, lib::forward<F>(f), lib::forward<V>(v), lib::forward<Vs>(vs)...)
+
+            switch (index) {
+              case B + 0: return MPARK_DISPATCH_AT(B + 0);
+              case B + 1: return MPARK_DISPATCH_AT(B + 1);
+              case B + 2: return MPARK_DISPATCH_AT(B + 2);
+              case B + 3: return MPARK_DISPATCH_AT(B + 3);
+              case B + 4: return MPARK_DISPATCH_AT(B + 4);
+              case B + 5: return MPARK_DISPATCH_AT(B + 5);
+              case B + 6: return MPARK_DISPATCH_AT(B + 6);
+              case B + 7: return MPARK_DISPATCH_AT(B + 7);
+              case B + 8: return MPARK_DISPATCH_AT(B + 8);
+              case B + 9: return MPARK_DISPATCH_AT(B + 9);
+              case B + 10: return MPARK_DISPATCH_AT(B + 10);
+              case B + 11: return MPARK_DISPATCH_AT(B + 11);
+              case B + 12: return MPARK_DISPATCH_AT(B + 12);
+              case B + 13: return MPARK_DISPATCH_AT(B + 13);
+              case B + 14: return MPARK_DISPATCH_AT(B + 14);
+              case B + 15: return MPARK_DISPATCH_AT(B + 15);
+              case B + 16: return MPARK_DISPATCH_AT(B + 16);
+              case B + 17: return MPARK_DISPATCH_AT(B + 17);
+              case B + 18: return MPARK_DISPATCH_AT(B + 18);
+              case B + 19: return MPARK_DISPATCH_AT(B + 19);
+              case B + 20: return MPARK_DISPATCH_AT(B + 20);
+              case B + 21: return MPARK_DISPATCH_AT(B + 21);
+              case B + 22: return MPARK_DISPATCH_AT(B + 22);
+              case B + 23: return MPARK_DISPATCH_AT(B + 23);
+              case B + 24: return MPARK_DISPATCH_AT(B + 24);
+              case B + 25: return MPARK_DISPATCH_AT(B + 25);
+              case B + 26: return MPARK_DISPATCH_AT(B + 26);
+              case B + 27: return MPARK_DISPATCH_AT(B + 27);
+              case B + 28: return MPARK_DISPATCH_AT(B + 28);
+              case B + 29: return MPARK_DISPATCH_AT(B + 29);
+              case B + 30: return MPARK_DISPATCH_AT(B + 30);
+              case B + 31: return MPARK_DISPATCH_AT(B + 31);
+              default: return MPARK_DEFAULT(B + 32);
+            }
+
+#undef MPARK_DEFAULT
+#undef MPARK_DISPATCH_AT
+          }
+        };
+#else
+        template <typename T>
+        inline static constexpr const T &at(const T &elem) noexcept {
+          return elem;
+        }
+
+        template <typename T, std::size_t N, typename... Is>
+        inline static constexpr const lib::remove_all_extents_t<T> &at(
+            const lib::array<T, N> &elems, std::size_t i, Is... is) noexcept {
+          return at(elems[i], is...);
+        }
+
+        template <typename F, typename... Fs>
+        inline static constexpr lib::array<lib::decay_t<F>, sizeof...(Fs) + 1>
+        make_farray(F &&f, Fs &&... fs) {
+          return {{lib::forward<F>(f), lib::forward<Fs>(fs)...}};
+        }
+
+        template <typename F, typename... Vs>
+        struct make_fmatrix_impl {
+
+          template <std::size_t... Is>
+          inline static constexpr dispatch_result_t<F, Vs...> dispatch(
+              F &&f, Vs &&... vs) {
+            using Expected = dispatch_result_t<F, Vs...>;
+            using Actual = decltype(lib::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<Is>(lib::forward<Vs>(vs))...));
+            return visit_return_type_check<Expected, Actual>::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<Is>(lib::forward<Vs>(vs))...);
+          }
+
+#ifdef MPARK_RETURN_TYPE_DEDUCTION
+          template <std::size_t... Is>
+          inline static constexpr auto impl(lib::index_sequence<Is...>) {
+            return &dispatch<Is...>;
+          }
+
+          template <typename Is, std::size_t... Js, typename... Ls>
+          inline static constexpr auto impl(Is,
+                                            lib::index_sequence<Js...>,
+                                            Ls... ls) {
+            return make_farray(impl(lib::push_back_t<Is, Js>{}, ls...)...);
+          }
+#else
+          template <typename...>
+          struct impl;
+
+          template <std::size_t... Is>
+          struct impl<lib::index_sequence<Is...>> {
+            inline constexpr AUTO operator()() const
+              AUTO_RETURN(&dispatch<Is...>)
+          };
+
+          template <typename Is, std::size_t... Js, typename... Ls>
+          struct impl<Is, lib::index_sequence<Js...>, Ls...> {
+            inline constexpr AUTO operator()() const
+              AUTO_RETURN(
+                  make_farray(impl<lib::push_back_t<Is, Js>, Ls...>{}()...))
+          };
+#endif
+        };
+
+#ifdef MPARK_RETURN_TYPE_DEDUCTION
+        template <typename F, typename... Vs>
+        inline static constexpr auto make_fmatrix() {
+          return make_fmatrix_impl<F, Vs...>::impl(
+              lib::index_sequence<>{},
+              lib::make_index_sequence<lib::decay_t<Vs>::size()>{}...);
+        }
+#else
+        template <typename F, typename... Vs>
+        inline static constexpr AUTO make_fmatrix()
+          AUTO_RETURN(
+              typename make_fmatrix_impl<F, Vs...>::template impl<
+                  lib::index_sequence<>,
+                  lib::make_index_sequence<lib::decay_t<Vs>::size()>...>{}())
+#endif
+
+        template <typename F, typename... Vs>
+        struct make_fdiagonal_impl {
+          template <std::size_t I>
+          inline static constexpr dispatch_result_t<F, Vs...> dispatch(
+              F &&f, Vs &&... vs) {
+            using Expected = dispatch_result_t<F, Vs...>;
+            using Actual = decltype(
+                lib::invoke(lib::forward<F>(f),
+                            access::base::get_alt<I>(lib::forward<Vs>(vs))...));
+            return visit_return_type_check<Expected, Actual>::invoke(
+                lib::forward<F>(f),
+                access::base::get_alt<I>(lib::forward<Vs>(vs))...);
+          }
+
+          template <std::size_t... Is>
+          inline static constexpr AUTO impl(lib::index_sequence<Is...>)
+            AUTO_RETURN(make_farray(&dispatch<Is>...))
+        };
+
+        template <typename F, typename V, typename... Vs>
+        inline static constexpr auto make_fdiagonal()
+            -> decltype(make_fdiagonal_impl<F, V, Vs...>::impl(
+                lib::make_index_sequence<lib::decay_t<V>::size()>{})) {
+          static_assert(lib::all<(lib::decay_t<V>::size() ==
+                                  lib::decay_t<Vs>::size())...>::value,
+                        "all of the variants must be the same size.");
+          return make_fdiagonal_impl<F, V, Vs...>::impl(
+              lib::make_index_sequence<lib::decay_t<V>::size()>{});
+        }
+#endif
+      };
+
+#if !defined(MPARK_VARIANT_SWITCH_VISIT) && \
+    (!defined(_MSC_VER) || _MSC_VER >= 1910)
+      template <typename F, typename... Vs>
+      using fmatrix_t = decltype(base::make_fmatrix<F, Vs...>());
+
+      template <typename F, typename... Vs>
+      struct fmatrix {
+        static constexpr fmatrix_t<F, Vs...> value =
+            base::make_fmatrix<F, Vs...>();
+      };
+
+      template <typename F, typename... Vs>
+      constexpr fmatrix_t<F, Vs...> fmatrix<F, Vs...>::value;
+
+      template <typename F, typename... Vs>
+      using fdiagonal_t = decltype(base::make_fdiagonal<F, Vs...>());
+
+      template <typename F, typename... Vs>
+      struct fdiagonal {
+        static constexpr fdiagonal_t<F, Vs...> value =
+            base::make_fdiagonal<F, Vs...>();
+      };
+
+      template <typename F, typename... Vs>
+      constexpr fdiagonal_t<F, Vs...> fdiagonal<F, Vs...>::value;
+#endif
+
+      struct alt {
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_alt(Visitor &&visitor,
+                                                        Vs &&... vs)
+#ifdef MPARK_VARIANT_SWITCH_VISIT
+          DECLTYPE_AUTO_RETURN(
+              base::dispatcher<
+                  true,
+                  base::dispatch_result_t<Visitor,
+                                          decltype(as_base(
+                                              lib::forward<Vs>(vs)))...>>::
+                  template dispatch<0>(lib::forward<Visitor>(visitor),
+                                       as_base(lib::forward<Vs>(vs))...))
+#elif !defined(_MSC_VER) || _MSC_VER >= 1910
+          DECLTYPE_AUTO_RETURN(base::at(
+              fmatrix<Visitor &&,
+                      decltype(as_base(lib::forward<Vs>(vs)))...>::value,
+              vs.index()...)(lib::forward<Visitor>(visitor),
+                             as_base(lib::forward<Vs>(vs))...))
+#else
+          DECLTYPE_AUTO_RETURN(base::at(
+              base::make_fmatrix<Visitor &&,
+                      decltype(as_base(lib::forward<Vs>(vs)))...>(),
+              vs.index()...)(lib::forward<Visitor>(visitor),
+                             as_base(lib::forward<Vs>(vs))...))
+#endif
+
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_alt_at(std::size_t index,
+                                                           Visitor &&visitor,
+                                                           Vs &&... vs)
+#ifdef MPARK_VARIANT_SWITCH_VISIT
+          DECLTYPE_AUTO_RETURN(
+              base::dispatcher<
+                  true,
+                  base::dispatch_result_t<Visitor,
+                                          decltype(as_base(
+                                              lib::forward<Vs>(vs)))...>>::
+                  template dispatch_at<0>(index,
+                                          lib::forward<Visitor>(visitor),
+                                          as_base(lib::forward<Vs>(vs))...))
+#elif !defined(_MSC_VER) || _MSC_VER >= 1910
+          DECLTYPE_AUTO_RETURN(base::at(
+              fdiagonal<Visitor &&,
+                        decltype(as_base(lib::forward<Vs>(vs)))...>::value,
+              index)(lib::forward<Visitor>(visitor),
+                     as_base(lib::forward<Vs>(vs))...))
+#else
+          DECLTYPE_AUTO_RETURN(base::at(
+              base::make_fdiagonal<Visitor &&,
+                        decltype(as_base(lib::forward<Vs>(vs)))...>(),
+              index)(lib::forward<Visitor>(visitor),
+                     as_base(lib::forward<Vs>(vs))...))
+#endif
+      };
+
+      struct variant {
+        private:
+        template <typename Visitor>
+        struct visitor {
+          template <typename... Values>
+          inline static constexpr bool does_not_handle() {
+            return lib::is_invocable<Visitor, Values...>::value;
+          }
+        };
+
+        template <typename Visitor, typename... Values>
+        struct visit_exhaustiveness_check {
+          static_assert(visitor<Visitor>::template does_not_handle<Values...>(),
+                        "`visit` requires the visitor to be exhaustive.");
+
+          inline static constexpr DECLTYPE_AUTO invoke(Visitor &&visitor,
+                                                       Values &&... values)
+            DECLTYPE_AUTO_RETURN(lib::invoke(lib::forward<Visitor>(visitor),
+                                             lib::forward<Values>(values)...))
+        };
+
+        template <typename Visitor>
+        struct value_visitor {
+          Visitor &&visitor_;
+
+          template <typename... Alts>
+          inline constexpr DECLTYPE_AUTO operator()(Alts &&... alts) const
+            DECLTYPE_AUTO_RETURN(
+                visit_exhaustiveness_check<
+                    Visitor,
+                    decltype((lib::forward<Alts>(alts).value))...>::
+                    invoke(lib::forward<Visitor>(visitor_),
+                           lib::forward<Alts>(alts).value...))
+        };
+
+        template <typename Visitor>
+        inline static constexpr AUTO make_value_visitor(Visitor &&visitor)
+          AUTO_RETURN(value_visitor<Visitor>{lib::forward<Visitor>(visitor)})
+
+        public:
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_alt(Visitor &&visitor,
+                                                        Vs &&... vs)
+          DECLTYPE_AUTO_RETURN(alt::visit_alt(lib::forward<Visitor>(visitor),
+                                              lib::forward<Vs>(vs).impl_...))
+
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_alt_at(std::size_t index,
+                                                           Visitor &&visitor,
+                                                           Vs &&... vs)
+          DECLTYPE_AUTO_RETURN(
+              alt::visit_alt_at(index,
+                                lib::forward<Visitor>(visitor),
+                                lib::forward<Vs>(vs).impl_...))
+
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_value(Visitor &&visitor,
+                                                          Vs &&... vs)
+          DECLTYPE_AUTO_RETURN(
+              visit_alt(make_value_visitor(lib::forward<Visitor>(visitor)),
+                        lib::forward<Vs>(vs)...))
+
+        template <typename Visitor, typename... Vs>
+        inline static constexpr DECLTYPE_AUTO visit_value_at(std::size_t index,
+                                                             Visitor &&visitor,
+                                                             Vs &&... vs)
+          DECLTYPE_AUTO_RETURN(
+              visit_alt_at(index,
+                           make_value_visitor(lib::forward<Visitor>(visitor)),
+                           lib::forward<Vs>(vs)...))
+      };
+
+    }  // namespace visitation
+
+    template <std::size_t Index, typename T>
+    struct alt {
+      using value_type = T;
+
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4244)
+#endif
+      template <typename... Args>
+      inline explicit constexpr alt(in_place_t, Args &&... args)
+          : value(lib::forward<Args>(args)...) {}
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+      T value;
+    };
+
+    template <Trait DestructibleTrait, std::size_t Index, typename... Ts>
+    union recursive_union;
+
+    template <Trait DestructibleTrait, std::size_t Index>
+    union recursive_union<DestructibleTrait, Index> {};
+
+#define MPARK_VARIANT_RECURSIVE_UNION(destructible_trait, destructor)      \
+  template <std::size_t Index, typename T, typename... Ts>                 \
+  union recursive_union<destructible_trait, Index, T, Ts...> {             \
+    public:                                                                \
+    inline explicit constexpr recursive_union(valueless_t) noexcept        \
+        : dummy_{} {}                                                      \
+                                                                           \
+    template <typename... Args>                                            \
+    inline explicit constexpr recursive_union(in_place_index_t<0>,         \
+                                              Args &&... args)             \
+        : head_(in_place_t{}, lib::forward<Args>(args)...) {}              \
+                                                                           \
+    template <std::size_t I, typename... Args>                             \
+    inline explicit constexpr recursive_union(in_place_index_t<I>,         \
+                                              Args &&... args)             \
+        : tail_(in_place_index_t<I - 1>{}, lib::forward<Args>(args)...) {} \
+                                                                           \
+    recursive_union(const recursive_union &) = default;                    \
+    recursive_union(recursive_union &&) = default;                         \
+                                                                           \
+    destructor                                                             \
+                                                                           \
+    recursive_union &operator=(const recursive_union &) = default;         \
+    recursive_union &operator=(recursive_union &&) = default;              \
+                                                                           \
+    private:                                                               \
+    char dummy_;                                                           \
+    alt<Index, T> head_;                                                   \
+    recursive_union<destructible_trait, Index + 1, Ts...> tail_;           \
+                                                                           \
+    friend struct access::recursive_union;                                 \
+  }
+
+    MPARK_VARIANT_RECURSIVE_UNION(Trait::TriviallyAvailable,
+                                  ~recursive_union() = default;);
+    MPARK_VARIANT_RECURSIVE_UNION(Trait::Available,
+                                  ~recursive_union() {});
+    MPARK_VARIANT_RECURSIVE_UNION(Trait::Unavailable,
+                                  ~recursive_union() = delete;);
+
+#undef MPARK_VARIANT_RECURSIVE_UNION
+
+    template <typename... Ts>
+    using index_t = typename std::conditional<
+            sizeof...(Ts) < std::numeric_limits<unsigned char>::max(),
+            unsigned char,
+            typename std::conditional<
+                sizeof...(Ts) < std::numeric_limits<unsigned short>::max(),
+                unsigned short,
+                unsigned int>::type
+            >::type;
+
+    template <Trait DestructibleTrait, typename... Ts>
+    class base {
+      public:
+      inline explicit constexpr base(valueless_t tag) noexcept
+          : data_(tag), index_(static_cast<index_t<Ts...>>(-1)) {}
+
+      template <std::size_t I, typename... Args>
+      inline explicit constexpr base(in_place_index_t<I>, Args &&... args)
+          : data_(in_place_index_t<I>{}, lib::forward<Args>(args)...),
+            index_(I) {}
+
+      inline constexpr bool valueless_by_exception() const noexcept {
+        return index_ == static_cast<index_t<Ts...>>(-1);
+      }
+
+      inline constexpr std::size_t index() const noexcept {
+        return valueless_by_exception() ? variant_npos : index_;
+      }
+
+      protected:
+      using data_t = recursive_union<DestructibleTrait, 0, Ts...>;
+
+      friend inline constexpr base &as_base(base &b) { return b; }
+      friend inline constexpr const base &as_base(const base &b) { return b; }
+      friend inline constexpr base &&as_base(base &&b) { return lib::move(b); }
+      friend inline constexpr const base &&as_base(const base &&b) { return lib::move(b); }
+
+      friend inline constexpr data_t &data(base &b) { return b.data_; }
+      friend inline constexpr const data_t &data(const base &b) { return b.data_; }
+      friend inline constexpr data_t &&data(base &&b) { return lib::move(b).data_; }
+      friend inline constexpr const data_t &&data(const base &&b) { return lib::move(b).data_; }
+
+      inline static constexpr std::size_t size() { return sizeof...(Ts); }
+
+      data_t data_;
+      index_t<Ts...> index_;
+
+      friend struct access::base;
+      friend struct visitation::base;
+    };
+
+    struct dtor {
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4100)
+#endif
+      template <typename Alt>
+      inline void operator()(Alt &alt) const noexcept { alt.~Alt(); }
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+    };
+
+#if !defined(_MSC_VER) || _MSC_VER >= 1910
+#define MPARK_INHERITING_CTOR(type, base) using base::base;
+#else
+#define MPARK_INHERITING_CTOR(type, base)         \
+  template <typename... Args>                     \
+  inline explicit constexpr type(Args &&... args) \
+      : base(lib::forward<Args>(args)...) {}
+#endif
+
+    template <typename Traits, Trait = Traits::destructible_trait>
+    class destructor;
+
+#define MPARK_VARIANT_DESTRUCTOR(destructible_trait, definition, destroy) \
+  template <typename... Ts>                                               \
+  class destructor<traits<Ts...>, destructible_trait>                     \
+      : public base<destructible_trait, Ts...> {                          \
+    using super = base<destructible_trait, Ts...>;                        \
+                                                                          \
+    public:                                                               \
+    MPARK_INHERITING_CTOR(destructor, super)                              \
+    using super::operator=;                                               \
+                                                                          \
+    destructor(const destructor &) = default;                             \
+    destructor(destructor &&) = default;                                  \
+    definition                                                            \
+    destructor &operator=(const destructor &) = default;                  \
+    destructor &operator=(destructor &&) = default;                       \
+                                                                          \
+    protected:                                                            \
+    destroy                                                               \
+  }
+
+    MPARK_VARIANT_DESTRUCTOR(
+        Trait::TriviallyAvailable,
+        ~destructor() = default;,
+        inline void destroy() noexcept {
+          this->index_ = static_cast<index_t<Ts...>>(-1);
+        });
+
+    MPARK_VARIANT_DESTRUCTOR(
+        Trait::Available,
+        ~destructor() { destroy(); },
+        inline void destroy() noexcept {
+          if (!this->valueless_by_exception()) {
+            visitation::alt::visit_alt(dtor{}, *this);
+          }
+          this->index_ = static_cast<index_t<Ts...>>(-1);
+        });
+
+    MPARK_VARIANT_DESTRUCTOR(
+        Trait::Unavailable,
+        ~destructor() = delete;,
+        inline void destroy() noexcept = delete;);
+
+#undef MPARK_VARIANT_DESTRUCTOR
+
+    template <typename Traits>
+    class constructor : public destructor<Traits> {
+      using super = destructor<Traits>;
+
+      public:
+      MPARK_INHERITING_CTOR(constructor, super)
+      using super::operator=;
+
+      protected:
+#ifndef MPARK_GENERIC_LAMBDAS
+      struct ctor {
+        template <typename LhsAlt, typename RhsAlt>
+        inline void operator()(LhsAlt &lhs_alt, RhsAlt &&rhs_alt) const {
+          constructor::construct_alt(lhs_alt,
+                                     lib::forward<RhsAlt>(rhs_alt).value);
+        }
+      };
+#endif
+
+      template <std::size_t I, typename T, typename... Args>
+      inline static T &construct_alt(alt<I, T> &a, Args &&... args) {
+        auto *result = ::new (static_cast<void *>(lib::addressof(a)))
+            alt<I, T>(in_place_t{}, lib::forward<Args>(args)...);
+        return result->value;
+      }
+
+      template <typename Rhs>
+      inline static void generic_construct(constructor &lhs, Rhs &&rhs) {
+        lhs.destroy();
+        if (!rhs.valueless_by_exception()) {
+          visitation::alt::visit_alt_at(
+              rhs.index(),
+#ifdef MPARK_GENERIC_LAMBDAS
+              [](auto &lhs_alt, auto &&rhs_alt) {
+                constructor::construct_alt(
+                    lhs_alt, lib::forward<decltype(rhs_alt)>(rhs_alt).value);
+              }
+#else
+              ctor{}
+#endif
+              ,
+              lhs,
+              lib::forward<Rhs>(rhs));
+          lhs.index_ = rhs.index_;
+        }
+      }
+    };
+
+    template <typename Traits, Trait = Traits::move_constructible_trait>
+    class move_constructor;
+
+#define MPARK_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, definition) \
+  template <typename... Ts>                                                  \
+  class move_constructor<traits<Ts...>, move_constructible_trait>            \
+      : public constructor<traits<Ts...>> {                                  \
+    using super = constructor<traits<Ts...>>;                                \
+                                                                             \
+    public:                                                                  \
+    MPARK_INHERITING_CTOR(move_constructor, super)                           \
+    using super::operator=;                                                  \
+                                                                             \
+    move_constructor(const move_constructor &) = default;                    \
+    definition                                                               \
+    ~move_constructor() = default;                                           \
+    move_constructor &operator=(const move_constructor &) = default;         \
+    move_constructor &operator=(move_constructor &&) = default;              \
+  }
+
+    MPARK_VARIANT_MOVE_CONSTRUCTOR(
+        Trait::TriviallyAvailable,
+        move_constructor(move_constructor &&that) = default;);
+
+    MPARK_VARIANT_MOVE_CONSTRUCTOR(
+        Trait::Available,
+        move_constructor(move_constructor &&that) noexcept(
+            lib::all<std::is_nothrow_move_constructible<Ts>::value...>::value)
+            : move_constructor(valueless_t{}) {
+          this->generic_construct(*this, lib::move(that));
+        });
+
+    MPARK_VARIANT_MOVE_CONSTRUCTOR(
+        Trait::Unavailable,
+        move_constructor(move_constructor &&) = delete;);
+
+#undef MPARK_VARIANT_MOVE_CONSTRUCTOR
+
+    template <typename Traits, Trait = Traits::copy_constructible_trait>
+    class copy_constructor;
+
+#define MPARK_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, definition) \
+  template <typename... Ts>                                                  \
+  class copy_constructor<traits<Ts...>, copy_constructible_trait>            \
+      : public move_constructor<traits<Ts...>> {                             \
+    using super = move_constructor<traits<Ts...>>;                           \
+                                                                             \
+    public:                                                                  \
+    MPARK_INHERITING_CTOR(copy_constructor, super)                           \
+    using super::operator=;                                                  \
+                                                                             \
+    definition                                                               \
+    copy_constructor(copy_constructor &&) = default;                         \
+    ~copy_constructor() = default;                                           \
+    copy_constructor &operator=(const copy_constructor &) = default;         \
+    copy_constructor &operator=(copy_constructor &&) = default;              \
+  }
+
+    MPARK_VARIANT_COPY_CONSTRUCTOR(
+        Trait::TriviallyAvailable,
+        copy_constructor(const copy_constructor &that) = default;);
+
+    MPARK_VARIANT_COPY_CONSTRUCTOR(
+        Trait::Available,
+        copy_constructor(const copy_constructor &that)
+            : copy_constructor(valueless_t{}) {
+          this->generic_construct(*this, that);
+        });
+
+    MPARK_VARIANT_COPY_CONSTRUCTOR(
+        Trait::Unavailable,
+        copy_constructor(const copy_constructor &) = delete;);
+
+#undef MPARK_VARIANT_COPY_CONSTRUCTOR
+
+    template <typename Traits>
+    class assignment : public copy_constructor<Traits> {
+      using super = copy_constructor<Traits>;
+
+      public:
+      MPARK_INHERITING_CTOR(assignment, super)
+      using super::operator=;
+
+      template <std::size_t I, typename... Args>
+      inline /* auto & */ auto emplace(Args &&... args)
+          -> decltype(this->construct_alt(access::base::get_alt<I>(*this),
+                                          lib::forward<Args>(args)...)) {
+        this->destroy();
+        auto &result = this->construct_alt(access::base::get_alt<I>(*this),
+                                           lib::forward<Args>(args)...);
+        this->index_ = I;
+        return result;
+      }
+
+      protected:
+#ifndef MPARK_GENERIC_LAMBDAS
+      template <typename That>
+      struct assigner {
+        template <typename ThisAlt, typename ThatAlt>
+        inline void operator()(ThisAlt &this_alt, ThatAlt &&that_alt) const {
+          self->assign_alt(this_alt, lib::forward<ThatAlt>(that_alt).value);
+        }
+        assignment *self;
+      };
+#endif
+
+      template <std::size_t I, typename T, typename Arg>
+      inline void assign_alt(alt<I, T> &a, Arg &&arg) {
+        if (this->index() == I) {
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4244)
+#endif
+          a.value = lib::forward<Arg>(arg);
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+        } else {
+          struct {
+            void operator()(std::true_type) const {
+              this_->emplace<I>(lib::forward<Arg>(arg_));
+            }
+            void operator()(std::false_type) const {
+              this_->emplace<I>(T(lib::forward<Arg>(arg_)));
+            }
+            assignment *this_;
+            Arg &&arg_;
+          } impl{this, lib::forward<Arg>(arg)};
+          impl(lib::bool_constant<
+                   std::is_nothrow_constructible<T, Arg>::value ||
+                   !std::is_nothrow_move_constructible<T>::value>{});
+        }
+      }
+
+      template <typename That>
+      inline void generic_assign(That &&that) {
+        if (this->valueless_by_exception() && that.valueless_by_exception()) {
+          // do nothing.
+        } else if (that.valueless_by_exception()) {
+          this->destroy();
+        } else {
+          visitation::alt::visit_alt_at(
+              that.index(),
+#ifdef MPARK_GENERIC_LAMBDAS
+              [this](auto &this_alt, auto &&that_alt) {
+                this->assign_alt(
+                    this_alt, lib::forward<decltype(that_alt)>(that_alt).value);
+              }
+#else
+              assigner<That>{this}
+#endif
+              ,
+              *this,
+              lib::forward<That>(that));
+        }
+      }
+    };
+
+    template <typename Traits, Trait = Traits::move_assignable_trait>
+    class move_assignment;
+
+#define MPARK_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, definition) \
+  template <typename... Ts>                                              \
+  class move_assignment<traits<Ts...>, move_assignable_trait>            \
+      : public assignment<traits<Ts...>> {                               \
+    using super = assignment<traits<Ts...>>;                             \
+                                                                         \
+    public:                                                              \
+    MPARK_INHERITING_CTOR(move_assignment, super)                        \
+    using super::operator=;                                              \
+                                                                         \
+    move_assignment(const move_assignment &) = default;                  \
+    move_assignment(move_assignment &&) = default;                       \
+    ~move_assignment() = default;                                        \
+    move_assignment &operator=(const move_assignment &) = default;       \
+    definition                                                           \
+  }
+
+    MPARK_VARIANT_MOVE_ASSIGNMENT(
+        Trait::TriviallyAvailable,
+        move_assignment &operator=(move_assignment &&that) = default;);
+
+    MPARK_VARIANT_MOVE_ASSIGNMENT(
+        Trait::Available,
+        move_assignment &
+        operator=(move_assignment &&that) noexcept(
+            lib::all<(std::is_nothrow_move_constructible<Ts>::value &&
+                      std::is_nothrow_move_assignable<Ts>::value)...>::value) {
+          this->generic_assign(lib::move(that));
+          return *this;
+        });
+
+    MPARK_VARIANT_MOVE_ASSIGNMENT(
+        Trait::Unavailable,
+        move_assignment &operator=(move_assignment &&) = delete;);
+
+#undef MPARK_VARIANT_MOVE_ASSIGNMENT
+
+    template <typename Traits, Trait = Traits::copy_assignable_trait>
+    class copy_assignment;
+
+#define MPARK_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, definition) \
+  template <typename... Ts>                                              \
+  class copy_assignment<traits<Ts...>, copy_assignable_trait>            \
+      : public move_assignment<traits<Ts...>> {                          \
+    using super = move_assignment<traits<Ts...>>;                        \
+                                                                         \
+    public:                                                              \
+    MPARK_INHERITING_CTOR(copy_assignment, super)                        \
+    using super::operator=;                                              \
+                                                                         \
+    copy_assignment(const copy_assignment &) = default;                  \
+    copy_assignment(copy_assignment &&) = default;                       \
+    ~copy_assignment() = default;                                        \
+    definition                                                           \
+    copy_assignment &operator=(copy_assignment &&) = default;            \
+  }
+
+    MPARK_VARIANT_COPY_ASSIGNMENT(
+        Trait::TriviallyAvailable,
+        copy_assignment &operator=(const copy_assignment &that) = default;);
+
+    MPARK_VARIANT_COPY_ASSIGNMENT(
+        Trait::Available,
+        copy_assignment &operator=(const copy_assignment &that) {
+          this->generic_assign(that);
+          return *this;
+        });
+
+    MPARK_VARIANT_COPY_ASSIGNMENT(
+        Trait::Unavailable,
+        copy_assignment &operator=(const copy_assignment &) = delete;);
+
+#undef MPARK_VARIANT_COPY_ASSIGNMENT
+
+    template <typename... Ts>
+    class impl : public copy_assignment<traits<Ts...>> {
+      using super = copy_assignment<traits<Ts...>>;
+
+      public:
+      MPARK_INHERITING_CTOR(impl, super)
+      using super::operator=;
+
+      template <std::size_t I, typename Arg>
+      inline void assign(Arg &&arg) {
+        this->assign_alt(access::base::get_alt<I>(*this),
+                         lib::forward<Arg>(arg));
+      }
+
+      inline void swap(impl &that) {
+        if (this->valueless_by_exception() && that.valueless_by_exception()) {
+          // do nothing.
+        } else if (this->index() == that.index()) {
+          visitation::alt::visit_alt_at(this->index(),
+#ifdef MPARK_GENERIC_LAMBDAS
+                                        [](auto &this_alt, auto &that_alt) {
+                                          using std::swap;
+                                          swap(this_alt.value,
+                                               that_alt.value);
+                                        }
+#else
+                                        swapper{}
+#endif
+                                        ,
+                                        *this,
+                                        that);
+        } else {
+          impl *lhs = this;
+          impl *rhs = lib::addressof(that);
+          if (lhs->move_nothrow() && !rhs->move_nothrow()) {
+            std::swap(lhs, rhs);
+          }
+          impl tmp(lib::move(*rhs));
+#ifdef MPARK_EXCEPTIONS
+          // EXTENSION: When the move construction of `lhs` into `rhs` throws
+          // and `tmp` is nothrow move constructible then we move `tmp` back
+          // into `rhs` and provide the strong exception safety guarantee.
+          try {
+            this->generic_construct(*rhs, lib::move(*lhs));
+          } catch (...) {
+            if (tmp.move_nothrow()) {
+              this->generic_construct(*rhs, lib::move(tmp));
+            }
+            throw;
+          }
+#else
+          this->generic_construct(*rhs, lib::move(*lhs));
+#endif
+          this->generic_construct(*lhs, lib::move(tmp));
+        }
+      }
+
+      private:
+#ifndef MPARK_GENERIC_LAMBDAS
+      struct swapper {
+        template <typename ThisAlt, typename ThatAlt>
+        inline void operator()(ThisAlt &this_alt, ThatAlt &that_alt) const {
+          using std::swap;
+          swap(this_alt.value, that_alt.value);
+        }
+      };
+#endif
+
+      inline constexpr bool move_nothrow() const {
+        return this->valueless_by_exception() ||
+               lib::array<bool, sizeof...(Ts)>{
+                   {std::is_nothrow_move_constructible<Ts>::value...}
+               }[this->index()];
+      }
+    };
+
+#undef MPARK_INHERITING_CTOR
+
+    template <std::size_t I, typename T>
+    struct overload_leaf {
+      using F = lib::size_constant<I> (*)(T);
+      operator F() const { return nullptr; }
+    };
+
+    template <typename... Ts>
+    struct overload_impl {
+      private:
+      template <typename>
+      struct impl;
+
+      template <std::size_t... Is>
+      struct impl<lib::index_sequence<Is...>> : overload_leaf<Is, Ts>... {};
+
+      public:
+      using type = impl<lib::index_sequence_for<Ts...>>;
+    };
+
+    template <typename... Ts>
+    using overload = typename overload_impl<Ts...>::type;
+
+    template <typename T, typename... Ts>
+    using best_match = lib::invoke_result_t<overload<Ts...>, T &&>;
+
+    template <typename T>
+    struct is_in_place_index : std::false_type {};
+
+    template <std::size_t I>
+    struct is_in_place_index<in_place_index_t<I>> : std::true_type {};
+
+    template <typename T>
+    struct is_in_place_type : std::false_type {};
+
+    template <typename T>
+    struct is_in_place_type<in_place_type_t<T>> : std::true_type {};
+
+  }  // detail
+
+  template <typename... Ts>
+  class variant {
+    static_assert(0 < sizeof...(Ts),
+                  "variant must consist of at least one alternative.");
+
+    static_assert(lib::all<!std::is_array<Ts>::value...>::value,
+                  "variant can not have an array type as an alternative.");
+
+    static_assert(lib::all<!std::is_reference<Ts>::value...>::value,
+                  "variant can not have a reference type as an alternative.");
+
+    static_assert(lib::all<!std::is_void<Ts>::value...>::value,
+                  "variant can not have a void type as an alternative.");
+
+    public:
+    template <
+        typename Front = lib::type_pack_element_t<0, Ts...>,
+        lib::enable_if_t<std::is_default_constructible<Front>::value, int> = 0>
+    inline constexpr variant() noexcept(
+        std::is_nothrow_default_constructible<Front>::value)
+        : impl_(in_place_index_t<0>{}) {}
+
+    variant(const variant &) = default;
+    variant(variant &&) = default;
+
+    template <
+        typename Arg,
+        typename Decayed = lib::decay_t<Arg>,
+        lib::enable_if_t<!std::is_same<Decayed, variant>::value, int> = 0,
+        lib::enable_if_t<!detail::is_in_place_index<Decayed>::value, int> = 0,
+        lib::enable_if_t<!detail::is_in_place_type<Decayed>::value, int> = 0,
+        std::size_t I = detail::best_match<Arg, Ts...>::value,
+        typename T = lib::type_pack_element_t<I, Ts...>,
+        lib::enable_if_t<std::is_constructible<T, Arg>::value, int> = 0>
+    inline constexpr variant(Arg &&arg) noexcept(
+        std::is_nothrow_constructible<T, Arg>::value)
+        : impl_(in_place_index_t<I>{}, lib::forward<Arg>(arg)) {}
+
+    template <
+        std::size_t I,
+        typename... Args,
+        typename T = lib::type_pack_element_t<I, Ts...>,
+        lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
+    inline explicit constexpr variant(
+        in_place_index_t<I>,
+        Args &&... args) noexcept(std::is_nothrow_constructible<T,
+                                                                Args...>::value)
+        : impl_(in_place_index_t<I>{}, lib::forward<Args>(args)...) {}
+
+    template <
+        std::size_t I,
+        typename Up,
+        typename... Args,
+        typename T = lib::type_pack_element_t<I, Ts...>,
+        lib::enable_if_t<std::is_constructible<T,
+                                               std::initializer_list<Up> &,
+                                               Args...>::value,
+                         int> = 0>
+    inline explicit constexpr variant(
+        in_place_index_t<I>,
+        std::initializer_list<Up> il,
+        Args &&... args) noexcept(std::
+                                      is_nothrow_constructible<
+                                          T,
+                                          std::initializer_list<Up> &,
+                                          Args...>::value)
+        : impl_(in_place_index_t<I>{}, il, lib::forward<Args>(args)...) {}
+
+    template <
+        typename T,
+        typename... Args,
+        std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
+        lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
+    inline explicit constexpr variant(
+        in_place_type_t<T>,
+        Args &&... args) noexcept(std::is_nothrow_constructible<T,
+                                                                Args...>::value)
+        : impl_(in_place_index_t<I>{}, lib::forward<Args>(args)...) {}
+
+    template <
+        typename T,
+        typename Up,
+        typename... Args,
+        std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
+        lib::enable_if_t<std::is_constructible<T,
+                                               std::initializer_list<Up> &,
+                                               Args...>::value,
+                         int> = 0>
+    inline explicit constexpr variant(
+        in_place_type_t<T>,
+        std::initializer_list<Up> il,
+        Args &&... args) noexcept(std::
+                                      is_nothrow_constructible<
+                                          T,
+                                          std::initializer_list<Up> &,
+                                          Args...>::value)
+        : impl_(in_place_index_t<I>{}, il, lib::forward<Args>(args)...) {}
+
+    ~variant() = default;
+
+    variant &operator=(const variant &) = default;
+    variant &operator=(variant &&) = default;
+
+    template <typename Arg,
+              lib::enable_if_t<!std::is_same<lib::decay_t<Arg>, variant>::value,
+                               int> = 0,
+              std::size_t I = detail::best_match<Arg, Ts...>::value,
+              typename T = lib::type_pack_element_t<I, Ts...>,
+              lib::enable_if_t<(std::is_assignable<T &, Arg>::value &&
+                                std::is_constructible<T, Arg>::value),
+                               int> = 0>
+    inline variant &operator=(Arg &&arg) noexcept(
+        (std::is_nothrow_assignable<T &, Arg>::value &&
+         std::is_nothrow_constructible<T, Arg>::value)) {
+      impl_.template assign<I>(lib::forward<Arg>(arg));
+      return *this;
+    }
+
+    template <
+        std::size_t I,
+        typename... Args,
+        typename T = lib::type_pack_element_t<I, Ts...>,
+        lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
+    inline T &emplace(Args &&... args) {
+      return impl_.template emplace<I>(lib::forward<Args>(args)...);
+    }
+
+    template <
+        std::size_t I,
+        typename Up,
+        typename... Args,
+        typename T = lib::type_pack_element_t<I, Ts...>,
+        lib::enable_if_t<std::is_constructible<T,
+                                               std::initializer_list<Up> &,
+                                               Args...>::value,
+                         int> = 0>
+    inline T &emplace(std::initializer_list<Up> il, Args &&... args) {
+      return impl_.template emplace<I>(il, lib::forward<Args>(args)...);
+    }
+
+    template <
+        typename T,
+        typename... Args,
+        std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
+        lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
+    inline T &emplace(Args &&... args) {
+      return impl_.template emplace<I>(lib::forward<Args>(args)...);
+    }
+
+    template <
+        typename T,
+        typename Up,
+        typename... Args,
+        std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
+        lib::enable_if_t<std::is_constructible<T,
+                                               std::initializer_list<Up> &,
+                                               Args...>::value,
+                         int> = 0>
+    inline T &emplace(std::initializer_list<Up> il, Args &&... args) {
+      return impl_.template emplace<I>(il, lib::forward<Args>(args)...);
+    }
+
+    inline constexpr bool valueless_by_exception() const noexcept {
+      return impl_.valueless_by_exception();
+    }
+
+    inline constexpr std::size_t index() const noexcept {
+      return impl_.index();
+    }
+
+    template <bool Dummy = true,
+              lib::enable_if_t<
+                  lib::all<Dummy,
+                           (lib::dependent_type<std::is_move_constructible<Ts>,
+                                                Dummy>::value &&
+                            lib::dependent_type<lib::is_swappable<Ts>,
+                                                Dummy>::value)...>::value,
+                  int> = 0>
+    inline void swap(variant &that) noexcept(
+        lib::all<(std::is_nothrow_move_constructible<Ts>::value &&
+                  lib::is_nothrow_swappable<Ts>::value)...>::value) {
+      impl_.swap(that.impl_);
+    }
+
+    private:
+    detail::impl<Ts...> impl_;
+
+    friend struct detail::access::variant;
+    friend struct detail::visitation::variant;
+  };
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr bool holds_alternative(const variant<Ts...> &v) noexcept {
+    return v.index() == I;
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr bool holds_alternative(const variant<Ts...> &v) noexcept {
+    return holds_alternative<detail::find_index_checked<T, Ts...>::value>(v);
+  }
+
+  namespace detail {
+    template <std::size_t I, typename V>
+    struct generic_get_impl {
+      constexpr generic_get_impl(int) noexcept {}
+
+      constexpr AUTO_REFREF operator()(V &&v) const
+        AUTO_REFREF_RETURN(
+            access::variant::get_alt<I>(lib::forward<V>(v)).value)
+    };
+
+    template <std::size_t I, typename V>
+    inline constexpr AUTO_REFREF generic_get(V &&v)
+      AUTO_REFREF_RETURN(generic_get_impl<I, V>(
+          holds_alternative<I>(v) ? 0 : (throw_bad_variant_access(), 0))(
+          lib::forward<V>(v)))
+  }  // namespace detail
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr variant_alternative_t<I, variant<Ts...>> &get(
+      variant<Ts...> &v) {
+    return detail::generic_get<I>(v);
+  }
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr variant_alternative_t<I, variant<Ts...>> &&get(
+      variant<Ts...> &&v) {
+    return detail::generic_get<I>(lib::move(v));
+  }
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr const variant_alternative_t<I, variant<Ts...>> &get(
+      const variant<Ts...> &v) {
+    return detail::generic_get<I>(v);
+  }
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr const variant_alternative_t<I, variant<Ts...>> &&get(
+      const variant<Ts...> &&v) {
+    return detail::generic_get<I>(lib::move(v));
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr T &get(variant<Ts...> &v) {
+    return get<detail::find_index_checked<T, Ts...>::value>(v);
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr T &&get(variant<Ts...> &&v) {
+    return get<detail::find_index_checked<T, Ts...>::value>(lib::move(v));
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr const T &get(const variant<Ts...> &v) {
+    return get<detail::find_index_checked<T, Ts...>::value>(v);
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr const T &&get(const variant<Ts...> &&v) {
+    return get<detail::find_index_checked<T, Ts...>::value>(lib::move(v));
+  }
+
+  namespace detail {
+
+    template <std::size_t I, typename V>
+    inline constexpr /* auto * */ AUTO generic_get_if(V *v) noexcept
+      AUTO_RETURN(v && holds_alternative<I>(*v)
+                      ? lib::addressof(access::variant::get_alt<I>(*v).value)
+                      : nullptr)
+
+  }  // namespace detail
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr lib::add_pointer_t<variant_alternative_t<I, variant<Ts...>>>
+  get_if(variant<Ts...> *v) noexcept {
+    return detail::generic_get_if<I>(v);
+  }
+
+  template <std::size_t I, typename... Ts>
+  inline constexpr lib::add_pointer_t<
+      const variant_alternative_t<I, variant<Ts...>>>
+  get_if(const variant<Ts...> *v) noexcept {
+    return detail::generic_get_if<I>(v);
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr lib::add_pointer_t<T>
+  get_if(variant<Ts...> *v) noexcept {
+    return get_if<detail::find_index_checked<T, Ts...>::value>(v);
+  }
+
+  template <typename T, typename... Ts>
+  inline constexpr lib::add_pointer_t<const T>
+  get_if(const variant<Ts...> *v) noexcept {
+    return get_if<detail::find_index_checked<T, Ts...>::value>(v);
+  }
+
+  namespace detail {
+    template <typename RelOp>
+    struct convert_to_bool {
+      template <typename Lhs, typename Rhs>
+      inline constexpr bool operator()(Lhs &&lhs, Rhs &&rhs) const {
+        static_assert(std::is_convertible<lib::invoke_result_t<RelOp, Lhs, Rhs>,
+                                          bool>::value,
+                      "relational operators must return a type"
+                      " implicitly convertible to bool");
+        return lib::invoke(
+            RelOp{}, lib::forward<Lhs>(lhs), lib::forward<Rhs>(rhs));
+      }
+    };
+  }  // namespace detail
+
+  template <typename... Ts>
+  inline constexpr bool operator==(const variant<Ts...> &lhs,
+                                   const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using equal_to = detail::convert_to_bool<lib::equal_to>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (lhs.index() != rhs.index()) return false;
+    if (lhs.valueless_by_exception()) return true;
+    return variant::visit_value_at(lhs.index(), equal_to{}, lhs, rhs);
+#else
+    return lhs.index() == rhs.index() &&
+           (lhs.valueless_by_exception() ||
+            variant::visit_value_at(lhs.index(), equal_to{}, lhs, rhs));
+#endif
+  }
+
+  template <typename... Ts>
+  inline constexpr bool operator!=(const variant<Ts...> &lhs,
+                                   const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using not_equal_to = detail::convert_to_bool<lib::not_equal_to>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (lhs.index() != rhs.index()) return true;
+    if (lhs.valueless_by_exception()) return false;
+    return variant::visit_value_at(lhs.index(), not_equal_to{}, lhs, rhs);
+#else
+    return lhs.index() != rhs.index() ||
+           (!lhs.valueless_by_exception() &&
+            variant::visit_value_at(lhs.index(), not_equal_to{}, lhs, rhs));
+#endif
+  }
+
+  template <typename... Ts>
+  inline constexpr bool operator<(const variant<Ts...> &lhs,
+                                  const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using less = detail::convert_to_bool<lib::less>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (rhs.valueless_by_exception()) return false;
+    if (lhs.valueless_by_exception()) return true;
+    if (lhs.index() < rhs.index()) return true;
+    if (lhs.index() > rhs.index()) return false;
+    return variant::visit_value_at(lhs.index(), less{}, lhs, rhs);
+#else
+    return !rhs.valueless_by_exception() &&
+           (lhs.valueless_by_exception() || lhs.index() < rhs.index() ||
+            (lhs.index() == rhs.index() &&
+             variant::visit_value_at(lhs.index(), less{}, lhs, rhs)));
+#endif
+  }
+
+  template <typename... Ts>
+  inline constexpr bool operator>(const variant<Ts...> &lhs,
+                                  const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using greater = detail::convert_to_bool<lib::greater>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (lhs.valueless_by_exception()) return false;
+    if (rhs.valueless_by_exception()) return true;
+    if (lhs.index() > rhs.index()) return true;
+    if (lhs.index() < rhs.index()) return false;
+    return variant::visit_value_at(lhs.index(), greater{}, lhs, rhs);
+#else
+    return !lhs.valueless_by_exception() &&
+           (rhs.valueless_by_exception() || lhs.index() > rhs.index() ||
+            (lhs.index() == rhs.index() &&
+             variant::visit_value_at(lhs.index(), greater{}, lhs, rhs)));
+#endif
+  }
+
+  template <typename... Ts>
+  inline constexpr bool operator<=(const variant<Ts...> &lhs,
+                                   const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using less_equal = detail::convert_to_bool<lib::less_equal>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (lhs.valueless_by_exception()) return true;
+    if (rhs.valueless_by_exception()) return false;
+    if (lhs.index() < rhs.index()) return true;
+    if (lhs.index() > rhs.index()) return false;
+    return variant::visit_value_at(lhs.index(), less_equal{}, lhs, rhs);
+#else
+    return lhs.valueless_by_exception() ||
+           (!rhs.valueless_by_exception() &&
+            (lhs.index() < rhs.index() ||
+             (lhs.index() == rhs.index() &&
+              variant::visit_value_at(lhs.index(), less_equal{}, lhs, rhs))));
+#endif
+  }
+
+  template <typename... Ts>
+  inline constexpr bool operator>=(const variant<Ts...> &lhs,
+                                   const variant<Ts...> &rhs) {
+    using detail::visitation::variant;
+    using greater_equal = detail::convert_to_bool<lib::greater_equal>;
+#ifdef MPARK_CPP14_CONSTEXPR
+    if (rhs.valueless_by_exception()) return true;
+    if (lhs.valueless_by_exception()) return false;
+    if (lhs.index() > rhs.index()) return true;
+    if (lhs.index() < rhs.index()) return false;
+    return variant::visit_value_at(lhs.index(), greater_equal{}, lhs, rhs);
+#else
+    return rhs.valueless_by_exception() ||
+           (!lhs.valueless_by_exception() &&
+            (lhs.index() > rhs.index() ||
+             (lhs.index() == rhs.index() &&
+              variant::visit_value_at(
+                  lhs.index(), greater_equal{}, lhs, rhs))));
+#endif
+  }
+
+  struct monostate {};
+
+  inline constexpr bool operator<(monostate, monostate) noexcept {
+    return false;
+  }
+
+  inline constexpr bool operator>(monostate, monostate) noexcept {
+    return false;
+  }
+
+  inline constexpr bool operator<=(monostate, monostate) noexcept {
+    return true;
+  }
+
+  inline constexpr bool operator>=(monostate, monostate) noexcept {
+    return true;
+  }
+
+  inline constexpr bool operator==(monostate, monostate) noexcept {
+    return true;
+  }
+
+  inline constexpr bool operator!=(monostate, monostate) noexcept {
+    return false;
+  }
+
+#ifdef MPARK_CPP14_CONSTEXPR
+  namespace detail {
+
+    inline constexpr bool all(std::initializer_list<bool> bs) {
+      for (bool b : bs) {
+        if (!b) {
+          return false;
+        }
+      }
+      return true;
+    }
+
+  }  // namespace detail
+
+  template <typename Visitor, typename... Vs>
+  inline constexpr decltype(auto) visit(Visitor &&visitor, Vs &&... vs) {
+    return (detail::all({!vs.valueless_by_exception()...})
+                ? (void)0
+                : throw_bad_variant_access()),
+           detail::visitation::variant::visit_value(
+               lib::forward<Visitor>(visitor), lib::forward<Vs>(vs)...);
+  }
+#else
+  namespace detail {
+
+    template <std::size_t N>
+    inline constexpr bool all_impl(const lib::array<bool, N> &bs,
+                                   std::size_t idx) {
+      return idx >= N || (bs[idx] && all_impl(bs, idx + 1));
+    }
+
+    template <std::size_t N>
+    inline constexpr bool all(const lib::array<bool, N> &bs) {
+      return all_impl(bs, 0);
+    }
+
+  }  // namespace detail
+
+  template <typename Visitor, typename... Vs>
+  inline constexpr DECLTYPE_AUTO visit(Visitor &&visitor, Vs &&... vs)
+    DECLTYPE_AUTO_RETURN(
+        (detail::all(
+             lib::array<bool, sizeof...(Vs)>{{!vs.valueless_by_exception()...}})
+             ? (void)0
+             : throw_bad_variant_access()),
+        detail::visitation::variant::visit_value(lib::forward<Visitor>(visitor),
+                                                 lib::forward<Vs>(vs)...))
+#endif
+
+  template <typename... Ts>
+  inline auto swap(variant<Ts...> &lhs,
+                   variant<Ts...> &rhs) noexcept(noexcept(lhs.swap(rhs)))
+      -> decltype(lhs.swap(rhs)) {
+    lhs.swap(rhs);
+  }
+
+  namespace detail {
+
+    template <typename T, typename...>
+    using enabled_type = T;
+
+    namespace hash {
+
+      template <typename H, typename K>
+      constexpr bool meets_requirements() noexcept {
+        return std::is_copy_constructible<H>::value &&
+               std::is_move_constructible<H>::value &&
+               lib::is_invocable_r<std::size_t, H, const K &>::value;
+      }
+
+      template <typename K>
+      constexpr bool is_enabled() noexcept {
+        using H = std::hash<K>;
+        return meets_requirements<H, K>() &&
+               std::is_default_constructible<H>::value &&
+               std::is_copy_assignable<H>::value &&
+               std::is_move_assignable<H>::value;
+      }
+
+    }  // namespace hash
+
+  }  // namespace detail
+
+#undef AUTO
+#undef AUTO_RETURN
+
+#undef AUTO_REFREF
+#undef AUTO_REFREF_RETURN
+
+#undef DECLTYPE_AUTO
+#undef DECLTYPE_AUTO_RETURN
+
+}  // namespace mpark
+
+namespace std {
+
+  template <typename... Ts>
+  struct hash<mpark::detail::enabled_type<
+      mpark::variant<Ts...>,
+      mpark::lib::enable_if_t<mpark::lib::all<mpark::detail::hash::is_enabled<
+          mpark::lib::remove_const_t<Ts>>()...>::value>>> {
+    using argument_type = mpark::variant<Ts...>;
+    using result_type = std::size_t;
+
+    inline result_type operator()(const argument_type &v) const {
+      using mpark::detail::visitation::variant;
+      std::size_t result =
+          v.valueless_by_exception()
+              ? 299792458  // Random value chosen by the universe upon creation
+              : variant::visit_alt(
+#ifdef MPARK_GENERIC_LAMBDAS
+                    [](const auto &alt) {
+                      using alt_type = mpark::lib::decay_t<decltype(alt)>;
+                      using value_type = mpark::lib::remove_const_t<
+                          typename alt_type::value_type>;
+                      return hash<value_type>{}(alt.value);
+                    }
+#else
+                    hasher{}
+#endif
+                    ,
+                    v);
+      return hash_combine(result, hash<std::size_t>{}(v.index()));
+    }
+
+    private:
+#ifndef MPARK_GENERIC_LAMBDAS
+    struct hasher {
+      template <typename Alt>
+      inline std::size_t operator()(const Alt &alt) const {
+        using alt_type = mpark::lib::decay_t<Alt>;
+        using value_type =
+            mpark::lib::remove_const_t<typename alt_type::value_type>;
+        return hash<value_type>{}(alt.value);
+      }
+    };
+#endif
+
+    static std::size_t hash_combine(std::size_t lhs, std::size_t rhs) {
+      return lhs ^= rhs + 0x9e3779b9 + (lhs << 6) + (lhs >> 2);
+    }
+  };
+
+  template <>
+  struct hash<mpark::monostate> {
+    using argument_type = mpark::monostate;
+    using result_type = std::size_t;
+
+    inline result_type operator()(const argument_type &) const noexcept {
+      return 66740831;  // return a fundamentally attractive random value.
+    }
+  };
+
+}  // namespace std
+
+#endif  // MPARK_VARIANT_HPP
diff --git a/headers/enduro2d/base/_base.hpp b/headers/enduro2d/base/_base.hpp
index 3cf6ab72..7ac33b3a 100644
--- a/headers/enduro2d/base/_base.hpp
+++ b/headers/enduro2d/base/_base.hpp
@@ -26,7 +26,6 @@
 #include <bitset>
 #include <string>
 #include <vector>
-#include <variant>
 #include <unordered_set>
 #include <unordered_map>
 
diff --git a/headers/enduro2d/base/types.hpp b/headers/enduro2d/base/types.hpp
index 8c779d54..9e2ffd59 100644
--- a/headers/enduro2d/base/types.hpp
+++ b/headers/enduro2d/base/types.hpp
@@ -8,6 +8,7 @@
 
 #include "_base.hpp"
 
+#include <3rdparty/variant/variant.hpp>
 #include <3rdparty/flat.hpp/flat_set.hpp>
 #include <3rdparty/flat.hpp/flat_map.hpp>
 
@@ -37,21 +38,21 @@ namespace e2d
     using vector = std::vector<Value, Allocator>;
 
     template < typename Key
-             , typename Comp = std::less<>
+             , typename Compare = std::less<>
              , typename Allocator = std::allocator<Key> >
-    using set = std::set<Key, Comp, Allocator>;
+    using set = std::set<Key, Compare, Allocator>;
 
     template < typename Key
              , typename Value
-             , typename Comp = std::less<>
+             , typename Compare = std::less<>
              , typename Allocator = std::allocator<std::pair<const Key, Value>> >
-    using map = std::map<Key, Value, Comp, Allocator>;
+    using map = std::map<Key, Value, Compare, Allocator>;
 
-    template < typename Value
-             , typename Hash = std::hash<Value>
+    template < typename Key
+             , typename Hash = std::hash<Key>
              , typename Pred = std::equal_to<>
-             , typename Allocator = std::allocator<Value> >
-    using hash_set = std::unordered_set<Value, Hash, Pred, Allocator>;
+             , typename Allocator = std::allocator<Key> >
+    using hash_set = std::unordered_set<Key, Hash, Pred, Allocator>;
 
     template < typename Key
              , typename Value
@@ -83,3 +84,8 @@ namespace e2d
              , typename Container = vector<std::pair<Key, Value>> >
     using flat_map = flat_hpp::flat_map<Key, Value, Compare, Container>;
 }
+
+namespace e2d::stdex
+{
+    using namespace mpark;
+}
diff --git a/headers/enduro2d/core/render.hpp b/headers/enduro2d/core/render.hpp
index f883556c..b07df836 100644
--- a/headers/enduro2d/core/render.hpp
+++ b/headers/enduro2d/core/render.hpp
@@ -609,7 +609,7 @@ namespace e2d
             sampler_mag_filter mag_filter_ = sampler_mag_filter::linear;
         };
 
-        using property_value = std::variant<
+        using property_value = stdex::variant<
             i32, f32,
             v2i, v3i, v4i,
             v2f, v3f, v4f,
@@ -862,7 +862,7 @@ namespace e2d
             bool scissoring_ = false;
         };
 
-        using command_value = std::variant<
+        using command_value = stdex::variant<
             zero_command,
             draw_command,
             clear_command,
diff --git a/headers/enduro2d/core/render.inl b/headers/enduro2d/core/render.inl
index 795ba456..d17854ca 100644
--- a/headers/enduro2d/core/render.inl
+++ b/headers/enduro2d/core/render.inl
@@ -195,7 +195,7 @@ namespace e2d
     const T* render::property_block::property(str_hash name) const noexcept {
         const property_value* prop = properties_.find(name);
         return prop
-            ? std::get_if<T>(prop)
+            ? stdex::get_if<T>(prop)
             : nullptr;
     }
 
diff --git a/modules/catch2 b/modules/catch2
index 97602b24..00347f1e 160000
--- a/modules/catch2
+++ b/modules/catch2
@@ -1 +1 @@
-Subproject commit 97602b248b4380eac28de4dd8961c3f1acf42471
+Subproject commit 00347f1e79260e76d5072cca5b3636868397dda5
diff --git a/modules/flat.hpp b/modules/flat.hpp
index a592e0ed..6bf7a026 160000
--- a/modules/flat.hpp
+++ b/modules/flat.hpp
@@ -1 +1 @@
-Subproject commit a592e0ed7cac5f879cf2428d1f44088a2b7424c6
+Subproject commit 6bf7a02644cdb02e9984795df500be7335cf96c7
diff --git a/modules/imgui b/modules/imgui
index 958d75c0..70a4be07 160000
--- a/modules/imgui
+++ b/modules/imgui
@@ -1 +1 @@
-Subproject commit 958d75c00ac83a98b6423e523d9b222bc94a0224
+Subproject commit 70a4be07df0c9802a5d987c802adabb35b175306
diff --git a/modules/variant b/modules/variant
new file mode 160000
index 00000000..99ef8fb1
--- /dev/null
+++ b/modules/variant
@@ -0,0 +1 @@
+Subproject commit 99ef8fb19f5ea5f229587da3dd425a7d24c4fd80
diff --git a/scripts/update_modules.sh b/scripts/update_modules.sh
index 9a4651a8..1a1f7338 100755
--- a/scripts/update_modules.sh
+++ b/scripts/update_modules.sh
@@ -67,3 +67,6 @@ cp -fv $MODULES_DIR/stb/stb_truetype.h $SOURCES_RDPARTY_DIR/stb/stb_truetype.h
 
 mkdir -p $SOURCES_RDPARTY_DIR/utfcpp
 cp -rfv $MODULES_DIR/utfcpp/source/. $SOURCES_RDPARTY_DIR/utfcpp/
+
+mkdir -p $HEADERS_RDPARTY_DIR/variant
+cp -rfv $MODULES_DIR/variant/include/mpark/. $HEADERS_RDPARTY_DIR/variant/
diff --git a/sources/3rdparty/imgui/imgui_demo.cpp b/sources/3rdparty/imgui/imgui_demo.cpp
index 9b56e429..11422252 100644
--- a/sources/3rdparty/imgui/imgui_demo.cpp
+++ b/sources/3rdparty/imgui/imgui_demo.cpp
@@ -1235,8 +1235,8 @@ static void ShowDemoWindowWidgets()
         ImGui::Text("HSV encoded colors");
         ImGui::SameLine(); HelpMarker("By default, colors are given to ColorEdit and ColorPicker in RGB, but ImGuiColorEditFlags_InputHSV allows you to store colors as HSV and pass them to ColorEdit and ColorPicker as HSV. This comes with the added benefit that you can manipulate hue values with the picker even when saturation or value are zero.");
         ImGui::Text("Color widget with InputHSV:");
-        ImGui::ColorEdit4("HSV shown as HSV##1", (float*)&color_stored_as_hsv, ImGuiColorEditFlags_DisplayRGB | ImGuiColorEditFlags_InputHSV | ImGuiColorEditFlags_Float);
-        ImGui::ColorEdit4("HSV shown as RGB##1", (float*)&color_stored_as_hsv, ImGuiColorEditFlags_DisplayHSV | ImGuiColorEditFlags_InputHSV | ImGuiColorEditFlags_Float);
+        ImGui::ColorEdit4("HSV shown as RGB##1", (float*)&color_stored_as_hsv, ImGuiColorEditFlags_DisplayRGB | ImGuiColorEditFlags_InputHSV | ImGuiColorEditFlags_Float);
+        ImGui::ColorEdit4("HSV shown as HSV##1", (float*)&color_stored_as_hsv, ImGuiColorEditFlags_DisplayHSV | ImGuiColorEditFlags_InputHSV | ImGuiColorEditFlags_Float);
         ImGui::DragFloat4("Raw HSV values", (float*)&color_stored_as_hsv, 0.01f, 0.0f, 1.0f);
 
         ImGui::TreePop();
diff --git a/sources/3rdparty/imgui/imgui_widgets.cpp b/sources/3rdparty/imgui/imgui_widgets.cpp
index cbf7ff72..e5dc8c2b 100644
--- a/sources/3rdparty/imgui/imgui_widgets.cpp
+++ b/sources/3rdparty/imgui/imgui_widgets.cpp
@@ -4258,7 +4258,7 @@ bool ImGui::ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flag
                 Spacing();
             }
             ImGuiColorEditFlags picker_flags_to_forward = ImGuiColorEditFlags__DataTypeMask | ImGuiColorEditFlags__PickerMask | ImGuiColorEditFlags__InputMask | ImGuiColorEditFlags_HDR | ImGuiColorEditFlags_NoAlpha | ImGuiColorEditFlags_AlphaBar;
-            ImGuiColorEditFlags picker_flags = (flags_untouched & picker_flags_to_forward) | ImGuiColorEditFlags_DisplayHSV | ImGuiColorEditFlags_NoLabel | ImGuiColorEditFlags_AlphaPreviewHalf;
+            ImGuiColorEditFlags picker_flags = (flags_untouched & picker_flags_to_forward) | ImGuiColorEditFlags__DisplayMask | ImGuiColorEditFlags_NoLabel | ImGuiColorEditFlags_AlphaPreviewHalf;
             SetNextItemWidth(square_sz * 12.0f); // Use 256 + bar sizes?
             value_changed |= ColorPicker4("##picker", col, picker_flags, &g.ColorPickerRef.x);
             EndPopup();
diff --git a/sources/enduro2d/core/render.cpp b/sources/enduro2d/core/render.cpp
index ac16a817..88b48466 100644
--- a/sources/enduro2d/core/render.cpp
+++ b/sources/enduro2d/core/render.cpp
@@ -1141,7 +1141,7 @@ namespace e2d
     render& render::execute(const command_value& command) {
         E2D_ASSERT(is_in_main_thread());
         E2D_ASSERT(!command.valueless_by_exception());
-        std::visit(command_value_visitor(*this), command);
+        stdex::visit(command_value_visitor(*this), command);
         return *this;
     }
 }
diff --git a/sources/enduro2d/core/render_impl/render_opengl.cpp b/sources/enduro2d/core/render_impl/render_opengl.cpp
index f01f0b39..3a4e4715 100644
--- a/sources/enduro2d/core/render_impl/render_opengl.cpp
+++ b/sources/enduro2d/core/render_impl/render_opengl.cpp
@@ -114,7 +114,7 @@ namespace
         pb.foreach_by_properties([&debug, &ps](str_hash name, const render::property_value& value) noexcept {
             ps->state().with_uniform_location(name, [&debug, &value](const uniform_info& ui) noexcept {
                 E2D_ASSERT(!value.valueless_by_exception());
-                std::visit(property_block_value_visitor(debug, ui), value);
+                stdex::visit(property_block_value_visitor(debug, ui), value);
             });
         });
         GLint unit = 0;
diff --git a/untests/catch/catch.hpp b/untests/catch/catch.hpp
index df14c357..02302b8d 100644
--- a/untests/catch/catch.hpp
+++ b/untests/catch/catch.hpp
@@ -1,6 +1,6 @@
 /*
- *  Catch v2.7.2
- *  Generated: 2019-04-22 23:13:14.687465
+ *  Catch v2.8.0
+ *  Generated: 2019-05-26 21:29:22.235281
  *  ----------------------------------------------------------
  *  This file has been merged from multiple headers. Please don't edit it directly
  *  Copyright (c) 2019 Two Blue Cubes Ltd. All rights reserved.
@@ -14,8 +14,8 @@
 
 
 #define CATCH_VERSION_MAJOR 2
-#define CATCH_VERSION_MINOR 7
-#define CATCH_VERSION_PATCH 2
+#define CATCH_VERSION_MINOR 8
+#define CATCH_VERSION_PATCH 0
 
 #ifdef __clang__
 #    pragma clang system_header
@@ -157,6 +157,12 @@ namespace Catch {
 #       define CATCH_INTERNAL_UNSUPPRESS_UNUSED_WARNINGS \
             _Pragma( "clang diagnostic pop" )
 
+#       define CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS \
+            _Pragma( "clang diagnostic push" ) \
+            _Pragma( "clang diagnostic ignored \"-Wgnu-zero-variadic-macro-arguments\"" )
+#       define CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS \
+            _Pragma( "clang diagnostic pop" )
+
 #endif // __clang__
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -364,6 +370,10 @@ namespace Catch {
 #   define CATCH_INTERNAL_SUPPRESS_UNUSED_WARNINGS
 #   define CATCH_INTERNAL_UNSUPPRESS_UNUSED_WARNINGS
 #endif
+#if !defined(CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS)
+#   define CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS
+#   define CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS
+#endif
 
 #if defined(CATCH_CONFIG_DISABLE_EXCEPTIONS)
 #define CATCH_TRY if ((true))
@@ -722,23 +732,152 @@ struct is_unique<T0, T1, Rest...> : std::integral_constant
 #define INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS(param) (INTERNAL_CATCH_STRINGIZE(INTERNAL_CATCH_REMOVE_PARENS(param)) + 1)
 #endif
 
+#define INTERNAL_CATCH_MAKE_NAMESPACE2(...) ns_##__VA_ARGS__
+#define INTERNAL_CATCH_MAKE_NAMESPACE(name) INTERNAL_CATCH_MAKE_NAMESPACE2(name)
+
 #define INTERNAL_CATCH_REMOVE_PARENS(...) INTERNAL_CATCH_EXPAND1(INTERNAL_CATCH_DEF __VA_ARGS__)
 
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME2(Name, ...) INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME3(Name, __VA_ARGS__)
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME3(Name,...) Name " - " #__VA_ARGS__
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME(Name,...) INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME2(Name, INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__))
+#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>())
+#define INTERNAL_CATCH_MAKE_TYPE_LIST(...) INTERNAL_CATCH_MAKE_TYPE_LIST2(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__))
 #else
-// MSVC is adding extra space and needs more calls to properly remove ()
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME3(Name,...) Name " -" #__VA_ARGS__
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME1(Name, ...) INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME2(Name, __VA_ARGS__)
-#define INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME(Name, ...) INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME1(Name, INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__)))
+#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) INTERNAL_CATCH_EXPAND_VARGS(decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>()))
+#define INTERNAL_CATCH_MAKE_TYPE_LIST(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_MAKE_TYPE_LIST2(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__)))
 #endif
 
-#define INTERNAL_CATCH_MAKE_TYPE_LIST(types) Catch::TypeList<INTERNAL_CATCH_REMOVE_PARENS(types)>
+#define INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(...)\
+    CATCH_REC_LIST(INTERNAL_CATCH_MAKE_TYPE_LIST,__VA_ARGS__)
 
-#define INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(types)\
-    CATCH_REC_LIST(INTERNAL_CATCH_MAKE_TYPE_LIST,INTERNAL_CATCH_REMOVE_PARENS(types))
+#define INTERNAL_CATCH_REMOVE_PARENS_1_ARG(_0) INTERNAL_CATCH_REMOVE_PARENS(_0)
+#define INTERNAL_CATCH_REMOVE_PARENS_2_ARG(_0, _1) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_1_ARG(_1)
+#define INTERNAL_CATCH_REMOVE_PARENS_3_ARG(_0, _1, _2) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_2_ARG(_1, _2)
+#define INTERNAL_CATCH_REMOVE_PARENS_4_ARG(_0, _1, _2, _3) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_3_ARG(_1, _2, _3)
+#define INTERNAL_CATCH_REMOVE_PARENS_5_ARG(_0, _1, _2, _3, _4) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_4_ARG(_1, _2, _3, _4)
+#define INTERNAL_CATCH_REMOVE_PARENS_6_ARG(_0, _1, _2, _3, _4, _5) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_5_ARG(_1, _2, _3, _4, _5)
+#define INTERNAL_CATCH_REMOVE_PARENS_7_ARG(_0, _1, _2, _3, _4, _5, _6) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_6_ARG(_1, _2, _4, _5, _6)
+#define INTERNAL_CATCH_REMOVE_PARENS_8_ARG(_0, _1, _2, _3, _4, _5, _6, _7) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_7_ARG(_1, _2, _3, _4, _5, _6, _7)
+#define INTERNAL_CATCH_REMOVE_PARENS_9_ARG(_0, _1, _2, _3, _4, _5, _6, _7, _8) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_8_ARG(_1, _2, _3, _4, _5, _6, _7, _8)
+#define INTERNAL_CATCH_REMOVE_PARENS_10_ARG(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_9_ARG(_1, _2, _3, _4, _5, _6, _7, _8, _9)
+#define INTERNAL_CATCH_REMOVE_PARENS_11_ARG(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) INTERNAL_CATCH_REMOVE_PARENS(_0), INTERNAL_CATCH_REMOVE_PARENS_10_ARG(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10)
+
+#define INTERNAL_CATCH_VA_NARGS_IMPL(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N
+
+#define INTERNAL_CATCH_TYPE_GEN\
+    template<typename...> struct TypeList {};\
+    template<typename...Ts>\
+    constexpr auto get_wrapper() noexcept -> TypeList<Ts...> { return {}; }\
+    \
+    template<template<typename...> class L1, typename...E1, template<typename...> class L2, typename...E2> \
+    constexpr auto append(L1<E1...>, L2<E2...>) noexcept -> L1<E1...,E2...> { return {}; }\
+    template< template<typename...> class L1, typename...E1, template<typename...> class L2, typename...E2, typename...Rest>\
+    constexpr auto append(L1<E1...>, L2<E2...>, Rest...) noexcept -> decltype(append(L1<E1...,E2...>{}, Rest{}...)) { return {}; }\
+    \
+    template< template<typename...> class Container, template<typename...> class List, typename...elems>\
+    constexpr auto rewrap(List<elems...>) noexcept -> TypeList<Container<elems...>> { return {}; }\
+    template< template<typename...> class Container, template<typename...> class List, class...Elems, typename...Elements>\
+    constexpr auto rewrap(List<Elems...>,Elements...) noexcept -> decltype(append(TypeList<Container<Elems...>>{}, rewrap<Container>(Elements{}...))) { return {}; }\
+    \
+    template<template <typename...> class Final, template< typename...> class...Containers, typename...Types>\
+    constexpr auto create(TypeList<Types...>) noexcept -> decltype(append(Final<>{}, rewrap<Containers>(Types{}...)...)) { return {}; }
+
+#define INTERNAL_CATCH_NTTP_1(signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)> struct Nttp{};\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    constexpr auto get_wrapper() noexcept -> Nttp<__VA_ARGS__> { return {}; } \
+    \
+    template< template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class Container, template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class List, INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    constexpr auto rewrap(List<__VA_ARGS__>) noexcept -> TypeList<Container<__VA_ARGS__>> { return {}; }\
+    template< template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class Container, template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class List, INTERNAL_CATCH_REMOVE_PARENS(signature), typename...Elements>\
+    constexpr auto rewrap(List<__VA_ARGS__>,Elements...elems) noexcept -> decltype(append(TypeList<Container<__VA_ARGS__>>{}, rewrap<Container>(elems...))) { return {}; }\
+    template<template <typename...> class Final, template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class...Containers, typename...Types>\
+    constexpr auto create(TypeList<Types...>) noexcept -> decltype(append(Final<>{}, rewrap<Containers>(Types{}...)...)) { return {}; }
+
+#define INTERNAL_CATCH_DECLARE_SIG_TEST0(TestName)
+#define INTERNAL_CATCH_DECLARE_SIG_TEST1(TestName, signature)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    static void TestName()
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_X(TestName, signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    static void TestName()
+
+#define INTERNAL_CATCH_DEFINE_SIG_TEST0(TestName)
+#define INTERNAL_CATCH_DEFINE_SIG_TEST1(TestName, signature)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    static void TestName()
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_X(TestName, signature,...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    static void TestName()
+
+#define INTERNAL_CATCH_NTTP_REGISTER0(TestFunc, signature)\
+    template<typename Type>\
+    void reg_test(TypeList<Type>, Catch::NameAndTags nameAndTags)\
+    {\
+        Catch::AutoReg( Catch::makeTestInvoker(&TestFunc<Type>), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), nameAndTags);\
+    }
+
+#define INTERNAL_CATCH_NTTP_REGISTER(TestFunc, signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    void reg_test(Nttp<__VA_ARGS__>, Catch::NameAndTags nameAndTags)\
+    {\
+        Catch::AutoReg( Catch::makeTestInvoker(&TestFunc<__VA_ARGS__>), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), nameAndTags);\
+    }
+
+#define INTERNAL_CATCH_NTTP_REGISTER_METHOD0(TestName, signature, ...)\
+    template<typename Type>\
+    void reg_test(TypeList<Type>, Catch::StringRef className, Catch::NameAndTags nameAndTags)\
+    {\
+        Catch::AutoReg( Catch::makeTestInvoker(&TestName<Type>::test), CATCH_INTERNAL_LINEINFO, className, nameAndTags);\
+    }
+
+#define INTERNAL_CATCH_NTTP_REGISTER_METHOD(TestName, signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
+    void reg_test(Nttp<__VA_ARGS__>, Catch::StringRef className, Catch::NameAndTags nameAndTags)\
+    {\
+        Catch::AutoReg( Catch::makeTestInvoker(&TestName<__VA_ARGS__>::test), CATCH_INTERNAL_LINEINFO, className, nameAndTags);\
+    }
+
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD0(TestName, ClassName)
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD1(TestName, ClassName, signature)\
+    template<typename TestType> \
+    struct TestName : INTERNAL_CATCH_REMOVE_PARENS(ClassName)<TestType> { \
+        void test();\
+    }
+
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X(TestName, ClassName, signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)> \
+    struct TestName : INTERNAL_CATCH_REMOVE_PARENS(ClassName)<__VA_ARGS__> { \
+        void test();\
+    }
+
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD0(TestName)
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD1(TestName, signature)\
+    template<typename TestType> \
+    void INTERNAL_CATCH_MAKE_NAMESPACE(TestName)::TestName<TestType>::test()
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X(TestName, signature, ...)\
+    template<INTERNAL_CATCH_REMOVE_PARENS(signature)> \
+    void INTERNAL_CATCH_MAKE_NAMESPACE(TestName)::TestName<__VA_ARGS__>::test()
+
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+#define INTERNAL_CATCH_NTTP_0
+#define INTERNAL_CATCH_NTTP_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__),INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_0)
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD1, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD0)(TestName, __VA_ARGS__)
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD1, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD0)(TestName, ClassName, __VA_ARGS__)
+#define INTERNAL_CATCH_NTTP_REG_METHOD_GEN(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD0, INTERNAL_CATCH_NTTP_REGISTER_METHOD0)(TestName, __VA_ARGS__)
+#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__)
+#define INTERNAL_CATCH_DEFINE_SIG_TEST(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST1, INTERNAL_CATCH_DEFINE_SIG_TEST0)(TestName, __VA_ARGS__)
+#define INTERNAL_CATCH_DECLARE_SIG_TEST(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST1, INTERNAL_CATCH_DECLARE_SIG_TEST0)(TestName, __VA_ARGS__)
+#define INTERNAL_CATCH_REMOVE_PARENS_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_REMOVE_PARENS_11_ARG,INTERNAL_CATCH_REMOVE_PARENS_10_ARG,INTERNAL_CATCH_REMOVE_PARENS_9_ARG,INTERNAL_CATCH_REMOVE_PARENS_8_ARG,INTERNAL_CATCH_REMOVE_PARENS_7_ARG,INTERNAL_CATCH_REMOVE_PARENS_6_ARG,INTERNAL_CATCH_REMOVE_PARENS_5_ARG,INTERNAL_CATCH_REMOVE_PARENS_4_ARG,INTERNAL_CATCH_REMOVE_PARENS_3_ARG,INTERNAL_CATCH_REMOVE_PARENS_2_ARG,INTERNAL_CATCH_REMOVE_PARENS_1_ARG)(__VA_ARGS__)
+#else
+#define INTERNAL_CATCH_NTTP_0(signature)
+#define INTERNAL_CATCH_NTTP_GEN(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1,INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_0)( __VA_ARGS__))
+#define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD1, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD0)(TestName, __VA_ARGS__))
+#define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD1, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD0)(TestName, ClassName, __VA_ARGS__))
+#define INTERNAL_CATCH_NTTP_REG_METHOD_GEN(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD0, INTERNAL_CATCH_NTTP_REGISTER_METHOD0)(TestName, __VA_ARGS__))
+#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__))
+#define INTERNAL_CATCH_DEFINE_SIG_TEST(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST1, INTERNAL_CATCH_DEFINE_SIG_TEST0)(TestName, __VA_ARGS__))
+#define INTERNAL_CATCH_DECLARE_SIG_TEST(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST1, INTERNAL_CATCH_DECLARE_SIG_TEST0)(TestName, __VA_ARGS__))
+#define INTERNAL_CATCH_REMOVE_PARENS_GEN(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_REMOVE_PARENS_11_ARG,INTERNAL_CATCH_REMOVE_PARENS_10_ARG,INTERNAL_CATCH_REMOVE_PARENS_9_ARG,INTERNAL_CATCH_REMOVE_PARENS_8_ARG,INTERNAL_CATCH_REMOVE_PARENS_7_ARG,INTERNAL_CATCH_REMOVE_PARENS_6_ARG,INTERNAL_CATCH_REMOVE_PARENS_5_ARG,INTERNAL_CATCH_REMOVE_PARENS_4_ARG,INTERNAL_CATCH_REMOVE_PARENS_3_ARG,INTERNAL_CATCH_REMOVE_PARENS_2_ARG,INTERNAL_CATCH_REMOVE_PARENS_1_ARG)(__VA_ARGS__))
+#endif
 
 // end catch_preprocessor.hpp
 // start catch_meta.hpp
@@ -747,66 +886,8 @@ struct is_unique<T0, T1, Rest...> : std::integral_constant
 #include <type_traits>
 
 namespace Catch {
-template< typename... >
-struct TypeList {};
-
-template< typename... >
-struct append;
-
-template< template<typename...> class L1
-    , typename...E1
-    , template<typename...> class L2
-    , typename...E2
->
-struct append< L1<E1...>, L2<E2...> > {
-    using type = L1<E1..., E2...>;
-};
-
-template< template<typename...> class L1
-    , typename...E1
-    , template<typename...> class L2
-    , typename...E2
-    , typename...Rest
->
-struct append< L1<E1...>, L2<E2...>, Rest...> {
-    using type = typename append< L1<E1..., E2...>, Rest... >::type;
-};
-
-template< template<typename...> class
-    , typename...
->
-struct rewrap;
-
-template< template<typename...> class Container
-    , template<typename...> class List
-    , typename...elems
->
-struct rewrap<Container, List<elems...>> {
-    using type = TypeList< Container< elems... > >;
-};
-
-template< template<typename...> class Container
-    , template<typename...> class List
-    , class...Elems
-    , typename...Elements>
-    struct rewrap<Container, List<Elems...>, Elements...> {
-    using type = typename append<TypeList<Container<Elems...>>, typename rewrap<Container, Elements...>::type>::type;
-};
-
-template< template<typename...> class...Containers >
-struct combine {
-    template< typename...Types >
-    struct with_types {
-        template< template <typename...> class Final >
-        struct into {
-            using type = typename append<Final<>, typename rewrap<Containers, Types...>::type...>::type;
-        };
-    };
-};
-
-template<typename T>
-struct always_false : std::false_type {};
-
+    template<typename T>
+    struct always_false : std::false_type {};
 } // namespace Catch
 
 // end catch_meta.hpp
@@ -854,18 +935,47 @@ struct AutoReg : NonCopyable {
             };                            \
         }                                 \
         void TestName::test()
-    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION( TestName, ... )  \
-        template<typename TestType>                                             \
-        static void TestName()
-    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION( TestName, ClassName, ... )    \
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION_2( TestName, TestFunc, Name, Tags, Signature, ... )  \
+        INTERNAL_CATCH_DEFINE_SIG_TEST(TestFunc, INTERNAL_CATCH_REMOVE_PARENS(Signature))
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION_2( TestNameClass, TestName, ClassName, Name, Tags, Signature, ... )    \
         namespace{                                                                                  \
-            template<typename TestType>                                                             \
-            struct TestName : INTERNAL_CATCH_REMOVE_PARENS(ClassName <TestType>) {     \
-                void test();                                                                        \
-            };                                                                                      \
+            namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestName) {                                      \
+            INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, INTERNAL_CATCH_REMOVE_PARENS(Signature));\
         }                                                                                           \
-        template<typename TestType>                                                                 \
-        void TestName::test()
+        }                                                                                           \
+        INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, INTERNAL_CATCH_REMOVE_PARENS(Signature))
+
+    #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(Name, Tags, ...) \
+            INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename TestType, __VA_ARGS__ )
+    #else
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(Name, Tags, ...) \
+            INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename TestType, __VA_ARGS__ ) )
+    #endif
+
+    #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(Name, Tags, Signature, ...) \
+            INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__ )
+    #else
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(Name, Tags, Signature, ...) \
+            INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__ ) )
+    #endif
+
+    #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION( ClassName, Name, Tags,... ) \
+            INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, typename T, __VA_ARGS__ )
+    #else
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION( ClassName, Name, Tags,... ) \
+            INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, typename T, __VA_ARGS__ ) )
+    #endif
+
+    #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION( ClassName, Name, Tags, Signature, ... ) \
+            INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, Signature, __VA_ARGS__ )
+    #else
+        #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION( ClassName, Name, Tags, Signature, ... ) \
+            INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, Signature, __VA_ARGS__ ) )
+    #endif
 #endif
 
     ///////////////////////////////////////////////////////////////////////////////
@@ -905,54 +1015,61 @@ struct AutoReg : NonCopyable {
         CATCH_INTERNAL_UNSUPPRESS_GLOBALS_WARNINGS
 
     ///////////////////////////////////////////////////////////////////////////////
-    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_2(TestName, TestFunc, Name, Tags, ... )\
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_2(TestName, TestFunc, Name, Tags, Signature, ... )\
         CATCH_INTERNAL_SUPPRESS_GLOBALS_WARNINGS \
-        template<typename TestType> \
-        static void TestFunc();\
+        CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS \
+        INTERNAL_CATCH_DECLARE_SIG_TEST(TestFunc, INTERNAL_CATCH_REMOVE_PARENS(Signature));\
         namespace {\
+        namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestName){\
+            INTERNAL_CATCH_TYPE_GEN\
+            INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
+            INTERNAL_CATCH_NTTP_REG_GEN(TestFunc,INTERNAL_CATCH_REMOVE_PARENS(Signature))\
             template<typename...Types> \
             struct TestName{\
-                template<typename...Ts> \
-                TestName(Ts...names){\
-                    CATCH_INTERNAL_CHECK_UNIQUE_TYPES(CATCH_REC_LIST(INTERNAL_CATCH_REMOVE_PARENS, __VA_ARGS__)) \
+                TestName(){\
+                    int index = 0;                                    \
+                    constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, __VA_ARGS__)};\
                     using expander = int[];\
-                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestFunc<Types> ), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), Catch::NameAndTags{ names, Tags } ), 0)... };/* NOLINT */ \
+                    (void)expander{(reg_test(Types{}, Catch::NameAndTags{ Name " - " + std::string(tmpl_types[index]), Tags } ), index++, 0)... };/* NOLINT */ \
                 }\
             };\
-            INTERNAL_CATCH_TEMPLATE_REGISTRY_INITIATE(TestName, Name, __VA_ARGS__) \
+            static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
+            TestName<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(__VA_ARGS__)>();\
+            return 0;\
+        }();\
+        }\
         }\
         CATCH_INTERNAL_UNSUPPRESS_GLOBALS_WARNINGS \
-        template<typename TestType> \
-        static void TestFunc()
-
-#if defined(CATCH_CPP17_OR_GREATER)
-#define CATCH_INTERNAL_CHECK_UNIQUE_TYPES(...) static_assert(Catch::is_unique<__VA_ARGS__>,"Duplicate type detected in declaration of template test case");
-#else
-#define CATCH_INTERNAL_CHECK_UNIQUE_TYPES(...) static_assert(Catch::is_unique<__VA_ARGS__>::value,"Duplicate type detected in declaration of template test case");
-#endif
+        CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS \
+        INTERNAL_CATCH_DEFINE_SIG_TEST(TestFunc,INTERNAL_CATCH_REMOVE_PARENS(Signature))
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
     #define INTERNAL_CATCH_TEMPLATE_TEST_CASE(Name, Tags, ...) \
-        INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, __VA_ARGS__ )
+        INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename TestType, __VA_ARGS__ )
 #else
     #define INTERNAL_CATCH_TEMPLATE_TEST_CASE(Name, Tags, ...) \
-        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, __VA_ARGS__ ) )
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename TestType, __VA_ARGS__ ) )
 #endif
 
-    #define INTERNAL_CATCH_TEMPLATE_REGISTRY_INITIATE(TestName, Name, ...)\
-        static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
-            TestName<CATCH_REC_LIST(INTERNAL_CATCH_REMOVE_PARENS, __VA_ARGS__)>(CATCH_REC_LIST_UD(INTERNAL_CATCH_TEMPLATE_UNIQUE_NAME,Name, __VA_ARGS__));\
-            return 0;\
-        }();
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG(Name, Tags, Signature, ...) \
+        INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__ )
+#else
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG(Name, Tags, Signature, ...) \
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__ ) )
+#endif
 
-    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2(TestName, TestFuncName, Name, Tags, TmplTypes, TypesList) \
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2(TestName, TestFuncName, Name, Tags, Signature, TmplTypes, TypesList) \
         CATCH_INTERNAL_SUPPRESS_GLOBALS_WARNINGS                      \
+        CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS                \
         template<typename TestType> static void TestFuncName();       \
-        namespace {                                                   \
+        namespace {\
+        namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestName) {                                     \
+            INTERNAL_CATCH_TYPE_GEN                                                  \
+            INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))         \
             template<typename... Types>                               \
             struct TestName {                                         \
-                TestName() {                                          \
-                    CATCH_INTERNAL_CHECK_UNIQUE_TYPES(Types...)       \
+                void reg_tests() {                                          \
                     int index = 0;                                    \
                     using expander = int[];                           \
                     constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes))};\
@@ -962,65 +1079,92 @@ struct AutoReg : NonCopyable {
                 }                                                     \
             };                                                        \
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){ \
-                using TestInit = Catch::combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)> \
-                            ::with_types<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(TypesList)>::into<TestName>::type; \
-                TestInit();                                           \
+                using TestInit = decltype(create<TestName, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>(TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>{})); \
+                TestInit t;                                           \
+                t.reg_tests();                                        \
                 return 0;                                             \
             }();                                                      \
         }                                                             \
+        }                                                             \
         CATCH_INTERNAL_UNSUPPRESS_GLOBALS_WARNINGS                    \
+        CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS              \
         template<typename TestType>                                   \
         static void TestFuncName()
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
     #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE(Name, Tags, ...)\
-        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ),Name,Tags,__VA_ARGS__)
+        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename T,__VA_ARGS__)
 #else
     #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE(Name, Tags, ...)\
-        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, __VA_ARGS__ ) )
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, typename T, __VA_ARGS__ ) )
 #endif
 
-    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( TestNameClass, TestName, ClassName, Name, Tags, ... ) \
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG(Name, Tags, Signature, ...)\
+        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__)
+#else
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG(Name, Tags, Signature, ...)\
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), Name, Tags, Signature, __VA_ARGS__ ) )
+#endif
+
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( TestNameClass, TestName, ClassName, Name, Tags, Signature, ... ) \
         CATCH_INTERNAL_SUPPRESS_GLOBALS_WARNINGS \
-        namespace{ \
-            template<typename TestType> \
-            struct TestName : INTERNAL_CATCH_REMOVE_PARENS(ClassName <TestType>) { \
-                void test();\
-            };\
+        CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS \
+        namespace {\
+        namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestName){ \
+            INTERNAL_CATCH_TYPE_GEN\
+            INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
+            INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, INTERNAL_CATCH_REMOVE_PARENS(Signature));\
+            INTERNAL_CATCH_NTTP_REG_METHOD_GEN(TestName, INTERNAL_CATCH_REMOVE_PARENS(Signature))\
             template<typename...Types> \
             struct TestNameClass{\
-                template<typename...Ts> \
-                TestNameClass(Ts...names){\
-                    CATCH_INTERNAL_CHECK_UNIQUE_TYPES(CATCH_REC_LIST(INTERNAL_CATCH_REMOVE_PARENS, __VA_ARGS__)) \
+                TestNameClass(){\
+                    int index = 0;                                    \
+                    constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, __VA_ARGS__)};\
                     using expander = int[];\
-                    (void)expander{(Catch::AutoReg( Catch::makeTestInvoker( &TestName<Types>::test ), CATCH_INTERNAL_LINEINFO, #ClassName, Catch::NameAndTags{ names, Tags } ), 0)... };/* NOLINT */ \
+                    (void)expander{(reg_test(Types{}, #ClassName, Catch::NameAndTags{ Name " - " + std::string(tmpl_types[index]), Tags } ), index++, 0)... };/* NOLINT */ \
                 }\
             };\
-            INTERNAL_CATCH_TEMPLATE_REGISTRY_INITIATE(TestNameClass, Name, __VA_ARGS__)\
+            static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
+                TestNameClass<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(__VA_ARGS__)>();\
+                return 0;\
+        }();\
+        }\
         }\
         CATCH_INTERNAL_UNSUPPRESS_GLOBALS_WARNINGS\
-        template<typename TestType> \
-        void TestName<TestType>::test()
+        CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS\
+        INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, INTERNAL_CATCH_REMOVE_PARENS(Signature))
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
     #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( ClassName, Name, Tags,... ) \
-        INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, __VA_ARGS__ )
+        INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, typename T, __VA_ARGS__ )
 #else
     #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( ClassName, Name, Tags,... ) \
-        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, __VA_ARGS__ ) )
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, typename T, __VA_ARGS__ ) )
 #endif
 
-    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2(TestNameClass, TestName, ClassName, Name, Tags, TmplTypes, TypesList)\
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( ClassName, Name, Tags, Signature, ... ) \
+        INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, Signature, __VA_ARGS__ )
+#else
+    #define INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( ClassName, Name, Tags, Signature, ... ) \
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____C_L_A_S_S____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) , ClassName, Name, Tags, Signature, __VA_ARGS__ ) )
+#endif
+
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2(TestNameClass, TestName, ClassName, Name, Tags, Signature, TmplTypes, TypesList)\
         CATCH_INTERNAL_SUPPRESS_GLOBALS_WARNINGS \
+        CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS \
         template<typename TestType> \
             struct TestName : INTERNAL_CATCH_REMOVE_PARENS(ClassName <TestType>) { \
                 void test();\
             };\
         namespace {\
+        namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestNameClass) {\
+            INTERNAL_CATCH_TYPE_GEN                  \
+            INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
             template<typename...Types>\
             struct TestNameClass{\
-                TestNameClass(){\
-                    CATCH_INTERNAL_CHECK_UNIQUE_TYPES(Types...)\
+                void reg_tests(){\
                     int index = 0;\
                     using expander = int[];\
                     constexpr char const* tmpl_types[] = {CATCH_REC_LIST(INTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes))};\
@@ -1030,22 +1174,32 @@ struct AutoReg : NonCopyable {
                 }\
             };\
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
-                using TestInit = Catch::combine<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>\
-                            ::with_types<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(TypesList)>::into<TestNameClass>::type;\
-                TestInit();\
+                using TestInit = decltype(create<TestNameClass, INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>(TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>{}));\
+                TestInit t;\
+                t.reg_tests();\
                 return 0;\
             }(); \
         }\
+        }\
         CATCH_INTERNAL_UNSUPPRESS_GLOBALS_WARNINGS \
+        CATCH_INTERNAL_UNSUPPRESS_ZERO_VARIADIC_WARNINGS \
         template<typename TestType> \
         void TestName<TestType>::test()
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
     #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( ClassName, Name, Tags, ... )\
-        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, __VA_ARGS__ )
+        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, typename T, __VA_ARGS__ )
 #else
     #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( ClassName, Name, Tags, ... )\
-        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, __VA_ARGS__ ) )
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, typename T,__VA_ARGS__ ) )
+#endif
+
+#ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( ClassName, Name, Tags, Signature, ... )\
+        INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, Signature, __VA_ARGS__ )
+#else
+    #define INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( ClassName, Name, Tags, Signature, ... )\
+        INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_2( INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____ ), ClassName, Name, Tags, Signature,__VA_ARGS__ ) )
 #endif
 
 // end catch_test_registry.h
@@ -1166,6 +1320,41 @@ namespace Catch {
 }
 
 // end catch_stream.h
+// start catch_interfaces_enum_values_registry.h
+
+#include <vector>
+
+namespace Catch {
+
+    namespace Detail {
+        struct EnumInfo {
+            StringRef m_name;
+            std::vector<std::pair<int, std::string>> m_values;
+
+            ~EnumInfo();
+
+            StringRef lookup( int value ) const;
+        };
+    } // namespace Detail
+
+    struct IMutableEnumValuesRegistry {
+        virtual ~IMutableEnumValuesRegistry();
+
+        virtual Detail::EnumInfo const& registerEnum( StringRef enumName, StringRef allEnums, std::vector<int> const& values ) = 0;
+
+        template<typename E>
+        Detail::EnumInfo const& registerEnum( StringRef enumName, StringRef allEnums, std::initializer_list<E> values ) {
+            std::vector<int> intValues;
+            intValues.reserve( values.size() );
+            for( auto enumValue : values )
+                intValues.push_back( static_cast<int>( enumValue ) );
+            return registerEnum( enumName, allEnums, intValues );
+        }
+    };
+
+} // Catch
+
+// end catch_interfaces_enum_values_registry.h
 
 #ifdef CATCH_CONFIG_CPP17_STRING_VIEW
 #include <string_view>
@@ -1451,10 +1640,13 @@ namespace Catch {
     template<>
     struct StringMaker<float> {
         static std::string convert(float value);
+        static int precision;
     };
+
     template<>
     struct StringMaker<double> {
         static std::string convert(double value);
+        static int precision;
     };
 
     template <typename T>
@@ -1827,6 +2019,18 @@ struct ratio_string<std::milli> {
 }
 #endif // CATCH_CONFIG_ENABLE_CHRONO_STRINGMAKER
 
+#define INTERNAL_CATCH_REGISTER_ENUM( enumName, ... ) \
+namespace Catch { \
+    template<> struct StringMaker<enumName> { \
+        static std::string convert( enumName value ) { \
+            static const auto& enumInfo = ::Catch::getMutableRegistryHub().getMutableEnumValuesRegistry().registerEnum( #enumName, #__VA_ARGS__, { __VA_ARGS__ } ); \
+            return enumInfo.lookup( static_cast<int>( value ) ); \
+        } \
+    }; \
+}
+
+#define CATCH_REGISTER_ENUM( enumName, ... ) INTERNAL_CATCH_REGISTER_ENUM( enumName, __VA_ARGS__ )
+
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif
@@ -2624,6 +2828,8 @@ namespace Catch {
     struct IReporterRegistry;
     struct IReporterFactory;
     struct ITagAliasRegistry;
+    struct IMutableEnumValuesRegistry;
+
     class StartupExceptionRegistry;
 
     using IReporterFactoryPtr = std::shared_ptr<IReporterFactory>;
@@ -2634,7 +2840,6 @@ namespace Catch {
         virtual IReporterRegistry const& getReporterRegistry() const = 0;
         virtual ITestCaseRegistry const& getTestCaseRegistry() const = 0;
         virtual ITagAliasRegistry const& getTagAliasRegistry() const = 0;
-
         virtual IExceptionTranslatorRegistry const& getExceptionTranslatorRegistry() const = 0;
 
         virtual StartupExceptionRegistry const& getStartupExceptionRegistry() const = 0;
@@ -2648,6 +2853,7 @@ namespace Catch {
         virtual void registerTranslator( const IExceptionTranslator* translator ) = 0;
         virtual void registerTagAlias( std::string const& alias, std::string const& tag, SourceLineInfo const& lineInfo ) = 0;
         virtual void registerStartupException() noexcept = 0;
+        virtual IMutableEnumValuesRegistry& getMutableEnumValuesRegistry() = 0;
     };
 
     IRegistryHub const& getRegistryHub();
@@ -2854,6 +3060,7 @@ struct StringMaker<Catch::Detail::Approx> {
 
 #include <string>
 #include <iosfwd>
+#include <vector>
 
 namespace Catch {
 
@@ -2865,6 +3072,9 @@ namespace Catch {
     void toLowerInPlace( std::string& s );
     std::string toLower( std::string const& s );
     std::string trim( std::string const& str );
+
+    // !!! Be aware, returns refs into original string - make sure original string outlives them
+    std::vector<StringRef> splitStringRef( StringRef str, char delimiter );
     bool replaceInPlace( std::string& str, std::string const& replaceThis, std::string const& withThis );
 
     struct pluralise {
@@ -8552,6 +8762,88 @@ namespace Catch {
 #endif
 } // namespace Catch;
 // end catch_enforce.cpp
+// start catch_enum_values_registry.cpp
+// start catch_enum_values_registry.h
+
+#include <vector>
+#include <memory>
+
+namespace Catch {
+
+    namespace Detail {
+
+        std::unique_ptr<EnumInfo> makeEnumInfo( StringRef enumName, StringRef allValueNames, std::vector<int> const& values );
+
+        class EnumValuesRegistry : public IMutableEnumValuesRegistry {
+
+            std::vector<std::unique_ptr<EnumInfo>> m_enumInfos;
+
+            EnumInfo const& registerEnum( StringRef enumName, StringRef allEnums, std::vector<int> const& values) override;
+        };
+
+        std::vector<std::string> parseEnums( StringRef enums );
+
+    } // Detail
+
+} // Catch
+
+// end catch_enum_values_registry.h
+
+#include <map>
+#include <cassert>
+
+namespace Catch {
+
+    IMutableEnumValuesRegistry::~IMutableEnumValuesRegistry() {}
+
+    namespace Detail {
+
+        std::vector<std::string> parseEnums( StringRef enums ) {
+            auto enumValues = splitStringRef( enums, ',' );
+            std::vector<std::string> parsed;
+            parsed.reserve( enumValues.size() );
+            for( auto const& enumValue : enumValues ) {
+                auto identifiers = splitStringRef( enumValue, ':' );
+                parsed.push_back( Catch::trim( identifiers.back() ) );
+            }
+            return parsed;
+        }
+
+        EnumInfo::~EnumInfo() {}
+
+        StringRef EnumInfo::lookup( int value ) const {
+            for( auto const& valueToName : m_values ) {
+                if( valueToName.first == value )
+                    return valueToName.second;
+            }
+            return "{** unexpected enum value **}";
+        }
+
+        std::unique_ptr<EnumInfo> makeEnumInfo( StringRef enumName, StringRef allValueNames, std::vector<int> const& values ) {
+            std::unique_ptr<EnumInfo> enumInfo( new EnumInfo );
+            enumInfo->m_name = enumName;
+            enumInfo->m_values.reserve( values.size() );
+
+            const auto valueNames = Catch::Detail::parseEnums( allValueNames );
+            assert( valueNames.size() == values.size() );
+            std::size_t i = 0;
+            for( auto value : values )
+                enumInfo->m_values.push_back({ value, valueNames[i++] });
+
+            return enumInfo;
+        }
+
+        EnumInfo const& EnumValuesRegistry::registerEnum( StringRef enumName, StringRef allValueNames, std::vector<int> const& values ) {
+            auto enumInfo = makeEnumInfo( enumName, allValueNames, values );
+            EnumInfo* raw = enumInfo.get();
+            m_enumInfos.push_back( std::move( enumInfo ) );
+            return *raw;
+        }
+
+    } // Detail
+} // Catch
+
+// end catch_enum_values_registry.cpp
 // start catch_errno_guard.cpp
 
 #include <cerrno>
@@ -9626,6 +9918,15 @@ namespace Catch {
             }
             return names.substr(start, end - start + 1);
         };
+        auto skipq = [&] (size_t start, char quote) {
+            for (auto i = start + 1; i < names.size() ; ++i) {
+                if (names[i] == quote)
+                    return i;
+                if (names[i] == '\\')
+                    ++i;
+            }
+            CATCH_INTERNAL_ERROR("CAPTURE parsing encountered unmatched quote");
+        };
 
         size_t start = 0;
         std::stack<char> openings;
@@ -9646,6 +9947,10 @@ namespace Catch {
 //           case '>':
                 openings.pop();
                 break;
+            case '"':
+            case '\'':
+                pos = skipq(pos, c);
+                break;
             case ',':
                 if (start != pos && openings.size() == 0) {
                     m_messages.emplace_back(macroName, lineInfo, resultType);
@@ -10184,6 +10489,9 @@ namespace Catch {
             void registerStartupException() noexcept override {
                 m_exceptionRegistry.add(std::current_exception());
             }
+            IMutableEnumValuesRegistry& getMutableEnumValuesRegistry() override {
+                return m_enumValuesRegistry;
+            }
 
         private:
             TestRegistry m_testCaseRegistry;
@@ -10191,6 +10499,7 @@ namespace Catch {
             ExceptionTranslatorRegistry m_exceptionTranslatorRegistry;
             TagAliasRegistry m_tagAliasRegistry;
             StartupExceptionRegistry m_exceptionRegistry;
+            Detail::EnumValuesRegistry m_enumValuesRegistry;
         };
     }
 
@@ -10988,6 +11297,9 @@ namespace Catch {
 #if !defined(CATCH_CONFIG_DISABLE_EXCEPTIONS)
         const auto& exceptions = getRegistryHub().getStartupExceptionRegistry().getExceptions();
         if ( !exceptions.empty() ) {
+            config();
+            getCurrentMutableContext().setConfig(m_config);
+
             m_startupExceptions = true;
             Colour colourGuard( Colour::Red );
             Catch::cerr() << "Errors occurred during startup!" << '\n';
@@ -11366,6 +11678,7 @@ namespace Catch {
 #include <ostream>
 #include <cstring>
 #include <cctype>
+#include <vector>
 
 namespace Catch {
 
@@ -11420,6 +11733,21 @@ namespace Catch {
         return replaced;
     }
 
+    std::vector<StringRef> splitStringRef( StringRef str, char delimiter ) {
+        std::vector<StringRef> subStrings;
+        std::size_t start = 0;
+        for(std::size_t pos = 0; pos < str.size(); ++pos ) {
+            if( str[pos] == delimiter ) {
+                if( pos - start > 1 )
+                    subStrings.push_back( str.substr( start, pos-start ) );
+                start = pos+1;
+            }
+        }
+        if( start < str.size() )
+            subStrings.push_back( str.substr( start, str.size()-start ) );
+        return subStrings;
+    }
+
     pluralise::pluralise( std::size_t count, std::string const& label )
     :   m_count( count ),
         m_label( label )
@@ -11467,9 +11795,11 @@ namespace Catch {
     }
 
     auto StringRef::c_str() const -> char const* {
-        if( isSubstring() )
-           const_cast<StringRef*>( this )->takeOwnership();
-        return m_start;
+        if( !isSubstring() )
+            return m_start;
+
+        const_cast<StringRef *>( this )->takeOwnership();
+        return m_data;
     }
     auto StringRef::currentData() const noexcept -> char const* {
         return m_start;
@@ -11487,7 +11817,6 @@ namespace Catch {
             m_data = new char[m_size+1];
             memcpy( m_data, m_start, m_size );
             m_data[m_size] = '\0';
-            m_start = m_data;
         }
     }
     auto StringRef::substr( size_type start, size_type size ) const noexcept -> StringRef {
@@ -12577,11 +12906,16 @@ std::string StringMaker<std::nullptr_t>::convert(std::nullptr_t) {
     return "nullptr";
 }
 
+int StringMaker<float>::precision = 5;
+
 std::string StringMaker<float>::convert(float value) {
-    return fpToString(value, 5) + 'f';
+    return fpToString(value, precision) + 'f';
 }
+
+int StringMaker<double>::precision = 10;
+
 std::string StringMaker<double>::convert(double value) {
-    return fpToString(value, 10);
+    return fpToString(value, precision);
 }
 
 std::string ratio_string<std::atto>::symbol() { return "a"; }
@@ -12699,7 +13033,7 @@ namespace Catch {
     }
 
     Version const& libraryVersion() {
-        static Version version( 2, 7, 2, "", 0 );
+        static Version version( 2, 8, 0, "", 0 );
         return version;
     }
 
@@ -14689,6 +15023,7 @@ int main (int argc, char * const argv[]) {
 #endif // CATCH_CONFIG_DISABLE_MATCHERS
 
 #define CATCH_INFO( msg ) INTERNAL_CATCH_INFO( "CATCH_INFO", msg )
+#define CATCH_UNSCOPED_INFO( msg ) INTERNAL_CATCH_UNSCOPED_INFO( "CATCH_UNSCOPED_INFO", msg )
 #define CATCH_WARN( msg ) INTERNAL_CATCH_MSG( "CATCH_WARN", Catch::ResultWas::Warning, Catch::ResultDisposition::ContinueOnFailure, msg )
 #define CATCH_CAPTURE( ... ) INTERNAL_CATCH_CAPTURE( INTERNAL_CATCH_UNIQUE_NAME(capturer), "CATCH_CAPTURE",__VA_ARGS__ )
 
@@ -14706,14 +15041,22 @@ int main (int argc, char * const argv[]) {
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
 #define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define CATCH_TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG( __VA_ARGS__ )
 #define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE( __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( __VA_ARGS__ )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ )
 #else
 #define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ ) )
+#define CATCH_TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG( __VA_ARGS__ ) )
 #define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ ) )
+#define CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ ) )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE( __VA_ARGS__ ) )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( __VA_ARGS__ ) )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, __VA_ARGS__ ) )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ ) )
 #endif
 
 #if !defined(CATCH_CONFIG_RUNTIME_STATIC_REQUIRE)
@@ -14786,14 +15129,22 @@ int main (int argc, char * const argv[]) {
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
 #define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG( __VA_ARGS__ )
 #define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ )
 #define TEMPLATE_PRODUCT_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE( __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( __VA_ARGS__ )
 #define TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ )
 #else
 #define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ ) )
+#define TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG( __VA_ARGS__ ) )
 #define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ ) )
+#define TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ ) )
 #define TEMPLATE_PRODUCT_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE( __VA_ARGS__ ) )
+#define TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( __VA_ARGS__ ) )
 #define TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, __VA_ARGS__ ) )
+#define TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, __VA_ARGS__ ) )
 #endif
 
 #if !defined(CATCH_CONFIG_RUNTIME_STATIC_REQUIRE)
@@ -14858,9 +15209,10 @@ using Catch::Detail::Approx;
 #define CATCH_REQUIRE_THAT( arg, matcher ) (void)(0)
 #endif // CATCH_CONFIG_DISABLE_MATCHERS
 
-#define CATCH_INFO( msg )    (void)(0)
-#define CATCH_WARN( msg )    (void)(0)
-#define CATCH_CAPTURE( msg ) (void)(0)
+#define CATCH_INFO( msg )          (void)(0)
+#define CATCH_UNSCOPED_INFO( msg ) (void)(0)
+#define CATCH_WARN( msg )          (void)(0)
+#define CATCH_CAPTURE( msg )       (void)(0)
 
 #define CATCH_TEST_CASE( ... ) INTERNAL_CATCH_TESTCASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_S_T____ ))
 #define CATCH_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TESTCASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_S_T____ ))
@@ -14875,15 +15227,23 @@ using Catch::Detail::Approx;
 #define CATCH_ANON_TEST_CASE() INTERNAL_CATCH_TESTCASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_S_T____ ))
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
-#define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) )
-#define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), className )
+#define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(__VA_ARGS__)
+#define CATCH_TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(__VA_ARGS__)
+#define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(className, __VA_ARGS__)
+#define CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION(className, __VA_ARGS__ )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE( ... ) CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
 #else
-#define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) ) )
-#define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), className ) )
+#define CATCH_TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(__VA_ARGS__) )
+#define CATCH_TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(__VA_ARGS__) )
+#define CATCH_TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(className, __VA_ARGS__ ) )
+#define CATCH_TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION(className, __VA_ARGS__ ) )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE( ... ) CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
 #define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define CATCH_TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) CATCH_TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
 #endif
 
 // "BDD-style" convenience wrappers
@@ -14934,6 +15294,7 @@ using Catch::Detail::Approx;
 #endif // CATCH_CONFIG_DISABLE_MATCHERS
 
 #define INFO( msg ) (void)(0)
+#define UNSCOPED_INFO( msg ) (void)(0)
 #define WARN( msg ) (void)(0)
 #define CAPTURE( msg ) (void)(0)
 
@@ -14949,15 +15310,23 @@ using Catch::Detail::Approx;
 #define ANON_TEST_CASE() INTERNAL_CATCH_TESTCASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_S_T____ ))
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
-#define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) )
-#define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), className )
+#define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(__VA_ARGS__)
+#define TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(__VA_ARGS__)
+#define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(className, __VA_ARGS__)
+#define TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION(className, __VA_ARGS__ )
 #define TEMPLATE_PRODUCT_TEST_CASE( ... ) TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) TEMPLATE_TEST_CASE( __VA_ARGS__ )
 #define TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
 #else
-#define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ) ) )
-#define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(INTERNAL_CATCH_UNIQUE_NAME( ____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____ ), className ) )
+#define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_NO_REGISTRATION(__VA_ARGS__) )
+#define TEMPLATE_TEST_CASE_SIG( ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_SIG_NO_REGISTRATION(__VA_ARGS__) )
+#define TEMPLATE_TEST_CASE_METHOD( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_NO_REGISTRATION(className, __VA_ARGS__ ) )
+#define TEMPLATE_TEST_CASE_METHOD_SIG( className, ... ) INTERNAL_CATCH_EXPAND_VARGS( INTERNAL_CATCH_TEMPLATE_TEST_CASE_METHOD_SIG_NO_REGISTRATION(className, __VA_ARGS__ ) )
 #define TEMPLATE_PRODUCT_TEST_CASE( ... ) TEMPLATE_TEST_CASE( __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_SIG( ... ) TEMPLATE_TEST_CASE( __VA_ARGS__ )
 #define TEMPLATE_PRODUCT_TEST_CASE_METHOD( className, ... ) TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
+#define TEMPLATE_PRODUCT_TEST_CASE_METHOD_SIG( className, ... ) TEMPLATE_TEST_CASE_METHOD( className, __VA_ARGS__ )
 #endif
 
 #define STATIC_REQUIRE( ... )       (void)(0)
diff --git a/untests/sources/untests_core/render.cpp b/untests/sources/untests_core/render.cpp
index 7257171b..a685e444 100644
--- a/untests/sources/untests_core/render.cpp
+++ b/untests/sources/untests_core/render.cpp
@@ -40,16 +40,16 @@ TEST_CASE("render"){
             REQUIRE_FALSE(pb1.property<i32>("f"));
             REQUIRE(pb1.property("i"));
             REQUIRE(pb1.property("f"));
-            REQUIRE(std::get<i32>(*pb1.property("i")) == 42);
-            REQUIRE(std::get<f32>(*pb1.property("f")) == 1.f);
+            REQUIRE(stdex::get<i32>(*pb1.property("i")) == 42);
+            REQUIRE(stdex::get<f32>(*pb1.property("f")) == 1.f);
             {
                 f32 acc = 0.f;
                 pb1.foreach_by_properties([&acc](str_hash n, const render::property_value& v){
                     if ( n == make_hash("f") ) {
-                        acc += std::get<f32>(v);
+                        acc += stdex::get<f32>(v);
                     }
                     if ( n == make_hash("i") ) {
-                        acc += std::get<i32>(v);
+                        acc += stdex::get<i32>(v);
                     }
                 });
                 REQUIRE(math::approximately(acc, 43.f));
diff --git a/untests/sources/untests_high/library.cpp b/untests/sources/untests_high/library.cpp
index 1f5ab22a..a4f2f678 100644
--- a/untests/sources/untests_high/library.cpp
+++ b/untests/sources/untests_high/library.cpp
@@ -258,7 +258,7 @@ TEST_CASE("library"){
                 const auto* property = material_res->content().properties().property("i");
                 REQUIRE(property);
                 REQUIRE(property->index() == 0);
-                REQUIRE(std::get<i32>(*property) == 42);
+                REQUIRE(stdex::get<i32>(*property) == 42);
             }
             REQUIRE(material_res->content().pass_count() == 1);
             const auto& pass = material_res->content().pass(0);
@@ -266,31 +266,31 @@ TEST_CASE("library"){
                 const auto* property = pass.properties().property("f");
                 REQUIRE(property);
                 REQUIRE(property->index() == 1);
-                REQUIRE(math::approximately(std::get<f32>(*property), 4.2f));
+                REQUIRE(math::approximately(stdex::get<f32>(*property), 4.2f));
             }
             {
                 const auto* property = pass.properties().property("v1");
                 REQUIRE(property);
                 REQUIRE(property->index() == 2);
-                REQUIRE(std::get<v2i>(*property) == v2i(1,2));
+                REQUIRE(stdex::get<v2i>(*property) == v2i(1,2));
             }
             {
                 const auto* property = pass.properties().property("v2");
                 REQUIRE(property);
                 REQUIRE(property->index() == 6);
-                REQUIRE(std::get<v3f>(*property) == v3f(3.f));
+                REQUIRE(stdex::get<v3f>(*property) == v3f(3.f));
             }
             {
                 const auto* property = pass.properties().property("v3");
                 REQUIRE(property);
                 REQUIRE(property->index() == 4);
-                REQUIRE(std::get<v4i>(*property) == v4i(1,2,3,4));
+                REQUIRE(stdex::get<v4i>(*property) == v4i(1,2,3,4));
             }
             {
                 const auto* property = pass.properties().property("m1");
                 REQUIRE(property);
                 REQUIRE(property->index() == 8);
-                REQUIRE(std::get<m2f>(*property) == m2f(1,2,3,4));
+                REQUIRE(stdex::get<m2f>(*property) == m2f(1,2,3,4));
 
                 const auto* property2 = pass.properties().property("m4");
                 REQUIRE(property2);
@@ -300,7 +300,7 @@ TEST_CASE("library"){
                 const auto* property = pass.properties().property("m2");
                 REQUIRE(property);
                 REQUIRE(property->index() == 9);
-                REQUIRE(std::get<m3f>(*property) == m3f(1,2,3,4,5,6,7,8,9));
+                REQUIRE(stdex::get<m3f>(*property) == m3f(1,2,3,4,5,6,7,8,9));
 
                 const auto* property2 = pass.properties().property("m5");
                 REQUIRE(property2);
@@ -310,7 +310,7 @@ TEST_CASE("library"){
                 const auto* property = pass.properties().property("m3");
                 REQUIRE(property);
                 REQUIRE(property->index() == 10);
-                REQUIRE(std::get<m4f>(*property) == m4f(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16));
+                REQUIRE(stdex::get<m4f>(*property) == m4f(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16));
 
                 const auto* property2 = pass.properties().property("m6");
                 REQUIRE(property2);