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diff --git a/src/third-party/scnlib/include/scn/util/optional.h b/src/third-party/scnlib/include/scn/util/optional.h
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+// Copyright 2017 Elias Kosunen
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// This file is a part of scnlib:
+//     https://github.com/eliaskosunen/scnlib
+
+#ifndef SCN_UTIL_OPTIONAL_H
+#define SCN_UTIL_OPTIONAL_H
+
+#include "memory.h"
+
+namespace scn {
+    SCN_BEGIN_NAMESPACE
+
+    struct nullopt_t {
+    };
+    namespace {
+        static constexpr auto& nullopt = detail::static_const<nullopt_t>::value;
+    }
+
+    /**
+     * A very lackluster optional implementation.
+     * Useful when scanning non-default-constructible types, especially with
+     * <tuple_return.h>:
+     *
+     * \code{.cpp}
+     * // implement scn::scanner for optional<mytype>
+     * optional<mytype> val;
+     * scn::scan(source, "{}", val);
+     *
+     * // with tuple_return:
+     * auto [result, val] = scn::scan_tuple<optional<mytype>>(source, "{}");
+     * \endcode
+     */
+    template <typename T>
+    class optional {
+    public:
+        using value_type = T;
+        using storage_type = detail::erased_storage<T>;
+
+        optional() = default;
+        optional(nullopt_t) : m_storage{} {}
+
+        optional(value_type val) : m_storage(SCN_MOVE(val)) {}
+        optional& operator=(value_type val)
+        {
+            m_storage = storage_type(SCN_MOVE(val));
+            return *this;
+        }
+
+        SCN_NODISCARD constexpr bool has_value() const noexcept
+        {
+            return m_storage.operator bool();
+        }
+        constexpr explicit operator bool() const noexcept
+        {
+            return has_value();
+        }
+
+        SCN_CONSTEXPR14 T& get() noexcept
+        {
+            return m_storage.get();
+        }
+        SCN_CONSTEXPR14 const T& get() const noexcept
+        {
+            return m_storage.get();
+        }
+
+        SCN_CONSTEXPR14 T& operator*() noexcept
+        {
+            return get();
+        }
+        SCN_CONSTEXPR14 const T& operator*() const noexcept
+        {
+            return get();
+        }
+
+        SCN_CONSTEXPR14 T* operator->() noexcept
+        {
+            return m_storage.operator->();
+        }
+        SCN_CONSTEXPR14 const T* operator->() const noexcept
+        {
+            return m_storage.operator->();
+        }
+
+    private:
+        storage_type m_storage;
+    };
+
+    SCN_END_NAMESPACE
+}  // namespace scn
+
+#endif