chromium/third_party/skia/include/private/base/SkTypeTraits.h

// Copyright 2022 Google LLC
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

#ifndef SkTypeTraits_DEFINED
#define SkTypeTraits_DEFINED

#include <memory>
#include <type_traits>

// Trait for identifying types which are relocatable via memcpy, for container optimizations.
template<typename, typename = void>
struct sk_has_trivially_relocatable_member : std::false_type { … };

// Types can declare themselves trivially relocatable with a public
//    using sk_is_trivially_relocatable = std::true_type;
sk_has_trivially_relocatable_member<T, std::void_t<typename T::sk_is_trivially_relocatable>>;

// By default, all trivially copyable types are trivially relocatable.
template <typename T>
struct sk_is_trivially_relocatable
        : std::disjunction<std::is_trivially_copyable<T>, sk_has_trivially_relocatable_member<T>>{ … };

// Here be some dragons: while technically not guaranteed, we count on all sane unique_ptr
// implementations to be trivially relocatable.
sk_is_trivially_relocatable<std::unique_ptr<T>>;

sk_is_trivially_relocatable_v;

#endif  // SkTypeTraits_DEFINED