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#pragma once
#include <type_traits>
#include "mongo/stdx/type_traits.h"
namespace mongo {
namespace concept {
/**
* The Constructable trait indicates whether `T` is constructible from `Constructible`.
*
* RETURNS: true if `T{ std::declval< Constructible >() }` is a valid expression and false
* otherwise.
*/
template <typename T, typename Constructible, typename = void>
struct is_constructible : std::false_type {};
template <typename T, typename Constructible>
struct is_constructible<T,
Constructible,
stdx::void_t<decltype(T{std::declval<Constructible<T>>()})>>
: std::true_type {};
/**
* The Constructable concept models a type which can be passed to a single-argument constructor of
* `T`.
* This is not possible to describe in the type `Constructible`.
*
* The expression: `T{ std::declval< Constructible< T > >() }` should be valid.
*
* This concept is more broadly applicable than `ConvertibleTo`. `ConvertibleTo` uses implicit
* conversion, whereas `Constructible` uses direct construction.
*/
template <typename T>
struct Constructible {};
} // namespace concept
} // namespace mongo
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