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Enable implicit construction for aggregates using {{ ... }}

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This commit is contained in:
Peter Dimov
2021-10-02 22:07:05 +03:00
parent ce37e23491
commit 5217e58a7d
5 changed files with 223 additions and 38 deletions
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include/boost/system/result.hpp
+10 -38
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@@ -62,35 +62,10 @@ public:
{
}
// explicit, value
template<class A, class En = typename std::enable_if<
std::is_constructible<T, A>::value &&
!std::is_convertible<A, T>::value &&
!std::is_constructible<E, A>::value
>::type>
explicit constexpr result( A&& a )
noexcept( std::is_nothrow_constructible<T, A>::value )
: v_( in_place_value, std::forward<A>(a) )
{
}
// explicit, error
template<class A, class En2 = void, class En = typename std::enable_if<
std::is_constructible<E, A>::value &&
!std::is_convertible<A, E>::value &&
!std::is_constructible<T, A>::value
>::type>
explicit constexpr result( A&& a )
noexcept( std::is_nothrow_constructible<E, A>::value )
: v_( in_place_error, std::forward<A>(a) )
{
}
// implicit, value
template<class A, class En2 = void, class En3 = void, class En = typename std::enable_if<
template<class A = T, typename std::enable_if<
std::is_convertible<A, T>::value &&
!std::is_constructible<E, A>::value
>::type>
!std::is_constructible<E, A>::value, int>::type = 0>
constexpr result( A&& a )
noexcept( std::is_nothrow_constructible<T, A>::value )
: v_( in_place_value, std::forward<A>(a) )
@@ -98,35 +73,32 @@ public:
}
// implicit, error
template<class A, class En2 = void, class En3 = void, class En4 = void, class En = typename std::enable_if<
template<class A = E, class = void, typename std::enable_if<
std::is_convertible<A, E>::value &&
!std::is_constructible<T, A>::value
>::type>
!std::is_constructible<T, A>::value, int>::type = 0>
constexpr result( A&& a )
noexcept( std::is_nothrow_constructible<E, A>::value )
: v_( in_place_error, std::forward<A>(a) )
{
}
// more than one arg, value
// explicit, value
template<class... A, class En = typename std::enable_if<
std::is_constructible<T, A...>::value &&
!std::is_constructible<E, A...>::value &&
sizeof...(A) >= 2
!std::is_constructible<E, A...>::value
>::type>
constexpr result( A&&... a )
explicit constexpr result( A&&... a )
noexcept( std::is_nothrow_constructible<T, A...>::value )
: v_( in_place_value, std::forward<A>(a)... )
{
}
// more than one arg, error
// explicit, error
template<class... A, class En2 = void, class En = typename std::enable_if<
!std::is_constructible<T, A...>::value &&
std::is_constructible<E, A...>::value &&
sizeof...(A) >= 2
std::is_constructible<E, A...>::value
>::type>
constexpr result( A&&... a )
explicit constexpr result( A&&... a )
noexcept( std::is_nothrow_constructible<E, A...>::value )
: v_( in_place_error, std::forward<A>(a)... )
{