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Implement LWG 2842, in_place_t check for optional::optional(U&&) should decay U. 

Implement LWG 2842, in_place_t check for optional::optional(U&&)
should decay U.
* include/std/optional (_Optional_base(in_place_t, _Args&&...)):
Constrain.
(_Optional_base(in_place_t, initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
(_Optional_base<_Tp, false>::_Optional_base(in_place_t, _Args&&...)):
Constrain.
(_Optional_base<_Tp, false>::_Optional_base(in_place_t,
initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
(optional(_Up&&)): Constrain against in_place_t.
(optional(in_place_t, _Args&&...)): Constrain.
(constexpr optional(in_place_t, initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
* testsuite/20_util/optional/cons/value_neg.cc: Add a test for
a type that is constructible from in_place.

From-SVN: r243966
This commit is contained in:
Ville Voutilainen 2016-12-29 21:19:59 +02:00 committed by Ville Voutilainen
parent f3d17b5e71
commit 2ae2d394c1
3 changed files with 42 additions and 15 deletions
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20
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,23 @@
2016-12-29 Ville Voutilainen <ville.voutilainen@gmail.com>
Implement LWG 2842, in_place_t check for optional::optional(U&&)
should decay U.
* include/std/optional (_Optional_base(in_place_t, _Args&&...)):
Constrain.
(_Optional_base(in_place_t, initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
(_Optional_base<_Tp, false>::_Optional_base(in_place_t, _Args&&...)):
Constrain.
(_Optional_base<_Tp, false>::_Optional_base(in_place_t,
initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
(optional(_Up&&)): Constrain against in_place_t.
(optional(in_place_t, _Args&&...)): Constrain.
(constexpr optional(in_place_t, initializer_list<_Up>, _Args&&...)):
Turn the int-pack constraint hack into a saner bool.
* testsuite/20_util/optional/cons/value_neg.cc: Add a test for
a type that is constructible from in_place.
2016-12-24 François Dumont <fdumont@gcc.gnu.org>
* include/ext/random.tcc: Fix usage of _OutputIteratorConcept.

32
libstdc++-v3/include/std/optional
View File

@ -128,15 +128,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: _Optional_base{} { }
// Constructors for engaged optionals.
template<typename... _Args>
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(std::forward<_Args>(__args)...), _M_engaged(true) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible<_Tp,
initializer_list<_Up>&,
_Args&&...>::value,
int>...>
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
@ -264,15 +264,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr _Optional_base(nullopt_t) noexcept
: _Optional_base{} { }
template<typename... _Args>
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t, _Args&&... __args)
: _M_payload(std::forward<_Args>(__args)...), _M_engaged(true) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible<_Tp,
initializer_list<_Up>&,
_Args&&...>::value,
int>...>
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
constexpr explicit _Optional_base(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)
@ -432,6 +432,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template <typename _Up = _Tp,
enable_if_t<__and_<
__not_<is_same<optional<_Tp>, decay_t<_Up>>>,
__not_<is_same<in_place_t, decay_t<_Up>>>,
is_constructible<_Tp, _Up&&>,
is_convertible<_Up&&, _Tp>
>::value, bool> = true>
@ -441,6 +442,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template <typename _Up = _Tp,
enable_if_t<__and_<
__not_<is_same<optional<_Tp>, decay_t<_Up>>>,
__not_<is_same<in_place_t, decay_t<_Up>>>,
is_constructible<_Tp, _Up&&>,
__not_<is_convertible<_Up&&, _Tp>>
>::value, bool> = false>
@ -499,15 +501,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
emplace(std::move(*__t));
}
template<typename... _Args>
template<typename... _Args,
enable_if_t<is_constructible_v<_Tp, _Args&&...>, bool> = false>
explicit constexpr optional(in_place_t, _Args&&... __args)
: _Base(std::in_place, std::forward<_Args>(__args)...) { }
template<typename _Up, typename... _Args,
enable_if_t<is_constructible<_Tp,
initializer_list<_Up>&,
_Args&&...>::value,
int>...>
enable_if_t<is_constructible_v<_Tp,
initializer_list<_Up>&,
_Args&&...>, bool> = false>
explicit constexpr optional(in_place_t,
initializer_list<_Up> __il,
_Args&&... __args)

5
libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
View File

@ -35,5 +35,10 @@ int main()
std::optional<X> ox2 = 42; // { dg-error "conversion" }
std::optional<std::unique_ptr<int>> oup{new int};
std::optional<std::unique_ptr<int>> oup2 = new int; // { dg-error "conversion" }
struct U { explicit U(std::in_place_t); };
std::optional<U> ou(std::in_place); // { dg-error "no matching" }
// { dg-error "no type" "" { target { *-*-* } } 438 }
// { dg-error "no type" "" { target { *-*-* } } 448 }
// { dg-error "no type" "" { target { *-*-* } } 505 }
}
}