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Commit df990182 by Ville Voutilainen Committed by Ville Voutilainen
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Implement LWG 2857, {variant,optional,any}::emplace should return the constructed value. 

Implement LWG 2857, {variant,optional,any}::emplace should
return the constructed value.
* include/std/any (emplace(_Args&&...)): Change the return type and
return a reference to the constructed value.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* include/std/optional (emplace(_Args&&...)): Likewise.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* include/std/variant (emplace<_Tp>(_Args&&...)): Likewise.
(emplace<_Tp>(initializer_list<_Up>, _Args&&...)): Likewise.
(emplace<_Np>(_Args&&...)): Likewise.
(emplace<_Np>(initializer_list<_Up>, _Args&&...)): Likewise.
* testsuite/20_util/any/assign/emplace.cc: Add tests for
checking the return value of emplace.
* testsuite/20_util/any/misc/any_cast_neg.cc: Adjust.
* testsuite/20_util/optional/assignment/6.cc: Add tests for
checking the return value of emplace.
* testsuite/20_util/variant/run.cc: Likewise.

From-SVN: r246182
parent 8b8e41e5
Showing with 68 additions and 11 deletions
libstdc++-v3/ChangeLog
2017-03-15 Ville Voutilainen <ville.voutilainen@gmail.com>
Implement LWG 2857, {variant,optional,any}::emplace should
return the constructed value.
* include/std/any (emplace(_Args&&...)): Change the return type and
return a reference to the constructed value.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* include/std/optional (emplace(_Args&&...)): Likewise.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* include/std/variant (emplace<_Tp>(_Args&&...)): Likewise.
(emplace<_Tp>(initializer_list<_Up>, _Args&&...)): Likewise.
(emplace<_Np>(_Args&&...)): Likewise.
(emplace<_Np>(initializer_list<_Up>, _Args&&...)): Likewise.
* testsuite/20_util/any/assign/emplace.cc: Add tests for
checking the return value of emplace.
* testsuite/20_util/any/misc/any_cast_neg.cc: Adjust.
* testsuite/20_util/optional/assignment/6.cc: Add tests for
checking the return value of emplace.
* testsuite/20_util/variant/run.cc: Likewise.
2017-03-15  Xi Ruoyao  <ryxi@stu.xidian.edu.cn>
PR libstdc++/62045
......
libstdc++-v3/include/std/any
......@@ -268,18 +268,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Emplace with an object created from @p __args as the contained object.
template <typename _ValueType, typename... _Args>
typename __any_constructible<void,
typename __any_constructible<_Decay<_ValueType>&,
_Decay<_ValueType>, _Args&&...>::type
emplace(_Args&&... __args)
{
__do_emplace<_Decay<_ValueType>>
(std::forward<_Args>(__args)...);
any::_Arg __arg;
this->_M_manager(any::_Op_access, this, &__arg);
return *static_cast<_Decay<_ValueType>*>(__arg._M_obj);
}
/// Emplace with an object created from @p __il and @p __args as
/// the contained object.
template <typename _ValueType, typename _Up, typename... _Args>
typename __any_constructible<void,
typename __any_constructible<_Decay<_ValueType>&,
_Decay<_ValueType>,
initializer_list<_Up>,
_Args&&...>::type
......@@ -287,6 +290,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
__do_emplace<_Decay<_ValueType>, _Up>
(__il, std::forward<_Args>(__args)...);
any::_Arg __arg;
this->_M_manager(any::_Op_access, this, &__arg);
return *static_cast<_Decay<_ValueType>*>(__arg._M_obj);
}
// modifiers
......
libstdc++-v3/include/std/optional
......@@ -592,20 +592,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
template<typename... _Args>
enable_if_t<is_constructible<_Tp, _Args&&...>::value>
enable_if_t<is_constructible<_Tp, _Args&&...>::value, _Tp&>
emplace(_Args&&... __args)
{
this->_M_reset();
this->_M_construct(std::forward<_Args>(__args)...);
return this->_M_get();
}
template<typename _Up, typename... _Args>
enable_if_t<is_constructible<_Tp, initializer_list<_Up>&,
_Args&&...>::value>
_Args&&...>::value, _Tp&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
this->_M_reset();
this->_M_construct(__il, std::forward<_Args>(__args)...);
return this->_M_get();
}
// Destructor is implicit, implemented in _Optional_base.
......
libstdc++-v3/include/std/variant
......@@ -1007,25 +1007,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
template<typename _Tp, typename... _Args>
enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>>
enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>,
_Tp&>
emplace(_Args&&... __args)
{
this->emplace<__index_of<_Tp>>(std::forward<_Args>(__args)...);
auto& ret =
this->emplace<__index_of<_Tp>>(std::forward<_Args>(__args)...);
__glibcxx_assert(holds_alternative<_Tp>(*this));
return ret;
}
template<typename _Tp, typename _Up, typename... _Args>
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>
&& __exactly_once<_Tp>>
&& __exactly_once<_Tp>,
_Tp&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
this->emplace<__index_of<_Tp>>(__il, std::forward<_Args>(__args)...);
auto& ret =
this->emplace<__index_of<_Tp>>(__il,
std::forward<_Args>(__args)...);
__glibcxx_assert(holds_alternative<_Tp>(*this));
return ret;
}
template<size_t _Np, typename... _Args>
enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
_Args...>>
_Args...>,
variant_alternative_t<_Np, variant>&>
emplace(_Args&&... __args)
{
static_assert(_Np < sizeof...(_Types),
......@@ -1042,11 +1050,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__throw_exception_again;
}
__glibcxx_assert(index() == _Np);
return std::get<_Np>(*this);
}
template<size_t _Np, typename _Up, typename... _Args>
enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
initializer_list<_Up>&, _Args...>>
initializer_list<_Up>&, _Args...>,
variant_alternative_t<_Np, variant>&>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
static_assert(_Np < sizeof...(_Types),
......@@ -1063,6 +1073,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__throw_exception_again;
}
__glibcxx_assert(index() == _Np);
return std::get<_Np>(*this);
}
constexpr bool valueless_by_exception() const noexcept
......
libstdc++-v3/testsuite/20_util/any/assign/emplace.cc
......@@ -72,4 +72,8 @@ int main()
std::any o10;
o10.emplace<char*>(nullptr);
VERIFY(o9.type() == o10.type());
std::any o11;
VERIFY(&o11.emplace<int>(42) == &std::any_cast<int&>(o11));
VERIFY(&o11.emplace<std::vector<int>>({1,2,3}) ==
&std::any_cast<std::vector<int>&>(o11));
}
libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc
......@@ -26,5 +26,5 @@ void test01()
using std::any_cast;
const any y(1);
any_cast<int&>(y); // { dg-error "invalid static_cast" "" { target { *-*-* } } 455 }
any_cast<int&>(y); // { dg-error "invalid static_cast" "" { target { *-*-* } } 461 }
}
libstdc++-v3/testsuite/20_util/optional/assignment/6.cc
......@@ -76,6 +76,11 @@ int main()
o.emplace({ 'a' }, "");
VERIFY( o && o->state == 2 );
}
{
O o;
VERIFY(&o.emplace(0) == &*o);
VERIFY(&o.emplace({ 'a' }, "") == &*o);
}
static_assert( !std::is_constructible<O, std::initializer_list<int>, int>(), "" );
......
libstdc++-v3/testsuite/20_util/variant/run.cc
......@@ -189,6 +189,15 @@ void emplace()
try { v.emplace<1>(AlwaysThrow{}); } catch (nullptr_t) { }
VERIFY(v.valueless_by_exception());
}
VERIFY(&v.emplace<0>(1) == &std::get<0>(v));
VERIFY(&v.emplace<int>(1) == &std::get<int>(v));
VERIFY(&v.emplace<1>("a") == &std::get<1>(v));
VERIFY(&v.emplace<string>("a") == &std::get<string>(v));
{
variant<vector<int>> v;
VERIFY(&v.emplace<0>({1,2,3}) == &std::get<0>(v));
VERIFY(&v.emplace<vector<int>>({1,2,3}) == &std::get<vector<int>>(v));
}
}
void test_get()
......
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