On 15 August 2016 at 14:55, Ville Voutilainen
<[email protected]> wrote:
>>> + template<typename _Tp>
>>> + struct __is_in_place
>>> + : public
>>> __is_in_place_impl<std::remove_cv_t<std::remove_reference_t<_Tp>>>
>>
>>
>> Any reason not to use decay_t here? In all the cases where decay is
>> different to stripping references and cv-qualifiers the result will be
>> false either way.
>>
>> I wouldn't have bothered with the std:: qualification either, but it's
>> fine as it is.
>
>
> The reason for not using decay and for the qualification is that the
> trait is closely
> related to its copy-paste origin, which is __is_optional. ;) I should
> also add a test
> for the case where in_place is attempted to pass through the
> ValueType&& parameter,
> aka a case where a type is not default-constructible but is
> constructible from in_place,
> and in_place-construction is used.
Argh, the trait shouldn't either decay or remove_reference, and the
remove_const is superfluous.
These tags are references to functions, decaying them will cause bad mojo.
Now that I actually test that the in_place avoidance in the perfect
forwarder works, it's fixed.
Tested on Linux-x64.
2016-08-15 Ville Voutilainen <[email protected]>
Implement LWG 2744 and LWG 2754.
* include/std/any (any(ValueType&&)): Constrain with __is_in_place_type.
(any(in_place_type_t<_ValueType>, _Args&&...)): Use _Decay.
(any(in_place_type_t<_ValueType>, initializer_list<_Up>, _Args&&...)):
Likewise.
(emplace(_Args&&...)): Likewise.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* include/std/utility: (__is_in_place_type_impl): New.
(__is_in_place_type): Likewise.
* testsuite/20_util/any/assign/emplace.cc: Add tests for decaying
emplace.
* testsuite/20_util/any/cons/in_place.cc: Add tests for decaying
in_place constructor.
* testsuite/20_util/any/misc/any_cast_neg.cc: Adjust.
* testsuite/20_util/any/requirements.cc: Add a test for
in_place-constructing a non-default-constructible type.
diff --git a/libstdc++-v3/include/std/any b/libstdc++-v3/include/std/any
index 4add118..9160035 100644
--- a/libstdc++-v3/include/std/any
+++ b/libstdc++-v3/include/std/any
@@ -153,7 +153,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Construct with a copy of @p __value as the contained object.
template <typename _ValueType, typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
- __any_constructible_t<_Tp, _ValueType&&> = true>
+ __any_constructible_t<_Tp, _ValueType&&> = true,
+ enable_if_t<!__is_in_place_type<_ValueType>::value, bool> = true>
any(_ValueType&& __value)
: _M_manager(&_Mgr::_S_manage)
{
@@ -164,9 +165,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template <typename _ValueType, typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
enable_if_t<__and_<is_copy_constructible<_Tp>,
- __not_<
- is_constructible<_Tp,
- _ValueType&&>>>::value,
+ __not_<is_constructible<_Tp, _ValueType&&>>,
+ __not_<__is_in_place_type<_ValueType>>>::value,
bool> = false>
any(_ValueType&& __value)
: _M_manager(&_Mgr::_S_manage)
@@ -175,10 +175,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
/// Construct with an object created from @p __args as the contained
object.
- template <typename _Tp, typename... _Args,
+ template <typename _ValueType, typename... _Args,
+ typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
__any_constructible_t<_Tp, _Args&&...> = false>
- any(in_place_type_t<_Tp>, _Args&&... __args)
+ any(in_place_type_t<_ValueType>, _Args&&... __args)
: _M_manager(&_Mgr::_S_manage)
{
_Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
@@ -186,11 +187,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Construct with an object created from @p __il and @p __args as
/// the contained object.
- template <typename _Tp, typename _Up, typename... _Args,
+ template <typename _ValueType, typename _Up, typename... _Args,
+ typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
__any_constructible_t<_Tp, initializer_list<_Up>,
_Args&&...> = false>
- any(in_place_type_t<_Tp>, initializer_list<_Up> __il, _Args&&... __args)
+ any(in_place_type_t<_ValueType>,
+ initializer_list<_Up> __il, _Args&&... __args)
: _M_manager(&_Mgr::_S_manage)
{
_Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...);
@@ -248,7 +251,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
/// Emplace with an object created from @p __args as the contained object.
- template <typename _Tp, typename... _Args,
+ template <typename _ValueType, typename... _Args,
+ typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
__any_constructible_t<_Tp, _Args&&...> = false>
void emplace(_Args&&... __args)
@@ -260,7 +264,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Emplace with an object created from @p __il and @p __args as
/// the contained object.
- template <typename _Tp, typename _Up, typename... _Args,
+ template <typename _ValueType, typename _Up, typename... _Args,
+ typename _Tp = _Decay<_ValueType>,
typename _Mgr = _Manager<_Tp>,
__any_constructible_t<_Tp, initializer_list<_Up>,
_Args&&...> = false>
diff --git a/libstdc++-v3/include/std/utility b/libstdc++-v3/include/std/utility
index 0c03644..6a6659b 100644
--- a/libstdc++-v3/include/std/utility
+++ b/libstdc++-v3/include/std/utility
@@ -356,6 +356,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template <size_t _Idx>
in_place_tag in_place(__in_place_index<_Idx>*) {terminate();}
+ template<typename>
+ struct __is_in_place_type_impl : false_type
+ { };
+
+ template<typename _Tp>
+ struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
+ { };
+
+ template<typename _Tp>
+ struct __is_in_place_type
+ : public __is_in_place_type_impl<_Tp>
+ { };
+
#define __cpp_lib_as_const 201510
template<typename _Tp>
constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
@@ -363,7 +376,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
void as_const(const _Tp&&) = delete;
-#endif
+#endif // C++17
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
diff --git a/libstdc++-v3/testsuite/20_util/any/assign/emplace.cc
b/libstdc++-v3/testsuite/20_util/any/assign/emplace.cc
index 663bae2..799c5ed 100644
--- a/libstdc++-v3/testsuite/20_util/any/assign/emplace.cc
+++ b/libstdc++-v3/testsuite/20_util/any/assign/emplace.cc
@@ -59,4 +59,17 @@ int main()
combined& c2 = std::any_cast<combined&>(o5);
VERIFY(c2.v[0] == 1 && c2.v[1] == 2
&& std::get<0>(c2.t) == 3 && std::get<1>(c2.t) == 4 );
+ std::any o6;
+ o6.emplace<const int&>(i);
+ VERIFY(o6.type() == o.type());
+ std::any o7;
+ o7.emplace<void()>(nullptr);
+ std::any o8;
+ o8.emplace<void(*)()>(nullptr);
+ VERIFY(o7.type() == o8.type());
+ std::any o9;
+ o9.emplace<char(&)[42]>(nullptr);
+ std::any o10;
+ o10.emplace<char*>(nullptr);
+ VERIFY(o9.type() == o10.type());
}
diff --git a/libstdc++-v3/testsuite/20_util/any/cons/in_place.cc
b/libstdc++-v3/testsuite/20_util/any/cons/in_place.cc
index 2368b83..52f2b38 100644
--- a/libstdc++-v3/testsuite/20_util/any/cons/in_place.cc
+++ b/libstdc++-v3/testsuite/20_util/any/cons/in_place.cc
@@ -54,4 +54,12 @@ int main()
combined& c2 = std::any_cast<combined&>(o5);
VERIFY(c2.v[0] == 1 && c2.v[1] == 2
&& std::get<0>(c2.t) == 3 && std::get<1>(c2.t) == 4 );
+ std::any o6(std::in_place<int&>, i);
+ VERIFY(o6.type() == o.type());
+ std::any o7(std::in_place<void()>, nullptr);
+ std::any o8(std::in_place<void(*)()>, nullptr);
+ VERIFY(o7.type() == o8.type());
+ std::any o9(std::in_place<char(&)[42]>, nullptr);
+ std::any o10(std::in_place<char*>, nullptr);
+ VERIFY(o9.type() == o10.type());
}
diff --git a/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc
b/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc
index 32b4e76..05fdeb7 100644
--- a/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc
+++ b/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 "qualifiers" "" { target { *-*-* } } 435 }
+ any_cast<int&>(y); // { dg-error "qualifiers" "" { target { *-*-* } } 440 }
}
diff --git a/libstdc++-v3/testsuite/20_util/any/requirements.cc
b/libstdc++-v3/testsuite/20_util/any/requirements.cc
index f33cd67..7b084be 100644
--- a/libstdc++-v3/testsuite/20_util/any/requirements.cc
+++ b/libstdc++-v3/testsuite/20_util/any/requirements.cc
@@ -34,3 +34,11 @@ static_assert(!std::is_assignable<any&, const
unique_ptr<int>&>::value);
static_assert(!std::is_constructible<any&, const unique_ptr<int>&>::value);
static_assert(!std::is_assignable<any&, unique_ptr<int>&>::value);
static_assert(!std::is_constructible<any&, unique_ptr<int>&>::value);
+
+struct NoDefaultCtor
+{
+ NoDefaultCtor() = delete;
+};
+
+static_assert(!std::is_constructible<any,
+ std::in_place_type_t<NoDefaultCtor>>::value);
