Implement LWG 2769, Redundant const in the return type of any_cast(const any&).

[gcc.git] / libstdc++-v3 / include / std / any

diff --git a/libstdc++-v3/include/std/any b/libstdc++-v3/include/std/any
index 9160035006e0f8019b7ef178e3528e88ac33453a..44546e18c0f1aa83ff1bdbd9b55fcfe0e838b38b 100644 (file)
--- a/libstdc++-v3/include/std/any
+++ b/libstdc++-v3/include/std/any
@@ -108,6 +108,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     template<typename _Tp, typename _Decayed = decay_t<_Tp>>
       using _Decay = enable_if_t<!is_same<_Decayed, any>::value, _Decayed>;
 
+    /// Emplace with an object created from @p __args as the contained object.
+    template <typename _Tp, typename... _Args,
+             typename _Mgr = _Manager<_Tp>>
+      void __do_emplace(_Args&&... __args)
+      {
+       reset();
+       _M_manager = &_Mgr::_S_manage;
+        _Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
+      }
+
+    /// Emplace with an object created from @p __il and @p __args as
+    /// the contained object.
+    template <typename _Tp, typename _Up, typename... _Args,
+             typename _Mgr = _Manager<_Tp>>
+      void __do_emplace(initializer_list<_Up> __il, _Args&&... __args)
+      {
+       reset();
+       _M_manager = &_Mgr::_S_manage;
+        _Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...);
+      }
+
   public:
     // construct/destruct
 
@@ -144,17 +165,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        }
     }
 
+    template <typename _Res, typename _Tp, typename... _Args>
+    using __any_constructible =
+      enable_if<__and_<is_copy_constructible<_Tp>,
+                        is_constructible<_Tp, _Args...>>::value,
+                 _Res>;
+
     template <typename _Tp, typename... _Args>
     using __any_constructible_t =
-      enable_if_t<__and_<is_copy_constructible<_Tp>,
-                        is_constructible<_Tp, _Args...>>::value,
-                 bool>;
+      typename __any_constructible<bool, _Tp, _Args...>::type;
 
     /// 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,
-             enable_if_t<!__is_in_place_type<_ValueType>::value, bool> = true>
+             enable_if_t<!__is_in_place_type<_Tp>::value, bool> = true>
       any(_ValueType&& __value)
       : _M_manager(&_Mgr::_S_manage)
       {
@@ -166,7 +191,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
              typename _Mgr = _Manager<_Tp>,
               enable_if_t<__and_<is_copy_constructible<_Tp>,
                                 __not_<is_constructible<_Tp, _ValueType&&>>,
-                                __not_<__is_in_place_type<_ValueType>>>::value,
+                                __not_<__is_in_place_type<_Tp>>>::value,
                          bool> = false>
       any(_ValueType&& __value)
       : _M_manager(&_Mgr::_S_manage)
@@ -179,6 +204,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
              typename _Tp = _Decay<_ValueType>,
              typename _Mgr = _Manager<_Tp>,
               __any_constructible_t<_Tp, _Args&&...> = false>
+      explicit
       any(in_place_type_t<_ValueType>, _Args&&... __args)
       : _M_manager(&_Mgr::_S_manage)
       {
@@ -192,6 +218,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
              typename _Mgr = _Manager<_Tp>,
               __any_constructible_t<_Tp, initializer_list<_Up>,
                                    _Args&&...> = false>
+      explicit
       any(in_place_type_t<_ValueType>,
          initializer_list<_Up> __il, _Args&&... __args)
       : _M_manager(&_Mgr::_S_manage)
@@ -207,16 +234,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     /// Copy the state of another object.
     any& operator=(const any& __rhs)
     {
-      if (!__rhs.has_value())
-       reset();
-      else if (this != &__rhs)
-       {
-         if (has_value())
-           _M_manager(_Op_destroy, this, nullptr);
-         _Arg __arg;
-         __arg._M_any = this;
-         __rhs._M_manager(_Op_clone, &__rhs, &__arg);
-       }
+      *this = any(__rhs);
       return *this;
     }
 
@@ -231,8 +249,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        reset();
       else if (this != &__rhs)
        {
-         if (has_value())
-           _M_manager(_Op_destroy, this, nullptr);
+         reset();
          _Arg __arg;
          __arg._M_any = this;
          __rhs._M_manager(_Op_xfer, &__rhs, &__arg);
@@ -241,9 +258,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 
     /// Store a copy of @p __rhs as the contained object.
-    template<typename _ValueType,
-            typename _Tp = _Decay<_ValueType>>
-    enable_if_t<is_copy_constructible<_Tp>::value, any&>
+    template<typename _ValueType>
+      enable_if_t<is_copy_constructible<_Decay<_ValueType>>::value, any&>
       operator=(_ValueType&& __rhs)
       {
        *this = any(std::forward<_ValueType>(__rhs));
@@ -251,29 +267,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
     /// Emplace with an object created from @p __args as the contained object.
-    template <typename _ValueType, typename... _Args,
-             typename _Tp = _Decay<_ValueType>,
-             typename _Mgr = _Manager<_Tp>,
-              __any_constructible_t<_Tp, _Args&&...> = false>
-      void emplace(_Args&&... __args)
+    template <typename _ValueType, typename... _Args>
+      typename __any_constructible<void,
+                                  _Decay<_ValueType>, _Args&&...>::type
+      emplace(_Args&&... __args)
       {
-       reset();
-       _M_manager = &_Mgr::_S_manage;
-        _Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
+       __do_emplace<_Decay<_ValueType>>
+         (std::forward<_Args>(__args)...);
       }
 
     /// Emplace with an object created from @p __il and @p __args as
     /// the contained object.
-    template <typename _ValueType, typename _Up, typename... _Args,
-             typename _Tp = _Decay<_ValueType>,
-             typename _Mgr = _Manager<_Tp>,
-              __any_constructible_t<_Tp, initializer_list<_Up>,
-                                   _Args&&...> = false>
-      void emplace(initializer_list<_Up> __il, _Args&&... __args)
+    template <typename _ValueType, typename _Up, typename... _Args>
+      typename __any_constructible<void,
+                                  _Decay<_ValueType>,
+                                  initializer_list<_Up>,
+                                  _Args&&...>::type
+      emplace(initializer_list<_Up> __il, _Args&&... __args)
       {
-       reset();
-       _M_manager = &_Mgr::_S_manage;
-        _Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...);
+       __do_emplace<_Decay<_ValueType>, _Up>
+         (__il, std::forward<_Args>(__args)...);
       }
 
     // modifiers
@@ -410,16 +423,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template <typename _Tp, typename... _Args>
     any make_any(_Args&&... __args)
     {
-      return any(in_place<_Tp>, std::forward<_Args>(__args)...);
+      return any(in_place_type<_Tp>, std::forward<_Args>(__args)...);
     }
 
   /// Create an any holding a @c _Tp constructed from @c __il and @c __args.
   template <typename _Tp, typename _Up, typename... _Args>
     any make_any(initializer_list<_Up> __il, _Args&&... __args)
     {
-      return any(in_place<_Tp>, __il, std::forward<_Args>(__args)...);
+      return any(in_place_type<_Tp>, __il, std::forward<_Args>(__args)...);
     }
 
+  template <typename _Tp>
+    using _AnyCast = remove_cv_t<remove_reference_t<_Tp>>;
   /**
    * @brief Access the contained object.
    *
@@ -435,9 +450,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       static_assert(any::__is_valid_cast<_ValueType>(),
          "Template argument must be a reference or CopyConstructible type");
-      auto __p = any_cast<add_const_t<remove_reference_t<_ValueType>>>(&__any);
+      auto __p = any_cast<_AnyCast<_ValueType>>(&__any);
       if (__p)
-       return *__p;
+       return static_cast<_ValueType>(*__p);
       __throw_bad_any_cast();
     }
 
@@ -458,9 +473,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       static_assert(any::__is_valid_cast<_ValueType>(),
          "Template argument must be a reference or CopyConstructible type");
-      auto __p = any_cast<remove_reference_t<_ValueType>>(&__any);
+      auto __p = any_cast<_AnyCast<_ValueType>>(&__any);
       if (__p)
-       return *__p;
+       return static_cast<_ValueType>(*__p);
       __throw_bad_any_cast();
     }
 
@@ -472,9 +487,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       static_assert(any::__is_valid_cast<_ValueType>(),
          "Template argument must be a reference or CopyConstructible type");
-      auto __p = any_cast<remove_reference_t<_ValueType>>(&__any);
+      auto __p = any_cast<_AnyCast<_ValueType>>(&__any);
       if (__p)
-       return *__p;
+       return static_cast<_ValueType>(*__p);
       __throw_bad_any_cast();
     }
 
@@ -486,9 +501,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       static_assert(any::__is_valid_cast<_ValueType>(),
          "Template argument must be a reference or CopyConstructible type");
-      auto __p = any_cast<remove_reference_t<_ValueType>>(&__any);
+      auto __p = any_cast<_AnyCast<_ValueType>>(&__any);
       if (__p)
-       return std::move(*__p);
+       return static_cast<_ValueType>(std::move(*__p));
       __throw_bad_any_cast();
     }
   // @}
@@ -556,7 +571,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        __ptr->~_Tp();
        break;
       case _Op_xfer:
-       ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp(*__ptr);
+       ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp
+         (std::move(*const_cast<_Tp*>(__ptr)));
        __ptr->~_Tp();
        __arg->_M_any->_M_manager = __any->_M_manager;
        const_cast<any*>(__any)->_M_manager = nullptr;