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 54882d797e20414655ce3c1c299db73921bbcd9a..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
 
@@ -144,16 +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>
+              __any_constructible_t<_Tp, _ValueType&&> = true,
+             enable_if_t<!__is_in_place_type<_Tp>::value, bool> = true>
       any(_ValueType&& __value)
       : _M_manager(&_Mgr::_S_manage)
       {
@@ -164,9 +190,8 @@ _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<_Tp>>>::value,
                          bool> = false>
       any(_ValueType&& __value)
       : _M_manager(&_Mgr::_S_manage)
@@ -175,10 +200,12 @@ _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)
+      explicit
+      any(in_place_type_t<_ValueType>, _Args&&... __args)
       : _M_manager(&_Mgr::_S_manage)
       {
         _Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
@@ -186,11 +213,14 @@ _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)
+      explicit
+      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)...);
@@ -204,16 +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;
     }
 
@@ -228,8 +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);
@@ -239,8 +259,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     /// Store a copy of @p __rhs as the contained object.
     template<typename _ValueType>
-    enable_if_t<__and_<__not_<is_same<any, decay_t<_ValueType>>>,
-                      is_copy_constructible<_ValueType>>::value, any&>
+      enable_if_t<is_copy_constructible<_Decay<_ValueType>>::value, any&>
       operator=(_ValueType&& __rhs)
       {
        *this = any(std::forward<_ValueType>(__rhs));
@@ -248,27 +267,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
     /// Emplace with an object created from @p __args as the contained object.
-    template <typename _Tp, typename... _Args,
-             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 _Tp, typename _Up, typename... _Args,
-             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
@@ -405,16 +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.
    *
@@ -430,9 +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();
     }
 
@@ -453,9 +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();
     }
 
@@ -467,9 +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();
     }
 
@@ -481,9 +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();
     }
   // @}
@@ -551,7 +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;