libstdc++-v3/testsuite/23_containers/vector/allocator/construction.cc

   1 // Copyright (C) 2016-2025 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do compile { target c++11 } }
  19
  20 #include <vector>
  21
  22 struct Tag { };
  23
  24 template<typename T>
  25   struct TaggingAllocator
  26   {
  27     using value_type = T;
  28
  29     TaggingAllocator() = default;
  30
  31     template<typename U>
  32       TaggingAllocator(const TaggingAllocator<U>&) { }
  33
  34     T*
  35     allocate(std::size_t n) { return std::allocator<T>{}.allocate(n); }
  36
  37     void
  38     deallocate(T* p, std::size_t n) { std::allocator<T>{}.deallocate(p, n); }
  39
  40     template<typename U, typename... Args>
  41       void
  42       construct(U* p, Args&&... args)
  43       { ::new((void*)p) U(Tag{}, std::forward<Args>(args)...); }
  44
  45     template<typename U, typename... Args>
  46       void
  47       destroy(U* p)
  48       { p->~U(); }
  49   };
  50
  51 template<typename T, typename U>
  52   bool
  53   operator==(const TaggingAllocator<T>&, const TaggingAllocator<U>&)
  54   { return true; }
  55
  56 template<typename T, typename U>
  57   bool
  58   operator!=(const TaggingAllocator<T>&, const TaggingAllocator<U>&)
  59   { return false; }
  60
  61 struct X
  62 {
  63   // All constructors must be passed the Tag type.
  64
  65   // DefaultInsertable into vector<X, TaggingAllocator<X>>,
  66   X(Tag) { }
  67   // CopyInsertable into vector<X, TaggingAllocator<X>>,
  68   X(Tag, const X&) { }
  69   // MoveInsertable into vector<X, TaggingAllocator<X>>, and
  70   X(Tag, X&&) { }
  71
  72   // EmplaceConstructible into vector<X, TaggingAllocator<X>> from args.
  73   template<typename... Args>
  74     X(Tag, Args&&...) { }
  75
  76   // not DefaultConstructible, CopyConstructible or MoveConstructible.
  77   X() = delete;
  78   X(const X&) = delete;
  79   X(X&&) = delete;
  80
  81   // CopyAssignable.
  82   X& operator=(const X&) { return *this; }
  83
  84   // MoveAssignable.
  85   X& operator=(X&&) { return *this; }
  86
  87 private:
  88   // Not Destructible.
  89   ~X() { }
  90
  91   // Erasable from vector<X, TaggingAllocator<X>>.
  92   friend class TaggingAllocator<X>;
  93 };
  94
  95 template class std::vector<X, TaggingAllocator<X>>;
  96
  97 void test01()
  98 {
  99   std::vector<X, TaggingAllocator<X>> v;
 100   v.reserve(3);
 101   v.emplace_back();
 102   v.emplace(v.begin());
 103   v.emplace(v.begin(), 1, 2, 3);
 104 }