libstdc++-v3/testsuite/20_util/allocator_traits/members/rebind_alloc.cc

   1 // Copyright (C) 2017-2020 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 <memory>
  21
  22 using std::is_same;
  23
  24 template<typename T, typename U>
  25   using Rebind = typename std::allocator_traits<T>::template rebind_alloc<U>;
  26
  27 template<typename T>
  28   struct HasRebind {
  29     using value_type = T;
  30     template<typename U> struct rebind { using other = std::allocator<U>; };
  31   };
  32
  33 static_assert(is_same<Rebind<HasRebind<int>, long>,
  34                       std::allocator<long>>::value,
  35               "nested alias template is used");
  36
  37 template<typename T>
  38   struct NoRebind0 {
  39     using value_type = T;
  40   };
  41
  42 static_assert(is_same<Rebind<NoRebind0<int>, long>,
  43                       NoRebind0<long>>::value,
  44               "first template argument is replaced");
  45
  46 template<typename T, typename>
  47   struct NoRebind1 {
  48     using value_type = T;
  49   };
  50
  51 static_assert(is_same<Rebind<NoRebind1<int, void>, long>,
  52                       NoRebind1<long, void>>::value,
  53               "first template argument is replaced");
  54
  55 template<typename T, typename, typename>
  56   struct NoRebind2 {
  57     using value_type = T;
  58   };
  59
  60 static_assert(is_same<Rebind<NoRebind2<int, void, void>, long>,
  61                       NoRebind2<long, void, void>>::value,
  62               "first template argument is replaced");
  63
  64 template<typename T, typename...>
  65   struct NoRebindN {
  66     using value_type = T;
  67   };
  68
  69 static_assert(is_same<Rebind<NoRebindN<int>, long>,
  70                       NoRebindN<long>>::value,
  71               "first template argument is replaced");
  72 static_assert(is_same<Rebind<NoRebindN<int, void>, long>,
  73                       NoRebindN<long, void>>::value,
  74               "first template argument is replaced");
  75
  76 template<typename T, int = 0>
  77   struct CannotRebind {
  78     using value_type = T;
  79   };
  80 // PR libstdc++/72792 specialization of allocator_traits is still well-formed:
  81 std::allocator_traits<CannotRebind<int>>::value_type v;