libstdc++-v3/testsuite/20_util/pointer_traits/rebind.cc

   1 // Copyright (C) 2017 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::pointer_traits<T>::template rebind<U>;
  26
  27 template<typename T>
  28   struct HasRebind {
  29     template<typename U> using rebind = U*;
  30   };
  31
  32 static_assert(is_same<Rebind<HasRebind<int>, long>,
  33                       long*>::value,
  34               "nested alias template is used");
  35
  36 template<typename T> struct NoRebind0 { };
  37
  38 static_assert(is_same<Rebind<NoRebind0<int>, long>,
  39                       NoRebind0<long>>::value,
  40               "first template argument is replaced");
  41
  42 template<typename T, typename> struct NoRebind1 { };
  43
  44 static_assert(is_same<Rebind<NoRebind1<int, void>, long>,
  45                       NoRebind1<long, void>>::value,
  46               "first template argument is replaced");
  47
  48 template<typename T, typename, typename> struct NoRebind2 { };
  49
  50 static_assert(is_same<Rebind<NoRebind2<int, void, void>, long>,
  51                       NoRebind2<long, void, void>>::value,
  52               "first template argument is replaced");
  53
  54 template<typename T, typename...> struct NoRebindN { };
  55
  56 static_assert(is_same<Rebind<NoRebindN<int>, long>,
  57                       NoRebindN<long>>::value,
  58               "first template argument is replaced");
  59 static_assert(is_same<Rebind<NoRebindN<int, void>, long>,
  60                       NoRebindN<long, void>>::value,
  61               "first template argument is replaced");
  62
  63 template<typename T, int = 0>
  64   struct CannotRebind {
  65     using element_type = T;
  66   };
  67 // PR libstdc++/72793 specialization of pointer_traits is still well-formed:
  68 std::pointer_traits<CannotRebind<int>>::element_type e;