libstdc++-v3/testsuite/20_util/shared_ptr/assign/sfinae.cc

   1 // Copyright (C) 2016-2023 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 // { dg-require-effective-target hosted }
  20
  21 #include <memory>
  22
  23 template<typename T, typename From>
  24 constexpr bool can_assign()
  25 { return std::is_assignable<std::shared_ptr<T>, From>::value; }
  26
  27 struct Base { };
  28 struct Derived : Base { };
  29
  30 // Positive cases:
  31
  32 static_assert( can_assign<const void, const std::shared_ptr<void>&>(),
  33     "void* convertible to const void*");
  34 static_assert( can_assign<const void, std::shared_ptr<void>&&>(),
  35     "void* convertible to const void*");
  36 static_assert( can_assign<const int, std::shared_ptr<int>>(),
  37     "int* convertible to const int*");
  38 static_assert( can_assign<Base, std::shared_ptr<Derived>>(),
  39     "Derived* convertible to Base*");
  40 static_assert( can_assign<const Base, std::shared_ptr<Derived>>(),
  41     "Derived* convertible to const Base*");
  42
  43 // Negative cases:
  44
  45 static_assert( !can_assign<int, const std::shared_ptr<void>&>(),
  46     "void* not convertible to int*");
  47 static_assert( !can_assign<int, std::shared_ptr<void>&&>(),
  48     "void* not convertible to int*");
  49
  50 static_assert( !can_assign<int, const std::shared_ptr<const int>&>(),
  51     "const int* not convertible to int*");
  52 static_assert( !can_assign<int, std::shared_ptr<const int>&&>(),
  53     "const int* not convertible to int*");
  54
  55 static_assert( !can_assign<int, const std::shared_ptr<long>&>(),
  56     "long* not convertible to int*");
  57 static_assert( !can_assign<int, std::shared_ptr<long>&&>(),
  58     "long* not convertible to int*");
  59
  60 static_assert( !can_assign<int, std::unique_ptr<long>&&>(),
  61     "unique_ptr<long>::pointer not convertible to int*");
  62
  63 static_assert( !can_assign<Derived, const std::shared_ptr<Base>&>(),
  64     "Base* not convertible to Derived*");
  65 static_assert( !can_assign<int, std::shared_ptr<long>&&>(),
  66     "Base* not convertible to Derived*");
  67 static_assert( !can_assign<Derived, std::unique_ptr<Base>&&>(),
  68     "unique_ptr<Base>::pointer not convertible to Derived*");
  69
  70 struct Deleter {
  71   using pointer = void*;
  72   void operator()(pointer) const { }
  73 };
  74
  75 static_assert( !can_assign<Derived, std::unique_ptr<Derived, Deleter>&&>(),
  76     "unique_ptr<Derived, Deleter>::pointer not convertible to Derived*");