libcxx/test/std/iterators/predef.iterators/move.iterators/move.sentinel/assign.converting.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // <iterator>
  12
  13 // move_sentinel
  14
  15 // template<class S2>
  16 //   requires assignable_from<S&, const S2&>
  17 //     constexpr move_sentinel& operator=(const move_sentinel<S2>& s);
  18
  19 #include <cassert>
  20 #include <concepts>
  21 #include <iterator>
  22 #include <type_traits>
  23
  24 struct NonAssignable {
  25   NonAssignable& operator=(int i);
  26 };
  27 static_assert(std::semiregular<NonAssignable>);
  28 static_assert(std::is_assignable_v<NonAssignable, int>);
  29 static_assert(!std::assignable_from<NonAssignable, int>);
  30
  31 constexpr bool test()
  32 {
  33   // Assigning from an lvalue.
  34   {
  35     std::move_sentinel<int> m(42);
  36     std::move_sentinel<long> m2;
  37     m2 = m;
  38     assert(m2.base() == 42L);
  39   }
  40
  41   // Assigning from an rvalue.
  42   {
  43     std::move_sentinel<long> m2;
  44     m2 = std::move_sentinel<int>(43);
  45     assert(m2.base() == 43L);
  46   }
  47
  48   // SFINAE checks.
  49   {
  50     static_assert( std::is_assignable_v<std::move_sentinel<int>, std::move_sentinel<long>>);
  51     static_assert(!std::is_assignable_v<std::move_sentinel<int*>, std::move_sentinel<const int*>>);
  52     static_assert( std::is_assignable_v<std::move_sentinel<const int*>, std::move_sentinel<int*>>);
  53     static_assert(!std::is_assignable_v<std::move_sentinel<NonAssignable>, std::move_sentinel<int>>);
  54   }
  55   return true;
  56 }
  57
  58 int main(int, char**)
  59 {
  60   test();
  61   static_assert(test());
  62
  63   return 0;
  64 }