libcxx/test/std/iterators/predef.iterators/iterators.common/ctor.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 // template<class I2, class S2>
  12 //   requires convertible_to<const I2&, I> && convertible_to<const S2&, S>
  13 //     constexpr common_iterator(const common_iterator<I2, S2>& x);
  14
  15 #include <cassert>
  16 #include <iterator>
  17 #include <type_traits>
  18
  19 constexpr bool test()
  20 {
  21   struct Base {};
  22   struct Derived : Base {};
  23
  24   using BaseIt = std::common_iterator<Base*, const Base*>;
  25   using DerivedIt = std::common_iterator<Derived*, const Derived*>;
  26   static_assert(std::is_convertible_v<DerivedIt, BaseIt>); // Derived* to Base*
  27   static_assert(!std::is_constructible_v<DerivedIt, BaseIt>); // Base* to Derived*
  28
  29   Derived a[10] = {};
  30   DerivedIt it = DerivedIt(a); // the iterator type
  31   BaseIt jt = BaseIt(it);
  32   assert(jt == BaseIt(a));
  33
  34   it = DerivedIt((const Derived*)a); // the sentinel type
  35   jt = BaseIt(it);
  36   assert(jt == BaseIt(a));
  37
  38   return true;
  39 }
  40
  41 int main(int, char**) {
  42   test();
  43   static_assert(test());
  44
  45   return 0;
  46 }