libcxx/test/std/iterators/iterator.primitives/range.iter.ops/range.iter.ops.next/constraints.compile.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 // ranges::next
  12 // Make sure we're SFINAE-friendly when the template argument constraints are not met.
  13
  14 #include <iterator>
  15
  16 #include <cstddef>
  17 #include <memory>
  18 #include <utility>
  19 #include "test_iterators.h"
  20
  21 template <class ...Args>
  22 concept has_ranges_next = requires (Args&& ...args) {
  23   { std::ranges::next(std::forward<Args>(args)...) };
  24 };
  25
  26 using It = std::unique_ptr<int>;
  27 static_assert(!has_ranges_next<It>);
  28 static_assert(!has_ranges_next<It, std::ptrdiff_t>);
  29 static_assert(!has_ranges_next<It, It>);
  30 static_assert(!has_ranges_next<It, std::ptrdiff_t, It>);
  31
  32 // Test the test
  33 using It2 = forward_iterator<int*>;
  34 static_assert(has_ranges_next<It2>);
  35 static_assert(has_ranges_next<It2, std::ptrdiff_t>);
  36 static_assert(has_ranges_next<It2, std::ptrdiff_t, It2>);