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 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // constexpr auto size()
13 //   requires sized_range<V>
14 // constexpr auto size() const
15 //   requires sized_range<const V>
16 
17 #include <ranges>
18 
19 #include "test_macros.h"
20 #include "types.h"
21 
22 template<class T>
23 concept SizeInvocable = requires(std::ranges::drop_view<T> t) { t.size(); };
24 
25 constexpr bool test() {
26   // sized_range<V>
27   std::ranges::drop_view dropView1(MoveOnlyView(), 4);
28   assert(dropView1.size() == 4);
29 
30   // sized_range<V>
31   std::ranges::drop_view dropView2(MoveOnlyView(), 0);
32   assert(dropView2.size() == 8);
33 
34   // sized_range<const V>
35   const std::ranges::drop_view dropView3(MoveOnlyView(), 8);
36   assert(dropView3.size() == 0);
37 
38   // sized_range<const V>
39   const std::ranges::drop_view dropView4(MoveOnlyView(), 10);
40   assert(dropView4.size() == 0);
41 
42   // Because ForwardView is not a sized_range.
43   static_assert(!SizeInvocable<ForwardView>);
44 
45   return true;
46 }
47 
48 int main(int, char**) {
49   test();
50   static_assert(test());
51 
52   return 0;
53 }
54