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-no-concepts
11 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
12 
13 // constexpr auto size()
14 //   requires sized_range<V>
15 // constexpr auto size() const
16 //   requires sized_range<const V>
17 
18 #include <ranges>
19 
20 #include "test_macros.h"
21 #include "types.h"
22 
23 template<class T>
24 concept SizeInvocable = requires(std::ranges::drop_view<T> t) { t.size(); };
25 
26 constexpr bool test() {
27   // sized_range<V>
28   std::ranges::drop_view dropView1(MoveOnlyView(), 4);
29   assert(dropView1.size() == 4);
30 
31   // sized_range<V>
32   std::ranges::drop_view dropView2(MoveOnlyView(), 0);
33   assert(dropView2.size() == 8);
34 
35   // sized_range<const V>
36   const std::ranges::drop_view dropView3(MoveOnlyView(), 8);
37   assert(dropView3.size() == 0);
38 
39   // sized_range<const V>
40   const std::ranges::drop_view dropView4(MoveOnlyView(), 10);
41   assert(dropView4.size() == 0);
42 
43   // Because ForwardView is not a sized_range.
44   static_assert(!SizeInvocable<ForwardView>);
45 
46   return true;
47 }
48 
49 int main(int, char**) {
50   test();
51   static_assert(test());
52 
53   return 0;
54 }
55