xref: /llvm-project/libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.bind/nested.pass.cpp (revision 13f5579caeee2c75baf1249b9f64de54f7c361e2)
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
10 
11 // <functional>
12 
13 // template<CopyConstructible Fn, CopyConstructible... Types>
14 //   unspecified bind(Fn, Types...);    // constexpr since C++20
15 // template<Returnable R, CopyConstructible Fn, CopyConstructible... Types>
16 //   unspecified bind(Fn, Types...);    // constexpr since C++20
17 
18 // https://llvm.org/PR16343
19 
20 #include <functional>
21 #include <cassert>
22 
23 #include "test_macros.h"
24 
25 struct multiply {
26   template <typename T>
operator ()multiply27   TEST_CONSTEXPR_CXX20 T operator()(T a, T b) {
28     return a * b;
29   }
30 };
31 
32 struct plus_one {
33   template <typename T>
operator ()plus_one34   TEST_CONSTEXPR_CXX20 T operator()(T a) {
35     return a + 1;
36   }
37 };
38 
test()39 TEST_CONSTEXPR_CXX20 bool test() {
40   using std::placeholders::_1;
41   auto g = std::bind(multiply(), 2, _1);
42   assert(g(5) == 10);
43   assert(std::bind(plus_one(), g)(5) == 11);
44 
45   return true;
46 }
47 
main(int,char **)48 int main(int, char**) {
49   test();
50 #if TEST_STD_VER >= 20
51   static_assert(test());
52 #endif
53 
54   return 0;
55 }
56