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
10
11// <functional>
12
13// template<class T> struct is_placeholder;
14// A program may specialize this template for a program-defined type T
15// to have a base characteristic of integral_constant<int, N> with N > 0
16// to indicate that T should be treated as a placeholder type.
17// https://llvm.org/PR51753
18
19#include <cassert>
20#include <functional>
21#include <type_traits>
22#include <utility>
23
24struct My2 {};
25template<> struct std::is_placeholder<My2> : std::integral_constant<int, 2> {};
26
27int main(int, char**)
28{
29 {
30 auto f = [](auto x) { return 10*x + 9; };
31 My2 place;
32 auto bound = std::bind(f&: f, args&: place);
33 assert(bound(7, 8) == 89);
34 }
35 {
36 auto f = [](auto x) { return 10*x + 9; };
37 const My2 place;
38 auto bound = std::bind(f&: f, args: place);
39 assert(bound(7, 8) == 89);
40 }
41 {
42 auto f = [](auto x) { return 10*x + 9; };
43 My2 place;
44 auto bound = std::bind(f&: f, args: std::move(place));
45 assert(bound(7, 8) == 89);
46 }
47 {
48 auto f = [](auto x) { return 10*x + 9; };
49 const My2 place;
50 auto bound = std::bind(f&: f, args: std::move(place));
51 assert(bound(7, 8) == 89);
52 }
53
54 return 0;
55}
56

source code of libcxx/test/std/utilities/function.objects/bind/func.bind/func.bind.isplace/specialization.pass.cpp