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// <unordered_map>
10
11// Check that std::unordered_set fails to instantiate if the hash function is
12// not copy-constructible. This is mentioned in LWG issue 2436
13
14#include <unordered_set>
15
16template <class T>
17struct Hash {
18 std::size_t operator()(const T& lhs) const { return 0; }
19
20 Hash() {}
21
22private:
23 Hash(const Hash&); // declared but not defined
24};
25
26int main(int, char**) {
27 std::unordered_set<int, Hash<int> > m;
28
29 return 0;
30}
31

source code of libcxx/test/std/containers/unord/unord.set/unord.set.cnstr/hash_copy_constructible.compile.fail.cpp