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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// REQUIRES: c++11 || c++14 || c++17 || c++20
// This test makes sure that we don't apply P1951 before C++23, since that is
// a breaking change. The examples in this test are taken from Richard Smith's
// comments on https://llvm.org/D109066.
#include <cassert>
#include <utility>
#include <vector>
struct A {
int *p_;
A(int *p) : p_(p) { *p_ += 1; }
A(const A& a) : p_(a.p_) { *p_ += 1; }
~A() { *p_ -= 1; }
};
int main(int, char**) {
// Example 1:
// Without P1951, we call the `pair(int, const A&)` constructor (the converting constructor is not usable because
// we can't deduce from an initializer list), which creates the A temporary as part of the call to f. With P1951,
// we call the `pair(U&&, V&&)` constructor, which creates a A temporary inside the pair constructor, and that
// temporary doesn't live long enough any more.
{
int i = 0;
auto f = [&](std::pair<std::vector<int>, const A&>) { assert(i >= 1); };
f({{42, 43}, &i});
}
// Example 2:
// Here, n doesn't need to be captured if we call the `pair(const int&, const long&)` constructor, because
// the lvalue-to-rvalue conversion happens in the lambda. But if we call the `pair(U&&, V&&)` constructor
// (deducing V = int), then n does need to be captured.
{
const int n = 5;
(void) []{ std::pair<int, long>({1}, n); };
}
return 0;
}
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