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// Copyright (C) 2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <functional>
#include <memory>
#include <string>
#include <testsuite_hooks.h>
// P1651R0 bind_front should not unwrap reference_wrapper
#ifndef __cpp_lib_bind_front
# error "Feature test macro for bind_front is missing"
#elif __cpp_lib_bind_front < 201907L
# error "Feature test macro for bind_front has wrong value"
#endif
void functionAcceptingStringView(std::string_view) { }
void
test01()
{
std::string s;
auto fs = std::bind_front(&functionAcceptingStringView, std::string_view(s));
fs();
}
template <typename F>
struct PartialApply {
PartialApply(F f) : f(f) {}
F f;
template <typename... A> decltype(auto) operator()(A const&... a) const {
if constexpr (std::is_invocable<F const&, A const&...>::value) {
return f(a...);
} else {
return bind_front(*this, a...);
}
}
};
void
test02()
{
struct Thingy { };
std::unique_ptr<Thingy> thingy;
auto func = [](const std::unique_ptr<Thingy>&, int) {};
PartialApply{func}(std::ref(thingy))(10);
}
void
test03()
{
std::string str;
auto func = [](const std::string& s, int) -> const std::string& { return s; };
// sref refers to copy of str stored in bind_front result:
const std::string& sref = PartialApply{func}(std::ref(str))(10);
// pre-P1651R0 this is a use of a dangling reference:
const char& c = sref[0];
// post-P1651R0 the bind_front result stores a reference_wrapper by value,
// and so sref is bound to str instead of dangling:
VERIFY( &c == str.data() );
VERIFY( &sref == &str );
}
int
main()
{
test01();
test02();
test03();
}
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