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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03
// <tuple>
// template <class TupleLike> tuple(TupleLike&&); // libc++ extension
// See llvm.org/PR31384
#include <tuple>
#include <cassert>
int count = 0;
struct Explicit {
Explicit() = default;
explicit Explicit(int) {}
};
struct Implicit {
Implicit() = default;
Implicit(int) {}
};
template<class T>
struct Derived : std::tuple<T> {
using std::tuple<T>::tuple;
template<class U>
operator std::tuple<U>() && { ++count; return {}; }
};
template<class T>
struct ExplicitDerived : std::tuple<T> {
using std::tuple<T>::tuple;
template<class U>
explicit operator std::tuple<U>() && { ++count; return {}; }
};
int main() {
{
std::tuple<Explicit> foo = Derived<int>{42}; ((void)foo);
assert(count == 1);
std::tuple<Explicit> bar(Derived<int>{42}); ((void)bar);
assert(count == 2);
}
count = 0;
{
std::tuple<Implicit> foo = Derived<int>{42}; ((void)foo);
assert(count == 1);
std::tuple<Implicit> bar(Derived<int>{42}); ((void)bar);
assert(count == 2);
}
count = 0;
{
static_assert(!std::is_convertible<
ExplicitDerived<int>, std::tuple<Explicit>>::value, "");
std::tuple<Explicit> bar(ExplicitDerived<int>{42}); ((void)bar);
assert(count == 1);
}
count = 0;
{
// FIXME: Libc++ incorrectly rejects this code.
#ifndef _LIBCPP_VERSION
std::tuple<Implicit> foo = ExplicitDerived<int>{42}; ((void)foo);
static_assert(std::is_convertible<
ExplicitDerived<int>, std::tuple<Implicit>>::value,
"correct STLs accept this");
#else
static_assert(!std::is_convertible<
ExplicitDerived<int>, std::tuple<Implicit>>::value,
"libc++ incorrectly rejects this");
#endif
assert(count == 0);
std::tuple<Implicit> bar(ExplicitDerived<int>{42}); ((void)bar);
assert(count == 1);
}
count = 0;
}
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