| // -*- 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; |
| |
| } |