| //===----------------------------------------------------------------------===// |
| // |
| // 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. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // <tuple> |
| |
| // template <class... Types> class tuple; |
| |
| // UNSUPPORTED: c++98, c++03 |
| |
| #include <tuple> |
| #include <utility> |
| #include <cassert> |
| |
| template <class ConstructFrom> |
| struct ConstructibleFromT { |
| ConstructibleFromT() = default; |
| ConstructibleFromT(ConstructFrom v) : value(v) {} |
| ConstructFrom value; |
| }; |
| |
| template <class AssertOn> |
| struct CtorAssertsT { |
| bool defaulted; |
| CtorAssertsT() : defaulted(true) {} |
| template <class T> |
| constexpr CtorAssertsT(T) : defaulted(false) { |
| static_assert(!std::is_same<T, AssertOn>::value, ""); |
| } |
| }; |
| |
| template <class AllowT, class AssertT> |
| struct AllowAssertT { |
| AllowAssertT() = default; |
| AllowAssertT(AllowT) {} |
| template <class U> |
| constexpr AllowAssertT(U) { |
| static_assert(!std::is_same<U, AssertT>::value, ""); |
| } |
| }; |
| |
| // Construct a tuple<T1, T2> from pair<int, int> where T1 and T2 |
| // are not constructible from ints but T1 is constructible from std::pair. |
| // This considers the following constructors: |
| // (1) tuple(TupleLike) -> checks is_constructible<Tn, int> |
| // (2) tuple(UTypes...) -> checks is_constructible<T1, pair<int, int>> |
| // and is_default_constructible<T2> |
| // The point of this test is to ensure that the consideration of (1) |
| // short circuits before evaluating is_constructible<T2, int>, which |
| // will cause a static assertion. |
| void test_tuple_like_lazy_sfinae() { |
| #if defined(_LIBCPP_VERSION) |
| // This test requires libc++'s reduced arity initialization. |
| using T1 = ConstructibleFromT<std::pair<int, int>>; |
| using T2 = CtorAssertsT<int>; |
| std::pair<int, int> p(42, 100); |
| std::tuple<T1, T2> t(p); |
| assert(std::get<0>(t).value == p); |
| assert(std::get<1>(t).defaulted); |
| #endif |
| } |
| |
| |
| struct NonConstCopyable { |
| NonConstCopyable() = default; |
| explicit NonConstCopyable(int v) : value(v) {} |
| NonConstCopyable(NonConstCopyable&) = default; |
| NonConstCopyable(NonConstCopyable const&) = delete; |
| int value; |
| }; |
| |
| template <class T> |
| struct BlowsUpOnConstCopy { |
| BlowsUpOnConstCopy() = default; |
| constexpr BlowsUpOnConstCopy(BlowsUpOnConstCopy const&) { |
| static_assert(!std::is_same<T, T>::value, ""); |
| } |
| BlowsUpOnConstCopy(BlowsUpOnConstCopy&) = default; |
| }; |
| |
| // Test the following constructors: |
| // (1) tuple(Types const&...) |
| // (2) tuple(UTypes&&...) |
| // Test that (1) short circuits before evaluating the copy constructor of the |
| // second argument. Constructor (2) should be selected. |
| void test_const_Types_lazy_sfinae() |
| { |
| NonConstCopyable v(42); |
| BlowsUpOnConstCopy<int> b; |
| std::tuple<NonConstCopyable, BlowsUpOnConstCopy<int>> t(v, b); |
| assert(std::get<0>(t).value == 42); |
| } |
| |
| int main() { |
| test_tuple_like_lazy_sfinae(); |
| test_const_Types_lazy_sfinae(); |
| } |