35ce4859dd
Summary: Adapt implementation of Library Fundamentals TS optional into an implementation of N4606 optional. - Update relational operators per http://wg21.link/P0307 - Update to requirements of http://wg21.link/P0032 - Extension: Implement trivial copy/move construction/assignment for `optional<T>` when `T` is trivially copyable. Audit P/Rs for optional LWG issues: - 2756 "C++ WP optional<T> should 'forward' T's implicit conversions" Implemented, which also resolves 2753 "Optional's constructors and assignments need constraints" (modulo my refusal to explicitly delete the move operations, which is a design error that I'm working on correcting in the 2756 P/R). - 2736 "nullopt_t insufficiently constrained" Already conforming. I've added a test ensuring that `nullopt_t` is not copy-initializable from an empty braced-init-list, which I believe is the root intent of the issue, to avoid regression. - 2740 "constexpr optional<T>::operator->" Already conforming. - 2746 "Inconsistency between requirements for emplace between optional and variant" No P/R, but note that the author's '"suggested resolution" is already implemented. - 2748 "swappable traits for optionals" Already conforming. - 2753 "Optional's constructors and assignments need constraints" Implemented. Most of the work for this patch was done by Casey Carter @ Microsoft. Thank you Casey! Reviewers: mclow.lists, CaseyCarter, EricWF Differential Revision: https://reviews.llvm.org/D22741 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283980 91177308-0d34-0410-b5e6-96231b3b80d8
82 lines
1.8 KiB
C++
82 lines
1.8 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14
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// XFAIL: libcpp-no-exceptions
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// <optional>
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// optional<T>& operator=(const optional<T>& rhs);
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#include <optional>
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#include <string>
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#include <type_traits>
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using std::optional;
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struct X {};
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struct Y
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{
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Y() = default;
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Y& operator=(const Y&) { return *this; }
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};
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struct Z1
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{
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Z1() = default;
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Z1(Z1&&) = default;
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Z1(const Z1&) = default;
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Z1& operator=(Z1&&) = default;
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Z1& operator=(const Z1&) = delete;
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};
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struct Z2
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{
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Z2() = default;
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Z2(Z2&&) = default;
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Z2(const Z2&) = delete;
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Z2& operator=(Z2&&) = default;
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Z2& operator=(const Z2&) = default;
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};
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#if __cplusplus >= 201402
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template <class T>
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constexpr bool
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test()
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{
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optional<T> opt;
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optional<T> opt2;
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opt = opt2;
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return true;
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}
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#endif
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int main()
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{
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{
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using T = int;
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static_assert((std::is_trivially_copy_assignable<optional<T>>::value), "");
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#if __cplusplus >= 201402
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static_assert(test<T>(), "");
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#endif
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}
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{
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using T = X;
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static_assert((std::is_trivially_copy_assignable<optional<T>>::value), "");
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#if __cplusplus >= 201402
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static_assert(test<T>(), "");
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#endif
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}
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static_assert(!(std::is_trivially_copy_assignable<optional<Y>>::value), "");
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static_assert(!(std::is_trivially_copy_assignable<optional<std::string>>::value), "");
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static_assert(!(std::is_copy_assignable<optional<Z1>>::value), "");
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static_assert(!(std::is_copy_assignable<optional<Z2>>::value), "");
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}
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