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a9e659619f
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 llvm-svn: 283980
40 lines
1.1 KiB
C++
40 lines
1.1 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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// <optional>
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// template <class T> constexpr bool operator<(const optional<T>& x, nullopt_t) noexcept;
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// template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept;
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#include <optional>
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int main()
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{
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using std::optional;
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using std::nullopt_t;
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using std::nullopt;
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{
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typedef int T;
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typedef optional<T> O;
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constexpr O o1; // disengaged
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constexpr O o2{1}; // engaged
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static_assert ( !(nullopt < o1), "" );
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static_assert ( (nullopt < o2), "" );
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static_assert ( !(o1 < nullopt), "" );
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static_assert ( !(o2 < nullopt), "" );
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static_assert (noexcept(nullopt < o1), "");
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static_assert (noexcept(o1 < nullopt), "");
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}
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}
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