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ldionneldionne
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[libc++] Add test coverage for our implementation of LWG4031 (llvm#87508)
This was actually already implemented in the initial version of std::expected, but this patch adds test coverage and makes it more explicit that we intend to make these functions noexcept.
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‎libcxx/docs/Status/Cxx2cIssues.csv

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@@ -52,7 +52,7 @@
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"`4023 <https://wg21.link/LWG4023>`__","Preconditions of ``std::basic_streambuf::setg/setp``","Tokyo March 2024","","",""
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"`4025 <https://wg21.link/LWG4025>`__","Move assignment operator of ``std::expected<cv void, E>`` should not be conditionally deleted","Tokyo March 2024","","",""
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"`4030 <https://wg21.link/LWG4030>`__","Clarify whether arithmetic expressions in ``[numeric.sat.func]`` are mathematical or C++","Tokyo March 2024","|Nothing To Do|","",""
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"`4031 <https://wg21.link/LWG4031>`__","``bad_expected_access<void>`` member functions should be ``noexcept``","Tokyo March 2024","","",""
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"`4031 <https://wg21.link/LWG4031>`__","``bad_expected_access<void>`` member functions should be ``noexcept``","Tokyo March 2024","|Complete|","16.0",""
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"`4035 <https://wg21.link/LWG4035>`__","``single_view`` should provide ``empty``","Tokyo March 2024","","","|ranges|"
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"`4036 <https://wg21.link/LWG4036>`__","``__alignof_is_defined`` is only implicitly specified in C++ and not yet deprecated","Tokyo March 2024","","",""
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"`4037 <https://wg21.link/LWG4037>`__","Static data members of ``ctype_base`` are not yet required to be usable in constant expressions","Tokyo March 2024","","",""

‎libcxx/include/__expected/bad_expected_access.h

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@@ -32,12 +32,12 @@ _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wweak-vtables")
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template <>
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class bad_expected_access<void> : public exception {
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protected:
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_LIBCPP_HIDE_FROM_ABI bad_expected_access() noexcept = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access(const bad_expected_access&) = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access(bad_expected_access&&) = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(const bad_expected_access&) = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(bad_expected_access&&) = default;
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_LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_expected_access() override = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access() noexcept = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access(const bad_expected_access&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access(bad_expected_access&&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(const bad_expected_access&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(bad_expected_access&&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_expected_access() override = default;
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public:
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// The way this has been designed (by using a class template below) means that we'll already

‎libcxx/test/std/utilities/expected/expected.bad/what.noexcept.compile.pass.cpp renamed to ‎libcxx/test/std/utilities/expected/expected.bad/base.compile.pass.cpp

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@@ -7,19 +7,12 @@
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// const char* what() const noexcept override;
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// Make sure std::bad_expected_access<E> inherits from std::bad_expected_access<void>.
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#include <expected>
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#include <utility>
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#include <type_traits>
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template <class T>
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concept WhatNoexcept =
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requires(const T& t) {
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{ t.what() } noexcept;
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};
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struct Foo {};
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struct foo{};
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static_assert(!WhatNoexcept<foo>);
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static_assert(WhatNoexcept<std::bad_expected_access<int>>);
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static_assert(WhatNoexcept<std::bad_expected_access<foo>>);
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static_assert(std::is_base_of_v<std::bad_expected_access<void>, std::bad_expected_access<int>>);
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static_assert(std::is_base_of_v<std::bad_expected_access<void>, std::bad_expected_access<Foo>>);

‎libcxx/test/std/utilities/expected/expected.bad/void-specialization.pass.cpp

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//===----------------------------------------------------------------------===//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// template<>
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// class bad_expected_access<void> : public exception {
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// protected:
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// bad_expected_access() noexcept;
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// bad_expected_access(const bad_expected_access&) noexcept;
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// bad_expected_access(bad_expected_access&&) noexcept;
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// bad_expected_access& operator=(const bad_expected_access&) noexcept;
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// bad_expected_access& operator=(bad_expected_access&&) noexcept;
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// ~bad_expected_access();
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//
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// public:
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// const char* what() const noexcept override;
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// };
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#include <cassert>
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#include <exception>
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#include <expected>
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#include <type_traits>
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#include <utility>
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#include "test_macros.h"
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struct Inherit : std::bad_expected_access<void> {};
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int main(int, char**) {
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// base class
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static_assert(std::is_base_of_v<std::exception, std::bad_expected_access<void>>);
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// default constructor
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{
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Inherit exc;
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ASSERT_NOEXCEPT(Inherit());
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}
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// copy constructor
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{
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Inherit exc;
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Inherit copy(exc);
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ASSERT_NOEXCEPT(Inherit(exc));
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}
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// move constructor
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{
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Inherit exc;
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Inherit copy(std::move(exc));
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ASSERT_NOEXCEPT(Inherit(std::move(exc)));
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}
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// copy assignment
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{
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Inherit exc;
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Inherit copy;
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[[maybe_unused]] Inherit& result = (copy = exc);
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ASSERT_NOEXCEPT(copy = exc);
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}
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// move assignment
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{
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Inherit exc;
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Inherit copy;
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[[maybe_unused]] Inherit& result = (copy = std::move(exc));
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ASSERT_NOEXCEPT(copy = std::move(exc));
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}
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// what()
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{
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Inherit exc;
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char const* what = exc.what();
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assert(what != nullptr);
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ASSERT_NOEXCEPT(exc.what());
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}
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return 0;
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}

‎libcxx/test/std/utilities/expected/expected.bad/what.pass.cpp

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//===----------------------------------------------------------------------===//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// const char* what() const noexcept override;
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#include <expected>
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#include <cassert>
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#include <utility>
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#include "test_macros.h"
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struct Foo {};
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int main(int, char**) {
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{
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std::bad_expected_access<int> const exc(99);
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char const* what = exc.what();
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assert(what != nullptr);
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ASSERT_NOEXCEPT(exc.what());
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}
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{
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std::bad_expected_access<Foo> const exc(Foo{});
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char const* what = exc.what();
30+
assert(what != nullptr);
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ASSERT_NOEXCEPT(exc.what());
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}
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return 0;
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}

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