e16f2cb678
Summary: LWG2510 makes tag types like allocator_arg_t explicitly default constructible instead of implicitly default constructible. It also makes the constructors for std::pair and std::tuple conditionally explicit based on the explicit-ness of the default constructibility for the pair/tuple's elements. This was previously committed as r372777 and reverted in r372832 due to the commit breaking LLVM's build in C++14 mode. This issue has now been addressed. Reviewers: mclow.lists Subscribers: christof, jkorous, dexonsmith, libcxx-commits Tags: #libc Differential Revision: https://reviews.llvm.org/D65161 llvm-svn: 372983
118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
//===----------------------------------------------------------------------===//
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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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// <tuple>
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// template <class... Types> class tuple;
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// explicit(see-below) constexpr tuple();
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// UNSUPPORTED: c++98, c++03
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#include <tuple>
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#include <string>
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#include <cassert>
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#include <type_traits>
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#include "test_macros.h"
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#include "DefaultOnly.h"
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struct NoDefault {
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NoDefault() = delete;
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explicit NoDefault(int) { }
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};
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struct NoExceptDefault {
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NoExceptDefault() noexcept = default;
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};
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struct ThrowingDefault {
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ThrowingDefault() { }
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};
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struct IllFormedDefault {
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IllFormedDefault(int x) : value(x) {}
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template <bool Pred = false>
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constexpr IllFormedDefault() {
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static_assert(Pred,
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"The default constructor should not be instantiated");
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}
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int value;
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};
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int main(int, char**)
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{
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{
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std::tuple<> t;
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(void)t;
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}
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{
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std::tuple<int> t;
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assert(std::get<0>(t) == 0);
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}
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{
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std::tuple<int, char*> t;
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assert(std::get<0>(t) == 0);
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assert(std::get<1>(t) == nullptr);
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}
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{
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std::tuple<int, char*, std::string> t;
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assert(std::get<0>(t) == 0);
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assert(std::get<1>(t) == nullptr);
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assert(std::get<2>(t) == "");
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}
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{
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std::tuple<int, char*, std::string, DefaultOnly> t;
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assert(std::get<0>(t) == 0);
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assert(std::get<1>(t) == nullptr);
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assert(std::get<2>(t) == "");
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assert(std::get<3>(t) == DefaultOnly());
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}
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{
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// See bug #21157.
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static_assert(!std::is_default_constructible<std::tuple<NoDefault>>(), "");
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static_assert(!std::is_default_constructible<std::tuple<DefaultOnly, NoDefault>>(), "");
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static_assert(!std::is_default_constructible<std::tuple<NoDefault, DefaultOnly, NoDefault>>(), "");
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}
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{
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static_assert(noexcept(std::tuple<NoExceptDefault>()), "");
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static_assert(noexcept(std::tuple<NoExceptDefault, NoExceptDefault>()), "");
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static_assert(!noexcept(std::tuple<ThrowingDefault, NoExceptDefault>()), "");
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static_assert(!noexcept(std::tuple<NoExceptDefault, ThrowingDefault>()), "");
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static_assert(!noexcept(std::tuple<ThrowingDefault, ThrowingDefault>()), "");
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}
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{
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constexpr std::tuple<> t;
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(void)t;
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}
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{
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constexpr std::tuple<int> t;
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assert(std::get<0>(t) == 0);
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}
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{
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constexpr std::tuple<int, char*> t;
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assert(std::get<0>(t) == 0);
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assert(std::get<1>(t) == nullptr);
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}
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{
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// Check that the SFINAE on the default constructor is not evaluated when
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// it isn't needed. If the default constructor is evaluated then this test
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// should fail to compile.
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IllFormedDefault v(0);
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std::tuple<IllFormedDefault> t(v);
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}
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{
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struct Base { };
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struct Derived : Base { protected: Derived() = default; };
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static_assert(!std::is_default_constructible<std::tuple<Derived, int> >::value, "");
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}
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return 0;
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}
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