59e26308e6
Summary: LWG 3158 marks the allocator_arg_t constructor of std::tuple as conditionnally explicit based on whether the default constructors of the tuple's members are explicitly default constructible. This was previously committed as r372778 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/D65232 llvm-svn: 373092
112 lines
3.7 KiB
C++
112 lines
3.7 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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// UNSUPPORTED: c++98, c++03
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// <tuple>
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// template <class... Types> class tuple;
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// template <class Alloc>
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// explicit(see-below) tuple(allocator_arg_t, const Alloc& a);
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// NOTE: this constructor does not currently support tags derived from
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// allocator_arg_t because libc++ has to deduce the parameter as a template
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// argument. See PR27684 (https://bugs.llvm.org/show_bug.cgi?id=27684)
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#include <tuple>
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#include <cassert>
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#include "test_macros.h"
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#include "DefaultOnly.h"
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#include "allocators.h"
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#include "../alloc_first.h"
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#include "../alloc_last.h"
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template <class T = void>
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struct NonDefaultConstructible {
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constexpr NonDefaultConstructible() {
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static_assert(!std::is_same<T, T>::value, "Default Ctor instantiated");
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}
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explicit constexpr NonDefaultConstructible(int) {}
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};
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struct DerivedFromAllocArgT : std::allocator_arg_t {};
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int main(int, char**)
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{
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{
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std::tuple<> t(std::allocator_arg, A1<int>());
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}
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{
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std::tuple<int> t(std::allocator_arg, A1<int>());
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assert(std::get<0>(t) == 0);
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}
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{
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std::tuple<DefaultOnly> t(std::allocator_arg, A1<int>());
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assert(std::get<0>(t) == DefaultOnly());
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}
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{
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assert(!alloc_first::allocator_constructed);
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std::tuple<alloc_first> t(std::allocator_arg, A1<int>(5));
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assert(alloc_first::allocator_constructed);
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assert(std::get<0>(t) == alloc_first());
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}
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{
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assert(!alloc_last::allocator_constructed);
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std::tuple<alloc_last> t(std::allocator_arg, A1<int>(5));
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assert(alloc_last::allocator_constructed);
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assert(std::get<0>(t) == alloc_last());
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}
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{
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alloc_first::allocator_constructed = false;
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std::tuple<DefaultOnly, alloc_first> t(std::allocator_arg, A1<int>(5));
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assert(std::get<0>(t) == DefaultOnly());
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assert(alloc_first::allocator_constructed);
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assert(std::get<1>(t) == alloc_first());
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}
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{
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alloc_first::allocator_constructed = false;
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alloc_last::allocator_constructed = false;
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std::tuple<DefaultOnly, alloc_first, alloc_last> t(std::allocator_arg,
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A1<int>(5));
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assert(std::get<0>(t) == DefaultOnly());
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assert(alloc_first::allocator_constructed);
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assert(std::get<1>(t) == alloc_first());
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assert(alloc_last::allocator_constructed);
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assert(std::get<2>(t) == alloc_last());
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}
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{
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alloc_first::allocator_constructed = false;
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alloc_last::allocator_constructed = false;
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std::tuple<DefaultOnly, alloc_first, alloc_last> t(std::allocator_arg,
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A2<int>(5));
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assert(std::get<0>(t) == DefaultOnly());
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assert(!alloc_first::allocator_constructed);
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assert(std::get<1>(t) == alloc_first());
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assert(!alloc_last::allocator_constructed);
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assert(std::get<2>(t) == alloc_last());
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}
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{
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// Test that the uses-allocator default constructor does not evaluate
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// its SFINAE when it otherwise shouldn't be selected. Do this by
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// using 'NonDefaultConstructible' which will cause a compile error
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// if std::is_default_constructible is evaluated on it.
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using T = NonDefaultConstructible<>;
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T v(42);
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std::tuple<T, T> t(v, v);
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(void)t;
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std::tuple<T, T> t2(42, 42);
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(void)t2;
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}
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return 0;
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}
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