7da4ee6f23
Disable the constructors taking `(size_type, const value_type&, allocator_type)` if `allocator_type` is not a valid allocator. Otherwise, these constructors are considered when resolving e.g. `(int*, int*, NotAnAllocator())`, leading to a hard error during instantiation. A hard error makes the Standard's requirement to not consider deduction guides of the form `(Iterator, Iterator, BadAllocator)` during overload resolution essentially non-functional. The previous approach was to SFINAE away `allocator_traits`. This patch SFINAEs away the specific constructors instead, for consistency with `basic_string` -- see [LWG3076](wg21.link/lwg3076) which describes a very similar problem for strings (note, however, that unlike LWG3076, no valid constructor call is affected by the bad instantiation). Differential Revision: https://reviews.llvm.org/D114311
56 lines
1.4 KiB
C++
56 lines
1.4 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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// <deque>
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// deque()
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// noexcept(is_nothrow_default_constructible<allocator_type>::value);
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// This tests a conforming extension
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// UNSUPPORTED: c++03
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#include <deque>
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#include <cassert>
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#include "test_macros.h"
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#include "MoveOnly.h"
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#include "test_allocator.h"
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template <class T>
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struct some_alloc
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{
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typedef T value_type;
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some_alloc(const some_alloc&);
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void allocate(size_t);
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};
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int main(int, char**)
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{
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#if defined(_LIBCPP_VERSION)
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{
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typedef std::deque<MoveOnly> C;
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static_assert(std::is_nothrow_default_constructible<C>::value, "");
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}
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{
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typedef std::deque<MoveOnly, test_allocator<MoveOnly>> C;
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static_assert(std::is_nothrow_default_constructible<C>::value, "");
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}
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#endif // _LIBCPP_VERSION
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{
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typedef std::deque<MoveOnly, other_allocator<MoveOnly>> C;
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static_assert(!std::is_nothrow_default_constructible<C>::value, "");
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}
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{
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typedef std::deque<MoveOnly, some_alloc<MoveOnly>> C;
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static_assert(!std::is_nothrow_default_constructible<C>::value, "");
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}
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return 0;
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}
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