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[libc++] Implement P0288R9 (move_only_function)
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‎libcxx/docs/ABIGuarantees.rst‎

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@@ -157,6 +157,10 @@ This flag adds ``[[clang::trivial_abi]]`` to ``unique_ptr``, which makes it triv
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---------------------------------------------
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This flag adds ``[[clang::trivial_abi]]`` to ``shared_ptr``, which makes it trivial for the purpose of calls.
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``_LIBCPP_ABI_MOVE_ONLY_FUNCTION_TRIVIAL_ABI``
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---------------------------------------------
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This flag adds ``[[clang::trivial_abi]]`` to ``move_only_function``, which makes it trivial for the purpose of calls.
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Types that public aliases reference
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===================================

‎libcxx/docs/FeatureTestMacroTable.rst‎

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---------------------------------------------------------- -----------------
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``__cpp_lib_modules`` ``202207L``
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---------------------------------------------------------- -----------------
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``__cpp_lib_move_only_function`` *unimplemented*
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``__cpp_lib_move_only_function`` ``202110L``
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---------------------------------------------------------- -----------------
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``__cpp_lib_optional`` ``202110L``
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---------------------------------------------------------- -----------------

‎libcxx/docs/ReleaseNotes/22.rst‎

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- P2835R7: Expose ``std::atomic_ref``'s object address (`Github <https://llvm.org/PR118377>`__)
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- P2944R3: Comparisons for ``reference_wrapper`` (`Github <https://llvm.org/PR105424>`__)
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- P3168R2: Give ``std::optional`` Range Support (`Github <https://llvm.org/PR105430>`__)
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- P0288R9 - ``move_only_function`` (`Github <https://llvm.org/PR105157>`__) This feature is currently experimental and
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thereofre requires ``-fexperimental-library``.
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Improvements and New Features
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-----------------------------

‎libcxx/docs/Status/Cxx23Papers.csv‎

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"`P2136R3 <https://wg21.link/P2136R3>`__","invoke_r","2021-06 (Virtual)","|Complete|","17","`#105155 <https://github.com/llvm/llvm-project/issues/105155>`__",""
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"`P2166R1 <https://wg21.link/P2166R1>`__","A Proposal to Prohibit std::basic_string and std::basic_string_view construction from nullptr","2021-06 (Virtual)","|Complete|","13","`#105156 <https://github.com/llvm/llvm-project/issues/105156>`__",""
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"","","","","","",""
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"`P0288R9 <https://wg21.link/P0288R9>`__","``any_invocable``","2021-10 (Virtual)","","","`#105157 <https://github.com/llvm/llvm-project/issues/105157>`__",""
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"`P0288R9 <https://wg21.link/P0288R9>`__","``move_only_function``","2021-10 (Virtual)","|Complete|","22","`#105157 <https://github.com/llvm/llvm-project/issues/105157>`__",""
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"`P0798R8 <https://wg21.link/P0798R8>`__","Monadic operations for ``std::optional``","2021-10 (Virtual)","|Complete|","14","`#105158 <https://github.com/llvm/llvm-project/issues/105158>`__",""
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"`P0849R8 <https://wg21.link/P0849R8>`__","``auto(x)``: ``DECAY_COPY`` in the language","2021-10 (Virtual)","|Complete|","14","`#105159 <https://github.com/llvm/llvm-project/issues/105159>`__",""
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"`P1072R10 <https://wg21.link/P1072R10>`__","``basic_string::resize_and_overwrite``","2021-10 (Virtual)","|Complete|","14","`#105160 <https://github.com/llvm/llvm-project/issues/105160>`__",""

‎libcxx/include/CMakeLists.txt‎

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__functional/is_transparent.h
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__functional/mem_fn.h
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__functional/mem_fun_ref.h
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__functional/move_only_function.h
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__functional/move_only_function_common.h
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__functional/move_only_function_impl.h
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__functional/not_fn.h
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__functional/operations.h
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__functional/perfect_forward.h

‎libcxx/include/__configuration/abi.h‎

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# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_ARRAY
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# define _LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW
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# define _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
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# define _LIBCPP_ABI_MOVE_ONLY_FUNCTION_TRIVIAL_ABI
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#elif _LIBCPP_ABI_VERSION == 1
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# if !(defined(_LIBCPP_OBJECT_FORMAT_COFF) || defined(_LIBCPP_OBJECT_FORMAT_XCOFF))

‎libcxx/include/__configuration/experimental.h‎

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#define _LIBCPP_HAS_EXPERIMENTAL_TZDB _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
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#define _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
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#define _LIBCPP_HAS_EXPERIMENTAL_HARDENING_OBSERVE_SEMANTIC _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
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#define _LIBCPP_HAS_EXPERIMENTAL_MOVE_ONLY_FUNCTION _LIBCPP_HAS_EXPERIMENTAL_LIBRARY
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#endif // _LIBCPP___CONFIGURATION_EXPERIMENTAL_H

‎libcxx/include/__functional/move_only_function.h‎

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//===----------------------------------------------------------------------===//
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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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#ifndef _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_H
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#define _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_H
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#include <__config>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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#if _LIBCPP_STD_VER >= 23 && _LIBCPP_HAS_EXPERIMENTAL_MOVE_ONLY_FUNCTION
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// move_only_function design:
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//
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// move_only_function has a small buffer with a size of `3 * sizeof(void*)` bytes. This buffer can only be used when the
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// object to be stored is "trivially relocatable" (currently only when it is trivially move constructible and trivially
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// destructible). The vtable entry for the destructor is a null pointer when the stored object is trivially
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// destructible.
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//
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// trivially relocatable: It would also be possible to store nothrow_move_constructible types, but that would mean
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// that move_only_function itself would not be trivially relocatable anymore. The decision to keep move_only_function
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// trivially relocatable was made because we expect move_only_function to be stored persistently most of the time, since
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// std::function_ref can be used for cases where a function object doesn't need to be stored.
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//
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// buffer size: We did a survey of six implementations from various vendors. Three of them had a buffer size of 24 bytes
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// on 64 bit systems. This will also allow storing a function object containing a std::string or std::vector inside the
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// small buffer once there is a language definition of "trivially relocatable".
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//
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// interaction with copyable_function: When converting a copyable_function into a move_only_function we want to avoid
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// wrapping the copyable_function inside the move_only_function to avoid a double indirection. Instead, we copy the
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// small buffer and use copyable_function's vtable.
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// NOLINTBEGIN(readability-duplicate-include)
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# define _LIBCPP_IN_MOVE_ONLY_FUNCTION_H
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &&
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &&
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &&
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &
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# include <__functional/move_only_function_impl.h>
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# define _LIBCPP_MOVE_ONLY_FUNCTION_NOEXCEPT true
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# define _LIBCPP_MOVE_ONLY_FUNCTION_CV const
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# define _LIBCPP_MOVE_ONLY_FUNCTION_REF &&
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# include <__functional/move_only_function_impl.h>
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# undef _LIBCPP_IN_MOVE_ONLY_FUNCTION_H
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// NOLINTEND(readability-duplicate-include)
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#endif // _LIBCPP_STD_VER >= 23 && _LIBCPP_HAS_EXPERIMENTAL_MOVE_ONLY_FUNCTION
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#endif // _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_H

‎libcxx/include/__functional/move_only_function_common.h‎

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//===----------------------------------------------------------------------===//
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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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#ifndef _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_COMMON_H
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#define _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_COMMON_H
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#include <__config>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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#if _LIBCPP_STD_VER >= 23 && _LIBCPP_HAS_EXPERIMENTAL_MOVE_ONLY_FUNCTION
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class...>
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class move_only_function;
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template <class>
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inline constexpr bool __is_move_only_function_v = false;
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template <class... _Args>
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inline constexpr bool __is_move_only_function_v<move_only_function<_Args...>> = true;
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template <class _BufferT, class _ReturnT, class... _ArgTypes>
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struct _MoveOnlyFunctionVTable {
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using _CallFunc _LIBCPP_NODEBUG = _ReturnT(_BufferT&, _ArgTypes...);
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using _DestroyFunc _LIBCPP_NODEBUG = void(_BufferT&) noexcept;
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_CallFunc* __call_;
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_DestroyFunc* __destroy_;
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};
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER >= 23 && _LIBCPP_HAS_EXPERIMENTAL_MOVE_ONLY_FUNCTION
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#endif // _LIBCPP___FUNCTIONAL_MOVE_ONLY_FUNCTION_COMMON_H

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