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[flang][runtime] Added Fortran::common::reference_wrapper for use on device.
This is a simplified implementation of std::reference_wrapper that can be used in the offload builds for the device code. The methods are properly marked with RT_API_ATTRS so that the device compilation succedes. Reviewers: jeanPerier, klausler Reviewed By: jeanPerier Pull Request: #85178
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‎flang/include/flang/Common/reference-wrapper.h

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//===-- include/flang/Common/reference-wrapper.h ----------------*- 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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// clang-format off
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//
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// Implementation of std::reference_wrapper borrowed from libcu++
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// https://github.com/NVIDIA/libcudacxx/blob/f7e6cd07ed5ba826aeac0b742feafddfedc1e400/include/cuda/std/detail/libcxx/include/__functional/reference_wrapper.h#L1
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// with modifications.
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//
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// The original source code is distributed under the Apache License v2.0
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// with LLVM Exceptions.
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//
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// TODO: using libcu++ is the best option for CUDA, but there is a couple
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// of issues:
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// * The include paths need to be set up such that all STD header files
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// are taken from libcu++.
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// * cuda:: namespace need to be forced for all std:: references.
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//
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// clang-format on
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#ifndef FORTRAN_COMMON_REFERENCE_WRAPPER_H
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#define FORTRAN_COMMON_REFERENCE_WRAPPER_H
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#include "flang/Runtime/api-attrs.h"
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#include <functional>
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#include <type_traits>
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#if !defined(STD_REFERENCE_WRAPPER_UNSUPPORTED) && \
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(defined(__CUDACC__) || defined(__CUDA__)) && defined(__CUDA_ARCH__)
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#define STD_REFERENCE_WRAPPER_UNSUPPORTED 1
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#endif
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namespace Fortran::common {
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template <class _Tp>
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using __remove_cvref_t = std::remove_cv_t<std::remove_reference_t<_Tp>>;
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template <class _Tp, class _Up>
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struct __is_same_uncvref
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: std::is_same<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up>> {};
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#if STD_REFERENCE_WRAPPER_UNSUPPORTED
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template <class _Tp> class reference_wrapper {
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public:
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// types
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typedef _Tp type;
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private:
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type *__f_;
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static RT_API_ATTRS void __fun(_Tp &);
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static void __fun(_Tp &&) = delete;
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public:
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template <class _Up,
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class =
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std::enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value,
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decltype(__fun(std::declval<_Up>()))>>
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constexpr RT_API_ATTRS reference_wrapper(_Up &&__u) {
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type &__f = static_cast<_Up &&>(__u);
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__f_ = std::addressof(__f);
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}
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// access
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constexpr RT_API_ATTRS operator type &() const { return *__f_; }
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constexpr RT_API_ATTRS type &get() const { return *__f_; }
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// invoke
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template <class... _ArgTypes>
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constexpr RT_API_ATTRS typename std::invoke_result_t<type &, _ArgTypes...>
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operator()(_ArgTypes &&...__args) const {
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return std::invoke(get(), std::forward<_ArgTypes>(__args)...);
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}
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};
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template <class _Tp> reference_wrapper(_Tp &) -> reference_wrapper<_Tp>;
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template <class _Tp>
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inline constexpr RT_API_ATTRS reference_wrapper<_Tp> ref(_Tp &__t) {
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return reference_wrapper<_Tp>(__t);
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}
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template <class _Tp>
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inline constexpr RT_API_ATTRS reference_wrapper<_Tp> ref(
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reference_wrapper<_Tp> __t) {
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return __t;
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}
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template <class _Tp>
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inline constexpr RT_API_ATTRS reference_wrapper<const _Tp> cref(
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const _Tp &__t) {
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return reference_wrapper<const _Tp>(__t);
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}
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template <class _Tp>
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inline constexpr RT_API_ATTRS reference_wrapper<const _Tp> cref(
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reference_wrapper<_Tp> __t) {
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return __t;
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}
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template <class _Tp> void ref(const _Tp &&) = delete;
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template <class _Tp> void cref(const _Tp &&) = delete;
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#else // !STD_REFERENCE_WRAPPER_UNSUPPORTED
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using std::cref;
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using std::ref;
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using std::reference_wrapper;
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#endif // !STD_REFERENCE_WRAPPER_UNSUPPORTED
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} // namespace Fortran::common
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#endif // FORTRAN_COMMON_REFERENCE_WRAPPER_H

‎flang/runtime/io-stmt.h

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#include "internal-unit.h"
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#include "io-error.h"
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#include "flang/Common/optional.h"
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#include "flang/Common/reference-wrapper.h"
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#include "flang/Common/visit.h"
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#include "flang/Runtime/descriptor.h"
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#include "flang/Runtime/io-api.h"
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}
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private:
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std::variant<std::reference_wrapper<OpenStatementState>,
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std::reference_wrapper<CloseStatementState>,
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std::reference_wrapper<NoopStatementState>,
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std::reference_wrapper<
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std::variant<Fortran::common::reference_wrapper<OpenStatementState>,
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Fortran::common::reference_wrapper<CloseStatementState>,
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Fortran::common::reference_wrapper<NoopStatementState>,
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Fortran::common::reference_wrapper<
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InternalFormattedIoStatementState<Direction::Output>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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InternalFormattedIoStatementState<Direction::Input>>,
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std::reference_wrapper<InternalListIoStatementState<Direction::Output>>,
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std::reference_wrapper<InternalListIoStatementState<Direction::Input>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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InternalListIoStatementState<Direction::Output>>,
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Fortran::common::reference_wrapper<
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InternalListIoStatementState<Direction::Input>>,
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Fortran::common::reference_wrapper<
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ExternalFormattedIoStatementState<Direction::Output>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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ExternalFormattedIoStatementState<Direction::Input>>,
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std::reference_wrapper<ExternalListIoStatementState<Direction::Output>>,
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std::reference_wrapper<ExternalListIoStatementState<Direction::Input>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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ExternalListIoStatementState<Direction::Output>>,
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Fortran::common::reference_wrapper<
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ExternalListIoStatementState<Direction::Input>>,
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Fortran::common::reference_wrapper<
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ExternalUnformattedIoStatementState<Direction::Output>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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ExternalUnformattedIoStatementState<Direction::Input>>,
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std::reference_wrapper<ChildFormattedIoStatementState<Direction::Output>>,
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std::reference_wrapper<ChildFormattedIoStatementState<Direction::Input>>,
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std::reference_wrapper<ChildListIoStatementState<Direction::Output>>,
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std::reference_wrapper<ChildListIoStatementState<Direction::Input>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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ChildFormattedIoStatementState<Direction::Output>>,
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Fortran::common::reference_wrapper<
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ChildFormattedIoStatementState<Direction::Input>>,
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Fortran::common::reference_wrapper<
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ChildListIoStatementState<Direction::Output>>,
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Fortran::common::reference_wrapper<
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ChildListIoStatementState<Direction::Input>>,
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Fortran::common::reference_wrapper<
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ChildUnformattedIoStatementState<Direction::Output>>,
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std::reference_wrapper<
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Fortran::common::reference_wrapper<
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ChildUnformattedIoStatementState<Direction::Input>>,
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std::reference_wrapper<InquireUnitState>,
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std::reference_wrapper<InquireNoUnitState>,
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std::reference_wrapper<InquireUnconnectedFileState>,
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std::reference_wrapper<InquireIOLengthState>,
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std::reference_wrapper<ExternalMiscIoStatementState>,
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std::reference_wrapper<ErroneousIoStatementState>>
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Fortran::common::reference_wrapper<InquireUnitState>,
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Fortran::common::reference_wrapper<InquireNoUnitState>,
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Fortran::common::reference_wrapper<InquireUnconnectedFileState>,
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Fortran::common::reference_wrapper<InquireIOLengthState>,
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Fortran::common::reference_wrapper<ExternalMiscIoStatementState>,
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Fortran::common::reference_wrapper<ErroneousIoStatementState>>
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u_;
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};
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