binutils-gdb/gdbsupport/invoke-result.h
Simon Marchi c95dd24e79 gdbsupport: add wrapper around result_of and invoke_result
When building with Clang 14 (using gcc 12 libstdc++ headers), I get:

      CXX    dwarf2/read.o
    In file included from /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:94:
    /home/simark/src/binutils-gdb/gdb/../gdbsupport/parallel-for.h:142:21: error: 'result_of<(lambda at /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:7124:5) (__gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter> *, std::__cxx1998::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>>, std::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>, std::random_access_iterator_tag>, __gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter> *, std::__cxx1998::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>>, std::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>, std::random_access_iterator_tag>)>' is deprecated: use 'std::invoke_result' instead [-Werror,-Wdeprecated-declarations]
        = typename std::result_of<RangeFunction (RandomIt, RandomIt)>::type;
                        ^
    /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:7122:14: note: in instantiation of function template specialization 'gdb::parallel_for_each<__gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter> *, std::__cxx1998::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>>, std::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>, std::random_access_iterator_tag>, (lambda at /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:7124:5)>' requested here
          = gdb::parallel_for_each (1, per_bfd->all_comp_units.begin (),
                 ^
    /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.1.1/../../../../include/c++/12.1.1/type_traits:2597:9: note: 'result_of<(lambda at /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:7124:5) (__gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter> *, std::__cxx1998::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>>, std::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>, std::random_access_iterator_tag>, __gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter> *, std::__cxx1998::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>>, std::vector<std::unique_ptr<dwarf2_per_cu_data, dwarf2_per_cu_data_deleter>>, std::random_access_iterator_tag>)>' has been explicitly marked deprecated here
        { } _GLIBCXX17_DEPRECATED_SUGGEST("std::invoke_result");
            ^
    /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.1.1/../../../../include/c++/12.1.1/x86_64-pc-linux-gnu/bits/c++config.h:120:45: note: expanded from macro '_GLIBCXX17_DEPRECATED_SUGGEST'
    # define _GLIBCXX17_DEPRECATED_SUGGEST(ALT) _GLIBCXX_DEPRECATED_SUGGEST(ALT)
                                                ^
    /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.1.1/../../../../include/c++/12.1.1/x86_64-pc-linux-gnu/bits/c++config.h:96:19: note: expanded from macro '_GLIBCXX_DEPRECATED_SUGGEST'
      __attribute__ ((__deprecated__ ("use '" ALT "' instead")))
                      ^

It complains about the use of std::result_of, which is deprecated in
C++17 and removed in C++20:

  https://en.cppreference.com/w/cpp/types/result_of

Given we'll have to transition to std::invoke_result eventually, make a
GDB wrapper to mimimc std::invoke_result, which uses std::invoke_result
for C++ >= 17 and std::result_of otherwise.  This way, it will be easy
to remove the wrapper in the future, just replace gdb:: with std::.

Tested by building with gcc 12 in -std=c++11 and -std=c++17 mode, and
clang in -std=c++17 mode (I did not test fully with clang in -std=c++11
mode because there are other unrelated issues).

Change-Id: I50debde0a3307a7bc67fcf8fceefda51860efc1d
2022-08-30 14:43:26 -04:00

38 lines
1.2 KiB
C++

/* Compatibility wrapper around std::result_of and std::invoke_result.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef GDBSUPPORT_INVOKE_RESULT_H
#define GDBSUPPORT_INVOKE_RESULT_H
#include <type_traits>
namespace gdb
{
#if __cplusplus >= 201703L
template<typename Callable, class... Args>
using invoke_result = std::invoke_result<Callable, Args...>;
#else
template<typename Callable, typename... Args>
using invoke_result = std::result_of<Callable (Args...)>;
#endif
} /* namespace gdb */
#endif /* GDBSUPPORT_INVOKE_RESULT_H */