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Although <ciso646> was removed from C++20, it was not formally deprecated in C++17. In contrast, <ctgmath>, <cstdalign>, etc. were formally deprecated in C++17 before being removed in C++20. Due to the widespread convention of including <ciso646> to detect implementation-specific macros (such as _GLIBCXX_RELEASE) it causes quite a lot of noise to issue deprecation warnings in C++17 mode. The recommendation to include <version> instead does work for recent compilers, even in C++17 mode, but isn't portable to older compilers that don't provide <version> yet (e.g. GCC 8). There are also potential objections to including <version> pre-C++20 when it wasn't defined by the standard. I don't have much sympathy for this position, because including <ciso646> for implementation-specific macros wasn't part of the C++17 standard either. It's no more non-standard to rely on <version> being present and defining those macros than to rely on <ciso646> defining them, and __has_include can be used to detect whether <version> is present. However, <ciso646> is being used in the wild by popular libraries like Abseil and we can't change versions of those that have already been released. This removes the #warning in <ciso646> for C++17 mode, so that we only emit diagnostics for C++20 and later. With this change, including <ciso646> in C++20 or later gives an error if _GLIBCXX_USE_DEPRECATED is defined to zero, otherwise a warning if -Wdeprecated is enabled, otherwise no diagnostic is given. This also adds "@since C++11 (removed in C++20)" to the Doxygen @file comments in all the relevant headers. The test for <ciso646> needs to be updated to no longer expect a warning for c++17_only. A new test is added to ensure that we get a warning instead of an error when -D_GLIBCXX_USE_DEPRECATED=0 is not used. libstdc++-v3/ChangeLog: PR libstdc++/120187 * include/c_global/ciso646: Only give deprecated warning for C++20 and later. * include/c_global/ccomplex: Add @since to Doxygen comment. * include/c_global/cstdalign: Likewise. * include/c_global/cstdbool: Likewise. * include/c_global/ctgmath: Likewise. * testsuite/18_support/headers/ciso646/macros.cc: Remove dg-warning for c++17_only effective target. * testsuite/18_support/headers/ciso646/macros-2.cc: New test. Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
// <ccomplex> -*- C++ -*-
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// Copyright (C) 2007-2025 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file include/ccomplex
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* This is a Standard C++ Library header.
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*
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* @since C++11 (removed in C++20)
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*/
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#ifndef _GLIBCXX_CCOMPLEX
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#define _GLIBCXX_CCOMPLEX 1
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#ifdef _GLIBCXX_SYSHDR
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#pragma GCC system_header
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#endif
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#endif
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extern "C++" {
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#include <complex>
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}
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#if __cplusplus >= 202002L && ! _GLIBCXX_USE_DEPRECATED
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# error "<ccomplex> is not a standard header in C++20, use <complex> instead"
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#elif __cplusplus >= 201703L && defined __DEPRECATED
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# pragma GCC diagnostic push
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# pragma GCC diagnostic ignored "-Wc++23-extensions"
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# warning "<ccomplex> is deprecated in C++17, use <complex> instead"
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# pragma GCC diagnostic pop
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#endif
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#endif
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