Jakub Jelinek
9c9061e041
GCC used to emit an instance of an empty ios_base::Init class in
every TU which included <iostream> to ensure it is std::cout etc.
is initialized, but thanks to Patrick work on some targets (which have
init_priority attribute support) it is now initialized only inside of
libstdc++.so.6/libstdc++.a.
This causes a problem if people do something that has never been supported,
try to run GCC 13 compiled C++ code against GCC 12 or earlier
libstdc++.so.6 - std::cout etc. are then never initialized because code
including <iostream> expects the library to initialize it and the library
expects code including <iostream> to do that.
The following patch is second attempt to make this work cheaply as the
earlier attempt of aliasing the std::cout etc. symbols with another symbol
version didn't work out due to copy relocation breaking the aliases appart.
The patch forces just a _ZSt21ios_base_library_initv undefined symbol
into all *.o files which include <iostream> and while there is no runtime
relocation against that, it seems to enforce the right version of
libstdc++.so.6. /home/jakub/src/gcc/obj08i/usr/local/ is the install
directory of trunk patched with this patch, /home/jakub/src/gcc/obj06/
is builddir of trunk without this patch, system g++ is GCC 12.1.1.
$ cat /tmp/hw.C
#include <iostream>
int
main ()
{
std::cout << "Hello, world!" << std::endl;
}
$ cd /home/jakub/src/gcc/obj08i/usr/local/bin
$ ./g++ -o /tmp/hw /tmp/hw.C
$ readelf -Wa /tmp/hw 2>/dev/null | grep initv
4: 0000000000000000 0 FUNC GLOBAL DEFAULT UND _ZSt21ios_base_library_initv@GLIBCXX_3.4.32 (4)
71: 0000000000000000 0 FUNC GLOBAL DEFAULT UND _ZSt21ios_base_library_initv@GLIBCXX_3.4.32
$ /tmp/hw
/tmp/hw: /lib64/libstdc++.so.6: version `GLIBCXX_3.4.32' not found (required by /tmp/hw)
$ LD_LIBRARY_PATH=/home/jakub/src/gcc/obj08i/usr/local/lib64/ /tmp/hw
Hello, world!
$ LD_LIBRARY_PATH=/home/jakub/src/gcc/obj06/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs/ /tmp/hw
/tmp/hw: /home/jakub/src/gcc/obj06/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs/libstdc++.so.6: version `GLIBCXX_3.4.32' not found (required by /tmp/hw)
$ g++ -o /tmp/hw /tmp/hw.C
$ /tmp/hw
Hello, world!
$ LD_LIBRARY_PATH=/home/jakub/src/gcc/obj06/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs/ /tmp/hw
Hello, world!
$ LD_LIBRARY_PATH=/home/jakub/src/gcc/obj08i/usr/local/lib64/ /tmp/hw
Hello, world!
On sparc-sun-solaris2.11 one I've actually checked a version which had
defined(_GLIBCXX_SYMVER_SUN) next to defined(_GLIBCXX_SYMVER_GNU), but
init_priority attribute doesn't seem to be supported there and so I couldn't
actually test how this works there. Using gas and Sun ld, Rainer, does one
need to use gas + gld for init_priority or something else?
2023-04-28 Jakub Jelinek <jakub@redhat.com>
PR libstdc++/108969
* config/abi/pre/gnu.ver (GLIBCXX_3.4.32): Export
_ZSt21ios_base_library_initv.
* testsuite/util/testsuite_abi.cc (check_version): Add GLIBCXX_3.4.32
symver and make it the latestp.
* src/c++98/ios_init.cc (ios_base_library_init): New alias.
* acinclude.m4 (libtool_VERSION): Change to 6:32:0.
* include/std/iostream: If init_priority attribute is supported
and _GLIBCXX_SYMVER_GNU, force undefined _ZSt21ios_base_library_initv
symbol into the object.
* configure: Regenerated.
(cherry picked from commit 9a41d2cdbcd2af77a3a91a840a3a13f0eb39971b)
88 lines
3.0 KiB
C++
88 lines
3.0 KiB
C++
// Standard iostream objects -*- C++ -*-
|
|
|
|
// Copyright (C) 1997-2023 Free Software Foundation, Inc.
|
|
//
|
|
// This file is part of the GNU ISO C++ Library. This library 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, or (at your option)
|
|
// any later version.
|
|
|
|
// This library 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.
|
|
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
|
// permissions described in the GCC Runtime Library Exception, version
|
|
// 3.1, as published by the Free Software Foundation.
|
|
|
|
// You should have received a copy of the GNU General Public License and
|
|
// a copy of the GCC Runtime Library Exception along with this program;
|
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
// <http://www.gnu.org/licenses/>.
|
|
|
|
/** @file include/iostream
|
|
* This is a Standard C++ Library header.
|
|
*/
|
|
|
|
//
|
|
// ISO C++ 14882: 27.3 Standard iostream objects
|
|
//
|
|
|
|
#ifndef _GLIBCXX_IOSTREAM
|
|
#define _GLIBCXX_IOSTREAM 1
|
|
|
|
#pragma GCC system_header
|
|
|
|
#include <bits/requires_hosted.h> // iostreams
|
|
|
|
#include <bits/c++config.h>
|
|
#include <ostream>
|
|
#include <istream>
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
/**
|
|
* @name Standard Stream Objects
|
|
*
|
|
* The `<iostream>` header declares the eight *standard stream objects*.
|
|
* For other declarations, see
|
|
* http://gcc.gnu.org/onlinedocs/libstdc++/manual/io.html
|
|
* and the @link iosfwd I/O forward declarations @endlink
|
|
*
|
|
* They are required by default to cooperate with the global C
|
|
* library's `FILE` streams, and to be available during program
|
|
* startup and termination. For more information, see the section of the
|
|
* manual linked to above.
|
|
*/
|
|
///@{
|
|
extern istream cin; ///< Linked to standard input
|
|
extern ostream cout; ///< Linked to standard output
|
|
extern ostream cerr; ///< Linked to standard error (unbuffered)
|
|
extern ostream clog; ///< Linked to standard error (buffered)
|
|
|
|
#ifdef _GLIBCXX_USE_WCHAR_T
|
|
extern wistream wcin; ///< Linked to standard input
|
|
extern wostream wcout; ///< Linked to standard output
|
|
extern wostream wcerr; ///< Linked to standard error (unbuffered)
|
|
extern wostream wclog; ///< Linked to standard error (buffered)
|
|
#endif
|
|
///@}
|
|
|
|
// For construction of filebuffers for cout, cin, cerr, clog et. al.
|
|
// When the init_priority attribute is usable, we do this initialization
|
|
// in the compiled library instead (src/c++98/globals_io.cc).
|
|
#if !__has_attribute(__init_priority__)
|
|
static ios_base::Init __ioinit;
|
|
#elif defined(_GLIBCXX_SYMVER_GNU)
|
|
__extension__ __asm (".globl _ZSt21ios_base_library_initv");
|
|
#endif
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif /* _GLIBCXX_IOSTREAM */
|