[Bug libstdc++/53838] New: _GLIBCXX_DEBUG and empty ostringstream

[Bug libstdc++/53838] New: _GLIBCXX_DEBUG and empty ostringstream

[akim.demaille at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

             Bug #: 53838
           Summary: _GLIBCXX_DEBUG and empty ostringstream
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: akim.demaille@gmail.com


Hi,

The following program fails on Mac OS X with both 4.7 and 4.8.


$ uname -a
Darwin erebus.lrde.epita.fr 11.4.0 Darwin Kernel Version 11.4.0: Mon Apr  9
19:32:15 PDT 2012; root:xnu-1699.26.8~1/RELEASE_X86_64 x86_64

$ g++-mp-4.7 --version
g++-mp-4.7 (MacPorts gcc47 4.7.1_1) 4.7.1
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++-mp-4.8 --version
g++-mp-4.8 (MacPorts gcc48 4.8-20120701_0) 4.8.0 20120701 (experimental)
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cat simpleaut.cc
# define _GLIBCXX_DEBUG 1
# include <sstream>

int main()
{
  std::ostringstream s;
  s.str();
}

$ g++-mp-4.8 tests/unit/simpleaut.cc
$ ./a.out
a.out(28056) malloc: *** error for object 0x10a5f2340: pointer being freed was
not allocated
*** set a breakpoint in malloc_error_break to debug
zsh: abort      ./a.out


(gdb) bt
#0  0x00007fff89bf582a in __kill ()
#1  0x00007fff89833a9c in abort ()
#2  0x00007fff8989284c in free ()
#3  0x0000000100000b86 in __gnu_cxx::new_allocator<char>::deallocate
(this=0x7fff5fbff847, 
    __p=0x1000d0340 "") at ext/new_allocator.h:102
#4  0x0000000100000b58 in std::string::_Rep::_M_destroy (this=0x1000d0340, 
    __a=@0x7fff5fbff89f) at bits/basic_string.tcc:451
#5  0x0000000100000ae6 in std::string::_Rep::_M_dispose (this=0x1000d0340, 
    __a=@0x7fff5fbff89f) at bits/basic_string.h:251
#6  0x00000001000009fd in std::basic_string<char, std::char_traits<char>,
std::allocator<char> >::~basic_string (this=0x7fff5fbffa20) at
bits/basic_string.h:541
#7  0x0000000100000968 in main () at tests/unit/simpleaut.cc:7

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-03 11:52:17 UTC ---
This is not a GCC bug, please report it to MacPorts not here.

At a guess I'd say you're linking to the system libstdc++.so not the one from
your mp builds, and the mp builds do not use the same setting for
--enable-fully-dynamic-string as the system libs.

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-07-03 13:55:05 UTC ---
Not a GCC bug as Mac OS X's installed libstdc++ is built with
--enable-fully-dynamic-string while the mac ports one is not.

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-03 14:48:38 UTC ---
Andrew, I'm not actually sure about that, see
https://trac.macports.org/ticket/22234

But in any case, it's a problem with MacPorts' GCC package not FSF's GCC.

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[akim.demaille at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #4 from Akim Demaille <akim.demaille at gmail dot com> 2012-07-19 13:16:23 UTC ---
Hi People,

I have therefore reported this to MacPorts, see
http://trac.macports.org/ticket/35070 .  The outcome is that (i) with
--enable-fully-dynamic-string fails to build on MacPorts, and (ii), no, the
linking is properly done with the MacPorts' version of stdlibc++:

> also when trying your example the resuling binary is linked to _our_ gcc's C++-lib

So really, there seem to be something weird about this on OS X, as indeed is
shown in other tickets.  What course of action would you recommend?

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-19 13:36:42 UTC ---
(In reply to comment #4)
> What course of action would you recommend?

I don't understand what the comments in the macports trac mean, but as far as
I'm concerned there's nothing for us to do, it's an issue with the macports
build, not GCC.

If they want to report a different bug about --enable-fully-dynamic-string
that's a separate issue and will be dealt with if it's reported properly.

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[tom at kera dot name]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

Tomalak Geret'kal <tom at kera dot name> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tom at kera dot name

--- Comment #6 from Tomalak Geret'kal <tom at kera dot name> ---
Not a GCC bug? Really? I beg to differ.

 - Bug 54173
 - Bug 33021
 - Bug 64504

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
One of those bugs is apparently not present in 4.2 or later, are you sure it's
the same?

Do you have a reproducible testcase to show the bug, not just "use macports, it
breaks"? or only links to other reports that show up for related search terms?

[Bug libstdc++/53838] _GLIBCXX_DEBUG and empty ostringstream

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53838

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
i.e. do you have the exact commands to build a gcc that shows the problem?

So it can be reproduced from a clean source tarball, without external
dependencies.