[Bug libstdc++/52540] New: std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[Bug libstdc++/52540] New: std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

             Bug #: 52540
           Summary: std::use_facet throws bad_cast when compiled with
                    _GLIBCXX_DEBUG
    Classification: Unclassified
           Product: gcc
           Version: 4.6.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: pluto@agmk.net
            Target: x86_64-w64-mingw32


#include <iostream>
#include <locale>
#include <cstring>
#include <ctime>

int main()
{
        std::tm tm;
        std::time_t tt;
        std::time( &tt );
        tm = *std::localtime( &tt );
        std::locale lc( "C" );
        std::cout.imbue( lc );
        std::time_put< char > const& timeFacet = std::use_facet< std::time_put<
char > >( std::cout.getloc() );
        char const pattern[] = "%x %X";
        timeFacet.put( std::cout, std::cout, std::cout.fill(), &tm, pattern,
pattern + std::strlen( pattern ) );
}

$ x86_64-w64-mingw32-g++ main.cpp -o main-release.exe -g2
$ x86_64-w64-mingw32-g++ main.cpp -o main-debug.exe -g2 -D_GLIBCXX_DEBUG

release-run:

Starting program: main-release.exe
[New Thread 2776.0xdbc]

Breakpoint 1, main () at main.cpp:7
7       {
(gdb) n
10              std::time( &tt );
(gdb)
11              tm = *std::localtime( &tt );
(gdb)
12              std::locale lc( "C" );
(gdb)
13              std::cout.imbue( lc );
(gdb) p lc
$2 = {static none = 0, static ctype = 1, static numeric = 2, static collate =
4, static time = 8, static monetary = 16,
  static messages = 32, static all = 63, _M_impl = 0x626e9460, static
_S_classic = 0x626e9460, static _S_global = 0x626e9460,
  static _S_categories = 0x626eadc0, static _S_once = {done = 1, started = 0}}
(gdb) c
Continuing.
03/09/12 11:53:50
Program exited normally.


debug-run:

Starting program: main-debug.exe
[New Thread 2704.0xd4c]

Breakpoint 1, main () at main.cpp:7
7       {
(gdb) l
2       #include <locale>
3       #include <cstring>
4       #include <ctime>
5
6       int main()
7       {
8               std::tm tm;
9               std::time_t tt;
10              std::time( &tt );
11              tm = *std::localtime( &tt );
(gdb) n
10              std::time( &tt );
(gdb)
11              tm = *std::localtime( &tt );
(gdb)
12              std::locale lc( "C" );
(gdb)
13              std::cout.imbue( lc );
(gdb) p lc
$1 = {static none = 0, static ctype = 1, static numeric = 2, static collate =
4, static time = 8, static monetary = 16,
  static messages = 32, static all = 63, _M_impl = 0x626e9460, static
_S_classic = 0x626e9460, static _S_global = 0x626e9460,
  static _S_categories = 0x626eadc0, static _S_once = {done = 1, started = 0}}
(gdb) n
14              std::time_put< char > const& timeFacet = std::use_facet<
std::time_put< char > >( std::cout.getloc() );
(gdb)
terminate called after throwing an instance of 'std::bad_cast'
  what():  std::bad_cast

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dave.korn.cygwin at gmail
                   |                            |dot com, ktietz at gcc dot
                   |                            |gnu.org

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-03-09 11:02:37 UTC ---
Doesn't happen on Linux, a mingw maintainer is needed.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #2 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-03-09 11:19:34 UTC ---
Hmm, I tested this testcase on my cygwin-cross-compiler for x64 and
I didn't noticed this failure.

I get for it by shown samples always proper output (eg '03/09/12 12:18:20').
So it might be related to something else in your crt/header-set?

I can't confirm it.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-03-09
     Ever Confirmed|0                           |1

--- Comment #3 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-03-09 11:21:23 UTC ---
Ah, with -g2 -D_GLIBCXX_DEBUG I can confirm it.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #4 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-03-09 12:00:00 UTC ---
Issue happens in
include/bits/locale_classes.tcc:

      template<typename _Facet>
        const _Facet&
        use_facet(const locale& __loc)
        {
          const size_t __i = _Facet::id._M_id();
          const locale::facet** __facets = __loc._M_impl->_M_facets;
134        if (__i >= __loc._M_impl->_M_facets_size || !__facets[__i])
135         __throw_bad_cast();
   #ifdef __GXX_RTTI
         return dynamic_cast<const _Facet&>(*__facets[__i]);
   #else
         return static_cast<const _Facet&>(*__facets[__i]);
   #endif
       }

The variable __i has value 30, but __loc.M_impl->_M_factes_size is just 28.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-03-09 12:55:30 UTC ---
I would recommend trying to figure out first when the problem has been
introduced, without excluding some sort of compiler issue, because these
library facilities are in general pretty old and stable.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #6 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-03-09 13:00:40 UTC ---
Hmm, it seems to be a shared/static issue on Windows.
As if I pass to command-line -static with the define, the test passes too.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #7 from Pawel Sikora <pluto at agmk dot net> 2012-03-10 13:14:18 UTC ---
Created attachment 26871
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26871
testcase

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #8 from Pawel Sikora <pluto at agmk dot net> 2012-03-10 13:16:45 UTC ---
i've compared the .ii files with and without _GLIBCXX_DEBUG definition.
the debug version doesn't contain 'extern template (...)' for some classes.
i suppose there're odr violations (global locale objects?) in debug mode.
it may work on linux due to elf's weak binding feature but explicit
dllimport/export exposes problem on windows.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #9 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-03-11 11:20:40 UTC ---
Then this is a very old issue, isn't it? Why nobody noticed it before? To be
clear, in debug-mode we don't use extern templates only for basic_string
(because _GLIBCXX_EXTERN_TEMPLATE becomes -1 when _GLIBCXX_DEBUG is defined),
all the other facilities remain the same still use extern tamplate. This is in
order to enable debug-mode checks also at -O0 for basic_string. Now, I don't
see why a few less extern template can make a difference on mingw in terms of
correctness of use_facet or anything else, but if that's really the case due to
fundamental limitations somehwhere, we can trade it for the -O0 basic_string
checks on the affected systems, I have no problems with that (note that,
AFAICS, the problem will not go away with a new C++11 conforming string class,
unless we decide to not export from the .so parts of basic_string)

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #10 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-03-11 18:35:59 UTC ---
(In reply to comment #9)
> Then this is a very old issue, isn't it? Why nobody noticed it before? To be
> clear, in debug-mode we don't use extern templates only for basic_string
> (because _GLIBCXX_EXTERN_TEMPLATE becomes -1 when _GLIBCXX_DEBUG is defined),
> all the other facilities remain the same still use extern tamplate. This is in
> order to enable debug-mode checks also at -O0 for basic_string. Now, I don't
> see why a few less extern template can make a difference on mingw in terms of
> correctness of use_facet or anything else, but if that's really the case due to
> fundamental limitations somehwhere, we can trade it for the -O0 basic_string
> checks on the affected systems, I have no problems with that (note that,
> AFAICS, the problem will not go away with a new C++11 conforming string class,
> unless we decide to not export from the .so parts of basic_string)

I tested it by making sure that _GLIBCXX_EXTERN_TEMPLATE is defined to 1 even
for _GLIBCXX_DEBUG (and PROFILE) mode.
Indeed the test passes now without issue.  The underlying issue here seems to
be that DLL-code and non-external code aren't sharing all underlying data.  For
ELF this gets resolved, as ELF doesn't have final link for .so, but for PE it
gets finally linked on DLL generation.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #11 from Pawel Sikora <pluto at agmk dot net> 2012-03-11 19:49:41 UTC ---
(In reply to comment #9)
> Then this is a very old issue, isn't it? Why nobody noticed it before? To be
> clear, in debug-mode we don't use extern templates only for basic_string
> (because _GLIBCXX_EXTERN_TEMPLATE becomes -1 when _GLIBCXX_DEBUG is defined),
> all the other facilities remain the same still use extern tamplate. This is in
> order to enable debug-mode checks also at -O0 for basic_string. Now, I don't
> see why a few less extern template can make a difference on mingw in terms of
> correctness of use_facet or anything else, but if that's really the case due to
> fundamental limitations somehwhere, we can trade it for the -O0 basic_string
> checks on the affected systems, I have no problems with that (note that,
> AFAICS, the problem will not go away with a new C++11 conforming string class,
> unless we decide to not export from the .so parts of basic_string)

i'm not sure the problem is in std::string details. in the debug-mode
the use_facet is no more extern template and instantiates in client code,
especially the static facet's field like std::locale::id. is this 'id'
and other static details correctly initialized in (non-extern-template)
debug-mode?

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #12 from Pawel Sikora <pluto at agmk dot net> 2012-03-15 15:49:09 UTC ---
hmm, i see something weird. in source tree the c++config.h contains:

# undef _GLIBCXX_EXTERN_TEMPLATE
#  define _GLIBCXX_EXTERN_TEMPLATE -1

but after make-install the c++config.h contains:

# undef _GLIBCXX_EXTERN_TEMPLATE
#  define _GLIBCXX_EXTERN_TEMPLATE 1 -1
                                   ^^^^

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #13 from Pawel Sikora <pluto at agmk dot net> 2012-03-15 16:36:33 UTC ---
Created attachment 26899
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26899
don't touch with sed the _GLIBCXX_EXTERN_TEMPLATE redefiniton.

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bkoz at redhat dot com

--- Comment #14 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-03-16 10:00:38 UTC ---
To be clear: the way the thing is supposed to work, **only** basic_string
should be special, because **only** the extern template for basic_string are
guarded by "#if _GLIBCXX_EXTERN_TEMPLATE > 0" instead of "#if
_GLIBCXX_EXTERN_TEMPLATE". If something special is happening elsewhere then
it's an unintended bug.

Now, if something got broken lately, like those sed, I have no idea, certainly
I didn't change that. But, please post and discuss the issue and tentative
fixes on the libstdc++ mailing list, not here.

Benjamin, any idea about those sed?

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[pluto at agmk dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #15 from Pawel Sikora <pluto at agmk dot net> 2012-03-16 10:27:53 UTC ---
(In reply to comment #14)
> 
> Now, if something got broken lately, like those sed, I have no idea, certainly
> I didn't change that. But, please post and discuss the issue and tentative
> fixes on the libstdc++ mailing list, not here.

ok, sent:  http://gcc.gnu.org/ml/libstdc++/2012-03/msg00103.html

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #16 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-03-19 23:48:21 UTC ---
Author: paolo
Date: Mon Mar 19 23:48:16 2012
New Revision: 185548

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=185548
Log:
2012-03-19  Paweł Sikora  <pawel.sikora@agmk.net>

    PR libstdc++/52540
    * include/Makefile.am (c++config.h): Fix sed rule to not break
    the _GLIBCXX_EXTERN_TEMPLATE redefinition.
    * include/Makefile.in: Regenerate.

2012-03-19  Paolo Carlini  <paolo.carlini@oracle.com>

    * testsuite/Makefile.in: Regenerate.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/Makefile.am
    trunk/libstdc++-v3/include/Makefile.in
    trunk/libstdc++-v3/testsuite/Makefile.in

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

--- Comment #17 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-03-23 11:01:01 UTC ---
Author: paolo
Date: Fri Mar 23 11:00:54 2012
New Revision: 185733

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=185733
Log:
2012-03-23  Paweł Sikora  <pawel.sikora@agmk.net>

    PR libstdc++/52540
    * include/Makefile.am (c++config.h): Fix sed rule to not break
    the _GLIBCXX_EXTERN_TEMPLATE redefinition.
    * include/Makefile.in: Regenerate.

Modified:
    branches/gcc-4_7-branch/libstdc++-v3/ChangeLog
    branches/gcc-4_7-branch/libstdc++-v3/include/Makefile.am
    branches/gcc-4_7-branch/libstdc++-v3/include/Makefile.in

[Bug libstdc++/52540] std::use_facet throws bad_cast when compiled with _GLIBCXX_DEBUG

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52540

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
            Version|4.6.4                       |4.7.1
         Resolution|                            |FIXED

--- Comment #18 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-03-23 11:03:59 UTC ---
Should be fixed mainline and 4.7.1.