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* [Bug libstdc++/16251] New: bogus default constructor for std::basic_iostream
@ 2004-06-28 19:48 ralfixx at gmx dot de
  2004-07-05 12:49 ` [Bug libstdc++/16251] " ralfixx at gmx dot de
                   ` (4 more replies)
  0 siblings, 5 replies; 10+ messages in thread
From: ralfixx at gmx dot de @ 2004-06-28 19:48 UTC (permalink / raw)
  To: gcc-bugs

% gcc -v
Reading specs from
/tmp_mnt/software/software/gcc/3.4.0/HP-UX-B.11/lib/gcc/hppa2.0w-hp-hpux11.00/3.4.0/specs
Configured with: ../configure --prefix=/software/gcc/3.4.0
--exec-prefix=/software/gcc/3.4.0/HP-UX-B.11 --with-local-prefix=/work
--enable-languages=c,c++ --enable-shared --with-gnu-as --with-as=/work/bin/as
Thread model: single
gcc version 3.4.0

c% cat t.cxx
#include <iostream>
class mystream : public std::iostream {
public:
  mystream () {};
};

int main() {
  mystream x;
  x.rdbuf(std::cout.rdbuf());
  x << "foobar" << std::endl;
}
% g++ -o t t.cxx
% ./t
./t
terminate called after throwing an instance of 'std::bad_cast'
  what():  St8bad_cast
foobarIOT trap (core dumped)

Analysis: in 3.4.0 a default constructor for basic_istream() was added
(include/.../istream, #562ff)
    protected:
      explicit 
      basic_istream(): _M_gcount(streamsize(0)) { }

which leaves the iostream in an ill state.  The other CTOR calls
this->init(__sb) which initializes the submembers correctly (ties, exceptions etc).

If I use 
     mystream () : std::iostream(NULL) {};
in the mystream class definition, the error does not occur.


3.3.2 refuses to compile the above, since no basic_iostream(void) CTOR is found.

IMHO the default CTORs should not leave the object in an ill-defined state.
(call init(NULL)).

The same problem is also present in basic_istream and basic_ostream (mayne
others as well).

Best 
R'

-- 
           Summary: bogus default constructor for std::basic_iostream
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ralfixx at gmx dot de
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: hppa2.0w-hp-hpux11.00
  GCC host triplet: hppa2.0w-hp-hpux11.00
GCC target triplet: hppa2.0w-hp-hpux11.00


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16251


^ permalink raw reply	[flat|nested] 10+ messages in thread
[parent not found: <bug-16251-658@http.gcc.gnu.org/bugzilla/>]
end of thread, other threads:[~2008-02-10 15:52 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-06-28 19:48 [Bug libstdc++/16251] New: bogus default constructor for std::basic_iostream ralfixx at gmx dot de
2004-07-05 12:49 ` [Bug libstdc++/16251] " ralfixx at gmx dot de
2004-07-06 23:09 ` bkoz at gcc dot gnu dot org
2004-07-07  7:25 ` ralfixx at gmx dot de
2005-06-28  3:24 ` danglin at gcc dot gnu dot org
2005-07-09 16:40 ` pinskia at gcc dot gnu dot org
     [not found] <bug-16251-658@http.gcc.gnu.org/bugzilla/>
2008-02-10 13:02 ` manu at gcc dot gnu dot org
2008-02-10 14:36 ` pcarlini at suse dot de
2008-02-10 15:49 ` paolo at gcc dot gnu dot org
2008-02-10 15:52 ` pcarlini at suse dot de

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