Serious breakage of fstream(s) ?!?

[Paolo Carlini <pcarlini at unitus dot it>]

Hi all, hi Benjamin,

today I'm seeing a new, serious problem when using fstream(s) on my
i686-pc-linux-gnu system (plain glibc2.2.4 -> generic_locale)

The testcase is the following (extracted from libstdc++/5424, which, in itself,
should not be very serious):

////////////////////////

#include <fstream>

bool stream_in( void )
{
  std::ifstream is( "foo.txt" );

  int i;

  is >> i;

  return true;
}

bool stream_out( void )
{
  std::ofstream os( "foo.txt" );

  os << 42 << '\n';

  return true;
}

int main()
{
  stream_out();
  stream_in();
}

///////////////////////////

Today, it segfaults in stream_in at "is >> i;" and this is the backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x0804f71d in std::ctype<char>::is(unsigned short, char) const (this=0x8053e68,
__m=8192, __c=0 '\0') at
/usr/local/gcc-exp/include/g++-v3/i686-pc-linux-gnu/bits/ctype_inline.h:40
(gdb) backtrace
#0  0x0804f71d in std::ctype<char>::is(unsigned short, char) const
(this=0x8053e68, __m=8192, __c=0 '\0') at
/usr/local/gcc-exp/include/g++-v3/i686-pc-linux-gnu/bits/ctype_inline.h:40
#1  0x0804d5f6 in sentry (this=0xbffff6ff, __in=@0xbffff730, __noskipws=false)
at /usr/local/gcc-exp/include/g++-v3/bits/istream.tcc:52
#2  0x0804cc05 in std::istream::operator>>(int&) (this=0xbffff730,
__n=@0xbffff72c) at /usr/local/gcc-exp/include/g++-v3/bits/istream.tcc:195
#3  0x0804c7c4 in stream_in() () at reduced.cc:9
#4  0x0804c8d0 in main () at reduced.cc:26
#5  0x4010e7fd in __libc_start_main (main=0x804c8b6 <main>, argc=1,
ubp_av=0xbffff8b4, init=0x804c3b8 <_init>, fini=0x8051280 <_fini>,
rtld_fini=0x4000ba34 <_dl_fini>, stack_end=0xbffff8ac) at
../sysdeps/generic/libc-start.c:129


Benjamin, honestly, I'm strongly suspecting your
http://gcc.gnu.org/ml/gcc-patches/2002-01/msg01221.html.

What do you think?

Cheers,
Paolo.