libstdc++/9563: ostream::sentry returns true after a failed preparation

[sebor@roguewave.com]

>Number:         9563
>Category:       libstdc++
>Synopsis:       ostream::sentry returns true after a failed preparation
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 04 02:26:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     sebor@roguewave.com
>Release:        3.2.1
>Organization:
>Environment:

>Description:
According to the requirements on the ostream::sentry ctor below, the program below should exit with the status of 0. It exits with 1 with gcc 3.2.1, indicating that the sentry ctor fails to check the state of the stream after the former has completed the preparation.

Regards
Martin

27.6.2.3:
 -2-  If os.good() is nonzero, prepares for formatted
      or unformatted output. If os.tie() is not a null
      pointer, calls os.tie()->flush().
 -3-  If, after any preparation is completed, os.good()
      is true, ok_ == true otherwise, ok_ == false.
>How-To-Repeat:
$ cat t.cpp; g++ t.cpp && ./a.out ; echo $?
#include <ostream>
#include <streambuf>

struct buf: std::streambuf
{
    std::ios *io_;

    buf (std::ios *io): io_ (io) { }

    virtual int sync () {
        io_->setstate (std::ios::failbit);
        return 0;
    }
};

int main ()
{
    buf b (0);
    std::ostream strm (&b);

    buf tb (&strm);
    std::ostream tied (&tb);

    strm.tie (&tied);
    std::ostream::sentry s (strm);

    return s;
}
1
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: