libstdc++/5268: More fun with global stream destruction semantics

[theonetruekenny at yahoo dot com]

>Number:         5268
>Category:       libstdc++
>Synopsis:       More fun with global stream destruction semantics
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jan 03 14:36:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Kenny Simpson
>Release:        cvs - probably also in 3.0
>Organization:
>Environment:
source
>Description:
Similar to PR 3045, in fact same example used.
The problem is that in ios.cc lines [190, 192] and [197, 199]
the flush method is called on the global stream objects cout, cerr, clog, etc

The reason this is a problem is that this will call methods on the
underlying stream buffer, which may no longer exist at this point.
(e.g. is the stream were redirected)
>How-To-Repeat:
// mostly copied from PR 3045
#include <fstream>
#include <iostream>

std::basic_filebuf b1;

int main()
{
  b1.open("foo");
  cout.rdbuf( b1 );
  std::cout << "hello\n";
  return 0;
}
// order of events:
//  magic std::ios_base::Init object is constructed causing
//    std::buf_cout constructed - BTW should this even be in std?
//    std::cout constructed to point at std::buf_cout
//  b1 is created
//  main begins
//  std::cout is redirected to b1
//  main ends
//  b1 is destroyed
//  magic std::ios_base::Init object destroyed causing
//    std::cout.flush, which in turn calls pubsync on b1 - oops

>Fix:
Don't call .flush on cout, cerr, clog, etc..
>Release-Note:
>Audit-Trail:
>Unformatted: