libstdc++/9562: ostream::sentry::operator bool () should be const

[sebor@roguewave.com]

>Number:         9562
>Category:       libstdc++
>Synopsis:       ostream::sentry::operator bool () should be const
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 04 01:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     sebor@roguewave.com
>Release:        3.2.1
>Organization:
>Environment:

>Description:
27.6.1.1.2 p1 and p8 declare the function

    std::ostream::sentry::operator bool () const;

libstdc++ declares it non-const, leading to compilation errors in programs such as the one below.

Regards
Martin
>How-To-Repeat:
$ cat t.cpp; g++ t.cpp -c

#include <ostream>

bool ok (std::ostream &strm)
{
    const std::ostream::sentry sentry (strm);

    return sentry;
}

t.cpp: In function `bool ok(std::ostream&)':
t.cpp:9: passing `const std::basic_ostream<char, std::char_traits<char> 
   >::sentry' as `this' argument of `std::basic_ostream<_CharT, 
   _Traits>::sentry::operator bool() [with _CharT = char, _Traits = 
   std::char_traits<char>]' discards qualifiers
>Fix:

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