Re: libstdc++/8636: global ostringstreams lose their data

[Michael Pronath <michael.pronath@gmx.de>]

The following reply was made to PR libstdc++/8636; it has been noted by GNATS.

From: Michael Pronath <michael.pronath@gmx.de>
To: Paolo Carlini <pcarlini@unitus.it>
Cc: gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, gcc-bugs@gcc.gnu.org,
        nobody@gcc.gnu.org
Subject: Re: libstdc++/8636: global ostringstreams lose their data
Date: 21 Nov 2002 13:11:49 +0100

 Hello again,
 I think I found the reason for this, it's not a bug.
 
 If 'oss' is an ostringstream, then calling
 
   x = oss.str().c_str();
 
 is a bad idea, because oss.str() returns a copy of the contents of oss
 by value, i.e. a temporary value that is free'd right after this
 statement.  Therefore x is invalid, pointing to a free'd memory region.
 
 --> oss.str().c_str() will always return a pointer to a temporary
     value.
     For example, strcpy(dest, oss.str().c_str()) would work, but
     not   x=oss.str().c_str(); strcpy(dest,x);
 
 I believe this is ok with the standard.
 Sorry, my fault.
 
 Regards,
 Michael