libstdc++/8636: global ostringstreams lose their data

[michael.pronath@gmx.de]

>Number:         8636
>Category:       libstdc++
>Synopsis:       global ostringstreams lose their data
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 19 05:46:05 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     michael.pronath@gmx.de
>Release:        unknown-1.0
>Organization:
>Environment:
Linux glibc2 g++ 3.2
both in debian package and when compiled from source
>Description:
global ostringstreams lose their data after calling
c_str on them when new memory is allocated.
See appended example.
Expected output: Hello World, where are you?
real output:     Hello Hello Hello Hello Hell

reason: when fillmystream() returns, the ostringstream content is forgotten, just like it was an automatic
variable.  The string operator+= then allocates new memory
for extension of the string and gets the address of x and
then appends itself.

Interestingly, this does not happen in valgrind.
>How-To-Repeat:
g++ -o teststream teststream.cc
./teststream
valgrind ./teststream
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="teststream.cc"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="teststream.cc"

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