memory hole in egcs or ginac

[Paul Grayson]

The following program uses up all of my RAM in about 20 seconds:
------------------------------
#include <ginac/ginac.h>
using namespace GiNaC;

int main() {
  while(1) symbol x("x");
}
------------------------------

...and here's how I compile it:
(using an fresh-out-of-the-box ./configure'd GiNaC)
------------------------------
capibara$ c++ -dumpversion
egcs-2.91.66
capibara$ c++ -dumpmachine
i386-slackware-linux
capibara$ c++ try.cc -lcln -lginac -o try
capibara$ try
[memory usage goes up and up...]
------------------------------

If I compile it with this line instead, I have no similar problem:

  while(1) basic x = symbol("x");

...any ideas?  Am I confused about C++ (likely), or do I just have an
old, buggy version of egcs, or is there a problem here?
Thanks
-Paul