[Bug c++/70909] Libiberty Demangler segfaults (4)

["trippels at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70909

--- Comment #10 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
(In reply to Mark Wielaard from comment #9)
> (In reply to Markus Trippelsdorf from comment #8)
> > This is what it should look like: [...]
> 
> How did you demangle that input string?
> With the proposed patch the mangled string is rejected by the libiberty
> demangler.
> 
> I assume since you were able to demangle it is a valid input string, but
> that the demangler creates a cyclic graph for it that then blows up the
> stack when trying to print out.

There a three demanglers that I know of. 
 libiberty
 Ian's demangler (written in Go) https://github.com/ianlancetaylor/demangle
 and LLVM's libc++abi demangler http://libcxxabi.llvm.org/

The symbol was demangled with libcxxabi's demangler.
The other two demanglers reject it.