proposed demangle plan is to let libiberty do all the work:
call cplus_demangle (libiberty::cplus-dem.c)
which calls one of:
     cplus_demangle_v3 (libiberty::cp-demangle.c)
     java_demangle_v3 (libiberty::cp-demangle.c)

cplus_demangle and setting the demangler require header file demangle.h, which
is not (yet) provided by binutils-devel.

Other possibilities include 
http://gcc.gnu.org/ml/gcc-patches/2003-11/msg01626.html

http://sources.redhat.com/ml/binutils/2003-07/msg00177.html

The c++ demangler
/usr/include/c++/4.1.1/cxxabi.h
__cxa_demangle(const char* __mangled_name, char* __output_buffer,
                 size_t* __length, int* __status);

Actually, seems like as long as demangle.h is included in frysk-imports and
-liberty is added to GEN_GCJ_LDADD it's building.

Currently it seems like -liberty needs to be added to each directory
frysk-imports, frysk-sys, frysk-core, frysk-gtk and frysk-gui. I wonder if there
is a way around this, Not doing so gives the error: (when not included in frysk-gtk)

gcj-dbtool -a frysk-gtk.db.tmp frysk-gtk.jar libfrysk-gtk.so
../frysk-imports//libfrysk-imports.so: undefined reference to `cplus_demangle'
collect2: ld returned 1 exit status
make[3]: *** [fryski] Error 1

The problem with just adding a random demangle.h, is that there is no guarentee
that it matches the installed libiberty.a library.

Managed to get cxa_demangle to work, the problem was that I wasn't including
libstdc++ during load, (thanks to Kyle Galloway) so my little test program
builds and outputs proper stuff, now to get the build system to accept it.

This code:

#include <cxxabi.h>
#include <stdio.h>
#include <libiberty.h>
/*
 * This is an ugly hack. In /usr/lib/ansidecl.h (included by libiberty.h) we have
 *       #define VOLATILE        volatile
 * This conflicts with /usr/include/c++/4.1.0/java/lang/reflect/Modifier.h:
 * 		 static const jint VOLATILE = 64L;
 * And makes cni cry
 */

#undef VOLATILE
#include <gcj/cni.h>

#include "lib/iberty/Demangler.h"

jstring
lib::iberty::Demangler::demangler (const jstring mangled_string)
{
	
	const char * mangled_name = (const char *) JvGetStringChars(mangled_string);
	  
	int status = -1;
    char *dem = __cxa_demangle(mangled_name, 0, 0, &status);
    if(status == 0)
        return JvNewStringUTF(dem);
    else
        return mangled_string;
}

with this compile:

 g++ -DPACKAGE_NAME=\"frysk\" -DPACKAGE_TARNAME=\"frysk\"
-DPACKAGE_VERSION=\"0.0.1.2006.12.08\" -DPACKAGE_STRING=\"frysk\
0.0.1.2006.12.08\" -DPACKAGE_BUGREPORT=\"\" -DPACKAGE=\"frysk\"
-DVERSION=\"0.0.1.2006.12.08\"  -I.
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports   
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/../frysk-imports -I.
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/../frysk-imports/elfutils/libelf
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/../frysk-imports/elfutils/libdw
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/../frysk-imports/elfutils/libdwfl
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/../frysk-imports/libunwind/include
-I./../frysk-imports/libunwind/include -Werror -Wall -fPIC 
-I/home/yyz/npremji/otherworkspace/frysk/frysk-imports/include -g -O -c -o
lib/iberty/cni/Demangler.o
/home/yyz/npremji/otherworkspace/frysk/frysk-imports/lib/iberty/cni/Demangler.cxx

Produces this error:
/home/yyz/npremji/otherworkspace/frysk/frysk-imports/lib/iberty/cni/Demangler.cxx:
In member function ‘java::lang::String*
lib::iberty::Demangler::demangler(java::lang::String*)’:
/home/yyz/npremji/otherworkspace/frysk/frysk-imports/lib/iberty/cni/Demangler.cxx:64:
error: ‘__cxa_demangle’ was not declared in this scope
make[3]: *** [lib/iberty/cni/Demangler.o] Error 1

I've also added lstdc++ to the GEN_GCJ_LDADD

although I don't see it in the g++ command. I must admit I know almost nothing
about linking

Fixed, took out the libiberty stuff, I don't know why I still had that, but the
problem was I didn't have the line:
using namespace abi. (Thanks to Andrew Cagney and Tom Tromey.)

December 9, 2006
        frysk-imports/lib/stdcpp/CL
        * TestDemangler.java: Added.
        * Demangler.java: Added.
        * cni/Demangler.cxx: Added.
        
        frysk-imports/CL
        * bootstrap.sh (FILE_LIST): Added lib/stdcpp.
        * Makefile.am (EXTRA_DIST): added lib/stdcpp/ChangeLog.
        (GEN_GCJ_LDADD): Added -lstdc++
        
        frysk-core/CL frysk-gui/CL frysk-gtk/CL
        Makefile.am (GEN_GCJ_LDADD): Added -lstdc++

Created attachment 1455 [details]
Mangled output of an fstack of eclipse java process

Created attachment 1456 [details]
Demangled output of same eclipse java process

Finished, StackFrame now demangles method names so anything using this (i.e.
fstack and sourcewindow) will have demangled names.

December 11, 2006
frysk-core/frysk/rt/CL
	* StackFrame.java (toPrint): Demangle method names.