gccfilter is a perl filter to colorize and simplify (or expand) 
        gcc diagnostic messages.
 gccfilter is particularly aimed at g++
        (i.e. dealinging with C++) messages which can contain lot of 
        template-related errors or warnings difficult to sort out.
        
Features:
        There exists a somewhat similar tool colorgcc (http://schlueters.de/colorgcc.html). 
        However it seems to be unmaintained for years now and does only coloring.
        
Note that the script relies on several perl modules, namely:
So far it also requires perl version 5.9.4 or above (for the "state" keyword).
        Download the script: http://www.mixtion.org/gccfilter/gccfilter and put it somewhere in your $PATH. 
        The man page is integrated in the file (type gccfilter -m), 
        or available in HTML here: http://www.mixtion.org/gccfilter/gccfilter.html
        
Emmanuel Le Trong, <manu@mixtion.org>
Compiling this test program:
class A {};
class B {};
int main () { A a(&B()); }
            
        
        
            
            
        
(Note that colors are customizable. These are the built-in defaults)
The test program comes from pegtl (http://code.google.com/p/pegtl/) which heavily uses some advanced template mecanisms. (I introduced the error.)
As is:

The same colored, without "with" clauses, template arguments, instanciation chains, paths and namespaces:

update: 2010-10-21, Copyright 2010 by Emmanuel Le Trong.