On Tue, 9 Mar 2004, Gavin Sinclair wrote:

> Some simple incompatibilities could be flagged by the interpreter.
> For example:
>
>   ruby2 -e --compatibility-diagnostics 'x = proc { 5 }'
>   -e:1: Ruby 1.8 'proc' no longer used; try 'lambda'

Though it would be nice if there were tools to help with this sort
of thing, which gets back to ruby-in-ruby and a proper Ruby parser
for itself...
>
> My 2c,
> Gavin
>

        Hugh