I believe Kent Sibilev has fixed this in the current SVN sources for
ruby-debug by putting in a frozen? test.

On Sat, Jul 19, 2008 at 2:56 PM, Stephen Bannasch
<stephen.bannasch / deanbrook.org> wrote:
> I get this error in latest patchlevel 289 of ruby 1.8.6
>
> file: test.rb
> x = 1
> y = 2
> z = x + y
>
> rdebug test.rb
>
> /usr/local/lib/ruby/gems/1.8/gems/ruby-debug-0.10.1/bin/rdebug:41:in `[]=':
> can't modify frozen string (TypeError)
>        from
> /usr/local/lib/ruby/gems/1.8/gems/ruby-debug-0.10.1/bin/rdebug:41:in
> `debug_program'
>        from
> /usr/local/lib/ruby/gems/1.8/gems/ruby-debug-0.10.1/bin/rdebug:330
>        from /usr/local/bin/rdebug:19:in `load'
>        from /usr/local/bin/rdebug:19
>
> The problem does not occur in p251 and first appears in p252.
>
> The problem appear with svn rev 17702.
>
> For more info see ruby-debug rubyforge bug report here:
>
> http://rubyforge.org/tracker/index.php?func=detail&aid=21276&group_id=1900&atid=7436
>
> The problem also occurs using trunk 1_8.
>
>
>