[RFA] New substitute-path commands

[Joel Brobecker]

[moving back to GDB - summary: On gdb-patches, I was convinced by the
feedback that I received that I should spend the effort of implementing
multiple rewrite rules immediately. I have a question about that].

The interface is as follow:

        (gdb) set substitute-path FROM TO
        (gdb) unset substitute-path [FROM]
        (gdb) show substitute-path

The "set" command will add a substitution rule.

My question is the following: When you enter a second rule, should it
take precedence over the first one you entered? More generally, should
the substitution rules entered last be used first, or the opposite?

I'm 50-50 on this:

   . With first-entered/first-used, you enter the rules following the
     logic "if blah, then replace with [...]; else if bloh, then replace
     with [...]; else if [...], then [...]". In other words, you enter
     the rules in the same order you would write a "program". It seems
     pretty natural.

   . With last-entered/first-used, it's possible to override previous
     entries without having to delete the previous rules. Not so natural
     to "program", though.

Actually, as I'm writing this, I now favor first-entered/first-used.
One can delete a rule if he wants to override it. It's marginal anyway.

What do you guys think?

Thanks,
-- 
Joel