Re: minimalistic MI catch support

[Eli Zaretskii <eliz@gnu.org>]

> From: Nick Roberts <nickrob@snap.net.nz>
> Date: Fri, 10 Feb 2006 19:33:28 +1300
> 
> (gdb) catch catch
> Catchpoint 2 (catch)
> (gdb) catch throw
> Catchpoint 3 (throw)
> (gdb) catch fork
> Catchpoint 4 (fork)
> (gdb) catch exec
> Catchpoint 5 (exec)
> (gdb) info break
> Num Type           Disp Enb Address    What
> 2   breakpoint     keep y   0x07dae1aa exception catch
> 3   breakpoint     keep y   0x07daf001 exception throw
> 4   catch fork     keep y
> 5   catch exec     keep y
> 
> The first two are of type breakpoint and their nature is given under the
> heading "What".
> 
> The second two have their own type: "catch fork" and "catch exec" (I must
> admit that I don't understand how this gives differerent behaviour from using
> "break fork" and "break exec").  Also for some reason, they have no address.

I think this is a bug (or undocumented misfeature) in
breakpoint.c:handle_gnu_v3_exceptions.  You will see that it sets the
type of the raw breakpoint it creates to bp_breakpoint, instead of
using the argument ex_event that is passed by the caller.  In
addition, for some reason, it forces a special function to be used for
printing these catchpoints, and that function
(print_one_exception_catchpoint) doesn't use the list of descriptions
in the bptypes[] array used by the more general code in
print_one_breakpoint.  I think it's bad to have more than one place to
have these description strings.

Can someone explain why we should use special code for gnu_v3
exceptions?

As for the address not being printed, can you step with a debugger
through the function that prints these breakpoints and see why they
are skipped?  I cannot for the moment see any reason, just looking at
the code.