Re: [RFA] Improve "start" command for Ada

[Joel Brobecker <brobecker@adacore.com>]

Hello Elena,

Thanks for the your review.

On Sun, Nov 28, 2004 at 09:08:21PM -0500, Elena Zannoni wrote:
> Joel Brobecker writes:
>  > Ping? (doco already approved by Eli)
>  > 
>  > On Thu, Oct 21, 2004 at 02:09:51PM -0700, Joel Brobecker wrote:
>  > > 2004-10-20  Joel Brobecker  <brobecker@gnat.com>
>  > > 
>  > >         * doc/observer.texi (executable_changed): New observer.
>  > >         * symtab.c: Include "observer.h".
>  > >         (find_main_name): New function.
>  > >         (main_name): If name_of_main is unset, then compute it
>  > >         using find_main_name.
>  > >         (symtab_observer_executable_changed): New function.
>  > >         (_initialize_symtab): Attach executable_changed observer.
>  > >         * exec.c: Include "observer.h".
>  > >         (exec_file_attach): Emit executable_changed notification.
>  > >         * symfile.c: Include "observer.h".
>  > >         (reread_symbols): Send an executable_changed if appropriate.
>  > >         * Makefile.in (exec.o): Add dependency on observer.h.
>  > >         (symfile.o): Likewise.
>  > >         (symtab.o): Likewise.
>  > > 
>  > > Tested on x86-linux. Still fixes 1 FAIL in gdb.ada/null_record.exp.
>  > > 
> 
> We need a testcase where the name of the executable is changed, and
> this code is exercised. Otherwise ok, except for this:

OK, I will add something along the line of reread.exp.

>  > > +/* Deduce the name of the main procedure, and set NAME_OF_MAIN
>  > > +   accordingly.  */
>  > > +
>  > > +static void
>  > > +find_main_name (void)
>  > > +{
>  > > +  char *new_main_name;
>  > > +
>  > > +  /* Try to see if the main procedure is in Ada.  */
>  > > +  new_main_name = ada_main_name ();
>  > > +  if (new_main_name != NULL)
>  > > +    { 
>  > > +      set_main_name (new_main_name);
>  > > +      return;
>  > > +    }
>  > > +
>  > > +  /* The languages above didn't identify the name of the main procedure.
>  > > +     Fallback to "main".  */
>  > > +  set_main_name ("main");
>  > > +}
>  > > +
>  > >  char *
>  > >  main_name (void)
>  > >  {
>  > > -  if (name_of_main != NULL)
>  > > -    return name_of_main;
>  > > -  else
>  > > -    return "main";
>  > > +  if (name_of_main == NULL)
>  > > +    find_main_name ();
>  > > +
>  > > +  return name_of_main;
>  > >  }
>  > >  
> 
> Can this find_main_name become an element in the language vector? I
> really don't want to have a special language cases in the symtab file.

This has actually been discussed already. There were several messages
exchanged between Daniel and myself, but here are some important ones:

    http://sources.redhat.com/ml/gdb-patches/2004-05/msg00607.html
    (one potential confusion if we use the *current* language vector
    to determine the name of main. This is also where the suggestion
    of calling the Ada routine directly was suggested.

    http://sources.redhat.com/ml/gdb-patches/2004-05/msg00612.html
    (we agree that it's ok to call ada_main_name directly)

In short, the answer to the discussion was that this was probably the
best approach for now. The reason why it can't be put in the language
vector is that this is not a property of the language (which can vary
within the same program, depending on the frame), but a property of
the executable. None of us like this approach much, but it was something
that we felt sucked the least.

If you want, what we can do is replace the hard-coded call to
ada_main_name() by a loop of calls to a new language method,
looping on all languages until we find a positive match. That
way, the hard wiring to Ada disappears. But I don't think we're
getting much from this extra slight complexity. 

-- 
Joel