From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Jacobowitz <drow@false.org>
To: Joel Brobecker <brobecker@gnat.com>
Cc: gdb-patches@sources.redhat.com
Subject: Re: [RFA/RFC] New command: ``start''
Date: Thu, 20 May 2004 17:14:00 -0000
Message-id: <20040520171404.GA3880@nevyn.them.org>
References: <20040518024700.GV10684@gnat.com> <20040518214712.GD4036@nevyn.them.org> <20040518222740.GZ10684@gnat.com> <20040518224131.GA6026@nevyn.them.org> <20040519153615.GD10684@gnat.com> <20040519154155.GA8567@nevyn.them.org> <20040520010145.GQ10684@gnat.com> <20040520134600.GA11705@nevyn.them.org> <20040520160259.GV10684@gnat.com>
X-SW-Source: 2004-05/msg00612.html

On Thu, May 20, 2004 at 09:02:59AM -0700, Joel Brobecker wrote:
> Here is how we find the name of the main procedure: We lookup a certain
> symbol which is created by our binder, __gnat_ada_main_program_name.
> This symbol points to a string holding the name of the main procedure.
> You'll find the code in ada-lang.c:begin_command().

OK.  So this has the property that I was hoping for; it won't return a
false positive for a non-Ada main program.

> > I think the best approach may be to iterate over the languages
> > included in the object file, asking each of them whether this language
> > appears to contain a main procedure.  Or even to simply skip the
> > langhook complexity and just call an Ada find-main function!  For gcj
> > I suspect we will just change the debug information.
> 
> I thought about several approaches along the same idea. One of them
> was to implement a sniffing mechanism, with certain sniffers having
> certain priorities. But you know, I really like the idea of dropping
> the langhook, and just call the ada function. Something like this:
> 
>         char *
>         main_name ()
>         {
>           /* If we found the name of main from the debug info, or
>              already looked it up, then return the name of main.  */
>           if (name_of_main != NULL)
>             return name_of_main;
> 
>           /* Is the main in Ada?  */
>           tmp_main_name = ada_find_main_name ();
>           if (tmp_main_name != NULL)
>             {
>               set_main_name (tmp_main_name);
>               return name_of_main;
>             }
> 
>           /* Is the main in Java?  */
>           tmp_main_name = java_find_main_name ();
>           [etc...]
> 
>           /* Fallback: main_name must be the usual "main".  */
>           set_main_name ("main);
>           return name_of_main;
>         }
> 
> The only drawback I see from this is that I will need to include
> ada-lang.h. It would have been nice to avoid this, which is possible
> with the langhooks. I could also add the ada_find_main_name()
> declaration in another more common .h file, but that would be a dirty
> trick, IMO.

This is fine with me.  Let's see if anyone else objects to it.

Since I don't know of any language other than Ada that will have a
fallback for this, I don't think it's worth inventing a lot of
machinery for it.  I'm not especially interested in allowing a language
to be compiled out, either.

-- 
Daniel Jacobowitz