Re: GDB/MI and ">" prompts

[Eli Zaretskii <eliz at gnu dot org>]

Ping!  Is the patch below OK for committing?

> Date: Sun, 22 Apr 2012 19:04:17 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: gdb-patches@sourceware.org
> 
> [I moved this to gdb-patches, since I propose a patch below.]
> 
> > Date: Thu, 19 Apr 2012 22:24:53 +0300
> > From: Eli Zaretskii <eliz@gnu.org>
> > Cc: gdb@sourceware.org
> > 
> > The crux of my question was why non-interactive mode does display a
> > prompt while the interactive one doesn't.
> 
> To answer my own question, here's why:
> 
>   char *
>   command_line_input (char *prompt_arg, int repeat, char *annotation_suffix)
>   {
>     ...
> 	/* Don't use fancy stuff if not talking to stdin.  */
> 	if (deprecated_readline_hook && input_from_terminal_p ())
> 	  {
> 	    rl = (*deprecated_readline_hook) (local_prompt);
> 	  }
> 	else if (command_editing_p && input_from_terminal_p ())
> 	  {
> 	    rl = gdb_readline_wrapper (local_prompt);
> 	  }
> 	else
> 	  {
> 	    rl = gdb_readline (local_prompt);
> 	  }
> 
> Now, the code is clear, but I cannot say I understand the logic.  If
> the input is from terminal, we ask (inside gdb_readline_wrapper) the
> current interpreter whether to show the prompt.  But if input is _not_
> from terminal, we display the prompt unconditionally (inside
> gdb_readline).  How does this make sense?
> 
> > Date: Thu, 19 Apr 2012 11:53:29 -0700
> > From: Joel Brobecker <brobecker@adacore.com>
> > Cc: gdb@sourceware.org
> > 
> > The other thing that occured to me was that, perhaps, we should instead
> > be switching the interpreter while executing the console command,
> 
> I arrived to the same conclusion, eventually.  See below.
> 
> > but I doubt that would be correct.
> 
> Why not?  The patch below works for me.
> 
> --- gdb/interps.c~0	2012-01-06 06:43:17.000000000 +0200
> +++ gdb/interps.c	2012-04-22 08:55:27.056588400 +0300
> @@ -253,6 +253,18 @@ interp_ui_out (struct interp *interp)
>    return current_interpreter->procs->ui_out_proc (current_interpreter);
>  }
>  
> +/* Temporarily overrides the current interpreter.  */
> +struct interp *
> +interp_set_temp (const char *name)
> +{
> +  struct interp *interp = interp_lookup (name);
> +  struct interp *old_interp = current_interpreter;
> +
> +  if (interp)
> +    current_interpreter = interp;
> +  return old_interp;
> +}
> +
>  /* Returns the interpreter's cookie.  */
>  
>  void *
> --- gdb/interps.h~0	2012-01-06 06:43:17.000000000 +0200
> +++ gdb/interps.h	2012-04-22 08:42:05.687879800 +0300
> @@ -69,6 +69,7 @@
>  extern struct ui_out *interp_ui_out (struct interp *interp);
>  extern void *interp_data (struct interp *interp);
>  extern const char *interp_name (struct interp *interp);
> +extern struct interp *interp_set_temp (const char *name);
>  
>  extern int current_interp_named_p (const char *name);
>  extern int current_interp_display_prompt_p (void);
> --- gdb/cli/cli-script.c~0	2012-01-06 06:43:32.000000000 +0200
> +++ gdb/cli/cli-script.c	2012-04-22 09:04:23.533807200 +0300
> @@ -1178,6 +1178,12 @@ recurse_read_control_structure (char * (
>    return ret;
>  }
>  
> +static void
> +restore_interp (void *arg)
> +{
> +  interp_set_temp (interp_name ((struct interp *)arg));
> +}
> +
>  /* Read lines from the input stream and accumulate them in a chain of
>     struct command_line's, which is then returned.  For input from a
>     terminal, the special command "end" is used to mark the end of the
> @@ -1210,8 +1216,21 @@ read_command_lines (char *prompt_arg, in
>  	}
>      }
>  
> -  head = read_command_lines_1 (read_next_line, parse_commands,
> -			       validator, closure);
> +
> +  /* Reading commands assumes the CLI behavior, so temporarily
> +     override the current interpreter with CLI.  */
> +  if (current_interp_named_p (INTERP_CONSOLE))
> +    head = read_command_lines_1 (read_next_line, parse_commands,
> +				 validator, closure);
> +  else
> +    {
> +      struct interp *old_interp = interp_set_temp (INTERP_CONSOLE);
> +      struct cleanup *old_chain = make_cleanup (restore_interp, old_interp);
> +
> +      head = read_command_lines_1 (read_next_line, parse_commands,
> +				   validator, closure);
> +      do_cleanups (old_chain);
> +    }
>  
>    if (deprecated_readline_end_hook && from_tty && input_from_terminal_p ())
>      {
>