Re: Breakpoint commands in MI mode and "backtrace"

[Eli Zaretskii <eliz at gnu dot org>]

> Cc: gdb@sourceware.org
> From: Simon Marchi <simark@simark.ca>
> Date: Sun, 8 Oct 2017 15:24:21 -0400
> 
> But here's the equivalent version with the corresponding cleanup,
> that applies on the 8.0 branch:
> 
> diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
> index f1db954a69..34ae4966de 100644
> --- a/gdb/cli/cli-script.c
> +++ b/gdb/cli/cli-script.c
> @@ -472,6 +472,8 @@ print_command_trace (const char *cmd)
>    printf_filtered ("%s\n", cmd);
>  }
> 
> +static void restore_interp (void *arg);
> +
>  enum command_control_type
>  execute_control_command (struct command_line *cmd)
>  {
> @@ -491,8 +493,14 @@ execute_control_command (struct command_line *cmd)
>        {
>  	/* A simple command, execute it and return.  */
>  	std::string new_line = insert_user_defined_cmd_args (cmd->line);
> -	execute_command (&new_line[0], 0);
> +
> +	struct interp *old_interp = interp_set_temp (INTERP_CONSOLE);
> +	struct cleanup *old_chain = make_cleanup (restore_interp, old_interp);
> +
> +	current_interpreter ()->exec (&new_line[0]);
>  	ret = cmd->control_type;
> +
> +	do_cleanups (old_chain);
>  	break;
>        }

Thanks, this works, but it seems to fail hookpost hooks.  The Emacs
.gdbinit file defines a hookpost-backtrace command to produce a
Lisp-level backtrace, and with this change that fails:

  ~"Lisp Backtrace:\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"
  &"Argument to arithmetic operation not a number or boolean.\n"

Whereas without the patch, the C-level backtrace is not shown, but the
Lisp-level backtrace is shown correctly:

  ~"Lisp Backtrace:\n"
  ~"\"redraw-display\""
  ~" (0x82de90)\n"
  ~"\"funcall-interactively\""
  ~" (0x82de88)\n"
  ~"\"call-interactively\""
  ~" (0x82e1e0)\n"
  ~"\"command-execute\""
  ~" (0x82e738)\n"
  ~"\"execute-extended-command\""
  ~" (0x82ee20)\n"
  ~"\"funcall-interactively\""
  ~" (0x82ee18)\n"
  ~"\"call-interactively\""
  ~" (0x82f220)\n"
  ~"\"command-execute\""
  ~" (0x82f748)\n"

> > In any case, there are more instances of calls to execute_command in
> > that function, and I guess they all need to be changed like that?
> 
> I don't see any other call.

You are right, sorry.

Thanks.