Re: Breakpoint commands in MI mode and "backtrace"

[Simon Marchi <simark at simark dot ca>]

On 2017-10-08 04:02 PM, Eli Zaretskii wrote:
>> 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"

Hmm, strange.  It is a quite complex function being executed in the hookpost-backtrace.
Do you have any idea what line generates the error?  It would be nice to have a
reproducer without having to build emacs...

Thanks,

Simon