Re: Breakpoint commands in MI mode and "backtrace"

Simon Marchi
2017-10-09T04:16:32Z

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