Re: [patch/rfc, rfa:doco, 6.0] "set backtrace past-main|limit"

[Eli Zaretskii <eliz at elta dot co dot il>]

> Date: Sat, 02 Aug 2003 19:16:18 -0400
> From: Andrew Cagney <ac131313@redhat.com>
> 
> This patch replaces the commands:
> 
> 	set/show backtrace-below-main
> 	show backtrace-below-main
> 
> with the pair of commands:
> 
> 	set/show backtrace past-main
> 	set/show backtrace limit

I'm not sure I like what happens when the backtrace is deeper than
the limit:

> +  if (this_frame->level > backtrace_limit)
> +    {
> +      error ("Backtrace limit of %d exceeded", backtrace_limit);
> +    }
> +

Why should this be anything as scary as `error'?  Isn't a simple
notice (not even a `warning') enough?

> where the latter sets an absolute bound on the number of backtraces. 
> 10000 (arbitrary) by default.

The 10000 default limit is not backward-compatible.  Why not just
leave it at zero, as that's how GDB behaves today?

If we do set the limit by default to some number, that number should
at least be documented in the manual.

> eli, the doco ok?

Yes, but...

> +If you need to examine the startup code, or limit the number of levels
> +in a backtrace, you can change this behavior:
>  
>  @table @code
> -@item set backtrace-below-main off
> +@item set backtrace past-main off
>  Backtraces will stop when they encounter the user entry point.  This is the
>  default.

I think it's better to put "@itemx set backtrace past-main on" first,
and "@item set backtrace past-main off" second, because otherwise the
above fragment of text doesn't make sense: you tell the reader that
the default behavior can be changed, but then show them the command
that sets the default behavior.

> +@item set backtrace limit @var{number}
> +@itemx set backtrace limit 0
> +Limit the the backtrace to @var{number} levels.  A value of zero means
> +unlimited.

I suggest a "@cindex backtrace limit" here.  That way, someone who
types "backtrace" in an Info reader and then hits TAB, will see this
item in the list of possible completions.

Also, isn't it better to use "n" instead of "number" here?  It seems
to me that

  Limit the backtrace to N levels

sounds better in English than

  Limit the backtrace to NUMBER levels

Do you agree?

Finally, note the two consecutive "the" before "backtrace"; a typo.

Otherwise, this docs change is okay; thanks.