bug#17986: 24.3.92; Evaluating (setq default-directory nil) freezes Emacs

[Stephen Berman]

On Tue, 15 Jul 2014 17:27:48 +0300 Eli Zaretskii <eliz@gnu.org> wrote:

>> I tried doing this, but neither with `s' nor with `f' did gdb show what
>> I could recognize as an infloop (`f' always went straight to frame #0,
>> and `s' never got to a loop, though I entered it very many times).  Is
>> there something more specific I could do the next time?
>
> etc/DEBUG doesn't say to use `s' and `f', it says to use 'finish' and
> 'next'.  'f' is not an abbreviation of 'finish', it is an abbreviation
> of 'frame'.  Also, 'step', or 's', is not useful in this situation,
> because it simply undoes what you did with 'finish', by getting you
> deeper and deeper into the code from which you just emerged.

Oh, dear.  I apologize for my hasty and careless reading of etc/DEBUG.

> The idea of that procedure is to first find the function where Emacs
> loops, by repeated 'finish' commands until 'finish' doesn't return,
> i.e. does not print a higher frame number and the value returned by
> the lower frame.  Then step with 'next' through the looping function
> and see why it loops, i.e. why it fails to return.  (In this case, it
> failed to return because displaying the mode line signaled an error,
> which immediately triggered another redisplay.)

Thanks for the elucidation; I'll try to remember to apply it the next time.

Steve Berman