Re: a bug of zsh

[Mikael Magnusson <mikachu@xxxxxxxxx>]

On Wed, Sep 28, 2016 at 5:04 PM, Peter Stephenson
<p.stephenson@xxxxxxxxxxx> wrote:
> On Wed, 28 Sep 2016 22:06:25 +0800
> ZiHan Zheng <zhengzihan1996@xxxxxxxxx> wrote:
>> to reproduce this bug:
>>
>> cd ~
>> mkdir aaa
>> cd aaa
>> rm ~/aaa -r
>> cd .
>>
>> then current working directory is just "." and you can do nothing until cd
>> into an absolute path.
>
> Hmmm... I can see you're point, I think --- before you do "cd .", the
> shell will happily use the logical directory structure to e.g. "cd ..",
> whereas after you do "cd ." you're stuck without something like cd
> $PWD/..
>
> It would certainly be good if there's some way of aborting the "cd ."
> consistently so we both don't actually change directory and don't lose
> state.  I think the problem may be once we find we can't cd any more we
> throw up our hands in horror and decide we don't know where we are,
> which is certainly a bit feeble, particularly since there's no
> outward indication of a problem until you find you're trapped.
>
> Is there some reason we can't just stat the directory first and bail
> out early? I know it's prohibitively expensive testing glob results
> with stat, but this is a rather different case.
>
> However, the cd logic is already more complicated than you would
> probably believe, and changing to a directory that no longer exists
> isn't going to have good effects, so I'm not sure how much sleep we're
> (well, I'm) actually going to lose over this, to be brutally honest.

FWIW this is only a problem if you use nochasedots/nochaselinks, which
while it is the default, is overall a very confusing option to have
set and hopefully most people disable it. In either case you can
always do cd -P .. to get out as well. I feel like it should be
possible to get the -L branch to detect this state and fall back to a
-P .. but honestly I'm not sure if the current state is unintended for
-L or not.

-- 
Mikael Magnusson