I tried "darcs record" as shown below, it failed. I am not sure it 
relates to the removing of a sub directory.
"darcs record" worked well until I did the following:

I removed a subdirectory

$rm  -rf test/*

then tried

$darcs remove test

and got error message

"darcs failed:  Can't remove compiler/test"

then tried

$darcs record -am "some changes"
darcs: bug in darcs!
Impossible case at PatchRead.lhs:56 compiled 00:48:54 Dec 27 2005
Please report this to bugs@darcs.net,
If possible include the output of 'darcs --exact-version'.

$darcs --exact-version
darcs compiled on Dec 27 2005, at 00:51:05
unknown

Best regards,
Dana

> I removed a subdirectory
>
> $rm  -rf test/*
>
> then tried
>
> $darcs remove test
>
> and got error message
>
> "darcs failed:  Can't remove compiler/test"

That's probably normal; it already has been removed (perhaps the UI/errors
messages need to be improved)

> $darcs record -am "some changes"
> darcs: bug in darcs!
> Impossible case at PatchRead.lhs:56 compiled 00:48:54 Dec 27 2005

That's not normal.  Thanks for the report.  We would be much obliged if you
could submit a minimal test case.  Also, do you get the same behaviour with a
recent darcs?

N.B, unlike issue394 and its cousins, this is with a darcs record, not a darcs get.

The interesting thing is that "darcs record -am "some changes"" worked on 
the following day, without me doing anything. I mean I left the machine on 
for the night and typed the same command at the same shell the following 
morning and it worked. Could the error relate to time? I am not sure how to 
generate a test case. The "darcs record" works normally from then on.

Best,
Dana. 

On Mar 8 2007, Eric Kow wrote:

>
>Eric Kow <eric.kow@gmail.com> added the comment:
>
>> I removed a subdirectory
>>
>> $rm  -rf test/*
>>
>> then tried
>>
>> $darcs remove test
>>
>> and got error message
>>
>> "darcs failed:  Can't remove compiler/test"
>
>That's probably normal; it already has been removed (perhaps the UI/errors
>messages need to be improved)
>
>> $darcs record -am "some changes"
>> darcs: bug in darcs!
>> Impossible case at PatchRead.lhs:56 compiled 00:48:54 Dec 27 2005
>
> That's not normal. Thanks for the report. We would be much obliged if you 
> could submit a minimal test case. Also, do you get the same behaviour 
> with a recent darcs?
>
> N.B, unlike issue394 and its cousins, this is with a darcs record, not a 
> darcs get.
>
> ---------- priority: -> bug status: unread -> chatting title: cannot 
> record -> record => Impossible case at PatchRead.lhs:56 (ca 2005-12)
>
>____________________________________
>Darcs issue tracker <bugs@darcs.net>
><http://bugs.darcs.net/issue415>
>____________________________________
>

From reviewing the code myself, this issue is "resolved-in-unstable" because the
"impossible case" has been eliminated from the code in Patch/Read.lhs. If you
find a similar issues exists with the Darcs 2 pre-releases, please let us know.