1. Summarise the issue (what were doing, what went wrong?)

I did 'darcs amend', selected a patch, added some stuff. Darcs said:

darcs failed:  bug at src/Darcs/Repository/PatchIndex.hs:246 compiled
Apr  4 2014 21:10:43

I attached the complete shell session in darcsbug.txt, including the
output of darcs --exact-version and uname -a.

Attachments

• darcsbug.txt

I attached a tar ball of the repo, taken directly after the failed amend.

Attachments

• nix-support.tar.gz

It seems that despite the crash the amend completed successfully:

ben@sarun[1]: .../Epics/nix-support > darcs changes
Sat Apr 12 21:38:50 CEST 2014  Ben Franksen
<benjamin.franksen@helmholtz-berlin.de>
  * added setup.sh, replaces /etc/profile.d stuff
Shall I view this patch? (1/?) [yN...], or ? for more options: x
    Sat Apr 12 21:38:50 CEST 2014  Ben Franksen
<benjamin.franksen@helmholtz-berlin.de>
      * added setup.sh, replaces /etc/profile.d stuff
    
        A ./setup.sh
Shall I view this patch? (1/?) [yN...], or ? for more options: q

I guess this will be hard to debug since the original patch I amended is
now lost. I can try to explain what the situation was IIRC:

I changed scripts/setup.sh, then (darcs move)-d it to ., then recorded.
Then I removed scripts (with a few remaining files) and recorded that.
Then I changed setup.sh again and amend the first of the two patches and
that is where the crash happened.

The repo is now broken. I tried to record some more stuff and got the
same error:

ben@sarun[1]: .../Epics/nix-support > darcs record pkgs/config.nix 
Recording changes in "pkgs/config.nix":

hunk ./pkgs/config.nix 6
-    epics_base = callPackage epics/base/full.nix { version =
"3.14.12.4"; };
-
-    epics_base_3_14_12_3 = callPackage epics/base/full.nix { version =
"3.14.12.3"; };
-
-#    epics_catools = callPackage epics/base/catools.nix {};
-#     epics_base = callPackage epics/base { base = epics_base; };
-#    sequencer = callPackage epics/seq { version = "2.1.16"; base =
epics_base; };
-
-    seq = {hash}: callPackage epics/local.nix {
-      name = "seq";
-      version = "2.1.16";
-      repo = "epics/support/seq/branch-2-1";
-      deps = { EPICS_BASE = epics_base; };
-      extraInputs = [ re2c ];
-      inherit hash;
-    };
-
-#     epics_env = myEnvFun {
-#       name = "epics-devel";
-#       shell = "zsh -l";
-#       extraCmds = ''
-#         export EPICS_HOST_ARCH=linux-x86_64
-#         export PERL5LIB=.nix-profile/lib/perl:$PERL5LIB
-#       '';
-#       buildInputs = [ stdenv perl readline re2c epics_base sequencer ];
-#     };
+    nix-make = callPackage epics/build-support/nix-make {};
Shall I record this change? (1/1)  [ynW...], or ? for more options: y
Do you want to record these changes? [Yglqk...], or ? for more options: y
What is the patch name? removed everything except fetchdarcs and
nix-make from config.nix 
Do you want to add a long comment? [yn]n

darcs failed:  bug at src/Darcs/Repository/PatchIndex.hs:246 compiled
Apr 12 2014 22:01:47
couldn't find ./scripts in patch index
See http://wiki.darcs.net/BugTracker/Reporting for help on bug reporting.
Failed to record patch 'removed everything except fetchdarcs and
nix-make from config.nix'

BTW, darcs is lying: it did record the new patch:

ben@sarun[1]: .../Epics/nix-support > darcs changes
Sat Apr 12 22:14:21 CEST 2014  Ben Franksen
<benjamin.franksen@helmholtz-berlin.de>
  * removed everything except fetchdarcs and nix-make from config.nix
Shall I view this patch? (1/?) [yN...], or ? for more options: q

I don't get the error with darcs-2.8.4.

I verified my suspicion that the error lies in the patches by Jose Luis
Neder that implement detection of replaces and moves and that need the
unreleased hashed-storage version that is currently bundled with the
darcs sources. When I obliterate these patches:

ben@sarun[1]: .../darcs/screened > darcs pull --dry-run   
Would pull from "http://darcs.net/screened"...
Welcome to the darcs screened repository.

If you would like to contribute, please read our guide for contributors:
http://wiki.darcs.net/Development/GettingStarted

Thanks and happy hacking!
**********************
Would pull the following changes:
Fri Jan 10 00:00:42 CET 2014  Jose Luis Neder <jlneder@gmail.com>
  * Show fileid info with show index
  Update timestamp index with new adds and moves in pending
  (darcs mv, darcs add)
  Require hashed-storage 0.5.11

Mon Sep 16 01:41:26 CEST 2013  Jose Luis Neder <jlneder@gmail.com>
  * resolve issue642: Automatic detection of file renames

Fri Jan 10 05:20:13 CET 2014  Jose Luis Neder <jlneder@gmail.com>
  * resolve issue2209: Automatically detect replace
  This patch add the flag --look-for-replaces to amend-record, record and
  whatsnew commands, to automatically detect possible replaces.

Fri Feb  7 20:29:23 CET 2014  Ganesh Sittampalam <ganesh@earth.li>
  * we need utf8-string on Windows too now for the fast-export/import code

Fri Feb  7 11:59:11 CET 2014  Dan Frumin <difrumin@gmail.com>
  * Cleaning up the headers in WhatsNew and SelectChanges
  

Fri Feb  7 12:00:51 CET 2014  Dan Frumin <difrumin@gmail.com>
  * resolve issue851: interactive mode for whatsnew

Sun Mar 16 15:47:49 CET 2014  Ganesh Sittampalam <ganesh@earth.li>
  * conditionally use local copy of Data.Map.Strict in Darcs.Repository.Util
  This is needed for building with containers<0.5, e.g. on Debian stable

Tue Apr  8 18:45:28 CEST 2014  Ale Gadea <alex.aegf@gmail.com>
  * Resolve Issue1416: put log files in tempdir instead of in working dir.
    
  The temporary files are found in _darcs.
  For the commands amend-record, record and tag, the temp file is
patch_description.txt
  and is persistent, ie always have the last message whether failed or
not the command.
  For send, we use two files, darcs-send for the editing and
darcs-send.final for the 
  backup. If all is ok, the files are removed.


and then remove the bundled hashed-storage from my cabal sandbox, and
then fix one line in the code:

ben@sarun[1]: .../darcs/screened > darcs record 
hunk ./src/Darcs/UI/Commands/Record.hs 280
-                 when (isJust logf) $ removeFile (fromJust logf)
+                 case logf of Nothing -> return (); Just f -> removeFile f
Shall I record this change? (1/1)  [ynW...], or ? for more options: y
Do you want to record these changes? [Yglqk...], or ? for more options: y
What is the patch name? fixed missing import of fromJust by not using it
(better style)

then I get a working version that does not choke on my repository.

I suggest that these patches (and/or the bundled hashed-storage version)
need serious review and fixing!

I don't know what made me think the error is gone. It is still there.

I am sorry. The patches I accused are probably innocent.

Now I am at a loss. I think I will have to temporarily revert to using
2.8.4 for my daily work until this is fixed. Too bad, I have been
growing very fond of some of the new features lately...

Just to clarify - are you able to reproduce it now? If so and if you could 
encode that in a shell script it would be very helpful.

I tried to reproduce it with a small toy example but failed so far.
Fortunately the repo I attached to the issue is small and has only a few
patches in it. You should be able to reproduce the bug by unpacking it,
and saying 'darcs changes scripts'.

See also issue2378

It seem this has been fixed somehow in the meantime because I can no
longer reproduce it with the attached repo.