[Nix-dev] Permissions error when removing file when using haskellngPackages

[Daniel J Beauregard]

Hi,

I am getting a puzzling error when using Haskell NG on a freshly
installed system.  My ~/.nixpkgs/config.nix is as follows:

------------------------------------
{ ... }:

{
  packageOverrides = super:
    let
      self = super.pkgs;
    in {
      hsEnv = self.haskellngPackages.ghcWithPackages (p: with p; [
        mtl
      ]);
    };
}
------------------------------------

I run 'nix-env --install --attr nixos.pkgs.hsEnv' and get the following:

installing ‘haskell-env-ghc-7.8.4’
these derivations will be built:
  /nix/store/x0msnp6a060gsxzr7x06hiqf4p95bpil-haskell-env-ghc-7.8.4.drv
building path(s) ‘/nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4’
building /nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4
created 46 symlinks in user environment
rm: cannot remove '/nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4/bin/ghc': Permission denied
builder for ‘/nix/store/x0msnp6a060gsxzr7x06hiqf4p95bpil-haskell-env-ghc-7.8.4.drv’ failed with exit code 1
error: build of ‘/nix/store/x0msnp6a060gsxzr7x06hiqf4p95bpil-haskell-env-ghc-7.8.4.drv’ failed

>From what I can tell, the rm is in
pkgs/development/askell-modules/with-packages-wrapper.nix:

  for prg in ghc ghci ghc-${ghc.version} ghci-${ghc.version}; do
    rm -f $out/bin/$prg
    makeWrapper ${ghc}/bin/$prg $out/bin/$prg ...

The permissions on my machine for that particular file and directory:

$ ls -ld /nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4/bin/{.,ghc{,-7.8.4}}
dr-xr-xr-x 1 root root 224 Dec 31  1969 /nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4/bin/.
lrwxrwxrwx 1 root root   9 Dec 31  1969 /nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4/bin/ghc -> ghc-7.8.4
-r-xr-xr-x 1 root root 492 Dec 31  1969 /nix/store/yqw7dp7x4yqcqf26bvygw9ayzypgwxap-haskell-env-ghc-7.8.4/bin/ghc-7.8.4


Any clues on how to debug this?  I am wondering if it has to do with the
user/group assumed by nix-daemon, but I do not have much knowledge about
that aspect.  I noticed that some of the files in /nix/store have a
group of 'nixbld', but many have the group 'root'.

Thanks,
Daniel