[Nix-dev] Hydra evaluation error: value is an attribute set while a string was expected

[Bjørn Forsman]

Hi,

It seems I've committed something that breaks the channel (sorry!).
Hydra has these evaluation errors[1]:

[...]
at `nixpkgs.linuxPackages.lttngModules.i686-linux' [nixosSrc = ...,
nixpkgs = ..., officialRelease = false]:
value is an attribute set while a string was expected
[...]

Unfortunately, I'm unable to figure out *which* value it complains
about. "nix-build -A linuxPackages.lttngModules" runs fine on my
system, so I'm thinking its something with the meta attributes. Btw, I
wouldn't mind a more helpful error message, one with a bit more
context. Hint Hint ;-)

The lttngModules expression is this

{ stdenv, fetchurl, kernelDev }:

stdenv.mkDerivation rec {
  pname = "lttng-modules-2.2.1";
  name = "${pname}-${kernelDev.version}";

  src = fetchurl {
    url = "https://lttng.org/files/lttng-modules/${pname}.tar.bz2";
    sha256 = "00ww1443ssv614s1ix6zby8llaf6zzlxcf5k4w7jsyji47ng33m2";
  };

  patches = [ ./lttng-fix-build-error-on-linux-3.2.patch ];

  preConfigure = ''
    export KERNELDIR="${kernelDev}/lib/modules/${kernelDev.modDirVersion}/build"
    export INSTALL_MOD_PATH="$out"
  '';

  installPhase = ''
    make modules_install
  '';

  meta = with stdenv.lib; {
    description = "Linux kernel modules for LTTng tracing";
    homepage = http://lttng.org/;
    license = with licenses; [ lgpl21 gpl2 mit ];
    platforms = platforms.linux;
    maintainers = [ maintainers.bjornfor ];
  };

}

Does anyone see what is wrong?

How do I reproduce this locally?

[1]: http://hydra.nixos.org/jobset/nixos/trunk-combined#tabs-errors