Commit 3f11515a authored by Adam Joseph's avatar Adam Joseph
Browse files

units: fix build with enableCurrenciesUpdater=false; pythonPackages=null; 

Units allows to build it without a python dependency by setting {
enableCurrenciesUpdater=false; pythonPackages=null; }.  Unfortunately
this feature is currently broken due to two problems:

1. The `pythonEnv` string is part of the builder environment, so it is
   not evaluated lazily.  This means that `pythonPackages==null` will
   always cause eval to fail.

2. `pythonEnv` is used unconditionally in an antiquotation in the
   `prePatch` phase; if it is null this will fail.

Let's fix these so we can build a pythonless "units" package.

This is helpful when cross-compiling, because right now a lot of
python packages (especially python-cryptography) fail to
cross-compile.
parent 7bc6fbcd

pkgs/tools/misc/units/default.nix

+5 −6
Original line number Diff line number Diff line
@@ -9,7 +9,10 @@ 


assert enableCurrenciesUpdater -> pythonPackages != null;



stdenv.mkDerivation rec {

let pythonEnv = pythonPackages.python.withPackages(ps: [

      ps.requests

    ]);

in stdenv.mkDerivation rec {

  pname = "units";

  version = "2.21";
@@ -18,16 +21,12 @@ stdenv.mkDerivation rec { 
    sha256 = "sha256-bD6AqfmAWJ/ZYqWFKiZ0ZCJX2xxf1bJ8TZ5mTzSGy68=";

  };



  pythonEnv = pythonPackages.python.withPackages(ps: [

    ps.requests

  ]);



  buildInputs = [ readline ]

    ++ lib.optionals enableCurrenciesUpdater [

      pythonEnv

    ]

  ;

  prePatch = ''

  prePatch = lib.optionalString enableCurrenciesUpdater ''

    substituteInPlace units_cur \

      --replace "#!/usr/bin/env python" ${pythonEnv}/bin/python

  '';