Generation from local cabal files broken about cabal2nix

[bennofs]

The reason for this behaviour is that when you give cabal2nix a file path as an argument, it still tries to fetch from hackage (because that's what it did before) and also generates expressions that fetch from hackage. To build a nix expression for a local project, you need to supply cabal2nix a directory:

$ cabal2nix /data/apps/cabal2nix
# This file was auto-generated by cabal2nix. Please do NOT edit manually!

{ cabal, Cabal, doctest, filepath, hackageDb, mtl, regexPosix
, transformers
}:

cabal.mkDerivation (self: {
  pname = "cabal2nix";
  version = "1.69";
  src = ./.;
  isLibrary = false;
  isExecutable = true;
  buildDepends = [
    Cabal filepath hackageDb mtl regexPosix transformers
  ];
  testDepends = [ doctest ];
  doCheck = self.stdenv.lib.versionOlder "7.6" self.ghc.version;
  meta = {
    homepage = "http://github.com/NixOS/cabal2nix";
    description = "Convert Cabal files into Nix build instructions";
    license = self.stdenv.lib.licenses.bsd3;
    platforms = self.ghc.meta.platforms;
  };
})

The logic behind this is that cabal2nix always generates derivations for building from hackage if you supply a cabal file. If you want to build directly from some source, you need to supply the path to that source, not to the cabal file.

$ cabal2nix /data/libs/fsnotify/fsnotify.cabal 
* trying fetcher: url
# This file was auto-generated by cabal2nix. Please do NOT edit manually!

{ cabal, async, hinotify, systemFileio, systemFilepath, tasty
, tastyHunit, text, time
}:

cabal.mkDerivation (self: {
  pname = "fsnotify";
  version = "0.0.11";
  sha256 = "03m911pncyzgfdx4aj38azbbmj25fdm3s9l1w27zv0l730fy8ywq";
  buildDepends = [
    async hinotify systemFileio systemFilepath text time
  ];
  testDepends = [
    async systemFileio systemFilepath tasty tastyHunit
  ];
  meta = {
    description = "Cross platform library for file change notification";
    license = self.stdenv.lib.licenses.bsd3;
    platforms = self.ghc.meta.platforms;
  };
})

There still remains the bug the specifying the sha256 manually didn't work, though. The error message / documentation could probably also be improved to mention this.

[Fuuzetsu]

OK, using directory works but as you say, the bug where we manually specify sha256 remains.