macOS Mojave support?

[paulyoung]

As mentioned in #146 (comment), I upgraded to macOS Mojave and started seeing the following error:

dyld: Library not loaded: /usr/lib/system/libsystem_network.dylib
  Referenced from: /nix/store/8ykfqv6jx9jvfhnc4cdygdzg0piy8253-Libsystem-osx-10.11.6/lib/libSystem.B.dylib
  Reason: image not found

After resolving that in general, I was still seeing it when trying to start a nix-shell with nixfromnpm:

...
building '/nix/store/0aw0k2pzibffd8l71hr29in5wnxmcnwa-remove-references-to.drv'...
dyld: Library not loaded: /usr/lib/system/libsystem_network.dylib
  Referenced from: /nix/store/8ykfqv6jx9jvfhnc4cdygdzg0piy8253-Libsystem-osx-10.11.6/lib/libSystem.B.dylib
  Reason: image not found
builder for '/nix/store/0aw0k2pzibffd8l71hr29in5wnxmcnwa-remove-references-to.drv' failed due to signal 6 (Abort trap: 6)
cannot build derivation '/nix/store/d32g7vmq4lsqj3nnjcg3k7lyv87ycm5y-nixfromnpm-0.13.0.drv': 1 dependencies couldn't be built
error: build of '/nix/store/79n3gcx51shhm650rmr7knwkxa9pppky-stdenv-darwin.drv', '/nix/store/d32g7vmq4lsqj3nnjcg3k7lyv87ycm5y-nixfromnpm-0.13.0.drv' failed

I realized that for nixfromnpm, I was still using the pinned version of nixpkgs that had the issue. I changed that to use my own:

{}:

self: super:

let
  nixfromnpmSrc = self.fetchFromGitHub {
    owner  = "paulyoung"; # Forked from adnelson
    repo   = "nixfromnpm";
    rev    = "ef49d70fffd37aac15ecca0adf1d8839f0840820";
    sha256 = "0knjqqpcm2ssc9p9zaq4bnm6d1403yz4mrnyzyw2lxnby052gyaz";
  };
in
  {
    nixfromnpm = (import "${nixfromnpmSrc}/release.nix" {
      nixpkgs = self.pkgs.src;
    }).nixfromnpm;
  }

But now I'm experiencing another issue that appears to be related to one of the dependencies.

Full trace:

$ nix-shell -p '[((import ../../default.nix {}).pkgs.nixfromnpm)]' --show-trace
error: while evaluating the attribute 'buildInputs' of the derivation 'shell' at /nix/store/6xz41g4cy8xw6rzh474nqkcvfw1xzhlx-nixpkgs-19.09pre171945.b36dc66bfea/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating the attribute 'pkgs.nixfromnpm' at /Users/paulyoung/projects/<my-project>/nix/overlays/nixfromnpm.nix:14:5:
while evaluating the attribute 'nixfromnpm' at /nix/store/1axna3bc1iafvx70wda167i9gqswdwfm-source/release.nix:58:35:
while evaluating the attribute 'buildInputs' of the derivation 'src-1.18' at /nix/store/bhcb0bpfyyq30azmqq5ybmf9rd70jp5n-source/pkgs/stdenv/generic/make-derivation.nix:180:11:
while evaluating the attribute 'handled' at /nix/store/bhcb0bpfyyq30azmqq5ybmf9rd70jp5n-source/pkgs/stdenv/generic/check-meta.nix:246:7:
while evaluating 'handleEvalIssue' at /nix/store/bhcb0bpfyyq30azmqq5ybmf9rd70jp5n-source/pkgs/stdenv/generic/check-meta.nix:142:28, called from /nix/store/bhcb0bpfyyq30azmqq5ybmf9rd70jp5n-source/pkgs/stdenv/generic/check-meta.nix:247:14:
Package ‘rcs-5.9.4’ in /nix/store/bhcb0bpfyyq30azmqq5ybmf9rd70jp5n-source/pkgs/applications/version-management/rcs/default.nix:19 is not supported on ‘x86_64-apple-darwin’, refusing to evaluate.

a) For `nixos-rebuild` you can set
  { nixpkgs.config.allowUnsupportedSystem = true; }
in configuration.nix to override this.

b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
  { allowUnsupportedSystem = true; }
to ~/.config/nixpkgs/config.nix.

[paulyoung]

I tried this on a NixOS VM (nixos-18.09.2327.37694c8cc0e-x86_64-linux):

$ nix-shell -p '[((import ../../default.nix {}).pkgs.nixfromnpm)]' --show-trace
error: while evaluating the attribute 'buildInputs' of the derivation 'shell' at /nix/store/146vj0vji5p4567p8idylfdzgfs4sbpv-nixos-18.09.2327.37694c8cc0e/nixos/pkgs/stdenv/generic/make-derivation.nix:177:11:
while evaluating the attribute 'pkgs.nixfromnpm' at /home/demo/projects/dfinity-lab/dev/nix/overlays/nixfromnpm.nix:14:5:
while evaluating the attribute 'nixfromnpm' at /nix/store/1axna3bc1iafvx70wda167i9gqswdwfm-source/release.nix:58:35:
opening file '/nix/store/y02ybc2xcjmm84k9kzhk677sd0lwqk24-src-1.18/default.nix': No such file or directory

[paulyoung]

So, it turns out I was doing something completely incorrect with nixpkgs = self.pkgs.src; and pulling in the src package. What I wanted was nixpkgs = self.pkgs.src;

I'm still working on getting this to build in Mojave, but it seems like nixpkgs 18.09 and GHC 8.4 is involved (see adnelson/semver-range#14)