flake.nix

@@ -23,8 +23,10 @@
       in
       {
         inherit pkgs;
-        packages.default = pkgs.nixVersions.nix_2_18;
+        packages = {
-        packages.nix-doc = pkgs.nix-doc;
+          default = pkgs.nixVersions.nix_2_18;
+          inherit (pkgs) nix-doc nix-eval-jobs;
+        };
 
         packages.system-profile = import ./system-profile.nix { inherit pkgs flakey-profile; };
       });

npins/default.nix

@@ -0,0 +1,47 @@
+# Generated by npins. Do not modify; will be overwritten regularly
+let
+  data = builtins.fromJSON (builtins.readFile ./sources.json);
+  version = data.version;
+
+  mkSource = spec:
+    assert spec ? type; let
+      path =
+        if spec.type == "Git" then mkGitSource spec
+        else if spec.type == "GitRelease" then mkGitSource spec
+        else if spec.type == "PyPi" then mkPyPiSource spec
+        else if spec.type == "Channel" then mkChannelSource spec
+        else builtins.throw "Unknown source type ${spec.type}";
+    in
+    spec // { outPath = path; };
+
+  mkGitSource = { repository, revision, url ? null, hash, ... }:
+    assert repository ? type;
+    # At the moment, either it is a plain git repository (which has an url), or it is a GitHub/GitLab repository
+    # In the latter case, there we will always be an url to the tarball
+    if url != null then
+      (builtins.fetchTarball {
+        inherit url;
+        sha256 = hash; # FIXME: check nix version & use SRI hashes
+      })
+    else assert repository.type == "Git"; builtins.fetchGit {
+      url = repository.url;
+      rev = revision;
+      # hash = hash;
+    };
+
+  mkPyPiSource = { url, hash, ... }:
+    builtins.fetchurl {
+      inherit url;
+      sha256 = hash;
+    };
+
+  mkChannelSource = { url, hash, ... }:
+    builtins.fetchTarball {
+      inherit url;
+      sha256 = hash;
+    };
+in
+if version == 3 then
+  builtins.mapAttrs (_: mkSource) data.pins
+else
+  throw "Unsupported format version ${toString version} in sources.json. Try running `npins upgrade`"

npins/sources.json

@@ -0,0 +1,16 @@
+{
+  "pins": {
+    "nix-eval-jobs": {
+      "type": "Git",
+      "repository": {
+        "type": "Git",
+        "url": "git+ssh://git@git.lix.systems/lheckemann/nix-eval-jobs"
+      },
+      "branch": "main",
+      "revision": "c3d8ca19b39f4cc5a2df1061baf649d1fe20517e",
+      "url": null,
+      "hash": "1bww5ymy9klysm5z5hi1i8604b4dfrkrvikhslwv0vkrbwvfk5p0"
+    }
+  },
+  "version": 3
+}

overlay.nix

@@ -19,6 +19,11 @@ let
   lix-doc = final.callPackage (lix + "/lix-doc/package.nix") { };
 in
 {
+  # used for things that one wouldn't necessarily want to update, but we
+  # nevertheless shove it in the overlay and fixed-point it in case one *does*
+  # want to do that.
+  lix-sources = import ./npins;
+
   nixVersions = prev.nixVersions // rec {
     # FIXME: do something less scuffed
     nix_2_18 = (prev.nixVersions.nix_2_18.override { boehmgc = boehmgc-patched; }).overrideAttrs (old: {
@@ -47,6 +52,18 @@ in
     nix_2_18_upstream = prev.nixVersions.nix_2_18;
   };
 
+  nix-eval-jobs = (prev.nix-eval-jobs.override {
+    # lix
+    nix = final.nixVersions.nix_2_18;
+  }).overrideAttrs (old: {
+    # FIXME: should this be patches instead?
+    src = final.lix-sources.nix-eval-jobs;
+
+    mesonBuildType = "debugoptimized";
+
+    ninjaFlags = old.ninjaFlags or [ ] ++ [ "-v" ];
+  });
+
   # force these onto upstream so we are not regularly rebuilding electron
   prefetch-yarn-deps = prev.prefetch-yarn-deps.override {
     nix = final.nixVersions.nix_2_18_upstream;