flakelike

pkgs/top-level/default.nix

@@ -0,0 +1,21 @@
+{ inputs ? import ../../inputs.nix {}
+, uninitializedNixpkgs ? import "${inputs.nixpkgs}/pkgs/top-level/default.nix"
+, ...
+} @ args:
+
+let
+  attrsToRemove = [
+    "inputs"
+    "overlays"
+    "uninitializedNixpkgs"
+  ];
+
+  options = (builtins.removeAttrs args attrsToRemove) // {
+    overlays = (args.overlays or []) ++ [
+      ( import ../overlays/selfExpr.nix { nixpkgsPath = ./impure.nix; } )
+      ( import ../overlays/unstable.nix )
+      ( import ../overlays/version-info-fixup.nix { inherit inputs; } )
+    ];
+  };
+in
+uninitializedNixpkgs options

pkgs/top-level/impure.nix

@@ -0,0 +1,70 @@
+# Modified copy of github:NixOS/nixpkgs pkgs/top-level/impure.nix
+# as of commit 242522b8fed8d63f262fd6e747ba1e4372b59a8e
+
+# I wish I could just import from nixpkgs and set different path to entry point.
+
+let
+  homeDir = builtins.getEnv "HOME";
+
+  # Return ‘x’ if it evaluates, or ‘def’ if it throws an exception.
+  try = x: def: let res = builtins.tryEval x; in if res.success then res.value else def;
+in
+
+{ localSystem ? { system = args.system or builtins.currentSystem; }
+, system ? localSystem.system
+, crossSystem ? localSystem
+, config ? let
+      configFile = builtins.getEnv "NIXPKGS_CONFIG";
+      configFile2 = homeDir + "/.config/nixpkgs/config.nix";
+      configFile3 = homeDir + "/.nixpkgs/config.nix"; # obsolete
+    in
+      if configFile != "" && builtins.pathExists configFile then import configFile
+      else if homeDir != "" && builtins.pathExists configFile2 then import configFile2
+      else if homeDir != "" && builtins.pathExists configFile3 then import configFile3
+      else {}
+, overlays ? let
+      isDir = path: builtins.pathExists (path + "/.");
+      pathOverlays = try (toString <nixpkgs-overlays>) "";
+      homeOverlaysFile = homeDir + "/.config/nixpkgs/overlays.nix";
+      homeOverlaysDir = homeDir + "/.config/nixpkgs/overlays";
+      overlays = path:
+        # check if the path is a directory or a file
+        if isDir path then
+          # it's a directory, so the set of overlays from the directory, ordered lexicographically
+          let content = builtins.readDir path; in
+          map (n: import (path + ("/" + n)))
+            (builtins.filter
+              (n:
+                (builtins.match ".*\\.nix" n != null &&
+                 # ignore Emacs lock files (.#foo.nix)
+                 builtins.match "\\.#.*" n == null) ||
+                builtins.pathExists (path + ("/" + n + "/default.nix")))
+              (builtins.attrNames content))
+        else
+          # it's a file, so the result is the contents of the file itself
+          import path;
+    in
+      if pathOverlays != "" && builtins.pathExists pathOverlays then overlays pathOverlays
+      else if builtins.pathExists homeOverlaysFile && builtins.pathExists homeOverlaysDir then
+        throw ''
+          Nixpkgs overlays can be specified with ${homeOverlaysFile} or ${homeOverlaysDir}, but not both.
+          Please remove one of them and try again.
+        ''
+      else if builtins.pathExists homeOverlaysFile then
+        if isDir homeOverlaysFile then
+          throw (homeOverlaysFile + " should be a file")
+        else overlays homeOverlaysFile
+      else if builtins.pathExists homeOverlaysDir then
+        if !(isDir homeOverlaysDir) then
+          throw (homeOverlaysDir + " should be a directory")
+        else overlays homeOverlaysDir
+      else []
+, crossOverlays ? []
+, ...
+} @ args:
+
+# Assertion checked in called nixpkgs upstream, thus removed here
+
+import ./. (builtins.removeAttrs args [ "system" ] // {
+  inherit config overlays localSystem;
+})