inputs: pin nixpkgs-unstable

inputs.nix

@@ -15,6 +15,11 @@ let self = {
     url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs.revision}.tar.gz";
     sha256 = "${lock.nixpkgs.sha256}";
   };
+  nixpkgs-unstable = builtins.fetchTarball {
+    name = "nixpkgs-unstable";
+    url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs-unstable.revision}.tar.gz";
+    sha256 = "${lock.nixpkgs-unstable.sha256}";
+  };
   cosmic-modules = builtins.fetchTarball {
     name = "cosmic-modules";
     url = "https://github.com/lilyinstarlight/nixos-cosmic/archive/${lock.cosmic-modules.revision}.tar.gz";

lock.nix

@@ -7,6 +7,10 @@
     revision = "3f0a8ac25fb674611b98089ca3a5dd6480175751";
     sha256 = "10i7fllqjzq171afzhdf2d9r1pk9irvmq5n55h92rc47vlaabvr4";
   };
+  nixpkgs-unstable = {
+    revision = "130595eba61081acde9001f43de3248d8888ac4a";
+    sha256 = "0sw7zg4gal3wpz51ch1v36pdan9z73d4f3yrggh8h2clxs8jdgsx";
+  };
   cosmic-modules = {
     revision = "a934c861065b6b1aca9a859c45631336e0e8560c";
     sha256 = "1p0hs2z1h9fl25qvrlprf63cj1v0m7hr2y051mykjvdxikvn5a47";

nix-os/unstable-packages.nix

@@ -1,8 +1,14 @@
-{config, pkgs, lib, ...}:
+{
+  config,
+  lib,
+  pkgs,
+  self,
+  ...
+}:
 
 let
   cfg = config.unstable;
-  unstableOverlay = import ../pkgs/overlays/unstable.nix;
+  unstableOverlay = self.overlays.unstableWithMeta;
 in
 {
   options.unstable = {

outputs.nix

@@ -15,7 +15,7 @@ self = {
   overlays = {
     cosmicPackages = import ./pkgs/overlays/cosmic-packages.nix { inherit inputs; };
     selfExpr = import ./pkgs/overlays/selfExpr.nix { nixpkgsPath = inputs.nixpkgs; };
-    unstable = import ./pkgs/overlays/unstable.nix;
+    unstableWithMeta = import ./pkgs/overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; };
     versionInfoFixup = import ./pkgs/overlays/version-info-fixup.nix { inherit inputs; };
   };
   nixosConfigurations = let

pkgs/overlays/unstable-with-meta.nix

@@ -0,0 +1,16 @@
+{
+  unstableSource,
+  revision,
+}: self: super:
+
+let
+  version = builtins.readFile "${unstableSource}/lib/.version" + ".git." + builtins.substring 0 12 revision;
+  useUnstable = self.config.useUnstable or true;
+
+in
+import ./unstable-from-source.nix {
+  inherit unstableSource;
+} self super // {
+  unstableVersion = self.lib.optionalString useUnstable version;
+  unstableRevision = self.lib.optionalString useUnstable revision;
+}

pkgs/overlays/unstable.nix

@@ -1,24 +0,0 @@
-self: super:
-
-let
-  nixos = self.config.nixos or true;
-  useUnstable = self.config.useUnstable or true;
-
-  unstablePkgsExprs = if nixos
-      then builtins.fetchTarball "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz"
-      else builtins.fetchTarball "https://channels.nixos.org/nixpkgs-unstable/nixexprs.tar.xz";
-
-  # Compiled nixpkgs expression eg expressions from a nix channel
-  nixpkgsVersion = builtins.concatStringsSep "." [
-    (builtins.readFile "${unstablePkgsExprs}/.version")
-    (builtins.readFile "${unstablePkgsExprs}/.version-suffix")
-  ];
-
-  nixpkgsRevision = (builtins.readFile "${unstablePkgsExprs}/.git-revision");
-in
-import ./unstable-from-source.nix {
-  unstableSource = unstablePkgsExprs;
-} self super // {
-  unstableVersion = self.lib.optionalString useUnstable nixpkgsVersion;
-  unstableRevision = self.lib.optionalString useUnstable nixpkgsRevision;
-}

pkgs/top-level/default.nix

@@ -14,7 +14,7 @@ let
     overlays = (args.overlays or []) ++ [
       # ../.. should be nix store path that represents self in outputs.nix that is gc-rooted by this point
       ( import ../overlays/selfExpr.nix { nixpkgsPath = "${builtins.toString ../..}/pkgs/top-level/impure.nix"; } )
-      ( import ../overlays/unstable.nix )
+      ( import ../overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; } )
       ( import ../overlays/version-info-fixup.nix { inherit inputs; } )
       ( import ./by-name-overlay.nix ../by-name )
     ];