nix: update to latest nixpkgs-unstable (a bit of a rough one)

- Cherry picked NixOS/nixpkgs#159516
- Starship workaround: NixOS/nixpkgs#160876

home/.nixpkgs/darwin-configuration.nix

@@ -2,6 +2,9 @@
 
 let
   overlays = import ./overlays.nix;
+  starship = pkgs.callPackage ./pkgs/starship.nix {
+    inherit (pkgs.darwin.apple_sdk.frameworks) Security;
+  };
 in
 {
   imports = [
@@ -29,7 +32,7 @@ in
       pkgs.ripgrep
       pkgs.sd
       pkgs.skim
-      pkgs.starship
+      starship # https://github.com/NixOS/nixpkgs/issues/160876#issuecomment-1046370485
       pkgs.tealdeer
       pkgs.yq
 
@@ -91,8 +94,8 @@ in
       pkgs.neovim
       pkgs.vim-vint
 
-      pkgs.python39Packages.pynvim
-      pkgs.python39Packages.grip
+      pkgs.python310Packages.pynvim
+      pkgs.python310Packages.grip
 
       #
       # Network utilities

home/.nixpkgs/overlays.nix

@@ -12,10 +12,6 @@ rec {
   #   buildInputs = oldAttrs.buildInputs ++ [ super.pkgs.tree-sitter ];
   # });
 
-  nixUnstable = super.nixUnstable.override {
-    patches = [ patches/unset-is-macho.patch ];
-  };
-
   darwin-zsh-completions = super.runCommandNoCC "darwin-zsh-completions-0.0.0"
     { preferLocalBuild = true; }
     ''

home/.nixpkgs/pkgs/starship.nix

@@ -0,0 +1,54 @@
+{ lib
+, stdenv
+, fetchFromGitHub
+, rustPlatform
+, pkg-config
+, openssl
+, installShellFiles
+, libiconv
+, nixosTests
+, Security
+}:
+
+rustPlatform.buildRustPackage rec {
+  pname = "starship";
+  version = "1.2.1";
+
+  src = fetchFromGitHub {
+    owner = "starship";
+    repo = pname;
+    rev = "v${version}";
+    sha256 = "sha256-5MJA8eHo1enOHlLpAOF1iDvOHCS/Nw0sc84VWu9nApE=";
+  };
+
+  nativeBuildInputs = [ installShellFiles ] ++ lib.optionals stdenv.isLinux [ pkg-config ];
+
+  buildInputs = lib.optionals stdenv.isLinux [ openssl ]
+    ++ lib.optionals stdenv.isDarwin [ libiconv Security ];
+
+  buildFeatures = lib.optional (!stdenv.isDarwin) "notify-rust";
+
+  postInstall = ''
+    for shell in bash fish zsh; do
+      STARSHIP_CACHE=$TMPDIR $out/bin/starship completions $shell > starship.$shell
+      installShellCompletion starship.$shell
+    done
+  '';
+
+  cargoSha256 = "sha256-DTQQFxj6stzlVzSdmv4J4Nsf8X/VMlwvfIumnuK0YDo=";
+
+  preCheck = ''
+    HOME=$TMPDIR
+  '';
+
+  passthru.tests = {
+    inherit (nixosTests) starship;
+  };
+
+  meta = with lib; {
+    description = "A minimal, blazing fast, and extremely customizable prompt for any shell";
+    homepage = "https://starship.rs";
+    license = licenses.isc;
+    maintainers = with maintainers; [ bbigras danth davidtwco Br1ght0ne Frostman marsam ];
+  };
+}