flake: Update to NixOS 23.11

About time :)

This required disabling `bear` on darwin as it's currently broken (fixed
on master, but not yet on 23.11).

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05-small";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11-small";
   inputs.nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
   inputs.flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
   inputs.libgit2 = { url = "github:libgit2/libgit2"; flake = false; };
@@ -10,20 +10,10 @@
 
     let
       inherit (nixpkgs) lib;
-
-      # Experimental fileset library: https://github.com/NixOS/nixpkgs/pull/222981
-      # Not an "idiomatic" flake input because:
-      #  - Propagation to dependent locks: https://github.com/NixOS/nix/issues/7730
-      #  - Subflake would download redundant and huge parent flake
-      #  - No git tree hash support: https://github.com/NixOS/nix/issues/6044
-      inherit (import (builtins.fetchTarball { url = "https://github.com/NixOS/nix/archive/1bdcd7fc8a6a40b2e805bad759b36e64e911036b.tar.gz"; sha256 = "sha256:14ljlpdsp4x7h1fkhbmc4bd3vsqnx8zdql4h3037wh09ad6a0893"; }))
-        fileset;
+      inherit (lib) fileset;
 
       officialRelease = false;
 
-      # Set to true to build the release notes for the next release.
-      buildUnreleasedNotes = false;
-
       version = lib.fileContents ./.version + versionSuffix;
       versionSuffix =
         if officialRelease
@@ -405,7 +395,9 @@
             XDG_DATA_DIRS+=:$out/share
           '';
           nativeBuildInputs = attrs.nativeBuildInputs or []
-            ++ lib.optional stdenv.cc.isClang pkgs.buildPackages.bear
+            # TODO: Remove the darwin check once
+            # https://github.com/NixOS/nixpkgs/pull/291814 is available
+            ++ lib.optional (stdenv.cc.isClang && !stdenv.isDarwin) pkgs.buildPackages.bear
             ++ lib.optional (stdenv.cc.isClang && stdenv.hostPlatform == stdenv.buildPlatform) pkgs.buildPackages.clang-tools;
         });
         in

package.nix

@@ -154,7 +154,7 @@ in {
     in
       fileset.toSource {
         root = ./.;
-        fileset = fileset.intersect baseFiles (fileset.unions ([
+        fileset = fileset.intersection baseFiles (fileset.unions ([
           # For configure
           ./.version
           ./configure.ac