Emacs source as flake input

flake.lock

@@ -146,6 +146,23 @@
         "type": "github"
       }
     },
+    "emacsSource": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1673616960,
+        "narHash": "sha256-nO3HbhF5s4Dg3WXe8lDoew2STks1cVU3vHIWd7ePFBQ=",
+        "ref": "emacs-29",
+        "rev": "861556c1339cd65842ec3e24ba48590e6b72bd48",
+        "revCount": 164162,
+        "type": "git",
+        "url": "git://git.savannah.gnu.org/emacs.git"
+      },
+      "original": {
+        "ref": "emacs-29",
+        "type": "git",
+        "url": "git://git.savannah.gnu.org/emacs.git"
+      }
+    },
     "evil-escape": {
       "flake": false,
       "locked": {
@@ -748,6 +765,7 @@
         "agenix": "agenix",
         "comma": "comma",
         "doomEmacs": "doomEmacs",
+        "emacsSource": "emacsSource",
         "homeManager": "homeManager",
         "nixosHardware": "nixosHardware",
         "nixpkgsStable": "nixpkgsStable",

flake.nix

@@ -15,6 +15,10 @@
     doomEmacs.url = "github:nix-community/nix-doom-emacs";
     comma.url = "github:nix-community/comma";
     rock5b.url = "github:aciceri/rock5b-nixos";
+    emacsSource = {
+      url = "git://git.savannah.gnu.org/emacs.git?ref=emacs-29";
+      flake = false;
+    };
   };
   outputs = {self, ...} @ inputs: let
     utils = import ./utils inputs;

hmModules/emacs/default.nix

@@ -4,8 +4,6 @@
   lib,
   ...
 }: let
-  rev = "72a94f91fd0570556ce770dc3a39e658f7588f7e"; # Current master, Emacs 29, seems a good commit
-  sha256 = "e5kKIEZJB9BGbBvGtiPK3gNygFoGxkG02nRLCwnGtmk=";
   emacsMaster =
     (pkgs.emacs.override {
       nativeComp = true;
@@ -14,17 +12,13 @@
       withGTK3 = true;
     })
     .overrideAttrs (old: {
-      src = pkgs.fetchFromSavannah {
-        repo = "emacs";
-        inherit rev sha256;
-      };
-      version = rev;
+      src = pkgs.emacsSource;
       patches = [];
       postPatch =
         old.postPatch
         + ''
           substituteInPlace lisp/loadup.el \
-          --replace '(emacs-repository-get-version)' '"${rev}"' \
+          --replace '(emacs-repository-get-version)' '"${pkgs.emacsSource.rev}"' \
           --replace '(emacs-repository-get-branch)' '"master"'
         ''
         + (lib.optionalString (old ? NATIVE_FULL_AOT)

utils/default.nix

@@ -8,6 +8,7 @@
   nur,
   preCommitHooks,
   rock5b,
+  emacsSource,
   self,
   ...
 }: let
@@ -43,7 +44,12 @@
                 value.file = ./.. + "/${name}";
               }) (import ../secrets);
             };
-            nixpkgs.overlays = [agenix.overlay comma.overlays.default nur.overlay];
+            nixpkgs.overlays = [
+              agenix.overlay
+              comma.overlays.default
+              nur.overlay
+              (_: _: {inherit emacsSource;})
+            ];
           }
           (../hosts + "/${name}")
           homeManager.nixosModule