From a95db128a65d2e4991c815d2f9d9d1620c5e383b Mon Sep 17 00:00:00 2001
From: Matt Sturgeon <matt@sturgeon.me.uk>
Date: Sat, 24 May 2025 09:32:19 +0100
Subject: [PATCH] update-scripts/version-info: convert to a script

This will allow us to do impure things if needed.
---
 update-scripts/update.nix               |  2 +-
 update-scripts/version-info/default.nix | 46 ++++++++-----------------
 update-scripts/version-info/main.nix    | 27 +++++++++++++++
 3 files changed, 43 insertions(+), 32 deletions(-)
 create mode 100644 update-scripts/version-info/main.nix

diff --git a/update-scripts/update.nix b/update-scripts/update.nix
index c4900aa1..597869f5 100644
--- a/update-scripts/update.nix
+++ b/update-scripts/update.nix
@@ -43,7 +43,7 @@ writeShellApplication {
 
     versionInfo() {
       nix-build ./update-scripts -A version-info
-      install -m 644 -T "$(realpath result)" ./version-info.toml
+      ./result
       if [ -n "$commit" ]; then
         git add version-info.toml
         git commit "$@"
diff --git a/update-scripts/version-info/default.nix b/update-scripts/version-info/default.nix
index a59867f0..c7f15aea 100644
--- a/update-scripts/version-info/default.nix
+++ b/update-scripts/version-info/default.nix
@@ -1,36 +1,20 @@
 {
   lib,
-  writers,
-  runCommand,
+  callPackage,
+  writeShellApplication,
 }:
 let
-  inherit (builtins)
-    all
-    match
-    attrNames
-    ;
-  inherit (lib)
-    importJSON
-    ;
-
-  lockFile = importJSON ../../flake.lock;
-  nixpkgsLock =
-    # Assert there is only one nixpkgs node
-    assert all (node: match "nixpkgs_[0-9]+" node == null) (attrNames lockFile.nodes);
-    lockFile.nodes.nixpkgs.original;
-
-  info = {
-    inherit (lib.trivial) release;
-    nixpkgs_rev = lib.trivial.revisionWithDefault (throw "nixpkgs revision not available");
-    unstable = lib.strings.hasSuffix "-unstable" nixpkgsLock.ref;
-  };
+  mainInfo = callPackage ./main.nix { };
 in
-runCommand "version-info.toml" { } ''
-  (
-    echo "# DO NOT MODIFY!"
-    echo "# This file was generated by ${
-      lib.strings.removePrefix (toString ../.. + "/") (toString ./default.nix)
-    }"
-    cat ${writers.writeTOML "version-info.toml" info}
-  ) > $out
-''
+writeShellApplication {
+  name = "version-info";
+  text = ''
+    (
+      echo "# DO NOT MODIFY!"
+      echo "# This file was generated by ${
+        lib.strings.removePrefix (toString ../.. + "/") (toString ./default.nix)
+      }"
+      cat ${mainInfo}
+    ) > version-info.toml
+  '';
+}
diff --git a/update-scripts/version-info/main.nix b/update-scripts/version-info/main.nix
new file mode 100644
index 00000000..5a083725
--- /dev/null
+++ b/update-scripts/version-info/main.nix
@@ -0,0 +1,27 @@
+{
+  lib,
+  writers,
+}:
+let
+  inherit (builtins)
+    all
+    match
+    attrNames
+    ;
+  inherit (lib)
+    importJSON
+    ;
+
+  lockFile = importJSON ../../flake.lock;
+  nixpkgsLock =
+    # Assert there is only one nixpkgs node
+    assert all (node: match "nixpkgs_[0-9]+" node == null) (attrNames lockFile.nodes);
+    lockFile.nodes.nixpkgs.original;
+
+  info = {
+    inherit (lib.trivial) release;
+    nixpkgs_rev = lib.trivial.revisionWithDefault (throw "nixpkgs revision not available");
+    unstable = lib.strings.hasSuffix "-unstable" nixpkgsLock.ref;
+  };
+in
+writers.writeTOML "version-info.toml" info