From a102c81c16e4734f7cf9f8155c35493324ee8d3b Mon Sep 17 00:00:00 2001
From: Ulysses Zhan <UlyssesZhan@gmail.com>
Date: Thu, 9 Oct 2025 15:40:06 -0700
Subject: [PATCH] feyngame: fix source reproducibility

---
 pkgs/by-name/fe/feyngame/package.nix | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pkgs/by-name/fe/feyngame/package.nix b/pkgs/by-name/fe/feyngame/package.nix
index 3272bff07a0f..fe636521a114 100644
--- a/pkgs/by-name/fe/feyngame/package.nix
+++ b/pkgs/by-name/fe/feyngame/package.nix
@@ -18,12 +18,17 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     repo = "FeynGame";
     tag = finalAttrs.version;
     leaveDotGit = true; # the build script uses git log to find last commit date
-    hash = "sha256-PhdspIr0Lnuv4e8bjMEAXnVDK1YVlrI5XI+rP9qXNQ0=";
+    hash = "sha256-ySBEka978jRWRRI6WpKNEfwsB3kZMhOrcotbstTAhzQ=";
+    postFetch = ''
+      git --git-dir=$out/.git log -1 --date=format:"%d.%m.%Y %H:%M:%S" --format="%ad" > $out/.gitdate
+      rm -rf $out/.git
+    '';
   };
 
   postPatch = ''
     patchShebangs buildfile
     substituteInPlace buildfile \
+      --replace-fail 'git log -1 --date=format:"%d.%m.%Y %H:%M:%S" --format="%ad"' 'cat .gitdate' \
       --replace-fail '$Prefix/bin/feyngame %U' 'feyngame %U' \
       --replace-fail '$Prefix/share/pixmaps/fglogo.png' 'fglogo'
   '';
@@ -40,7 +45,6 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   '';
 
   nativeBuildInputs = [
-    git
     jdk
     desktop-file-utils
   ];