From 9db1e83c07dd7006889deb839ceb83e8b0102101 Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Tue, 5 Sep 2023 18:57:08 -0400
Subject: [PATCH] libmodplug: fix build with clang 16

Remove usage of the register storage class, which is not allowed in
C++17 (the default for clang 16).
---
 pkgs/development/libraries/libmodplug/default.nix | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pkgs/development/libraries/libmodplug/default.nix b/pkgs/development/libraries/libmodplug/default.nix
index 69c36dc718cb..334dfa9d8015 100644
--- a/pkgs/development/libraries/libmodplug/default.nix
+++ b/pkgs/development/libraries/libmodplug/default.nix
@@ -9,6 +9,11 @@ stdenv.mkDerivation rec {
     sha256 = "1pnri98a603xk47smnxr551svbmgbzcw018mq1k6srbrq6kaaz25";
   };
 
+  # Unfortunately, upstream appears inactive and the patches from the fork don’t apply cleanly.
+  # Modify `src/fastmix.cpp` to remove usage of the register storage class, which is
+  # not allowed in C++17 and is an error in clang 16.
+  prePatch = "substituteInPlace src/fastmix.cpp --replace 'register ' ''";
+
   outputs = [ "out" "dev" ];
 
   preConfigure = ''