From 82e0078428dbca9836a26cee9ed2aacfaea2bfcf Mon Sep 17 00:00:00 2001
From: whispers <whispersofthedawn@duck.com>
Date: Mon, 27 Jul 2026 17:54:43 -0400
Subject: [PATCH] hm: apply upstream patch for gcc 16
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GCC 16 has better analysis of unused variables than previous versions.
Since HM builds with -Werror by default, this causes a build failure, so
we fetch the commit that fixed this issue upstream.

We elected to take a patch instead of suppressing the error (with
-Wno-error=…) since patches will be removed on the next update while
flags often sit untouched and unnoticed long after they're necessary.
---
 pkgs/by-name/hm/hm/package.nix | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pkgs/by-name/hm/hm/package.nix b/pkgs/by-name/hm/hm/package.nix
index 600a07b375e5..ac584e7939ae 100644
--- a/pkgs/by-name/hm/hm/package.nix
+++ b/pkgs/by-name/hm/hm/package.nix
@@ -20,6 +20,18 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-zWBwrnCNKi2sIopdu2XQj/7IoTsJQzlcIFNNKM0glDQ=";
   };
 
+  patches = [
+    # GCC 16 has better analysis of unused variables than previous versions.
+    # Since HM builds with -Werror by default, this causes a build failure, so
+    # we fetch the commit that fixed this issue upstream until it makes it into
+    # a release.
+    (fetchpatch {
+      name = "gcc16-unused-variable.patch";
+      url = "https://vcgit.hhi.fraunhofer.de/jvet/HM/-/commit/884d704b9d04ac1728b2c6049174e47eb04987d2.patch";
+      hash = "sha256-UqZf7XFTEOpfE0Uyyrq+ydScR9GzMgR+JQVeZGFjc1c=";
+    })
+  ];
+
   postPatch = ''
     substituteInPlace CMakeLists.txt \
       --replace-fail "-msse4.1" ""