From 667483b8243d730a2dae726191e2394d2029ee67 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=A9clairevoyant?=
 <848000+eclairevoyant@users.noreply.github.com>
Date: Thu, 12 Mar 2026 18:56:09 -0400
Subject: [PATCH] lilypond: fix build with clang21

---
 pkgs/by-name/li/lilypond-unstable/package.nix |  2 ++
 pkgs/by-name/li/lilypond/package.nix          | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/pkgs/by-name/li/lilypond-unstable/package.nix b/pkgs/by-name/li/lilypond-unstable/package.nix
index 05ea34a323fa..d0f46eca1787 100644
--- a/pkgs/by-name/li/lilypond-unstable/package.nix
+++ b/pkgs/by-name/li/lilypond-unstable/package.nix
@@ -14,6 +14,8 @@ lilypond.overrideAttrs (
       hash = "sha256-UFuL8TZ7uLZhXgFoMGxAye04dNcvrw1gqQMOnE4P2fc=";
     };
 
+    patches = [ ];
+
     passthru.updateScript = writeScript "update-lilypond-unstable" ''
       #!/usr/bin/env nix-shell
       #!nix-shell -i bash -p common-updater-scripts curl
diff --git a/pkgs/by-name/li/lilypond/package.nix b/pkgs/by-name/li/lilypond/package.nix
index e18023db30f5..0fad1654d612 100644
--- a/pkgs/by-name/li/lilypond/package.nix
+++ b/pkgs/by-name/li/lilypond/package.nix
@@ -41,6 +41,7 @@
     ]
   ),
   writeScript,
+  fetchpatch2,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -78,6 +79,18 @@ stdenv.mkDerivation (finalAttrs: {
       --replace-fail "mem=mf2pt1" "mem=$PWD/mf/mf2pt1"
   '';
 
+  patches = [
+    # fixes #475503
+    # distilled version of https://gitweb.git.savannah.gnu.org/gitweb/?p=lilypond.git;a=commit;h=f2192eb294e
+    # so, remove once that commit reaches a stable release
+    (fetchpatch2 {
+      name = "fix-clang-21-build.patch";
+      url = "https://cgit.freebsd.org/ports/plain/print/lilypond/files/patch-lily_include_smobs.hh?id=58bab68c706086774b17dcacc61c8fd37ecc8a15";
+      extraPrefix = ""; # adds old/new prefixes to process properly in patchPhase
+      hash = "sha256-nT8+nYU+m6lLTvHEvSIpG/yAwy1Omb6+4Z+NGwEVE4Q=";
+    })
+  ];
+
   strictDeps = true;
 
   depsBuildBuild = [