From e05182c4e83b6e4d3a6f5d696ca4f4dd1bfeeb81 Mon Sep 17 00:00:00 2001
From: Audrey Dutcher <audrey@rhelmot.io>
Date: Mon, 17 Jun 2024 01:30:34 -0700
Subject: [PATCH] libpng: force-declare feenableexcept on FreeBSD

---
 pkgs/development/libraries/libpng/default.nix | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/libraries/libpng/default.nix b/pkgs/development/libraries/libpng/default.nix
index 4a8c52ae279d..11e3fb31604f 100644
--- a/pkgs/development/libraries/libpng/default.nix
+++ b/pkgs/development/libraries/libpng/default.nix
@@ -20,7 +20,11 @@ in stdenv.mkDerivation (finalAttrs: {
     url = "mirror://sourceforge/libpng/libpng-${finalAttrs.version}.tar.xz";
     hash = "sha256-alygZSOSotfJ2yrltAIQhDwLvAgcvUEIJasAzFnxSmw=";
   };
-  postPatch = whenPatched "gunzip < ${patch_src} | patch -Np1";
+  postPatch = whenPatched "gunzip < ${patch_src} | patch -Np1"
+  + lib.optionalString stdenv.isFreeBSD ''
+
+    sed -i 1i'int feenableexcept(int __mask);' contrib/libtests/pngvalid.c
+  '';
 
   outputs = [ "out" "dev" "man" ];
   outputBin = "dev";