nixpkgs/pkgs/development/libraries/fontconfig/config-compat.patch

From 2ff9b53ce755be183ef9274f7dd3f9ac537173f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20=C4=8Cun=C3=A1t?= <vcunat@gmail.com>
Date: Tue, 4 Nov 2014 12:24:25 +0100
Subject: [PATCH] add check for /etc/fonts/@configVersion@/fonts.conf

It's checked between FONTCONFIG_FILE and the in-package etc/fonts/fonts.conf.
The latter is used so that on non-NixOS distributions, fontconfig works at least
with upstream defaults, even when the global config is incompatible.

Co-Authored-By: Jan Tojnar <jtojnar@gmail.com>
---
 src/fccfg.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/fccfg.c b/src/fccfg.c
index 342c996..98a1324 100644
--- a/src/fccfg.c
+++ b/src/fccfg.c
@@ -2391,8 +2391,13 @@ FcConfigGetFilename (FcConfig      *config,
     if (!url || !*url)
     {
 	url = (FcChar8 *) getenv ("FONTCONFIG_FILE");
+	if (!url) {
+	    static const FcChar8 *cfPath = "/etc/fonts/@configVersion@/fonts.conf";
+	    if (access (cfPath, R_OK) == 0)
+		url = cfPath;
+	}
 	if (!url)
-	    url = (FcChar8 *) FONTCONFIG_FILE;
+	    url = (FcChar8 *) FONTCONFIG_PATH "/" FONTCONFIG_FILE;
     }
     file = 0;
 
-- 
2.26.2