Feature Request: Override fonts.conf location with env var FONTCONFIG_FILE

[na4zagin3]

Hi team,
I would like to override fontconfig configuration for each project by specifying environment variable FONTCONFIG_FILE.

Environment variables

FONTCONFIG_FILE is used to override the default configuration file.

Currently it's hardcoded as the following.

luaotfload/src/luaotfload-database.lua

Lines 2433 to 2436 in 7256136

	local fonts_conves = { --- plural, much?
	"/usr/local/etc/fonts/fonts.conf",
	"/etc/fonts/fonts.conf",
	}

This makes it possible to compile LuaLaTeX documents reproducibily with Nix which generates fonts.conf at some arbitrary directory with makeFontsConf.

Thanks!

[cfr42]

Wouldn't it be better to use a TeX-specific variable? TL configuration, for example, is basically done in texmf.cnf/texmfcnf.lua.

Not that my opinion is worth squat, but I don't think it would be a great idea to make the behaviour dependent on the value of an environmental variable which doesn't belong to the TeX installation. (Aside from PATH which is unavoidable.)