XDG directory functions do not respect XDG variables on macOS

[uncenter]

Due to long standing difficulties with (a/the) maintainer of dirs-rs, they refuse to recognize XDG environment variables explicitly defined by the user on macOS: dirs-dev/directories-rs#47. config_directory() will always go to /Users/<username>/Library/Application Support on macOS, even if you have set XDG_CONFIG_HOME. I would suggest using https://github.com/lunacookies/etcetera instead, though there may be other alternatives that also respect user preferences.

[laniakea64]

Changing the behavior of the existing functions would break just's backwards-compatibility guarantee. This would need to be a new function (maybe named xdg_config_directory()?)

[uncenter]

Yeah that's sound good, we should still update the documentation for the normal config_directory() functions to clarify that they return the path for the operating system specification - right now they are literally called "XDG Directories", that name (and description) would be fitting for xdg_config_directory() instead :)

[uncenter]

Well, dirs is used for other features like global justfile locating:

just/src/search.rs

Lines 14 to 19 in 4f31853

	fn global_justfile_paths() -> Vec<PathBuf> {
	let mut paths = Vec::new();
	if let Some(config_dir) = dirs::config_dir() {
	paths.push(config_dir.join("just").join(DEFAULT_JUSTFILE_NAME));
	}

But since that wouldn't affect the backwards compatability of the justfiles themselves would that be a change that could be made at some point as well?

[casey]

Regarding #2439, I see the benefit, but it seems unfortunate to add a bunch more functions that are very close to existing functions.

An alternative option would be to add a setting, like set use-xdg-directories, which would change the behavior of directory functions to respect the XDG variables.