Better integration with xdg dirs.

[Dudemanguy]

Fixes #9147 and also supercedes #8184.

This basically does four things here.

1. Splits off the paths for macos into its own separate file (path-darwin.c).
2. Changes the internal path selection to allow for selecting different types (i.e. so you can get more than just the config directory.
3. Moves the watch_later directory to XDG_STATE_DIR (no change for the stuff that doesn't use path-unix.c).
4. Sets the cache directory to XDG_CACHE_DIR and it's used by default if applicable options aren't explicitly set (--cache-dir, --icc-cache-dir, and --gpu-shader-cache-dir). On non-linux/bsd OSes, this means cache would start being saved by default in the default config dir so it's a little more invasive than the other changes. For the icc and gpu shaders, cache being saved or not is now controlled with the --icc-cache and --gpu-shader-cache options.

[Dudemanguy]

It's HOME in the code but yeah let me fix the commit messages.

[txtsd]

Came here to make an issue about watch_later being in $XDG_CONFIG_HOME. Glad to see it's already being worked on. Hopefully it will be in the next release.

Can you also make it so the existing watch_later folder is moved from $XDG_CONFIG_HOME if found?

[Dudemanguy]

Can you also make it so the existing watch_later folder is moved from $XDG_CONFIG_HOME if found?

Not impossible of course, but that strikes me as unnecessary. The hypothetical move should only happen on certain platforms and should only happen once. I think it's better for the user to just move the directory themselves instead of trying to code this.

[txtsd]

Fair enough. Thought it was worth asking.

[Dudemanguy]

I reworked the last commit so it instead adds two new options: --icc-cache and --gpu-shader-cache. These are both off by default (i.e. no cache is saved). If you enable those and leave the respective directory options unset (--icc-cache-dir and --gpu-shader-cache-dir), then it will save the files in XDG_CACHE_HOME now. This matches the --cache and --cache-dir behavior.

[Dudemanguy]

I've rewritten the implementation, and this approach now has a few differences.

• The global --config-dir option now has no effect on cache or state data. On my previous implementation, setting this option would always force everything to be written into that directory.
• --cache-dir is now a global option essentially equivalent to --config-dir but for cache. This deprecates --icc-cache-dir and --gpu-shader-cache-dir (they alias to --cache-dir now).

Doesn't really matter to users, but internally the path selection api now takes into account these potential global paths (--cache-dir, --config-dir, and --watch-later-directory). So different platforms do not have to actually write code for these path types. It will fallback to "home" (aka the config directory) if it does not exist.

Seems to work just fine for me (linux) but more testing would be appreciated. Especially on macOS.

[Dudemanguy]

I realized my previous approach was flawed with regards to runtime changes of the directories, so I rewrote it yet again. This time, the --icc-cache-dir and --gpu-shader-cache-dir options are preserved because it turns out it's easier to keep them, and I also rely less on the global state. I'll try to get more testing in later to be sure, but hopefully this goes in soon.

[txtsd]

Awesome!