proposal: cmd/go: change default $GOPATH to $XDG_CACHE_HOME/go when modules are enabled by default

[nhooyr]

At the moment, the default $GOPATH is ~/go which is fine given how $GOPATH is frequently accessed by the user because it holds the source of all their go code.

However, with vgo, it isn't necessary for a user to head into $GOPATH often because its only going to store the cache of their dependencies. Thus it shouldn't clutter their home directory. $GOPATH should instead go into $XDG_CACHE_HOME/go. $XDG_CACHE_HOME is the standard directory for user related cached data. See https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

This will ensure it doesn't clutter a user's home directory unless they want it to as $XDG_CACHE_HOME defaults to ~/.cache.

[bcmills]

XDG_CACHE_HOME is explicitly for “non-essential” data, but the module cache is kind of a grey area: it might not be possible in general for a user to re-download missing module source at any given time (for example, if they are working on a laptop disconnected from the network), but Go builds should continue to work unless the user takes some explicit step to clean them up.

[nhooyr]

I agree, lets change this proposal to make the default $GOPATH $XDG_DATA_HOME/go because $XDG_DATA_HOME is for user specific essential data. It'll be safer like you said.

[rsc]

The default GOPATH is already set. Let's not change it. I don't want to see my files in $HOME/.local/share.

[ELLIOTTCABLE]

👍 here; at least on macOS, having additional directories cluttering up ~/ is non-idiomatic (and honestly, quite annoying.) This is a horrible default; something based on $XDG_DATA_HOME (and thus, by default, something in a hidden-by-default dot-directory) is much more end-user friendly.

I'd love to see this reopened!