Rustup: Rename ~/.multirust to ~/.rustup.

[brson]

This is a legacy name that needs to be transitioned away from.

[mgattozzi]

I'd like to take a stab at this issue. I was wondering what this would entail changing in the code in order to make this update smooth for existing users as well as making sure all new installs will follow this convention.

[brson]

@mgattozzi The story for upgrading rustup data formats isn't very consistent right now.

For this I would suggest the following:

• At startup ~/.multirust exists and looks valid (the configuration loads), and ~/.rustup does not exist, just attempt the rename silently, print an error if it fails.
• If ~/.multirust exists and looks valid and ~/.rustup already exists, then print an error saying to the effect of 'I want to rename this dir but I can't. Help me'.

In both cases we _could_ continue on error using ~/.multirust but the complexity probably isn't worth it.

One tricky bit here is that the initial update needs to use _either_ the ~/.multirust directory so that upgrades from previous releases work, but also from the ~/.rustup directory be defensive against downgrades and other weird scenarios. This code path is in self_update::self_replace.

[fenhl]

Please consider switching to the XDG Base Directory specification instead, to remove clutter from our home directories.

[flying-sheep]

can we close this please and put a 0.4 milestone on #247?

i’ll immediately start working on it once i get green light (in both cargo and here)

[brson]

@flying-sheep No we can't do that. There is an RFC on the subject if you would like to follow.

[flying-sheep]

thanks, i already do. and why can’t we do that? won’t the RFC be followed?

[steveklabnik]

won’t the RFC be followed?

The RFC has not yet been accepted.

[flying-sheep]

of course, sorry. then i’ll wait until it is!

[Diggsey]

This happened.

[Siilwyn]

@Diggsey in the readme it still states .multirust is used though. The description of this issue is to get rid of that name right?

[johndrinkwater]

A fresh Rust install still creates ~/.multirust/

lrwxrwxrwx 1 john john    18 Nov  5 18:21 .multirust -> /home/john/.rustup
drwxrwxr-x 6 john john  4096 Nov  5 18:22 .rustup

Could this ‘legacy name’ be transitioned away quicker?
Intent of the issue seems to still be WIP, so maybe it could be reopened.