Support use *; and use ::*;.

[jseyfried]

Fixes#31484.
r? @nrc

[jseyfried]

cc @rust-lang/lang, @petrochenkov, @retep998

[nrc]

This seems reasonable to me (r=me), but is technically a language change, so I'd like the lang team to approve and/or discuss.

@rfcbot fcp merge

[rfcbot]

Team member nrc has proposed to merge this. The next step is review by the rest of the tagged teams:

• @aturon
• @eddyb
• @nikomatsakis
• @nrc
• @pnkfelix
• @withoutboats

No concerns currently listed.
Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[withoutboats]

@rfcbot reviewed

Accepting this is definitely the behavior I would expect.

(I'd also really like to see use path::{self, *}; accepted someday, but that's neither here nor there.)

[steveklabnik]

What's the motivation here? use :: is not actually useful; I agree that supporting some of this stuff makes it more orthogonal, but if it's not something that you're supposed to write anyway...

basically, there's nearly no actual motivation here or in #31484.

[nrc]

What's the motivation here? use :: is not actually useful;

This doesn't support use :: it supports use ::* which imports everything from the crate root module. That seems just as useful as glob importing from any other module.

[nrc]

@withoutboats@dikaiosune the rfcbot reviewed comment didn't tick off the box in the request for feedback, is it meant to?

[nrc]

@bors: r+

[bors]

📌 Commit 4a93648 has been approved by nrc

[anp]

@nrc it's a race condition with some DB interaction that I fixed this morning, but haven't deployed yet. Can you manually check the box for now? (see rust-lang/rfcbot-rs#91)

EDIT: Or not, just realized you already r+'d :)

[rfcbot]

All relevant subteam members have reviewed. No concerns remain.

[steveklabnik]

This doesn't support use :: it supports use ::* which imports everything from the crate root module.

Given that use always starts from the crate root, shouldn't that be the same as use *?

What I meant with my earlier comment is, use ::<ANYTHING> isn't useful, since it's the same as use <ANYTHING>

[withoutboats]

@steveklabnik you're right that the :: in use ::[path] is redundant, but its already supported. This just adds glob imports of the module root (using both of the path forms that are supported for use statements in general).

[steveklabnik]

Okay, so it's more that the use ::* case falls out than it is specifically adding support for this case. That makes sense, then.

[bors]

⌛ Testing commit 4a93648 with merge f0ab4a4...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-cargotest, auto-linux-64-cross-freebsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-rustbuild
Approved by: nrc
Pushing f0ab4a4 to master...

[nikomatsakis]

Similarly to #37035, arguably this should have been feature-gated (and moved for stabilization in the next cycle).