+++ /dev/null
-# `use_nested_groups`
-
-The tracking issue for this feature is: [#44494]
-
-[#44494]: https://github.com/rust-lang/rust/issues/44494
-
-------------------------
-
-The `use_nested_groups` feature allows you to import multiple items from a
-complex module tree easily, by nesting different imports in the same
-declaration. For example:
-
-```rust
-#![feature(use_nested_groups)]
-# #![allow(unused_imports, dead_code)]
-#
-# mod foo {
-# pub mod bar {
-# pub type Foo = ();
-# }
-# pub mod baz {
-# pub mod quux {
-# pub type Bar = ();
-# }
-# }
-# }
-
-use foo::{
- bar::{self, Foo},
- baz::{*, quux::Bar},
-};
-#
-# fn main() {}
-```
-
-## Snippet for the book's new features appendix
-
-When stabilizing, add this to
-`src/doc/book/second-edition/src/appendix-07-newest-features.md`:
-
-### Nested groups in `use` declarations
-
-If you have a complex module tree with many different submodules and you need
-to import a few items from each one, it might be useful to group all the
-imports in the same declaration to keep your code clean and avoid repeating the
-base modules' name.
-
-The `use` declaration supports nesting to help you in those cases, both with
-simple imports and glob ones. For example this snippets imports `bar`, `Foo`,
-all the items in `baz` and `Bar`:
-
-```rust
-# #![feature(use_nested_groups)]
-# #![allow(unused_imports, dead_code)]
-#
-# mod foo {
-# pub mod bar {
-# pub type Foo = ();
-# }
-# pub mod baz {
-# pub mod quux {
-# pub type Bar = ();
-# }
-# }
-# }
-#
-use foo::{
- bar::{self, Foo},
- baz::{*, quux::Bar},
-};
-#
-# fn main() {}
-```
-
-## Updated reference
-
-When stabilizing, replace the shortcut list in
-`src/doc/reference/src/items/use-declarations.md` with this updated one:
-
-* Simultaneously binding a list of paths with a common prefix, using the
- glob-like brace syntax `use a::b::{c, d, e::f, g::h::i};`
-* Simultaneously binding a list of paths with a common prefix and their common
- parent module, using the `self` keyword, such as `use a::b::{self, c, d::e};`
-* Rebinding the target name as a new local name, using the syntax `use p::q::r
- as x;`. This can also be used with the last two features:
- `use a::b::{self as ab, c as abc}`.
-* Binding all paths matching a given prefix, using the asterisk wildcard syntax
- `use a::b::*;`.
-* Nesting groups of the previous features multiple times, such as
- `use a::b::{self as ab, c d::{*, e::f}};`
// In-band lifetime bindings (e.g. `fn foo(x: &'a u8) -> &'a u8`)
(active, in_band_lifetimes, "1.23.0", Some(44524)),
- // Nested groups in `use` (RFC 2128)
- (active, use_nested_groups, "1.23.0", Some(44494)),
-
// generic associated types (RFC 1598)
(active, generic_associated_types, "1.23.0", Some(44265)),
(accepted, repr_align, "1.24.0", Some(33626)),
// allow '|' at beginning of match arms (RFC 1925)
(accepted, match_beginning_vert, "1.25.0", Some(44101)),
+ // Nested groups in `use` (RFC 2128)
+ (accepted, use_nested_groups, "1.25.0", Some(44494)),
);
// If you change this, please modify src/doc/unstable-book as well. You must
visit::walk_path(self, path);
}
- fn visit_use_tree(&mut self, use_tree: &'a ast::UseTree, id: NodeId, nested: bool) {
- if nested {
- match use_tree.kind {
- ast::UseTreeKind::Simple(_) => {
- if use_tree.prefix.segments.len() != 1 {
- gate_feature_post!(&self, use_nested_groups, use_tree.span,
- "paths in `use` groups are experimental");
- }
- }
- ast::UseTreeKind::Glob => {
- gate_feature_post!(&self, use_nested_groups, use_tree.span,
- "glob imports in `use` groups are experimental");
- }
- ast::UseTreeKind::Nested(_) => {
- gate_feature_post!(&self, use_nested_groups, use_tree.span,
- "nested groups in `use` are experimental");
- }
- }
- }
-
- visit::walk_use_tree(self, use_tree, id);
- }
-
fn visit_vis(&mut self, vis: &'a ast::Visibility) {
if let ast::Visibility::Crate(span, ast::CrateSugar::JustCrate) = *vis {
gate_feature_post!(&self, crate_visibility_modifier, span,
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-#![feature(use_nested_groups)]
#![allow(unused_imports)]
mod foo {}
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-#![feature(use_nested_groups)]
#![allow(unused_import)]
use {{}, {}};
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-#![feature(use_nested_groups)]
-
mod a {
pub enum B {}
+++ /dev/null
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-#![allow(unused_imports, dead_code)]
-
-mod a {
- pub enum B {}
- pub enum C {}
-
- pub mod d {
- pub enum E {}
- pub enum F {}
-
- pub mod g {
- pub enum H {}
- }
- }
-}
-
-use a::{B, d::{*, g::H}}; //~ ERROR glob imports in `use` groups are experimental
- //~^ ERROR nested groups in `use` are experimental
- //~^^ ERROR paths in `use` groups are experimental
-
-fn main() {}
+++ /dev/null
-error[E0658]: nested groups in `use` are experimental (see issue #44494)
- --> $DIR/feature-gate-use_nested_groups.rs:27:12
- |
-27 | use a::{B, d::{*, g::H}}; //~ ERROR glob imports in `use` groups are experimental
- | ^^^^^^^^^^^^
- |
- = help: add #![feature(use_nested_groups)] to the crate attributes to enable
-
-error[E0658]: glob imports in `use` groups are experimental (see issue #44494)
- --> $DIR/feature-gate-use_nested_groups.rs:27:16
- |
-27 | use a::{B, d::{*, g::H}}; //~ ERROR glob imports in `use` groups are experimental
- | ^
- |
- = help: add #![feature(use_nested_groups)] to the crate attributes to enable
-
-error[E0658]: paths in `use` groups are experimental (see issue #44494)
- --> $DIR/feature-gate-use_nested_groups.rs:27:19
- |
-27 | use a::{B, d::{*, g::H}}; //~ ERROR glob imports in `use` groups are experimental
- | ^^^^
- |
- = help: add #![feature(use_nested_groups)] to the crate attributes to enable
-
-error: aborting due to 3 previous errors
-
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-#![feature(use_nested_groups)]
-
mod a {
pub mod b1 {
pub enum C2 {}
error[E0432]: unresolved import `a::b1::C1`
- --> $DIR/use-nested-groups-error.rs:21:14
+ --> $DIR/use-nested-groups-error.rs:19:14
|
-21 | use a::{b1::{C1, C2}, B2};
+19 | use a::{b1::{C1, C2}, B2};
| ^^ no `C1` in `a::b1`. Did you mean to use `C2`?
error: aborting due to previous error
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