Document importing path-segment keyword#2136
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mu001999 wants to merge 11 commits intorust-lang:masterfrom
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Document importing path-segment keyword#2136mu001999 wants to merge 11 commits intorust-lang:masterfrom
mu001999 wants to merge 11 commits intorust-lang:masterfrom
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It looks like I don't have permission to push to this branch. I have pushed my edits to https://github.com/ehuss/reference/commits/doc/import-path-kw/. |
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@ehuss I have invited you :). Or I can merge your branch directly |
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@traviscross Sadly, this seems to be only available for forks in personal accounts (link):
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We talked about this on the lang-docs office hours call. This seems to be pending some decisions and clarifications on the lang side over in rust-lang/rust#146972. @ehuss has now posted a question over in rust-lang/rust#146972 (comment). |
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Added the restriction and marked this PR ready for review. @traviscross @ehuss Could you review this PR, thanks! |
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Thanks! Will merge after rust-lang/rust#146972 has merged. |
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…ate, r=petrochenkov Support importing path-segment keyword with renaming *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/146972)* #### Reference PR - rust-lang/reference#2010 - rust-lang/reference#2136 #### Description This PR unifies and extends the behavior of importing path-segment keywords (`crate`/`$crate`/`super`/`self`), resolving several long-standing inconsistencies. Previously, Rust only allowed `use crate as name;` without renaming support for other path keywords. This PR enables importing these keywords with explicit renaming. And it also denies importing these keywords without renaming. ##### What's now allowed For **`crate`** and **`$crate`**: - `use crate as name;` - `use crate::{self as name};` - `use $crate as name;` - `use $crate::{self as name};` For **`super`** (including chained `super::super`): - `use super as name;` - `use super::{self as name};` - `use super::super as name;` - `use super::super::{self as name};` For **`self`**: - `use self as name;` - `use self::{self as name};` ##### Removed error codes Two error codes are no longer emitted: - **E0430**: Previously emitted for duplicate `self` imports like `std::fmt::{self, self}`. The existing E0252 ("name defined multiple times") provides sufficient guidance. - **E0431**: Previously emitted for `use {self [as name]};` and `use ::{self [as name]};`. These patterns are now allowed or denied but with new clearer errors. - For `use {self as name};` and `use ::{self as name};` (in edition 2015), they are allowed now and equivalent to `use crate as name`; - For `use {self};` and `use ::{self};` (in edition 2015) without renaming, they are equivalent to `use crate;`, the new clearer error suggests adding an explicit rename. - For `use ::{self [as name]};` after edition 2015, it is equivalent to `use ${extern-prelude} [as name];`, it is denied with new errors. ##### Future We plan to remove error [E0429](https://doc.rust-lang.org/stable/error_codes/E0429.html#error-code-e0429) and support `self` at the end of paths (rust-lang#146972 (comment)). This language extension and lint for redundant `::self` instead of hard error `E0429` will be landed separately in the future. --- Fixes rust-lang#29036 Fixes rust-lang#35612 Fixes rust-lang#37156 Fixes rust-lang#146967 Fixes rust-lang#149811 r? petrochenkov
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Rollup merge of #146972 - mu001999-contrib:fix/use-dollar-crate, r=petrochenkov Support importing path-segment keyword with renaming *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/146972)* #### Reference PR - rust-lang/reference#2010 - rust-lang/reference#2136 #### Description This PR unifies and extends the behavior of importing path-segment keywords (`crate`/`$crate`/`super`/`self`), resolving several long-standing inconsistencies. Previously, Rust only allowed `use crate as name;` without renaming support for other path keywords. This PR enables importing these keywords with explicit renaming. And it also denies importing these keywords without renaming. ##### What's now allowed For **`crate`** and **`$crate`**: - `use crate as name;` - `use crate::{self as name};` - `use $crate as name;` - `use $crate::{self as name};` For **`super`** (including chained `super::super`): - `use super as name;` - `use super::{self as name};` - `use super::super as name;` - `use super::super::{self as name};` For **`self`**: - `use self as name;` - `use self::{self as name};` ##### Removed error codes Two error codes are no longer emitted: - **E0430**: Previously emitted for duplicate `self` imports like `std::fmt::{self, self}`. The existing E0252 ("name defined multiple times") provides sufficient guidance. - **E0431**: Previously emitted for `use {self [as name]};` and `use ::{self [as name]};`. These patterns are now allowed or denied but with new clearer errors. - For `use {self as name};` and `use ::{self as name};` (in edition 2015), they are allowed now and equivalent to `use crate as name`; - For `use {self};` and `use ::{self};` (in edition 2015) without renaming, they are equivalent to `use crate;`, the new clearer error suggests adding an explicit rename. - For `use ::{self [as name]};` after edition 2015, it is equivalent to `use ${extern-prelude} [as name];`, it is denied with new errors. ##### Future We plan to remove error [E0429](https://doc.rust-lang.org/stable/error_codes/E0429.html#error-code-e0429) and support `self` at the end of paths (#146972 (comment)). This language extension and lint for redundant `::self` instead of hard error `E0429` will be landed separately in the future. --- Fixes #29036 Fixes #35612 Fixes #37156 Fixes #146967 Fixes #149811 r? petrochenkov
As with other parts of the reference, the structure is moving more towards a set of rules, and the bullet list here isn't necessary.
This note was more of a general commentary on `self`, and was not specifically attached to its previous rule of items.use.self.namespace.
This is somewhat duplicated with the `self` section and the restrictions section which already describes about renaming.
This moves `$crate` to be next to `crate` since they are closely related.
This tries to simplify the wording and to maintain consistency, since they are all essentially saying the same thing.
The rules in the paths chapter don't entirely reflect what a valid path in a `use` declaration is. I'm not entirely sure what's the best approach for describing how paths work since there are several differences between `use` paths and expression paths.
Co-authored-by: Eric Huss <eric@huss.org>
Per what was discussed in rust-lang/rust#146972 (comment)
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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Companion PR to rust-lang/rust#146972