Allow trailing `self` in more contexts by mu001999 · Pull Request #155137 · rust-lang/rust

mu001999 · 2026-04-11T03:13:45Z

Reference PR:

Document trailing self in paths reference#2237

View all comments

As a follow-up PR to #152996, after this PR:

Trailing self can appear in paths
E0429 will be no longer emitted, use ...::self [as target]; will be equivalent to use ...::{self [as target]};

r? petrochenkov

mu001999 · 2026-04-13T13:38:55Z

@rustbot review

petrochenkov · 2026-04-13T14:07:47Z

@mu001999 could you write a change description for lang team for this PR, like in the previous PRs?
I'll nominate it once it's written and the other comments are addressed.
@rustbot author

rustbot · 2026-04-13T14:07:52Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

mu001999 · 2026-04-13T15:46:15Z

Description for lang team

This PR implements the last part of the lang team guidance from #146972 (comment).
It relaxes the rules to allow trailing self in more context.

Concretely, after this PR

use foo::self [as bar]; would be accepted and is resolved the same way as use foo::{self [as bar]};, instead of being rejected with E0429.
In non-import paths, trailing self would be accepted as well. This will make things like type E = path::to::Enum::self; and pub(in path::to::Mod::self) accepted.

And technically, this PR will not break existing code.

mu001999 · 2026-04-13T15:47:21Z

@rustbot review

traviscross · 2026-04-15T15:45:54Z

Makes sense to me. Thanks @mu001999 for pushing this along. Let's propose to do it.

@rfcbot fcp merge lang

rust-rfcbot · 2026-04-15T15:45:57Z

Team member @traviscross has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), 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!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

tmandry · 2026-04-15T15:46:12Z

@rfcbot reviewed

rustbot · 2026-04-27T02:59:58Z

This PR was rebased onto a different main 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.

petrochenkov · 2026-04-27T15:25:23Z

@bors r+

rust-bors · 2026-04-27T15:25:27Z

📌 Commit d93395c has been approved by petrochenkov

It is now in the queue for this repository.

…trochenkov Allow trailing `self` in more contexts Reference PR: - rust-lang/reference#2237 As a follow-up PR to rust-lang#152996, after this PR: 1. Trailing `self` can appear in paths 2. [E0429](https://doc.rust-lang.org/stable/error_codes/E0429.html#error-code-e0429) will be no longer emitted, `use ...::self [as target];` will be equivalent to `use ...::{self [as target]};` r? petrochenkov

…uwer Rollup of 9 pull requests Successful merges: - #155760 (Remove `AttributeLintKind`) - #154510 (Partially stabilize LoongArch target features) - #155137 (Allow trailing `self` in more contexts) - #155433 (Rip out rustc_layout_scalar_valid_range_* attribute support) - #155702 (Change `ItemKind::Trait` to a field variant.) - #154896 (Fix ICE: Scalar layout for non-primitive non-enum type unsafe binder) - #155675 (Disallow non_exhaustive structs and enums with non_exhaustive variants from implementing `ConstParamTy`) - #155874 (Avoid misleading closure return type note) - #155876 (CI: rfl: move job forward to Linux v7.1-rc1)

…uwer Rollup of 8 pull requests Successful merges: - #154510 (Partially stabilize LoongArch target features) - #155137 (Allow trailing `self` in more contexts) - #155513 (rustc_public: implement `Pattern` type) - #155702 (Change `ItemKind::Trait` to a field variant.) - #154896 (Fix ICE: Scalar layout for non-primitive non-enum type unsafe binder) - #155675 (Disallow non_exhaustive structs and enums with non_exhaustive variants from implementing `ConstParamTy`) - #155874 (Avoid misleading closure return type note) - #155876 (CI: rfl: move job forward to Linux v7.1-rc1)

Rollup merge of #155137 - mu001999-contrib:self-at-end, r=petrochenkov Allow trailing `self` in more contexts Reference PR: - rust-lang/reference#2237 As a follow-up PR to #152996, after this PR: 1. Trailing `self` can appear in paths 2. [E0429](https://doc.rust-lang.org/stable/error_codes/E0429.html#error-code-e0429) will be no longer emitted, `use ...::self [as target];` will be equivalent to `use ...::{self [as target]};` r? petrochenkov

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [rust](https://github.com/rust-lang/rust) | minor | `1.96.1` → `1.97.0` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>rust-lang/rust (rust)</summary> ### [`v1.97.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1970-2026-07-09) [Compare Source](rust-lang/rust@1.96.1...1.97.0) \========================== <a id="1.97.0-Language"></a> ## Language - [Consider `Result<T, Uninhabited>` and `ControlFlow<Uninhabited, T>` to be equivalent to `T` for must use lint](rust-lang/rust#148214) - [Add allow-by-default `dead_code_pub_in_binary` lint for unused pub items in binary crates](rust-lang/rust#149509) - [Stabilize the `div32`, `lam-bh`, `lamcas`, `ld-seq-sa` and `scq` target features](rust-lang/rust#154510) - [Stabilize `cfg(target_has_atomic_primitive_alignment)`](rust-lang/rust#155006) - [Allow trailing `self` in imports in more cases](rust-lang/rust#155137) <a id="1.97.0-Platform-Support"></a> ## Platform Support - [nvptx64-nvidia-cuda: drop support for old architectures and old ISAs](rust-lang/rust#152443) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. [platform-support-doc]: https://doc.rust-lang.org/rustc/platform-support.html <a id="1.97.0-Stabilized-APIs"></a> ## Stabilized APIs - [`Default for RepeatN`](https://doc.rust-lang.org/stable/std/iter/struct.RepeatN.html#impl-Default-for-RepeatN%3CA%3E) - [`Copy for ffi::FromBytesUntilNulError`](https://doc.rust-lang.org/stable/std/ffi/struct.FromBytesUntilNulError.html#impl-Copy-for-FromBytesUntilNulError) - [`Send for std::fs::File` on UEFI](rust-lang/rust#154003) - [`<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_highest_one) - [`<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_lowest_one) - [`<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.highest_one) - [`<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.lowest_one) - [`<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.bit_width) - [`NonZero<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_highest_one) - [`NonZero<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_lowest_one) - [`NonZero<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.highest_one) - [`NonZero<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.lowest_one) - [`NonZero<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.bit_width) These previously stable APIs are now stable in const contexts: - [`char::is_control`](https://doc.rust-lang.org/stable/std/primitive.char.html#method.is_control) <a id="1.97.0-Cargo"></a> ## Cargo - [Stabilize `build.warnings` config.](rust-lang/cargo#16796) This controls how lint warnings from local packages are treated. Useful for enforcing a warning-free build in CI, replacing `-Dwarnings`. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildwarnings) - [Stabilize `resolver.lockfile-path` config.](rust-lang/cargo#16694) This allows specifying the path to the lockfile to use when resolving dependencies. Useful when working with read-only source directories. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#resolverlockfile-path) - [cargo-clean: Error when `--target-dir` doesn't look like a Cargo target directory.](rust-lang/cargo#16712) This prevents accidental deletion of non-target directories. - [Add `-m` shorthand for `--manifest-path`](rust-lang/cargo#16858) - [Remove `curl` dependency from `crates-io` crate](rust-lang/cargo#16936) <a id="1.97.0-Rustdoc"></a> ## Rustdoc - [Stabilize `--emit` flag](rust-lang/rust#146220) - [Stabilize `--remap-path-prefix`](rust-lang/rust#155307) <a id="1.97.0-Compatibility-Notes"></a> ## Compatibility Notes - [Emit a future-compatibility warning when relying on `f32: From<{float}>` to constrain `{float}`](rust-lang/rust#139087) - [Rust will use the v0 symbol mangling scheme by default.](rust-lang/rust#151994) This may cause some tools (such as debuggers or profilers, especially with old versions) to fail to demangle symbols emitted by Rust. It may also cause the formatting of text in backtraces to change. - [Prevent deref coercions in `pin!`, in order to prevent unsoundness.](rust-lang/rust#153457) The most likely case where this might impact users is: writing `pin!(x)` where `x` has type `&mut T` will now always correctly produce a value of type `Pin<&mut &mut T>`, instead of sometimes allowing a coercion that produces a value of type `Pin<&mut T>`. This coercion was previously incorrectly allowed since Rust 1.88.0. - [Deprecate `std::char` constants and functions](rust-lang/rust#153873) - [Warn on linker output by default](rust-lang/rust#153968) - [Remove hidden `f64` methods which have been deprecated since 1.0](rust-lang/rust#153975) - [report the `varargs_without_pattern` lint in deps](rust-lang/rust#154599) - [Forbid passing generic arguments to module path segments even if the module reexports a generic enum variant](rust-lang/rust#154971) - [Error on invalid macho `link_section` specifier](rust-lang/rust#155065) - The encoding of certain `enum`s [have changed](rust-lang/rust#155473). This is not a breaking change, as it only applies to `enum`s without layout guarantees, but is noted here as we've seen people impacted from having made assumptions about the layout algorithm. - [Error on `#[export_name = "..."]` where the name is empty](rust-lang/rust#155515) - [Syntactically reject tuple index shorthands in struct patterns](rust-lang/rust#155698) - [validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters](rust-lang/rust#155817) - On Windows, after calling `shutdown` on a socket to shut down the write side, attempting to write to the socket will now produce a `BrokenPipe` error rather than `Other`. [Map `WSAESHUTDOWN` to `io::ErrorKind::BrokenPipe`](rust-lang/rust#156063) </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - At any time (no schedule defined) - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [rust](https://github.com/rust-lang/rust) | | minor | `1.96.1` → `1.97.0` | | rust | stage | minor | `1.96-bookworm` → `1.97-bookworm` | --- ### Release Notes <details> <summary>rust-lang/rust (rust)</summary> ### [`v1.97.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1970-2026-07-09) [Compare Source](rust-lang/rust@1.96.1...1.97.0) \========================== <a id="1.97.0-Language"></a> ## Language - [Consider `Result<T, Uninhabited>` and `ControlFlow<Uninhabited, T>` to be equivalent to `T` for must use lint](rust-lang/rust#148214) - [Add allow-by-default `dead_code_pub_in_binary` lint for unused pub items in binary crates](rust-lang/rust#149509) - [Stabilize the `div32`, `lam-bh`, `lamcas`, `ld-seq-sa` and `scq` target features](rust-lang/rust#154510) - [Stabilize `cfg(target_has_atomic_primitive_alignment)`](rust-lang/rust#155006) - [Allow trailing `self` in imports in more cases](rust-lang/rust#155137) <a id="1.97.0-Platform-Support"></a> ## Platform Support - [nvptx64-nvidia-cuda: drop support for old architectures and old ISAs](rust-lang/rust#152443) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. [platform-support-doc]: https://doc.rust-lang.org/rustc/platform-support.html <a id="1.97.0-Stabilized-APIs"></a> ## Stabilized APIs - [`Default for RepeatN`](https://doc.rust-lang.org/stable/std/iter/struct.RepeatN.html#impl-Default-for-RepeatN%3CA%3E) - [`Copy for ffi::FromBytesUntilNulError`](https://doc.rust-lang.org/stable/std/ffi/struct.FromBytesUntilNulError.html#impl-Copy-for-FromBytesUntilNulError) - [`Send for std::fs::File` on UEFI](rust-lang/rust#154003) - [`<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_highest_one) - [`<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_lowest_one) - [`<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.highest_one) - [`<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.lowest_one) - [`<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.bit_width) - [`NonZero<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_highest_one) - [`NonZero<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_lowest_one) - [`NonZero<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.highest_one) - [`NonZero<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.lowest_one) - [`NonZero<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.bit_width) These previously stable APIs are now stable in const contexts: - [`char::is_control`](https://doc.rust-lang.org/stable/std/primitive.char.html#method.is_control) <a id="1.97.0-Cargo"></a> ## Cargo - [Stabilize `build.warnings` config.](rust-lang/cargo#16796) This controls how lint warnings from local packages are treated. Useful for enforcing a warning-free build in CI, replacing `-Dwarnings`. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildwarnings) - [Stabilize `resolver.lockfile-path` config.](rust-lang/cargo#16694) This allows specifying the path to the lockfile to use when resolving dependencies. Useful when working with read-only source directories. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#resolverlockfile-path) - [cargo-clean: Error when `--target-dir` doesn't look like a Cargo target directory.](rust-lang/cargo#16712) This prevents accidental deletion of non-target directories. - [Add `-m` shorthand for `--manifest-path`](rust-lang/cargo#16858) - [Remove `curl` dependency from `crates-io` crate](rust-lang/cargo#16936) <a id="1.97.0-Rustdoc"></a> ## Rustdoc - [Stabilize `--emit` flag](rust-lang/rust#146220) - [Stabilize `--remap-path-prefix`](rust-lang/rust#155307) <a id="1.97.0-Compatibility-Notes"></a> ## Compatibility Notes - [Emit a future-compatibility warning when relying on `f32: From<{float}>` to constrain `{float}`](rust-lang/rust#139087) - [Rust will use the v0 symbol mangling scheme by default.](rust-lang/rust#151994) This may cause some tools (such as debuggers or profilers, especially with old versions) to fail to demangle symbols emitted by Rust. It may also cause the formatting of text in backtraces to change. - [Prevent deref coercions in `pin!`, in order to prevent unsoundness.](rust-lang/rust#153457) The most likely case where this might impact users is: writing `pin!(x)` where `x` has type `&mut T` will now always correctly produce a value of type `Pin<&mut &mut T>`, instead of sometimes allowing a coercion that produces a value of type `Pin<&mut T>`. This coercion was previously incorrectly allowed since Rust 1.88.0. - [Deprecate `std::char` constants and functions](rust-lang/rust#153873) - [Warn on linker output by default](rust-lang/rust#153968) - [Remove hidden `f64` methods which have been deprecated since 1.0](rust-lang/rust#153975) - [report the `varargs_without_pattern` lint in deps](rust-lang/rust#154599) - [Forbid passing generic arguments to module path segments even if the module reexports a generic enum variant](rust-lang/rust#154971) - [Error on invalid macho `link_section` specifier](rust-lang/rust#155065) - The encoding of certain `enum`s [have changed](rust-lang/rust#155473). This is not a breaking change, as it only applies to `enum`s without layout guarantees, but is noted here as we've seen people impacted from having made assumptions about the layout algorithm. - [Error on `#[export_name = "..."]` where the name is empty](rust-lang/rust#155515) - [Syntactically reject tuple index shorthands in struct patterns](rust-lang/rust#155698) - [validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters](rust-lang/rust#155817) - On Windows, after calling `shutdown` on a socket to shut down the write side, attempting to write to the socket will now produce a `BrokenPipe` error rather than `Other`. [Map `WSAESHUTDOWN` to `io::ErrorKind::BrokenPipe`](rust-lang/rust#156063) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 👻 **Immortal**: This PR will be recreated if closed unmerged. Get [config help](https://github.com/renovatebot/renovate/discussions) if that's undesired. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://codeberg.org/towonel/towonel/pulls/58

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rustbot mentioned this pull request Apr 25, 2026

Tracking issue for release notes of #155137: Allow trailing self in more contexts #155782

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Support trailing self in import paths

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mu001999 added 4 commits April 27, 2026 14:02

Support trailing self in normal paths

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Remove type_ns_only

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Add test for middle self

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Remove the special case of ::self after edition 2018

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Rollup of 9 pull requests #155885

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Rollup of 8 pull requests #155890

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Draft release notes for 1.97.0 #158353

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