Clean up some traits by nnethercote · Pull Request #156021 · rust-lang/rust

nnethercote · 2026-05-01T00:56:12Z

I was looking at various traits and found some unnecessary trait bounds, and some unnecessary traits. Details in individual commits.

r? @Nadrieril

rustbot · 2026-05-01T00:56:15Z

Some changes occurred in exhaustiveness checking

cc @Nadrieril

rustc_error_messages was changed

cc @TaKO8Ki

rustbot · 2026-05-01T00:56:17Z

Nadrieril is currently at their maximum review capacity.
They may take a while to respond.

It has a single method and a single impl and the trait isn't directly used. It can just become an inherent method.

When you have `impl Foo for Bar` and `Bar` has no generics it's useless (and odd) to have `where Self: Baz` bounds on methods when the trait itself doesn't have those bounds. This commit removes a few.

FWIW, note that `Diagnostic` doesn't have this bound.

rust-log-analyzer · 2026-05-01T03:37:08Z

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

  local time: Fri May  1 03:35:52 UTC 2026
  network time: Fri, 01 May 2026 03:35:52 GMT
##[endgroup]
sccache: Starting the server...
sccache: error: Server startup failed: cache storage failed to read: ConfigInvalid (permanent) at read => S3Error { code: "NoSuchBucket", message: "The specified bucket does not exist", resource: "", request_id: "1K1AZHQE18A8M48V" }

Context:
   uri: https://s3.us-west-1.amazonaws.com/rust-lang-ci-sccache2/.sccache_check
   response: Parts { status: 404, version: HTTP/1.1, headers: {"x-amz-request-id": "1K1AZHQE18A8M48V", "x-amz-id-2": "bCg8tcYfcWq6poWKOQDT7WHmJ4kaRu3WsiccWsvK3UCtGrP//HPOCpbxsmy/eKxatiePAMC94YTfke8qZeaOO9ldvfrOI5/Z", "content-type": "application/xml", "transfer-encoding": "chunked", "date": "Fri, 01 May 2026 03:35:52 GMT", "server": "AmazonS3"} }
   service: s3
   path: .sccache_check
   range: 0-

Backtrace:
---
[TIMING:end] compile::StdLink { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target_compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, crates: [], force_recompile: false } -- 0.001
##[group]Building stage1 compiler artifacts (stage0 -> stage1, x86_64-unknown-linux-gnu)
error: process didn't exit successfully: `sccache /checkout/obj/build/bootstrap/debug/rustc -vV` (exit status: 2)
--- stderr
sccache: error: Server startup failed: cache storage failed to read: ConfigInvalid (permanent) at read => S3Error { code: "NoSuchBucket", message: "The specified bucket does not exist", resource: "", request_id: "P9636RSR62Y0P898" }

Context:
   uri: https://s3.us-west-1.amazonaws.com/rust-lang-ci-sccache2/.sccache_check
   response: Parts { status: 404, version: HTTP/1.1, headers: {"x-amz-request-id": "P9636RSR62Y0P898", "x-amz-id-2": "as/7i9zfbHJvTZ+XTImWsnvMwJnHj/EC6mIPH9ac8mHB/PU3LjphiAHEFFrZE0tpvKwwBnxT5gI=", "content-type": "application/xml", "transfer-encoding": "chunked", "date": "Fri, 01 May 2026 03:36:54 GMT", "server": "AmazonS3"} }
   service: s3
   path: .sccache_check
   range: 0-

Backtrace:
---
  11: <unknown>
  12: <unknown>


Run with SCCACHE_LOG=debug SCCACHE_NO_DAEMON=1 to get more information

Bootstrap failed while executing `build --stage 2 compiler rustdoc`
Build completed unsuccessfully in 0:00:26
  local time: Fri May  1 03:36:55 UTC 2026
  network time: Fri, 01 May 2026 03:36:55 GMT

jackh726 · 2026-05-01T14:34:15Z

@bors r+ rollup

r? jackh726

rust-bors · 2026-05-01T14:34:18Z

📌 Commit 9119225 has been approved by jackh726

It is now in the queue for this repository.

@Nadrieril

…r=jackh726 Clean up some traits I was looking at various traits and found some unnecessary trait bounds, and some unnecessary traits. Details in individual commits. r? @Nadrieril

Rollup of 7 pull requests Successful merges: - #152487 (core: drop unmapped ZSTs in array `map`) - #155940 (refactor rustc_on_unimplemented's filtering) - #156020 (Improve source code for `librustdoc/visit_ast.rs`) - #156021 (Clean up some traits) - #156028 (Add a `Local::arg(i)` helper constructor) - #156037 (Add AcceptContext::expect_no_args) - #156040 (Add missing alias to mailmap)

@Nadrieril

…r=jackh726 Clean up some traits I was looking at various traits and found some unnecessary trait bounds, and some unnecessary traits. Details in individual commits. r? @Nadrieril

Rollup of 7 pull requests Successful merges: - #155940 (refactor rustc_on_unimplemented's filtering) - #156020 (Improve source code for `librustdoc/visit_ast.rs`) - #156021 (Clean up some traits) - #156028 (Add a `Local::arg(i)` helper constructor) - #156037 (Add AcceptContext::expect_no_args) - #156040 (Add missing alias to mailmap) - #156048 (Make `diverging_type_vars` a vec of `TyVid`)

@Nadrieril

…r=jackh726 Clean up some traits I was looking at various traits and found some unnecessary trait bounds, and some unnecessary traits. Details in individual commits. r? @Nadrieril

…uwer Rollup of 9 pull requests Successful merges: - #156030 (Make stable hashing names consistent (part 1)) - #156020 (Improve source code for `librustdoc/visit_ast.rs`) - #156021 (Clean up some traits) - #156028 (Add a `Local::arg(i)` helper constructor) - #156037 (Add AcceptContext::expect_no_args) - #156040 (Add missing alias to mailmap) - #156048 (Make `diverging_type_vars` a vec of `TyVid`) - #156053 (Reuse CTFE MIR for constructors.) - #156059 (compiler: Print valid `-Zmir-enable-passes` names if invalid name is used) Failed merges: - #155940 (refactor rustc_on_unimplemented's filtering) - #156065 (Remove unused spans from AttributeKind)

@Nadrieril

Rollup merge of #156021 - nnethercote:clean-up-some-traits, r=jackh726 Clean up some traits I was looking at various traits and found some unnecessary trait bounds, and some unnecessary traits. Details in individual commits. r? @Nadrieril

…uwer Rollup of 9 pull requests Successful merges: - rust-lang/rust#156030 (Make stable hashing names consistent (part 1)) - rust-lang/rust#156020 (Improve source code for `librustdoc/visit_ast.rs`) - rust-lang/rust#156021 (Clean up some traits) - rust-lang/rust#156028 (Add a `Local::arg(i)` helper constructor) - rust-lang/rust#156037 (Add AcceptContext::expect_no_args) - rust-lang/rust#156040 (Add missing alias to mailmap) - rust-lang/rust#156048 (Make `diverging_type_vars` a vec of `TyVid`) - rust-lang/rust#156053 (Reuse CTFE MIR for constructors.) - rust-lang/rust#156059 (compiler: Print valid `-Zmir-enable-passes` names if invalid name is used) Failed merges: - rust-lang/rust#155940 (refactor rustc_on_unimplemented's filtering) - rust-lang/rust#156065 (Remove unused spans from AttributeKind)

rustbot assigned Nadrieril May 1, 2026

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nnethercote added 5 commits May 1, 2026 13:32

Remove unused IntoVisitor trait.

7313fc6

Remove unused Captures trait.

e92ca90

Eliminate IsPrefixOf trait.

bc0e581

It has a single method and a single impl and the trait isn't directly used. It can just become an inherent method.

Remove useless bounds on Self for impls of concrete types.

82cfcaf

When you have `impl Foo for Bar` and `Bar` has no generics it's useless (and odd) to have `where Self: Baz` bounds on methods when the trait itself doesn't have those bounds. This commit removes a few.

Remove unnecessary trait bound on Subdiagnostic.

9119225

FWIW, note that `Diagnostic` doesn't have this bound.

nnethercote force-pushed the clean-up-some-traits branch from d7f14d3 to 9119225 Compare May 1, 2026 03:33

rustbot assigned jackh726 May 1, 2026

rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label May 1, 2026

rustbot unassigned Nadrieril May 1, 2026

rust-bors Bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label May 1, 2026

GuillaumeGomez mentioned this pull request May 1, 2026

Rollup of 7 pull requests #156056

Closed

GuillaumeGomez mentioned this pull request May 1, 2026

Rollup of 7 pull requests #156066

Closed

This was referenced May 2, 2026

Rollup of 7 pull requests #156076

Closed

Rollup of 9 pull requests #156078

Merged

rust-bors Bot merged commit 9149135 into rust-lang:main May 2, 2026
13 of 22 checks passed

rustbot added this to the 1.97.0 milestone May 2, 2026

nnethercote deleted the clean-up-some-traits branch May 3, 2026 23:22

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Clean up some traits#156021

Clean up some traits#156021
rust-bors[bot] merged 5 commits intorust-lang:mainfrom
nnethercote:clean-up-some-traits

nnethercote commented May 1, 2026 •

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nnethercote commented May 1, 2026 •

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