Add suggestions for `must_implement_one_of` by joshtriplett · Pull Request #160106 · rust-lang/rust

joshtriplett · 2026-07-28T23:14:37Z

As with the suggestions for mandatory trait methods, provide suggestions for must_implement_one_of, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block.

Invoke the same logic from check_drop_xor_pin_drop, to provide suggestions with the signatures of drop and pin_drop.

Using #106643 (read/read_buf) as an example, without this change, the diagnostics look like this:

error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf`
 --> src/main.rs:3:1
  |
3 | impl std::io::Read for R {
  | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation

For more information about this error, try `rustc --explain E0046`.

With this change, they include suggestions:

error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf`
 --> src/main.rs:3:1
  |
3 | impl std::io::Read for R {
  | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation
  |
  = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }`
  = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }`

For more information about this error, try `rustc --explain E0046`.

…span `missing_items_err` has logic to figure out where in the impl to insert suggestions. Factor that logic out into a function to support reusing it.

`missing_items_err` has logic to compute a set of suggestions regarding the missing items. Factor that logic out into a function to support reusing it.

rustbot · 2026-07-28T23:14:42Z

r? @chenyukang

rustbot has assigned @chenyukang.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler, types
compiler, types expanded to 74 candidates
Random selection from 17 candidates

mejrs

r? me

Thanks, great idea.

Can you also add a rustfix test?

View changes since this review

As with the suggestions for mandatory trait methods, provide suggestions for `must_implement_one_of`, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block. Invoke the same logic from `check_drop_xor_pin_drop`, to provide suggestions with the signatures of `drop` and `pin_drop`. Without this change: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation For more information about this error, try `rustc --explain E0046`. ``` With this change: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation | = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }` = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }` For more information about this error, try `rustc --explain E0046`. ```

mejrs

Thanks!

@bors r+ rollup

View changes since this review

rust-bors · 2026-07-29T12:47:17Z

📌 Commit bf8708e has been approved by mejrs

It is now in the queue for this repository.

rust-bors · 2026-07-29T15:08:22Z

⚠️ A new commit 84087a82ef87ed82b82271359ea46cc1d4ccbaa1 was pushed.

This pull request was unapproved.

joshtriplett · 2026-07-29T15:44:46Z

(Sorry, pushed to the wrong branch.)

joshtriplett · 2026-07-29T15:45:10Z

@bors r=mejrs

rust-bors · 2026-07-29T15:45:13Z

📌 Commit bf8708e has been approved by mejrs

It is now in the queue for this repository.

…-suggestions, r=mejrs Add suggestions for `must_implement_one_of` As with the suggestions for mandatory trait methods, provide suggestions for `must_implement_one_of`, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block. Invoke the same logic from `check_drop_xor_pin_drop`, to provide suggestions with the signatures of `drop` and `pin_drop`. Using rust-lang#106643 (`read`/`read_buf`) as an example, without this change, the diagnostics look like this: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation For more information about this error, try `rustc --explain E0046`. ``` With this change, they include suggestions: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation | = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }` = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }` For more information about this error, try `rustc --explain E0046`. ```

Rollup of 17 pull requests Successful merges: - #159014 ([rustdoc] Do not take `doc(cfg())` into account when filtering doctests) - #159130 (a bit optimize four-digit chunks in integer formatting) - #159592 (core: implement bounded random sampling) - #159898 (Add intrinsic-test alias and set sample rate) - #158247 (hermit/fs: Return `unsupported()` instead of `from_raw_os_error(22)`) - #158649 (Hermit: fix `readdir()` ) - #159049 (Avoid ICE in From/TryFrom cast suggestion when encountering HRTBs) - #160053 (test: add test suite for the 85681 issue) - #160087 (Add regression test for nested associated-type projection ICE) - #160090 (rustc_resolve: Further reduce mutability in resolver) - #160099 (Resolver: split module resolutions into local and external resolutions) - #160106 (Add suggestions for `must_implement_one_of`) - #160117 (Remove unnecessary format usage) - #160134 (Work around Wine bug 60084 by calling WSAStartup at most once) - #160142 (bootstrap: remove use-lld config alias) - #160148 (Rename `errors.rs` file to `diagnostics.rs` (15/N)) - #160151 (Mark a doctest as requiring unwinding)

…-suggestions, r=mejrs Add suggestions for `must_implement_one_of` As with the suggestions for mandatory trait methods, provide suggestions for `must_implement_one_of`, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block. Invoke the same logic from `check_drop_xor_pin_drop`, to provide suggestions with the signatures of `drop` and `pin_drop`. Using rust-lang#106643 (`read`/`read_buf`) as an example, without this change, the diagnostics look like this: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation For more information about this error, try `rustc --explain E0046`. ``` With this change, they include suggestions: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation | = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }` = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }` For more information about this error, try `rustc --explain E0046`. ```

Rollup of 18 pull requests Successful merges: - #159130 (a bit optimize four-digit chunks in integer formatting) - #159592 (core: implement bounded random sampling) - #159898 (Add intrinsic-test alias and set sample rate) - #158247 (hermit/fs: Return `unsupported()` instead of `from_raw_os_error(22)`) - #158649 (Hermit: fix `readdir()` ) - #159049 (Avoid ICE in From/TryFrom cast suggestion when encountering HRTBs) - #160053 (test: add test suite for the 85681 issue) - #160087 (Add regression test for nested associated-type projection ICE) - #160090 (rustc_resolve: Further reduce mutability in resolver) - #160099 (Resolver: split module resolutions into local and external resolutions) - #160106 (Add suggestions for `must_implement_one_of`) - #160117 (Remove unnecessary format usage) - #160134 (Work around Wine bug 60084 by calling WSAStartup at most once) - #160139 (iter: specialize Take::count using advance_by) - #160142 (bootstrap: remove use-lld config alias) - #160148 (Rename `errors.rs` file to `diagnostics.rs` (15/N)) - #160151 (Mark a doctest as requiring unwinding) - #160166 (Use correct feature gates for `f16`/`f128` `From` impls)

…-suggestions, r=mejrs Add suggestions for `must_implement_one_of` As with the suggestions for mandatory trait methods, provide suggestions for `must_implement_one_of`, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block. Invoke the same logic from `check_drop_xor_pin_drop`, to provide suggestions with the signatures of `drop` and `pin_drop`. Using rust-lang#106643 (`read`/`read_buf`) as an example, without this change, the diagnostics look like this: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation For more information about this error, try `rustc --explain E0046`. ``` With this change, they include suggestions: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation | = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }` = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }` For more information about this error, try `rustc --explain E0046`. ```

…uwer Rollup of 18 pull requests Successful merges: - #159898 (Add intrinsic-test alias and set sample rate) - #158247 (hermit/fs: Return `unsupported()` instead of `from_raw_os_error(22)`) - #158649 (Hermit: fix `readdir()` ) - #158693 (Add type-check to offload intrinisc calls) - #159049 (Avoid ICE in From/TryFrom cast suggestion when encountering HRTBs) - #159411 ([rustdoc] Correctly handle output options with --show-coverage) - #160053 (test: add test suite for the 85681 issue) - #160087 (Add regression test for nested associated-type projection ICE) - #160090 (rustc_resolve: Further reduce mutability in resolver) - #160099 (Resolver: split module resolutions into local and external resolutions) - #160106 (Add suggestions for `must_implement_one_of`) - #160117 (Remove unnecessary format usage) - #160134 (Work around Wine bug 60084 by calling WSAStartup at most once) - #160139 (iter: specialize Take::count using advance_by) - #160142 (bootstrap: remove use-lld config alias) - #160148 (Rename `errors.rs` file to `diagnostics.rs` (15/N)) - #160151 (Mark a doctest as requiring unwinding) - #160166 (Use correct feature gates for `f16`/`f128` `From` impls)

Rollup of 20 pull requests Successful merges: - #157669 (cfi: add diag mode support) - #158247 (hermit/fs: Return `unsupported()` instead of `from_raw_os_error(22)`) - #158649 (Hermit: fix `readdir()` ) - #158693 (Add type-check to offload intrinisc calls) - #159049 (Avoid ICE in From/TryFrom cast suggestion when encountering HRTBs) - #159411 ([rustdoc] Correctly handle output options with --show-coverage) - #160053 (test: add test suite for the 85681 issue) - #160087 (Add regression test for nested associated-type projection ICE) - #160090 (rustc_resolve: Further reduce mutability in resolver) - #160099 (Resolver: split module resolutions into local and external resolutions) - #160101 (Add missing `needs-unwind` annotation to `add-spawn-hook-reentrancy-159923` test) - #160106 (Add suggestions for `must_implement_one_of`) - #160117 (Remove unnecessary format usage) - #160134 (Work around Wine bug 60084 by calling WSAStartup at most once) - #160139 (iter: specialize Take::count using advance_by) - #160142 (bootstrap: remove use-lld config alias) - #160148 (Rename `errors.rs` file to `diagnostics.rs` (15/N)) - #160151 (Mark a doctest as requiring unwinding) - #160166 (Use correct feature gates for `f16`/`f128` `From` impls) - #160178 (Remove unused `va_start` intrinsic)

Rollup merge of #160106 - joshtriplett:must-implement-one-of-suggestions, r=mejrs Add suggestions for `must_implement_one_of` As with the suggestions for mandatory trait methods, provide suggestions for `must_implement_one_of`, which include the signatures of the trait methods. This makes it easy to copy-paste the signatures into the impl block. Invoke the same logic from `check_drop_xor_pin_drop`, to provide suggestions with the signatures of `drop` and `pin_drop`. Using #106643 (`read`/`read_buf`) as an example, without this change, the diagnostics look like this: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation For more information about this error, try `rustc --explain E0046`. ``` With this change, they include suggestions: ``` error[E0046]: not all trait items implemented, missing one of: `read`, `read_buf` --> src/main.rs:3:1 | 3 | impl std::io::Read for R { | ^^^^^^^^^^^^^^^^^^^^^^^^ missing one of `read`, `read_buf` in implementation | = help: implement the missing item: `fn read(&mut self, _: &mut [u8]) -> Result<usize, std::io::Error> { todo!() }` = help: implement the missing item: `fn read_buf(&mut self, _: BorrowedCursor<'_, u8>) -> Result<(), std::io::Error> { todo!() }` For more information about this error, try `rustc --explain E0046`. ```

joshtriplett added 2 commits July 28, 2026 15:41

Refactor missing_items_err: factor out function to find suggestion …

66f3da0

…span `missing_items_err` has logic to figure out where in the impl to insert suggestions. Factor that logic out into a function to support reusing it.

Refactor missing_items_err: factor out function to find suggestions

6640449

`missing_items_err` has logic to compute a set of suggestions regarding the missing items. Factor that logic out into a function to support reusing it.

rustbot assigned chenyukang Jul 28, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 28, 2026

This comment has been minimized.

Sign in to view

mejrs requested changes Jul 29, 2026

View reviewed changes

Comment thread compiler/rustc_hir_analysis/src/check/mod.rs

Comment thread compiler/rustc_hir_analysis/src/diagnostics.rs

rustbot assigned mejrs and unassigned chenyukang Jul 29, 2026

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 29, 2026

joshtriplett force-pushed the must-implement-one-of-suggestions branch from 2e10c49 to de1a020 Compare July 29, 2026 04:39

This comment has been minimized.

Sign in to view

joshtriplett force-pushed the must-implement-one-of-suggestions branch from de1a020 to bf8708e Compare July 29, 2026 08:42

mejrs approved these changes Jul 29, 2026

View reviewed changes

joshtriplett force-pushed the must-implement-one-of-suggestions branch from 84087a8 to bf8708e Compare July 29, 2026 15:44

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 29, 2026

jhpratt mentioned this pull request Jul 29, 2026

Rollup of 17 pull requests #160168

Closed

jhpratt mentioned this pull request Jul 29, 2026

Rollup of 18 pull requests #160174

Closed

JonathanBrouwer mentioned this pull request Jul 29, 2026

Rollup of 18 pull requests #160182

Closed

jhpratt mentioned this pull request Jul 30, 2026

Rollup of 20 pull requests #160190

Merged

rust-bors Bot merged commit e56dd19 into rust-lang:main Jul 30, 2026
26 checks passed

rustbot added this to the 1.99.0 milestone Jul 30, 2026

joshtriplett deleted the must-implement-one-of-suggestions branch July 30, 2026 18:47

joshtriplett mentioned this pull request Jul 30, 2026

Allow only implementing Read::read_buf #106643

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

Add suggestions for `must_implement_one_of` - #160106

Add suggestions for `must_implement_one_of`#160106
rust-bors[bot] merged 3 commits into
rust-lang:mainfrom
joshtriplett:must-implement-one-of-suggestions

joshtriplett commented Jul 28, 2026

Uh oh!

rustbot commented Jul 28, 2026

Uh oh!

This comment has been minimized.

mejrs left a comment •

edited by rustbot

Loading

Uh oh!

Uh oh!

Uh oh!

This comment has been minimized.

mejrs left a comment •

edited by rustbot

Loading

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

joshtriplett commented Jul 29, 2026

Uh oh!

joshtriplett commented Jul 29, 2026

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Uh oh!

Uh oh!

Conversation

joshtriplett commented Jul 28, 2026

Uh oh!

rustbot commented Jul 28, 2026

Uh oh!

This comment has been minimized.

mejrs left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

This comment has been minimized.

mejrs left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

joshtriplett commented Jul 29, 2026

Uh oh!

joshtriplett commented Jul 29, 2026

Uh oh!

rust-bors Bot commented Jul 29, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

mejrs left a comment •

edited by rustbot

Loading

mejrs left a comment •

edited by rustbot

Loading