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Avoid suggesting closures when captures cross associated item boundaries - #162821

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kulinsky:fix-153363-closure-suggestion
Sep 21, 2026
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Avoid suggesting closures when captures cross associated item boundaries#162821
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
kulinsky:fix-153363-closure-suggestion

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@kulinsky kulinsky commented Sep 15, 2026 •
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Fixes #153363

We check the boundaries between a variable's declaration and its usage. If an associated item boundary is crossed, replacing a nested function with a closure does not eliminate this boundary. We retain the error but remove the ineffective suggestion.

The hint is preserved for an ordinary nested function capturing a local variable of the method.

Checks: full UI test run ./x test tests/ui --force-rerun, 21853 passed / 410 ignored, and ./x test tidy.

Used an LLM for code navigation

@rustbot 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 Sep 15, 2026
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r? @mejrs

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mejrs approved these changes Sep 21, 2026
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Thanks!

@bors r+ rollup

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📌 Commit a757a13 has been approved by mejrs

It is now in the queue for this repository.

@rust-bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Sep 21, 2026
@JonathanBrouwer JonathanBrouwer mentioned this pull request Sep 21, 2026
Merged
rust-bors Bot pushed a commit that referenced this pull request Sep 21, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
60cd7d0 
…uwer

Rollup of 10 pull requests

Successful merges:

 - #163083 (Remove `G` generic param from `Diag<'_, G>`)
 - #160679 (Staticlib rename internal symbols: add COFF support)
 - #160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - #162007 (Preserve parentheses in raw borrow suggestions)
 - #162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - #163057 (Use span context for enclosing item(s) of unmet bound)
 - #163070 (label the path segment that is not an associated item of the trait)
 - #163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - #163107 (Implement Allocator for Pin unstably)
 - #163108 (remove old solver use of `SolverRelating`)
rust-bors Bot pushed a commit that referenced this pull request Sep 21, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
56fad88 
…uwer

Rollup of 10 pull requests

Successful merges:

 - #163083 (Remove `G` generic param from `Diag<'_, G>`)
 - #160679 (Staticlib rename internal symbols: add COFF support)
 - #160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - #162007 (Preserve parentheses in raw borrow suggestions)
 - #162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - #163057 (Use span context for enclosing item(s) of unmet bound)
 - #163070 (label the path segment that is not an associated item of the trait)
 - #163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - #163107 (Implement Allocator for Pin unstably)
 - #163108 (remove old solver use of `SolverRelating`)
@rust-bors
rust-bors Bot merged commit 0c365b0 into rust-lang:main Sep 21, 2026
13 checks passed
@rustbot rustbot added this to the 1.100.0 milestone Sep 21, 2026
rust-bors Bot pushed a commit that referenced this pull request Sep 21, 2026
@bors
Unrolled build for #162821 in rollup 163111
c2f9d25 
Rollup merge of #162821 - kulinsky:fix-153363-closure-suggestion, r=mejrs

Avoid suggesting closures when captures cross associated item boundaries

Fixes #153363

We check the boundaries between a variable's declaration and its usage. If an associated item boundary is crossed, replacing a nested function with a closure does not eliminate this boundary. We retain the error but remove the ineffective suggestion.

The hint is preserved for an ordinary nested function capturing a local variable of the method.

Checks: full UI test run `./x test tests/ui --force-rerun`, 21853 passed / 410 ignored, and `./x test tidy`.

Used an LLM for code navigation
github-actions Bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Sep 21, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
3b18834 
…uwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang/rust#163083 (Remove `G` generic param from `Diag<'_, G>`)
 - rust-lang/rust#160679 (Staticlib rename internal symbols: add COFF support)
 - rust-lang/rust#160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - rust-lang/rust#162007 (Preserve parentheses in raw borrow suggestions)
 - rust-lang/rust#162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - rust-lang/rust#163057 (Use span context for enclosing item(s) of unmet bound)
 - rust-lang/rust#163070 (label the path segment that is not an associated item of the trait)
 - rust-lang/rust#163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - rust-lang/rust#163107 (Implement Allocator for Pin unstably)
 - rust-lang/rust#163108 (remove old solver use of `SolverRelating`)
bjorn3 pushed a commit to rust-lang/rustc_codegen_cranelift that referenced this pull request Sep 22, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
ca3fb81 
…uwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang/rust#163083 (Remove `G` generic param from `Diag<'_, G>`)
 - rust-lang/rust#160679 (Staticlib rename internal symbols: add COFF support)
 - rust-lang/rust#160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - rust-lang/rust#162007 (Preserve parentheses in raw borrow suggestions)
 - rust-lang/rust#162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - rust-lang/rust#163057 (Use span context for enclosing item(s) of unmet bound)
 - rust-lang/rust#163070 (label the path segment that is not an associated item of the trait)
 - rust-lang/rust#163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - rust-lang/rust#163107 (Implement Allocator for Pin unstably)
 - rust-lang/rust#163108 (remove old solver use of `SolverRelating`)
pull Bot pushed a commit to xtqqczze/rust-lang-miri that referenced this pull request Sep 22, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
bd9f550 
…uwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang/rust#163083 (Remove `G` generic param from `Diag<'_, G>`)
 - rust-lang/rust#160679 (Staticlib rename internal symbols: add COFF support)
 - rust-lang/rust#160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - rust-lang/rust#162007 (Preserve parentheses in raw borrow suggestions)
 - rust-lang/rust#162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - rust-lang/rust#163057 (Use span context for enclosing item(s) of unmet bound)
 - rust-lang/rust#163070 (label the path segment that is not an associated item of the trait)
 - rust-lang/rust#163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - rust-lang/rust#163107 (Implement Allocator for Pin unstably)
 - rust-lang/rust#163108 (remove old solver use of `SolverRelating`)
makai410 pushed a commit to makai410/rust that referenced this pull request Oct 1, 2026
@bors
Auto merge of rust-lang#163111 - JonathanBrouwer:rollup-ky5V96R, r=Jo…
56bedea 
…nathanBrouwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang#163083 (Remove `G` generic param from `Diag<'_, G>`)
 - rust-lang#160679 (Staticlib rename internal symbols: add COFF support)
 - rust-lang#160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - rust-lang#162007 (Preserve parentheses in raw borrow suggestions)
 - rust-lang#162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - rust-lang#163057 (Use span context for enclosing item(s) of unmet bound)
 - rust-lang#163070 (label the path segment that is not an associated item of the trait)
 - rust-lang#163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - rust-lang#163107 (Implement Allocator for Pin unstably)
 - rust-lang#163108 (remove old solver use of `SolverRelating`)
makai410 pushed a commit to makai410/rustc_public that referenced this pull request Oct 1, 2026
@bors
Auto merge of #163111 - JonathanBrouwer:rollup-ky5V96R, r=JonathanBro…
9445aed 
…uwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang/rust#163083 (Remove `G` generic param from `Diag<'_, G>`)
 - rust-lang/rust#160679 (Staticlib rename internal symbols: add COFF support)
 - rust-lang/rust#160859 (`core::num::f16b` Rust's 16bit Brain Float)
 - rust-lang/rust#162007 (Preserve parentheses in raw borrow suggestions)
 - rust-lang/rust#162821 (Avoid suggesting closures when captures cross associated item boundaries)
 - rust-lang/rust#163057 (Use span context for enclosing item(s) of unmet bound)
 - rust-lang/rust#163070 (label the path segment that is not an associated item of the trait)
 - rust-lang/rust#163078 ( Add a README in tests/rustdoc-html to explain what each folder content is for)
 - rust-lang/rust#163107 (Implement Allocator for Pin unstably)
 - rust-lang/rust#163108 (remove old solver use of `SolverRelating`)
@github-actions github-actions Bot mentioned this pull request Oct 2, 2026
Merged
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E0434 suggests changing the fn item of a trait impl to a closure

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