Suggest making binding mut on &mut reborrow
#147141
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☔ The latest upstream changes (presumably #142390) made this pull request unmergeable. Please resolve the merge conflicts. |
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r? compiler |
When a binding needs to be mutably reborrowed multiple times, suggesting removing `&mut` will lead to follow up errors. Instead suggest both making the binding mutable and removing the reborrow.
```
error[E0596]: cannot borrow `outer` as mutable, as it is not declared as mutable
--> f14.rs:2:12
|
2 | match (&mut outer, 23) {
| ^^^^^^^^^^ cannot borrow as mutable
|
note: the binding is already a mutable borrow
--> f14.rs:1:16
|
1 | fn test(outer: &mut Option<i32>) {
| ^^^^^^^^^^^^^^^^
help: consider making the binding mutable if you need to reborrow multiple times
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1 | fn test(mut outer: &mut Option<i32>) {
| +++
help: if there is only one mutable reborrow, remove the `&mut`
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2 - match (&mut outer, 23) {
2 + match (outer, 23) {
|
```
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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. |
jackh726
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Nov 3, 2025
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@bors r+ rollup |
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Suggest making binding `mut` on `&mut` reborrow
When a binding needs to be mutably reborrowed multiple times, suggesting removing `&mut` will lead to follow up errors. Instead suggest both making the binding mutable and removing the reborrow.
```
error[E0596]: cannot borrow `outer` as mutable, as it is not declared as mutable
--> f14.rs:2:12
|
2 | match (&mut outer, 23) {
| ^^^^^^^^^^ cannot borrow as mutable
|
note: the binding is already a mutable borrow
--> f14.rs:1:16
|
1 | fn test(outer: &mut Option<i32>) {
| ^^^^^^^^^^^^^^^^
help: consider making the binding mutable if you need to reborrow multiple times
|
1 | fn test(mut outer: &mut Option<i32>) {
| +++
help: if there is only one mutable reborrow, remove the `&mut`
|
2 - match (&mut outer, 23) {
2 + match (outer, 23) {
|
```
Address rust-lang#81059.
bors
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Nov 3, 2025
Rollup of 7 pull requests Successful merges: - #147141 (Suggest making binding `mut` on `&mut` reborrow) - #147945 (Port `cfg!()` macro to the new attribute parsing system ) - #147951 (Add check for `+=` typo in let chains) - #148004 (fix: Only special case single line item attribute suggestions) - #148264 (reflect that type and const parameter can be intermixed) - #148363 (Fix `wasm_import_module` attribute cross-crate) - #148447 (Tweak E0401) r? `@ghost` `@rustbot` modify labels: rollup
rust-timer
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Nov 4, 2025
Rollup merge of #147141 - estebank:issue-81059, r=jackh726 Suggest making binding `mut` on `&mut` reborrow When a binding needs to be mutably reborrowed multiple times, suggesting removing `&mut` will lead to follow up errors. Instead suggest both making the binding mutable and removing the reborrow. ``` error[E0596]: cannot borrow `outer` as mutable, as it is not declared as mutable --> f14.rs:2:12 | 2 | match (&mut outer, 23) { | ^^^^^^^^^^ cannot borrow as mutable | note: the binding is already a mutable borrow --> f14.rs:1:16 | 1 | fn test(outer: &mut Option<i32>) { | ^^^^^^^^^^^^^^^^ help: consider making the binding mutable if you need to reborrow multiple times | 1 | fn test(mut outer: &mut Option<i32>) { | +++ help: if there is only one mutable reborrow, remove the `&mut` | 2 - match (&mut outer, 23) { 2 + match (outer, 23) { | ``` Address #81059.
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When a binding needs to be mutably reborrowed multiple times, suggesting removing
&mutwill lead to follow up errors. Instead suggest both making the binding mutable and removing the reborrow.Address #81059.