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Current suggestion for when taking a mutable reference to self in a closure (as an upvar) will produce a machine-applicable suggestion to change the self in the function signature to mut self, but does not account for the specialness of implicit self in that it can already have & and &mut (see #111554). This causes the function signature to become test(&mut mut self) which does not seem desirable.

error[E0596]: cannot borrow `self` as mutable, as it is not declared as mutable
   --> src/sound_player.rs:870:11
    |
869 |     pub fn test(&mut self) {
    |                      ---- help: consider changing this to be mutable: `mut self`
870 |     || test2(&mut self);
    |              ^^^^^^^^^ cannot borrow as mutable

This PR suppresses the "changing this to be mutable" suggestion if the implicit self is either ImplicitSelfKind::ImmRef or ImplicitSelfKind::MutRef.

Fixes #111554.

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rustbot commented May 27, 2023

r? @jackh726

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@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 May 27, 2023
@jieyouxu jieyouxu changed the title Don't suggest changing &self and &mut self to be mutable Don't suggest changing &self and &mut self in function signature to be mutable when taking &mut self in closure May 27, 2023
@compiler-errors compiler-errors 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 May 29, 2023
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@rustbot ready

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels May 29, 2023
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@bors r+ rollup

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bors commented Jun 5, 2023

📌 Commit 57e67e4 has been approved by compiler-errors

It is now in the queue for this repository.

@bors bors 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 Jun 5, 2023
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Jun 6, 2023
…errors

Don't suggest changing `&self` and `&mut self` in function signature to be mutable when taking `&mut self` in closure

Current suggestion for when taking a mutable reference to `self` in a closure (as an upvar) will produce a machine-applicable suggestion to change the `self` in the function signature to `mut self`, but does not account for the specialness of implicit self in that it can already have `&` and `&mut` (see rust-lang#111554). This causes the function signature to become `test(&mut mut self)` which does not seem desirable.

```
error[E0596]: cannot borrow `self` as mutable, as it is not declared as mutable
   --> src/sound_player.rs:870:11
    |
869 |     pub fn test(&mut self) {
    |                      ---- help: consider changing this to be mutable: `mut self`
870 |     || test2(&mut self);
    |              ^^^^^^^^^ cannot borrow as mutable
```

This PR suppresses the "changing this to be mutable" suggestion if the implicit self is either `ImplicitSelfKind::ImmRef` or `ImplicitSelfKind::MutRef`.

Fixes rust-lang#111554.
bors added a commit to rust-lang-ci/rust that referenced this pull request Jun 6, 2023
…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#111058 (Correct fortanix LVI test print function)
 - rust-lang#111369 (Added custom risc32-imac for esp-espidf target)
 - rust-lang#111962 (Make GDB Python Pretty Printers loadable after spawning GDB, avoiding required `rust-gdb`)
 - rust-lang#112019 (Don't suggest changing `&self` and `&mut self` in function signature to be mutable when taking `&mut self` in closure)
 - rust-lang#112199 (Fix suggestion for matching struct with `..` on both ends)
 - rust-lang#112220 (Cleanup some `EarlyBinder::skip_binder()` -> `EarlyBinder::subst_identity()`)
 - rust-lang#112325 (diagnostics: do not suggest type name tweaks on type-inferred closure args)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 21e7463 into rust-lang:master Jun 6, 2023
@rustbot rustbot added this to the 1.72.0 milestone Jun 6, 2023
@jieyouxu jieyouxu deleted the issue-111554 branch December 20, 2024 17:37
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Taking a mutable reference to self in a closure leads to suggestion to change "self" in function signature
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