Suggest mutable method when iterating over binding - #160001
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When encountering a for loop that requires a mutable iterator item, we previously suggested changing the method on the iterated expression, but ignored bindings. We now go to the binding's definition and suggest changing the method there too.
```
error[E0594]: cannot assign to `v.v`, which is behind a `&` reference
--> $DIR/suggest-mut-method-for-loop-hashmap.rs:31:9
|
LL | for (_k, v) in x {
| - this iterator yields `&` references
...
LL | v.v += 1;
| ^^^^^^^^ `v` is a `&` reference, so it cannot be written to
|
help: use mutable method
|
LL | let mut x = map.iter_mut();
| ++++
```
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r? @mati865 rustbot has assigned @mati865. Use Why was this reviewer chosen?The reviewer was selected based on:
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estebank
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Jul 27, 2026
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| assoc_items | ||
| .in_definition_order() | ||
| .map(|assoc_item_def| assoc_item_def.ident(tcx)) | ||
| .filter(|&ident| { | ||
| let original_method_ident = path_segment.ident; | ||
| original_method_ident != ident | ||
| && ident | ||
| .as_str() | ||
| .starts_with(&original_method_ident.name.to_string()) | ||
| }) | ||
| .map(|ident| format!("{ident}()")) | ||
| .peekable() |
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I would want us to make this logic more principled and actually check that the associated function will give back an appropriate iterator of mutable items, even if the name is different.
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@rustbot reroll |
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When encountering a for loop that requires a mutable iterator item, we previously suggested changing the method on the iterated expression, but ignored bindings. We now go to the binding's definition and suggest changing the method there too.
Fix #49839.