bjoernager/rust
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Provide suggestion to dereference closure tail if appropriate

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When encoutnering a case like

```rust
//@ run-rustfix
use std::collections::HashMap;

fn main() {
    let vs = vec![0, 0, 1, 1, 3, 4, 5, 6, 3, 3, 3];

    let mut counts = HashMap::new();
    for num in vs {
        let count = counts.entry(num).or_insert(0);
        *count += 1;
    }

    let _ = counts.iter().max_by_key(|(_, v)| v);
```
produce the following suggestion
```
error: lifetime may not live long enough
  --> $DIR/return-value-lifetime-error.rs:13:47
   |
LL |     let _ = counts.iter().max_by_key(|(_, v)| v);
   |                                       ------- ^ returning this value requires that `'1` must outlive `'2`
   |                                       |     |
   |                                       |     return type of closure is &'2 &i32
   |                                       has type `&'1 (&i32, &i32)`
   |
help: dereference the return value
   |
LL |     let _ = counts.iter().max_by_key(|(_, v)| **v);
   |                                               ++
```

Fix #50195.
This commit is contained in:
Esteban Küber 2024-03-08 22:59:53 +00:00
parent 76cf07d5df
commit 9de6b70bb6
8 changed files with 298 additions and 5 deletions
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3
compiler/rustc_middle/src/query/mod.rs
View file

@ -989,6 +989,9 @@ rustc_queries! {
query diagnostic_only_typeck(key: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> {
desc { |tcx| "type-checking `{}`", tcx.def_path_str(key) }
}
query lookup_method_for_diagnostic((def_id, hir_id): (LocalDefId, hir::HirId)) -> Option<DefId> {
desc { |tcx| "lookup_method_for_diagnostics `{}`", tcx.def_path_str(def_id) }
}
query used_trait_imports(key: LocalDefId) -> &'tcx UnordSet<LocalDefId> {
desc { |tcx| "finding used_trait_imports `{}`", tcx.def_path_str(key) }