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Mention when type parameter could be Clone

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```
error[E0382]: use of moved value: `t`
  --> $DIR/use_of_moved_value_copy_suggestions.rs:7:9
   |
LL | fn duplicate_t<T>(t: T) -> (T, T) {
   |                   - move occurs because `t` has type `T`, which does not implement the `Copy` trait
...
LL |     (t, t)
   |      -  ^ value used here after move
   |      |
   |      value moved here
   |
help: if `T` implemented `Clone`, you could clone the value
  --> $DIR/use_of_moved_value_copy_suggestions.rs:4:16
   |
LL | fn duplicate_t<T>(t: T) -> (T, T) {
   |                ^ consider constraining this type parameter with `Clone`
...
LL |     (t, t)
   |      - you could clone this value
help: consider restricting type parameter `T`
   |
LL | fn duplicate_t<T: Copy>(t: T) -> (T, T) {
   |                 ++++++
```

The `help` is new. On ADTs, we also extend the output with span labels:

```
error[E0507]: cannot move out of static item `FOO`
  --> $DIR/issue-17718-static-move.rs:6:14
   |
LL |     let _a = FOO;
   |              ^^^ move occurs because `FOO` has type `Foo`, which does not implement the `Copy` trait
   |
note: if `Foo` implemented `Clone`, you could clone the value
  --> $DIR/issue-17718-static-move.rs:1:1
   |
LL | struct Foo;
   | ^^^^^^^^^^ consider implementing `Clone` for this type
...
LL |     let _a = FOO;
   |              --- you could clone this value
help: consider borrowing here
   |
LL |     let _a = &FOO;
   |              +
```
This commit is contained in:
Esteban Küber
2024-04-18 22:18:19 +00:00
parent 4aba2c55e6
commit d68f2a6b71
51 changed files with 640 additions and 86 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
compiler/rustc_borrowck/src/diagnostics/move_errors.rs
View File

@@ -447,7 +447,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
};
if let Some(expr) = self.find_expr(span) {
self.suggest_cloning(err, place_ty, expr, self.find_expr(other_span));
self.suggest_cloning(err, place_ty, expr, self.find_expr(other_span), None);
}
err.subdiagnostic(
@@ -482,7 +482,13 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
};
if let Some(expr) = self.find_expr(use_span) {
self.suggest_cloning(err, place_ty, expr, self.find_expr(span));
self.suggest_cloning(
err,
place_ty,
expr,
self.find_expr(span),
Some(use_spans),
);
}
err.subdiagnostic(
@@ -595,7 +601,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
let place_desc = &format!("`{}`", self.local_names[*local].unwrap());
if let Some(expr) = self.find_expr(binding_span) {
self.suggest_cloning(err, bind_to.ty, expr, None);
self.suggest_cloning(err, bind_to.ty, expr, None, None);
}
err.subdiagnostic(