085da0cee4
On type errors where the difference is expecting an owned type and getting a reference, if the expression is a `.clone()` call and the type is annotated with `#[derive(Clone)]`, we now explain implicit bounds and suggest manually implementing `Clone`.
```
error[E0308]: mismatched types
--> $DIR/derive-implicit-bound-on-clone.rs:10:5
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LL | fn clone_me<T, K>(x: &ContainsRc<T, K>) -> ContainsRc<T, K> {
| ---------------- expected `ContainsRc<T, K>` because of return type
LL | x.clone()
| ^^^^^^^^^ expected `ContainsRc<T, K>`, found `&ContainsRc<T, K>`
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= note: expected struct `ContainsRc<_, _>`
found reference `&ContainsRc<_, _>`
note: `ContainsRc<T, K>` does not implement `Clone`, so `&ContainsRc<T, K>` was cloned instead
--> $DIR/derive-implicit-bound-on-clone.rs:10:5
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LL | x.clone()
| ^
help: `Clone` is not implemented because the some trait bounds could not be satisfied
--> $DIR/derive-implicit-bound-on-clone.rs:5:19
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LL | #[derive(Clone)]
| ----- in this derive macro expansion
LL | struct ContainsRc<T, K> {
| ^ ^ derive introduces an implicit unsatisfied trait bound `K: Clone`
| |
| derive introduces an implicit unsatisfied trait bound `T: Clone`
= help: consider manually implementing `Clone` to avoid the implict type parameter bounds
```
24 lines
562 B
Rust
24 lines
562 B
Rust
// Issue #146515
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use std::rc::Rc;
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#[derive(Clone)]
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struct ContainsRc<T, K> { //~ HELP `Clone` is not implemented
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value: Rc<(T, K)>,
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}
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fn clone_me<T, K>(x: &ContainsRc<T, K>) -> ContainsRc<T, K> {
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x.clone() //~ ERROR E0308
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//~^ HELP consider manually implementing `Clone`
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}
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#[derive(Clone)]
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struct ContainsRcSingle<T> { //~ HELP `Clone` is not implemented
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value: Rc<T>,
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}
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fn clone_me_single<T>(x: &ContainsRcSingle<T>) -> ContainsRcSingle<T> {
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x.clone() //~ ERROR E0308
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//~^ HELP consider manually implementing `Clone`
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}
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fn main() {}
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