Given the following code:
fn foo<T>(t: Option<T>) {
let _ = t == t;
}It gives a nice error:
error[E0369]: binary operation `==` cannot be applied to type `Option<T>`
--> src/main.rs:6:15
|
6 | let _ = t == t;
| - ^^ - Option<T>
| |
| Option<T>
|
help: consider restricting type parameter `T`
|
5 | fn duplicate<T: std::cmp::PartialEq>(t: Option<T>) {
| +++++++++++++++++++++
OTOH it doesn't work for say Copy:
fn duplicate<T>(t: Option<T>) -> (Option<T>, Option<T>) {
(t, t)
}which gives a somewhat unhelpful message:
error[E0382]: use of moved value: `t`
--> src/main.rs:6:9
|
5 | fn duplicate<T>(t: Option<T>) -> (Option<T>, Option<T>) {
| - move occurs because `t` has type `Option<T>`, which does not implement the `Copy` trait
6 | (t, t)
| - ^ value used here after move
| |
| value moved here
It would make sense to have this suggestion appearing here as well, e.g.
help: consider restricting type parameter `T`
|
5 | fn duplicate<T: Copy>(t: Option<T>) {
| ++++++
Given the following code:
It gives a nice error:
OTOH it doesn't work for say
Copy:which gives a somewhat unhelpful message:
It would make sense to have this suggestion appearing here as well, e.g.