E0507 could perhaps suggest fixing subsequent uses if it changes T to &T #106882
Description
Code
use std::any::TypeId;
use std::collections::HashMap;
use std::hash::Hash;
trait State {
type EventType;
fn get_type_id_of_state(&self) -> TypeId;
}
struct StateMachine<EventType: Hash + Eq> {
current_state: Box<dyn State<EventType = EventType>>,
transition_table:
HashMap<TypeId, HashMap<EventType, fn() -> Box<dyn State<EventType = EventType>>>>,
}
impl<EventType: Hash + Eq> StateMachine<EventType> {
fn inner_process_event(&mut self, event: EventType) -> Result<(), i8> {
let new_state_creation_function = self
.transition_table
.iter()
.find(|(&event_typeid, _)| event_typeid == self.current_state.get_type_id_of_state())
.ok_or(1)?
.1
.iter()
.find(|(&event_type, _)| event == event_type)
//~^ ERROR cannot move out of a shared reference
.ok_or(2)?
.1;
self.current_state = new_state_creation_function();
Ok(())
}
}
fn main() {}Current output
error[E0507]: cannot move out of a shared reference
--> src/lib.rs:25:20
|
25 | .find(|(&event_type, _)| event == event_type)
| ^^----------^^^^
| |
| data moved here
| move occurs because `event_type` has type `EventType`, which does not implement the `Copy` trait
|
help: consider borrowing the pattern binding
|
25 | .find(|(&ref event_type, _)| event == event_type)
| +++
For more information about this error, try `rustc --explain E0507`.Desired output
help: consider borrowing the pattern binding
|
25 | .find(|(&ref event_type, _)| event == *event_type)
| +++ +Rationale and extra context
Applying the suggestion will cause type mismatch in event == event_type, so perhaps rust could suggest borrowing/dereferencing automatically to fix that?
error[E0308]: mismatched types
--> src/lib.rs:25:51
|
16 | impl<EventType: Hash + Eq> StateMachine<EventType> {
| --------- this type parameter
...
25 | .find(|(&ref event_type, _)| event == event_type)
| ----- ^^^^^^^^^^ expected type parameter `EventType`, found `&EventType`
| |
| expected because this is `EventType`
|
= note: expected type parameter `EventType`
found reference `&EventType`
For more information about this error, try `rustc --explain E0308`.
Other cases
No response
Anything else?
No response