Calling nonexistent function on a trait causes spurious object safety errors #58734
Description
trait Trait {
fn exists(self) -> ();
fn not_object_safe() -> Self;
}
impl Trait for () {
fn exists(self) -> () {
}
fn not_object_safe() -> Self {
()
}
}
fn main() {
// object-safe or not, this call is OK
Trait::exists(());
// but, in addition to nonexistence, this causes an object safety error
Trait::nonexistent(());
}Gives
error[E0599]: no function or associated item named `nonexistent` found for type `dyn Trait` in the current scope
--> src/main.rs:20:5
|
20 | Trait::nonexistent(());
| ^^^^^^^^^^^^^^^^^^ function or associated item not found in `dyn Trait`
error[E0038]: the trait `Trait` cannot be made into an object
--> src/main.rs:20:5
|
20 | Trait::nonexistent(());
| ^^^^^^^^^^^^^^^^^^ the trait `Trait` cannot be made into an object
|
= note: method `not_object_safe` has no receiver
error: aborting due to 2 previous errors
As the first call shows, it is in fact possible to call a non-object-safe trait's methods in this manner, but calling a nonexistent method gives an object safety error, adding noise to the output.
Note as well the E0599 error says the receiver type is dyn Trait.