rust/tests/ui/object-safety/issue-19538.stderr
Esteban Küber 8c04999226 On object safety error, mention new enum as alternative
When we encounter a `dyn Trait` that isn't object safe, look for its
implementors. If there's one, mention using it directly If there are
less than 9, mention the possibility of creating a new enum and using
that instead.

Account for object unsafe `impl Trait on dyn Trait {}`.  Make a
distinction between public and sealed traits.

Fix #80194.
2023-10-29 23:55:46 +00:00

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error[E0038]: the trait `Bar` cannot be made into an object
--> $DIR/issue-19538.rs:17:15
|
LL | let test: &mut dyn Bar = &mut thing;
| ^^^^^^^^^^^^ `Bar` cannot be made into an object
|
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/issue-19538.rs:2:8
|
LL | fn foo<T>(&self, val: T);
| ^^^ ...because method `foo` has generic type parameters
...
LL | trait Bar: Foo { }
| --- this trait cannot be made into an object...
= help: consider moving `foo` to another trait
= help: only type `Thing` implements the trait, consider using it directly instead
error[E0038]: the trait `Bar` cannot be made into an object
--> $DIR/issue-19538.rs:17:30
|
LL | let test: &mut dyn Bar = &mut thing;
| ^^^^^^^^^^ `Bar` cannot be made into an object
|
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/issue-19538.rs:2:8
|
LL | fn foo<T>(&self, val: T);
| ^^^ ...because method `foo` has generic type parameters
...
LL | trait Bar: Foo { }
| --- this trait cannot be made into an object...
= help: consider moving `foo` to another trait
= help: only type `Thing` implements the trait, consider using it directly instead
= note: required for the cast from `&mut Thing` to `&mut dyn Bar`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0038`.