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8c04999226
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.
51 lines
2.1 KiB
Plaintext
51 lines
2.1 KiB
Plaintext
error[E0038]: the trait `Tr` cannot be made into an object
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--> $DIR/safety.rs:15:22
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LL | let _: &dyn Tr = &St;
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| ^^^ `Tr` cannot be made into an object
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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>
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--> $DIR/safety.rs:4:8
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LL | trait Tr {
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| -- this trait cannot be made into an object...
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LL | fn foo();
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| ^^^ ...because associated function `foo` has no `self` parameter
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= help: only type `St` implements the trait, consider using it directly instead
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= note: required for the cast from `&St` to `&dyn Tr`
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help: consider turning `foo` into a method by giving it a `&self` argument
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LL | fn foo(&self);
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| +++++
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help: alternatively, consider constraining `foo` so it does not apply to trait objects
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LL | fn foo() where Self: Sized;
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| +++++++++++++++++
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error[E0038]: the trait `Tr` cannot be made into an object
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--> $DIR/safety.rs:15:12
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LL | let _: &dyn Tr = &St;
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| ^^^^^^^ `Tr` cannot be made into an object
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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>
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--> $DIR/safety.rs:4:8
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LL | trait Tr {
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| -- this trait cannot be made into an object...
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LL | fn foo();
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| ^^^ ...because associated function `foo` has no `self` parameter
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= help: only type `St` implements the trait, consider using it directly instead
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help: consider turning `foo` into a method by giving it a `&self` argument
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LL | fn foo(&self);
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| +++++
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help: alternatively, consider constraining `foo` so it does not apply to trait objects
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LL | fn foo() where Self: Sized;
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| +++++++++++++++++
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0038`.
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