169 lines
6.2 KiB
Plaintext
169 lines
6.2 KiB
Plaintext
error: associated item referring to unboxed trait object for its own trait
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13
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LL | trait A: Sized {
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| - in this trait
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LL | fn f(a: A) -> A;
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| ^ ^
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help: you might have meant to use `Self` to refer to the implementing type
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LL | fn f(a: Self) -> Self;
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| ~~~~ ~~~~
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error[E0038]: the trait `A` cannot be made into an object
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13
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LL | fn f(a: A) -> A;
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| ^ `A` 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/object-unsafe-trait-should-use-self-2021-without-dyn.rs:3:10
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LL | trait A: Sized {
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| - ^^^^^ ...because it requires `Self: Sized`
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| |
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| this trait cannot be made into an object...
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error: associated item referring to unboxed trait object for its own trait
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13
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LL | trait B {
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| - in this trait
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LL | fn f(a: B) -> B;
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| ^ ^
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help: you might have meant to use `Self` to refer to the implementing type
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LL | fn f(a: Self) -> Self;
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| ~~~~ ~~~~
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error[E0038]: the trait `B` cannot be made into an object
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13
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LL | fn f(a: B) -> B;
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| ^ `B` 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/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:8
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LL | trait B {
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| - this trait cannot be made into an object...
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LL | fn f(a: B) -> B;
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| ^ ...because associated function `f` has no `self` parameter
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help: consider turning `f` into a method by giving it a `&self` argument
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LL | fn f(&self, a: B) -> B;
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| ++++++
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help: alternatively, consider constraining `f` so it does not apply to trait objects
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LL | fn f(a: B) -> B where Self: Sized;
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| +++++++++++++++++
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13
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LL | fn f(a: A) -> A;
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| ^
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help: use a new generic type parameter, constrained by `A`
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LL | fn f<T: A>(a: T) -> A;
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| ++++++ ~
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help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
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LL | fn f(a: impl A) -> A;
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| ++++
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help: alternatively, use a trait object to accept any type that implements `A`, accessing its methods at runtime using dynamic dispatch
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LL | fn f(a: &dyn A) -> A;
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| ++++
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:19
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LL | fn f(a: A) -> A;
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| ^
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help: use `impl A` to return an opaque type, as long as you return a single underlying type
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LL | fn f(a: A) -> impl A;
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| ++++
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help: alternatively, you can return an owned trait object
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LL | fn f(a: A) -> Box<dyn A>;
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| +++++++ +
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13
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LL | fn f(a: B) -> B;
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| ^
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help: use a new generic type parameter, constrained by `B`
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LL | fn f<T: B>(a: T) -> B;
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| ++++++ ~
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help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
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LL | fn f(a: impl B) -> B;
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| ++++
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help: alternatively, use a trait object to accept any type that implements `B`, accessing its methods at runtime using dynamic dispatch
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LL | fn f(a: &dyn B) -> B;
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| ++++
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:19
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LL | fn f(a: B) -> B;
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| ^
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help: use `impl B` to return an opaque type, as long as you return a single underlying type
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LL | fn f(a: B) -> impl B;
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| ++++
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help: alternatively, you can return an owned trait object
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LL | fn f(a: B) -> Box<dyn B>;
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| +++++++ +
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20
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LL | fn f(&self, a: C) -> C;
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| ^
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help: use a new generic type parameter, constrained by `C`
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LL | fn f<T: C>(&self, a: T) -> C;
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| ++++++ ~
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help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
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LL | fn f(&self, a: impl C) -> C;
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| ++++
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help: alternatively, use a trait object to accept any type that implements `C`, accessing its methods at runtime using dynamic dispatch
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LL | fn f(&self, a: &dyn C) -> C;
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| ++++
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error[E0782]: trait objects must include the `dyn` keyword
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--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:26
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LL | fn f(&self, a: C) -> C;
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| ^
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help: use `impl C` to return an opaque type, as long as you return a single underlying type
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LL | fn f(&self, a: C) -> impl C;
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| ++++
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help: alternatively, you can return an owned trait object
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LL | fn f(&self, a: C) -> Box<dyn C>;
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| +++++++ +
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error: aborting due to 10 previous errors
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Some errors have detailed explanations: E0038, E0782.
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For more information about an error, try `rustc --explain E0038`.
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