error: associated item referring to unboxed trait object for its own trait --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13 | LL | trait A: Sized { | - in this trait LL | fn f(a: A) -> A; | ^ ^ | help: you might have meant to use `Self` to refer to the implementing type | LL | fn f(a: Self) -> Self; | ~~~~ ~~~~ error[E0038]: the trait `A` cannot be made into an object --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13 | LL | fn f(a: A) -> A; | ^ `A` 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 --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:3:10 | LL | trait A: Sized { | - ^^^^^ ...because it requires `Self: Sized` | | | this trait cannot be made into an object... error: associated item referring to unboxed trait object for its own trait --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13 | LL | trait B { | - in this trait LL | fn f(b: B) -> B; | ^ ^ | help: you might have meant to use `Self` to refer to the implementing type | LL | fn f(b: Self) -> Self; | ~~~~ ~~~~ error[E0038]: the trait `B` cannot be made into an object --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13 | LL | fn f(b: B) -> B; | ^ `B` 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 --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:8 | LL | trait B { | - this trait cannot be made into an object... LL | fn f(b: B) -> B; | ^ ...because associated function `f` has no `self` parameter help: consider turning `f` into a method by giving it a `&self` argument | LL | fn f(&self, b: B) -> B; | ++++++ help: alternatively, consider constraining `f` so it does not apply to trait objects | LL | fn f(b: B) -> B where Self: Sized; | +++++++++++++++++ error: associated item referring to unboxed trait object for its own trait --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20 | LL | trait C { | - in this trait LL | fn f(&self, c: C) -> C; | ^ ^ | help: you might have meant to use `Self` to refer to the implementing type | LL | fn f(&self, c: Self) -> Self; | ~~~~ ~~~~ error[E0038]: the trait `C` cannot be made into an object --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20 | LL | fn f(&self, c: C) -> C; | ----- ^ `C` cannot be made into an object | | | help: consider changing method `f`'s `self` parameter to be `&self` (notice the capitalization): `&Self` | 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 --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:10 | LL | trait C { | - this trait cannot be made into an object... LL | fn f(&self, c: C) -> C; | ^^^^^ ...because method `f`'s `self` parameter cannot be dispatched on error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13 | LL | fn f(a: A) -> A; | ^ | = note: `A` it is not object safe, so it can't be `dyn` help: use a new generic type parameter, constrained by `A` | LL | fn f(a: T) -> A; | ++++++ ~ 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 | LL | fn f(a: impl A) -> A; | ++++ error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:19 | LL | fn f(a: A) -> A; | ^ | help: `A` is not object safe, use `impl A` to return an opaque type, as long as you return a single underlying type | LL | fn f(a: A) -> impl A; | ++++ error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13 | LL | fn f(b: B) -> B; | ^ | = note: `B` it is not object safe, so it can't be `dyn` help: use a new generic type parameter, constrained by `B` | LL | fn f(b: T) -> B; | ++++++ ~ 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 | LL | fn f(b: impl B) -> B; | ++++ error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:19 | LL | fn f(b: B) -> B; | ^ | help: `B` is not object safe, use `impl B` to return an opaque type, as long as you return a single underlying type | LL | fn f(b: B) -> impl B; | ++++ error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20 | LL | fn f(&self, c: C) -> C; | ^ | = note: `C` it is not object safe, so it can't be `dyn` help: use a new generic type parameter, constrained by `C` | LL | fn f(&self, c: T) -> C; | ++++++ ~ 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 | LL | fn f(&self, c: impl C) -> C; | ++++ error[E0782]: trait objects must include the `dyn` keyword --> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:26 | LL | fn f(&self, c: C) -> C; | ^ | help: `C` is not object safe, use `impl C` to return an opaque type, as long as you return a single underlying type | LL | fn f(&self, c: C) -> impl C; | ++++ error: aborting due to 12 previous errors Some errors have detailed explanations: E0038, E0782. For more information about an error, try `rustc --explain E0038`.