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.
54 lines
2.6 KiB
Plaintext
54 lines
2.6 KiB
Plaintext
error[E0038]: the trait `NotObjectSafe` cannot be made into an object
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--> $DIR/object-unsafe-trait-in-return-position-dyn-trait.rs:21:13
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LL | fn car() -> dyn NotObjectSafe {
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| ^^^^^^^^^^^^^^^^^ `NotObjectSafe` 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-in-return-position-dyn-trait.rs:3:8
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LL | trait NotObjectSafe {
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| ------------- this trait cannot be made into an object...
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LL | fn foo() -> Self;
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| ^^^ ...because associated function `foo` has no `self` parameter
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= help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `NotObjectSafe` for this new enum and using it instead:
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A
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B
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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) -> 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() -> Self where Self: Sized;
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| +++++++++++++++++
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error[E0038]: the trait `NotObjectSafe` cannot be made into an object
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--> $DIR/object-unsafe-trait-in-return-position-dyn-trait.rs:28:17
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LL | fn cat() -> Box<dyn NotObjectSafe> {
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| ^^^^^^^^^^^^^^^^^ `NotObjectSafe` 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-in-return-position-dyn-trait.rs:3:8
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LL | trait NotObjectSafe {
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| ------------- this trait cannot be made into an object...
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LL | fn foo() -> Self;
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| ^^^ ...because associated function `foo` has no `self` parameter
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= help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `NotObjectSafe` for this new enum and using it instead:
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A
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B
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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) -> 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() -> Self 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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