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.
69 lines
3.4 KiB
Plaintext
69 lines
3.4 KiB
Plaintext
error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/object-safety.rs:14:33
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LL | let i = Box::new(42_u32) as Box<dyn Foo>;
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| ^^^^^^^^^^^^ `Foo` 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-safety.rs:4:22
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LL | trait Foo {
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| --- this trait cannot be made into an object...
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LL | fn baz(&self) -> impl Debug;
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| ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
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= help: consider moving `baz` to another trait
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= help: only type `u32` implements the trait, consider using it directly instead
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/object-safety.rs:17:15
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LL | let s = i.baz();
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| ^^^ `Foo` 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-safety.rs:4:22
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LL | trait Foo {
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| --- this trait cannot be made into an object...
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LL | fn baz(&self) -> impl Debug;
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| ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
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= help: consider moving `baz` to another trait
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= help: only type `u32` implements the trait, consider using it directly instead
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/object-safety.rs:17:13
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LL | let s = i.baz();
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| ^^^^^^^ `Foo` 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-safety.rs:4:22
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LL | trait Foo {
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| --- this trait cannot be made into an object...
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LL | fn baz(&self) -> impl Debug;
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| ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
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= help: consider moving `baz` to another trait
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= help: only type `u32` implements the trait, consider using it directly instead
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/object-safety.rs:14:13
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LL | let i = Box::new(42_u32) as Box<dyn Foo>;
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| ^^^^^^^^^^^^^^^^ `Foo` 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-safety.rs:4:22
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LL | trait Foo {
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| --- this trait cannot be made into an object...
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LL | fn baz(&self) -> impl Debug;
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| ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
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= help: consider moving `baz` to another trait
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= help: only type `u32` implements the trait, consider using it directly instead
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= note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
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error: aborting due to 4 previous errors
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For more information about this error, try `rustc --explain E0038`.
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