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WaffleLapkinWaffleLapkin
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add a test for pointer casts involving un/re/wrapping trait objects
the errors should not be there, this is a bug/missing feature.
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Diff for: ‎tests/ui/cast/ptr-to-trait-obj-wrap-add-auto.rs

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// Combination of `ptr-to-trait-obj-wrap.rs` and `ptr-to-trait-obj-add-auto.rs`.
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//
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// Checks that you *can't* add auto traits to trait object in pointer casts involving wrapping said
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// traits structures.
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trait A {}
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struct W<T: ?Sized>(T);
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struct X<T: ?Sized>(T);
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fn unwrap(a: *const W<dyn A>) -> *const (dyn A + Send) {
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a as _
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//~^ error
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//~| error
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//~| error
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}
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fn unwrap_nested(a: *const W<W<dyn A>>) -> *const W<dyn A + Send> {
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a as _
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//~^ error
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//~| error
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//~| error
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}
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fn rewrap(a: *const W<dyn A>) -> *const X<dyn A + Send> {
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a as _
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//~^ error: cannot add auto trait `Send` to dyn bound via pointer cast
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}
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fn rewrap_nested(a: *const W<W<dyn A>>) -> *const W<X<dyn A + Send>> {
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a as _
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//~^ error: cannot add auto trait `Send` to dyn bound via pointer cast
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}
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fn wrap(a: *const dyn A) -> *const W<dyn A + Send> {
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a as _
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//~^ error: cannot add auto trait `Send` to dyn bound via pointer cast
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}
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fn main() {}

Diff for: ‎tests/ui/cast/ptr-to-trait-obj-wrap-add-auto.stderr

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error[E0277]: the trait bound `W<(dyn A + 'static)>: A` is not satisfied
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:12:5
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|
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LL | a as _
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| ^ the trait `A` is not implemented for `W<(dyn A + 'static)>`
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|
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help: this trait has no implementations, consider adding one
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:6:1
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|
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LL | trait A {}
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| ^^^^^^^
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= note: required for the cast from `*const W<(dyn A + 'static)>` to `*const dyn A + Send`
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error[E0277]: `(dyn A + 'static)` cannot be sent between threads safely
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:12:5
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|
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LL | a as _
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| ^ `(dyn A + 'static)` cannot be sent between threads safely
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|
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= help: within `W<(dyn A + 'static)>`, the trait `Send` is not implemented for `(dyn A + 'static)`
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note: required because it appears within the type `W<(dyn A + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<(dyn A + 'static)>` to `*const dyn A + Send`
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error[E0277]: the size for values of type `(dyn A + 'static)` cannot be known at compilation time
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:12:5
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|
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LL | a as _
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| ^ doesn't have a size known at compile-time
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|
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= help: within `W<(dyn A + 'static)>`, the trait `Sized` is not implemented for `(dyn A + 'static)`
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note: required because it appears within the type `W<(dyn A + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<(dyn A + 'static)>` to `*const dyn A + Send`
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error[E0277]: the trait bound `W<(dyn A + 'static)>: A` is not satisfied
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:19:5
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|
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LL | a as _
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| ^ the trait `A` is not implemented for `W<(dyn A + 'static)>`
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|
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help: this trait has no implementations, consider adding one
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:6:1
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|
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LL | trait A {}
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| ^^^^^^^
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= note: required for the cast from `*const W<W<(dyn A + 'static)>>` to `*const W<dyn A + Send>`
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error[E0277]: `(dyn A + 'static)` cannot be sent between threads safely
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:19:5
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|
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LL | a as _
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| ^ `(dyn A + 'static)` cannot be sent between threads safely
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|
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= help: within `W<(dyn A + 'static)>`, the trait `Send` is not implemented for `(dyn A + 'static)`
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note: required because it appears within the type `W<(dyn A + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<W<(dyn A + 'static)>>` to `*const W<dyn A + Send>`
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error[E0277]: the size for values of type `(dyn A + 'static)` cannot be known at compilation time
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:19:5
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|
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LL | a as _
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| ^ doesn't have a size known at compile-time
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|
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= help: within `W<(dyn A + 'static)>`, the trait `Sized` is not implemented for `(dyn A + 'static)`
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note: required because it appears within the type `W<(dyn A + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<W<(dyn A + 'static)>>` to `*const W<dyn A + Send>`
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error[E0804]: cannot add auto trait `Send` to dyn bound via pointer cast
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:26:5
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|
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LL | a as _
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| ^^^^^^ unsupported cast
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|
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= note: this could allow UB elsewhere
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= help: use `transmute` if you're sure this is sound
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error[E0804]: cannot add auto trait `Send` to dyn bound via pointer cast
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:31:5
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|
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LL | a as _
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| ^^^^^^ unsupported cast
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|
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= note: this could allow UB elsewhere
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= help: use `transmute` if you're sure this is sound
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error[E0804]: cannot add auto trait `Send` to dyn bound via pointer cast
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--> $DIR/ptr-to-trait-obj-wrap-add-auto.rs:36:5
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|
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LL | a as _
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| ^^^^^^ unsupported cast
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|
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= note: this could allow UB elsewhere
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= help: use `transmute` if you're sure this is sound
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error: aborting due to 9 previous errors
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Some errors have detailed explanations: E0277, E0804.
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For more information about an error, try `rustc --explain E0277`.

Diff for: ‎tests/ui/cast/ptr-to-trait-obj-wrap-different-args.rs

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// Combination of `ptr-to-trait-obj-different-args.rs` and `ptr-to-trait-obj-wrap.rs`.
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//
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// Checks that you *can't* change type arguments of trait objects in pointer casts involving
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// wrapping said traits structures.
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trait A<T> {}
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struct W<T: ?Sized>(T);
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struct X<T: ?Sized>(T);
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fn unwrap<F, G>(a: *const W<dyn A<F>>) -> *const dyn A<G> {
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a as _
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//~^ error
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//~| error
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}
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fn unwrap_nested<F, G>(a: *const W<W<dyn A<F>>>) -> *const W<dyn A<G>> {
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a as _
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//~^ error
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//~| error
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}
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fn rewrap<F, G>(a: *const W<dyn A<F>>) -> *const X<dyn A<G>> {
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a as _
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//~^ error: casting `*const W<(dyn A<F> + 'static)>` as `*const X<dyn A<G>>` is invalid
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}
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fn rewrap_nested<F, G>(a: *const W<W<dyn A<F>>>) -> *const W<X<dyn A<G>>> {
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a as _
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//~^ error: casting `*const W<W<(dyn A<F> + 'static)>>` as `*const W<X<dyn A<G>>>` is invalid
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}
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fn wrap<F, G>(a: *const dyn A<F>) -> *const W<dyn A<G>> {
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a as _
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//~^ error: casting `*const (dyn A<F> + 'static)` as `*const W<dyn A<G>>` is invalid
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}
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fn main() {}

Diff for: ‎tests/ui/cast/ptr-to-trait-obj-wrap-different-args.stderr

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error[E0277]: the trait bound `W<(dyn A<F> + 'static)>: A<G>` is not satisfied
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:12:5
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|
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LL | a as _
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| ^ the trait `A<G>` is not implemented for `W<(dyn A<F> + 'static)>`
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|
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help: this trait has no implementations, consider adding one
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:6:1
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|
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LL | trait A<T> {}
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| ^^^^^^^^^^
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= note: required for the cast from `*const W<(dyn A<F> + 'static)>` to `*const dyn A<G>`
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error[E0277]: the size for values of type `(dyn A<F> + 'static)` cannot be known at compilation time
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:12:5
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|
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LL | a as _
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| ^ doesn't have a size known at compile-time
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|
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= help: within `W<(dyn A<F> + 'static)>`, the trait `Sized` is not implemented for `(dyn A<F> + 'static)`
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note: required because it appears within the type `W<(dyn A<F> + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<(dyn A<F> + 'static)>` to `*const dyn A<G>`
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error[E0277]: the trait bound `W<(dyn A<F> + 'static)>: A<G>` is not satisfied
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:18:5
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|
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LL | a as _
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| ^ the trait `A<G>` is not implemented for `W<(dyn A<F> + 'static)>`
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|
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help: this trait has no implementations, consider adding one
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:6:1
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|
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LL | trait A<T> {}
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| ^^^^^^^^^^
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= note: required for the cast from `*const W<W<(dyn A<F> + 'static)>>` to `*const W<dyn A<G>>`
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error[E0277]: the size for values of type `(dyn A<F> + 'static)` cannot be known at compilation time
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:18:5
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|
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LL | a as _
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| ^ doesn't have a size known at compile-time
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|
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= help: within `W<(dyn A<F> + 'static)>`, the trait `Sized` is not implemented for `(dyn A<F> + 'static)`
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note: required because it appears within the type `W<(dyn A<F> + 'static)>`
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:8:8
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|
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LL | struct W<T: ?Sized>(T);
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| ^
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= note: required for the cast from `*const W<W<(dyn A<F> + 'static)>>` to `*const W<dyn A<G>>`
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error[E0606]: casting `*const W<(dyn A<F> + 'static)>` as `*const X<dyn A<G>>` is invalid
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:24:5
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|
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LL | a as _
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| ^^^^^^
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|
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= note: the trait objects may have different vtables
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error[E0606]: casting `*const W<W<(dyn A<F> + 'static)>>` as `*const W<X<dyn A<G>>>` is invalid
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:29:5
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|
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LL | a as _
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| ^^^^^^
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|
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= note: the trait objects may have different vtables
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error[E0606]: casting `*const (dyn A<F> + 'static)` as `*const W<dyn A<G>>` is invalid
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--> $DIR/ptr-to-trait-obj-wrap-different-args.rs:34:5
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|
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LL | a as _
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| ^^^^^^
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|
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= note: the trait objects may have different vtables
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error: aborting due to 7 previous errors
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Some errors have detailed explanations: E0277, E0606.
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For more information about an error, try `rustc --explain E0277`.

Diff for: ‎tests/ui/cast/ptr-to-trait-obj-wrap-different-regions.rs

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// Combination of `ptr-to-trait-obj-different-regions-misc.rs` and `ptr-to-trait-obj-wrap.rs`.
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//
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// Checks that you *can't* change lifetime arguments of trait objects in pointer casts involving
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// wrapping said traits structures.
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trait A<'a> {}
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struct W<T: ?Sized>(T);
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struct X<T: ?Sized>(T);
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fn unwrap<'a, 'b>(a: *const W<dyn A<'a>>) -> *const dyn A<'b> {
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a as _
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//~^ error
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//~| error
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}
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fn unwrap_nested<'a, 'b>(a: *const W<W<dyn A<'a>>>) -> *const W<dyn A<'b>> {
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a as _
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//~^ error
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//~| error
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}
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fn rewrap<'a, 'b>(a: *const W<dyn A<'a>>) -> *const X<dyn A<'b>> {
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a as _
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//~^ error: lifetime may not live long enough
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//~| error: lifetime may not live long enough
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}
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fn rewrap_nested<'a, 'b>(a: *const W<W<dyn A<'a>>>) -> *const W<X<dyn A<'b>>> {
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a as _
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//~^ error: lifetime may not live long enough
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//~| error: lifetime may not live long enough
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}
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fn wrap<'a, 'b>(a: *const dyn A<'a>) -> *const W<dyn A<'b>> {
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a as _
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//~^ error: lifetime may not live long enough
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//~| error: lifetime may not live long enough
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}
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fn main() {}

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