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304 lines
13 KiB
Plaintext
304 lines
13 KiB
Plaintext
error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:35
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LL | fn fuz() -> (usize, Trait) { (42, Struct) }
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| ^^^^^^ expected `dyn Trait`, found `Struct`
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= note: expected trait object `(dyn Trait + 'static)`
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found struct `Struct`
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error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:13
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LL | fn fuz() -> (usize, Trait) { (42, Struct) }
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| ^^^^^^^^^^^^^^ ------------ this returned value is of type `(usize, (dyn Trait + 'static))`
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| |
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| doesn't have a size known at compile-time
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= help: within `(usize, (dyn Trait + 'static))`, the trait `Sized` is not implemented for `(dyn Trait + 'static)`
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= note: required because it appears within the type `(usize, dyn Trait)`
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= note: the return type of a function must have a statically known size
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:39
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LL | fn bar() -> (usize, dyn Trait) { (42, Struct) }
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| ^^^^^^ expected `dyn Trait`, found `Struct`
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= note: expected trait object `(dyn Trait + 'static)`
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found struct `Struct`
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error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:13
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LL | fn bar() -> (usize, dyn Trait) { (42, Struct) }
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| ^^^^^^^^^^^^^^^^^^ ------------ this returned value is of type `(usize, (dyn Trait + 'static))`
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| |
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| doesn't have a size known at compile-time
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= help: within `(usize, (dyn Trait + 'static))`, the trait `Sized` is not implemented for `(dyn Trait + 'static)`
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= note: required because it appears within the type `(usize, dyn Trait)`
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= note: the return type of a function must have a statically known size
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:13:13
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LL | fn bap() -> Trait { Struct }
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| ^^^^^ doesn't have a size known at compile-time
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait`
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LL | fn bap() -> impl Trait { Struct }
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| ~~~~~~~~~~
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:15:13
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LL | fn ban() -> dyn Trait { Struct }
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait`
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LL | fn ban() -> impl Trait { Struct }
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| ~~~~~~~~~~
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:17:13
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LL | fn bak() -> dyn Trait { unimplemented!() }
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| ^^^^^^^^^ doesn't have a size known at compile-time
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help: use `impl Trait` as the return type if all return paths have the same type but you want to expose only the trait in the signature
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LL | fn bak() -> impl Trait { unimplemented!() }
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| ~~~~~~~~~~
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help: use a boxed trait object if all return paths implement trait `Trait`
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LL | fn bak() -> Box<dyn Trait> { unimplemented!() }
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| ++++ +
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:19:13
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LL | fn bal() -> dyn Trait {
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
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= note: if all the returned values were of the same type you could use `impl Trait` as the return type
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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= note: you can create a new `enum` with a variant for each returned type
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help: return a boxed trait object instead
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LL | fn bal() -> Box<dyn Trait> {
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| ++++ +
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help: ... and box this value
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LL | return Box::new(Struct);
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| +++++++++ +
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help: ... and box this value
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LL | Box::new(42)
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| +++++++++ +
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error[E0308]: `if` and `else` have incompatible types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:29:9
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LL | / if true {
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LL | | Struct
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| | ------ expected because of this
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LL | | } else {
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LL | | 42
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| | ^^ expected `Struct`, found integer
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LL | | }
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| |_____- `if` and `else` have incompatible types
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:25:13
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LL | fn bax() -> dyn Trait {
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types>
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= note: if all the returned values were of the same type you could use `impl Trait` as the return type
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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= note: you can create a new `enum` with a variant for each returned type
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help: return a boxed trait object instead
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LL | fn bax() -> Box<dyn Trait> {
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| ++++ +
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help: ... and box this value
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LL | Box::new(Struct)
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| +++++++++ +
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help: ... and box this value
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LL | Box::new(42)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:34:16
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LL | fn bam() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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LL | if true {
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LL | return Struct;
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| ^^^^^^ expected `Box<dyn Trait>`, found `Struct`
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found struct `Struct`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | return Box::new(Struct);
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:36:5
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LL | fn bam() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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...
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LL | 42
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| ^^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(42)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:40:16
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LL | fn baq() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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LL | if true {
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LL | return 0;
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| ^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | return Box::new(0);
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:42:5
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LL | fn baq() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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...
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LL | 42
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| ^^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(42)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:46:9
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LL | fn baz() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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LL | if true {
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LL | Struct
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| ^^^^^^ expected `Box<dyn Trait>`, found `Struct`
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found struct `Struct`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(Struct)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:48:9
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LL | fn baz() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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...
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LL | 42
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| ^^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(42)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:53:9
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LL | fn baw() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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LL | if true {
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LL | 0
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| ^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(0)
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:55:9
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LL | fn baw() -> Box<dyn Trait> {
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| -------------- expected `Box<(dyn Trait + 'static)>` because of return type
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...
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LL | 42
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| ^^ expected `Box<dyn Trait>`, found integer
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= note: expected struct `Box<(dyn Trait + 'static)>`
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found type `{integer}`
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= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
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help: store this in the heap by calling `Box::new`
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LL | Box::new(42)
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| +++++++++ +
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:60:13
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LL | fn bat() -> dyn Trait {
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait`
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LL | fn bat() -> impl Trait {
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| ~~~~~~~~~~
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/dyn-trait-return-should-be-impl-trait.rs:66:13
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LL | fn bay() -> dyn Trait {
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
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help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait`
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LL | fn bay() -> impl Trait {
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| ~~~~~~~~~~
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error: aborting due to 20 previous errors
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Some errors have detailed explanations: E0277, E0308, E0746.
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For more information about an error, try `rustc --explain E0277`.
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