error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:35
   |
LL | fn fuz() -> (usize, Trait) { (42, Struct) }
   |                                   ^^^^^^ expected `dyn Trait`, found `Struct`
   |
   = note: expected trait object `(dyn Trait + 'static)`
                    found struct `Struct`
   = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well

error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:13
   |
LL | fn fuz() -> (usize, Trait) { (42, Struct) }
   |             ^^^^^^^^^^^^^^   ------------ this returned value is of type `(usize, (dyn Trait + 'static))`
   |             |
   |             doesn't have a size known at compile-time
   |
   = help: within `(usize, (dyn Trait + 'static))`, the trait `Sized` is not implemented for `(dyn Trait + 'static)`, which is required by `(usize, (dyn Trait + 'static)): Sized`
   = note: required because it appears within the type `(usize, (dyn Trait + 'static))`
   = note: the return type of a function must have a statically known size

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:39
   |
LL | fn bar() -> (usize, dyn Trait) { (42, Struct) }
   |                                       ^^^^^^ expected `dyn Trait`, found `Struct`
   |
   = note: expected trait object `(dyn Trait + 'static)`
                    found struct `Struct`
   = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well

error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:13
   |
LL | fn bar() -> (usize, dyn Trait) { (42, Struct) }
   |             ^^^^^^^^^^^^^^^^^^   ------------ this returned value is of type `(usize, (dyn Trait + 'static))`
   |             |
   |             doesn't have a size known at compile-time
   |
   = help: within `(usize, (dyn Trait + 'static))`, the trait `Sized` is not implemented for `(dyn Trait + 'static)`, which is required by `(usize, (dyn Trait + 'static)): Sized`
   = note: required because it appears within the type `(usize, (dyn Trait + 'static))`
   = note: the return type of a function must have a statically known size

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:13:13
   |
LL | fn bap() -> Trait { Struct }
   |             ^^^^^ doesn't have a size known at compile-time
   |
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL | fn bap() -> Box<Trait> { Box::new(Struct) }
   |             ++++     +   +++++++++      +

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:15:13
   |
LL | fn ban() -> dyn Trait { Struct }
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn ban() -> impl Trait { Struct }
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL | fn ban() -> Box<dyn Trait> { Box::new(Struct) }
   |             ++++         +   +++++++++      +

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:17:13
   |
LL | fn bak() -> dyn Trait { unimplemented!() }
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn bak() -> impl Trait { unimplemented!() }
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL | fn bak() -> Box<dyn Trait> { Box::new(unimplemented!()) }
   |             ++++         +   +++++++++                +

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:19:13
   |
LL | fn bal() -> dyn Trait {
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn bal() -> impl Trait {
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL ~ fn bal() -> Box<dyn Trait> {
LL |     if true {
LL ~         return Box::new(Struct);
LL |     }
LL ~     Box::new(42)
   |

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:25:13
   |
LL | fn bax() -> dyn Trait {
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn bax() -> impl Trait {
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL ~ fn bax() -> Box<dyn Trait> {
LL |     if true {
LL ~         Box::new(Struct)
LL |     } else {
LL ~         Box::new(42)
   |

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:34:16
   |
LL | fn bam() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
LL |     if true {
LL |         return Struct;
   |                ^^^^^^ expected `Box<dyn Trait>`, found `Struct`
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
              found struct `Struct`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         return Box::new(Struct);
   |                +++++++++      +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:36:5
   |
LL | fn bam() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
...
LL |     42
   |     ^^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |     Box::new(42)
   |     +++++++++  +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:40:16
   |
LL | fn baq() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
LL |     if true {
LL |         return 0;
   |                ^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         return Box::new(0);
   |                +++++++++ +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:42:5
   |
LL | fn baq() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
...
LL |     42
   |     ^^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |     Box::new(42)
   |     +++++++++  +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:46:9
   |
LL | fn baz() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
LL |     if true {
LL |         Struct
   |         ^^^^^^ expected `Box<dyn Trait>`, found `Struct`
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
              found struct `Struct`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         Box::new(Struct)
   |         +++++++++      +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:48:9
   |
LL | fn baz() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
...
LL |         42
   |         ^^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         Box::new(42)
   |         +++++++++  +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:53:9
   |
LL | fn baw() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
LL |     if true {
LL |         0
   |         ^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         Box::new(0)
   |         +++++++++ +

error[E0308]: mismatched types
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:55:9
   |
LL | fn baw() -> Box<dyn Trait> {
   |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
...
LL |         42
   |         ^^ expected `Box<dyn Trait>`, found integer
   |
   = note: expected struct `Box<(dyn Trait + 'static)>`
                found type `{integer}`
   = 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
help: store this in the heap by calling `Box::new`
   |
LL |         Box::new(42)
   |         +++++++++  +

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:60:13
   |
LL | fn bat() -> dyn Trait {
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn bat() -> impl Trait {
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL ~ fn bat() -> Box<dyn Trait> {
LL |     if true {
LL ~         return Box::new(0);
LL |     }
LL ~     Box::new(42)
   |

error[E0746]: return type cannot have an unboxed trait object
  --> $DIR/dyn-trait-return-should-be-impl-trait.rs:66:13
   |
LL | fn bay() -> dyn Trait {
   |             ^^^^^^^^^ doesn't have a size known at compile-time
   |
help: return an `impl Trait` instead of a `dyn Trait`, if all returned values are the same type
   |
LL | fn bay() -> impl Trait {
   |             ~~~~
help: box the return type, and wrap all of the returned values in `Box::new`
   |
LL ~ fn bay() -> Box<dyn Trait> {
LL |     if true {
LL ~         Box::new(0)
LL |     } else {
LL ~         Box::new(42)
   |

error: aborting due to 19 previous errors

Some errors have detailed explanations: E0277, E0308, E0746.
For more information about an error, try `rustc --explain E0277`.