diff options
Diffstat (limited to 'src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr')
| -rw-r--r-- | src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr new file mode 100644 index 000000000..f90399b6b --- /dev/null +++ b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr @@ -0,0 +1,307 @@ +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:35 + | +LL | fn fuz() -> (usize, Trait) { (42, Struct) } + | ^^^^^^ expected trait object `dyn Trait`, found struct `Struct` + | + = note: expected trait object `(dyn Trait + 'static)` + found struct `Struct` + +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)` + = 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 trait object `dyn Trait`, found struct `Struct` + | + = note: expected trait object `(dyn Trait + 'static)` + found struct `Struct` + +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)` + = 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 + | + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> +help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait` + | +LL | fn bap() -> impl Trait { 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 + | + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> +help: use `impl Trait` as the return type, as all return paths are of type `Struct`, which implements `Trait` + | +LL | fn ban() -> impl Trait { 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: use some type `T` that is `T: Sized` as the return type if all return paths have the same type + | +LL | fn bak() -> T { unimplemented!() } + | ~ +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 + | +LL | fn bak() -> impl Trait { unimplemented!() } + | ~~~~~~~~~~ +help: use a boxed trait object if all return paths implement trait `Trait` + | +LL | fn bak() -> Box<dyn Trait> { 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 + | + = 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> + = note: if all the returned values were of the same type you could use `impl Trait` as the return type + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> + = note: you can create a new `enum` with a variant for each returned type +help: return a boxed trait object instead + | +LL | fn bal() -> Box<dyn Trait> { + | ++++ + +help: ... and box this value + | +LL | return Box::new(Struct); + | +++++++++ + +help: ... and box this value + | +LL | Box::new(42) + | +++++++++ + + +error[E0308]: `if` and `else` have incompatible types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:29:9 + | +LL | / if true { +LL | | Struct + | | ------ expected because of this +LL | | } else { +LL | | 42 + | | ^^ expected struct `Struct`, found integer +LL | | } + | |_____- `if` and `else` have incompatible types + +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 + | + = 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> + = note: if all the returned values were of the same type you could use `impl Trait` as the return type + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> + = note: you can create a new `enum` with a variant for each returned type +help: return a boxed trait object instead + | +LL | fn bax() -> Box<dyn Trait> { + | ++++ + +help: ... and box this value + | +LL | Box::new(Struct) + | +++++++++ + +help: ... and box this value + | +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 struct `Box`, found struct `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 struct `Box`, 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 struct `Box`, 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 struct `Box`, 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 struct `Box`, found struct `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 struct `Box`, 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 struct `Box`, 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 struct `Box`, 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 + | + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> +help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait` + | +LL | fn bat() -> impl Trait { + | ~~~~~~~~~~ + +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 + | + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> +help: use `impl Trait` as the return type, as all return paths are of type `{integer}`, which implements `Trait` + | +LL | fn bay() -> impl Trait { + | ~~~~~~~~~~ + +error: aborting due to 20 previous errors + +Some errors have detailed explanations: E0277, E0308, E0746. +For more information about an error, try `rustc --explain E0277`. |