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43 lines
2.0 KiB
Plaintext
43 lines
2.0 KiB
Plaintext
error[E0308]: `if` and `else` have incompatible types
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--> $DIR/box-instead-of-dyn-fn.rs:10:9
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LL | / if a % 2 == 0 {
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LL | | move || println!("{a}")
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| | -----------------------
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| | |
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| | the expected closure
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| | expected because of this
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LL | | } else {
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LL | | Box::new(move || println!("{}", b))
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| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected closure, found `Box<[closure@box-instead-of-dyn-fn.rs:10:18]>`
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LL | |
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LL | | }
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| |_____- `if` and `else` have incompatible types
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= note: expected closure `[closure@$DIR/box-instead-of-dyn-fn.rs:8:9: 8:16]`
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found struct `Box<[closure@$DIR/box-instead-of-dyn-fn.rs:10:18: 10:25]>`
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/box-instead-of-dyn-fn.rs:5:56
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LL | fn print_on_or_the_other<'a>(a: i32, b: &'a String) -> dyn Fn() + 'a {
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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 Fn() + 'a` 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 print_on_or_the_other<'a>(a: i32, b: &'a String) -> Box<dyn Fn() + 'a> {
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| ++++ +
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help: ... and box this value
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LL | Box::new(move || println!("{a}"))
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| +++++++++ +
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error: aborting due to 2 previous errors
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Some errors have detailed explanations: E0308, E0746.
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For more information about an error, try `rustc --explain E0308`.
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