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When encountering `-> Trait`, suggest `-> Box<dyn Trait>` (instead of `-> Box<Trait>`. If there's a single returned type within the `fn`, suggest `-> impl Trait`.
35 lines
1.1 KiB
Plaintext
35 lines
1.1 KiB
Plaintext
error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/E0746.rs:8:13
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LL | fn foo() -> dyn Trait { Struct }
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| ^^^^^^^^^ doesn't have a size known at compile-time
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help: consider returning an `impl Trait` instead of a `dyn Trait`
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LL | fn foo() -> impl Trait { Struct }
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| ~~~~
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help: alternatively, box the return type, and wrap all of the returned values in `Box::new`
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LL | fn foo() -> Box<dyn Trait> { Box::new(Struct) }
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| ++++ + +++++++++ +
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error[E0746]: return type cannot have an unboxed trait object
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--> $DIR/E0746.rs:11:13
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LL | fn bar() -> dyn Trait {
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| ^^^^^^^^^ doesn't have a size known at compile-time
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= help: if there were a single returned type, you could use `impl Trait` instead
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help: box the return type, and wrap all of the returned values in `Box::new`
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LL ~ fn bar() -> Box<dyn Trait> {
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LL | if true {
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LL ~ return Box::new(0);
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LL | }
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LL ~ Box::new(42)
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0746`.
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