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#[non_exhaustive] on variant blocks cross-crate as casts #1249

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Aug 16, 2022
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#[non_exhaustive] on variant blocks cross-crate as casts #1249

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3036b18
cannot cast non-exhaustive enum from foreign crate
lambinoo Aug 14, 2022
bce9bb3
Update type_system.md
lambinoo Aug 16, 2022
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8 changes: 8 additions & 0 deletions src/attributes/type_system.md
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Expand Up @@ -127,6 +127,14 @@ match message {
}
```

It's also impossible to cast non-exhaustive types from foreign crates.
```rust, ignore
use othercrate::NonExhaustiveEnum;

// Cannot cast a non-exhaustive enum outside of its defining crate.
let _ = NonExhaustiveEnum::default() as u8;
```

Non-exhaustive types are always considered inhabited in downstream crates.

[_MetaWord_]: ../attributes.md#meta-item-attribute-syntax
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