1d9fe9cd06
Suggest dereference of `Box` when inner type is expected
For example:
enum Ty {
Unit,
List(Box<Ty>),
}
fn foo(x: Ty) -> Ty {
match x {
Ty::Unit => Ty::Unit,
Ty::List(elem) => foo(elem),
}
}
Before, the only suggestion was to rewrap `inner` with `Ty::Wrapper`,
which is unhelpful and confusing:
error[E0308]: mismatched types
--> src/test/ui/suggestions/boxed-variant-field.rs:9:31
|
9 | Ty::List(elem) => foo(elem),
| ^^^^
| |
| expected enum `Ty`, found struct `Box`
| help: try using a variant of the expected enum: `Ty::List(elem)`
|
= note: expected enum `Ty`
found struct `Box<Ty>`
Now, rustc will first suggest dereferencing the `Box`, which is most
likely what the user intended:
error[E0308]: mismatched types
--> src/test/ui/suggestions/boxed-variant-field.rs:9:31
|
9 | Ty::List(elem) => foo(elem),
| ^^^^ expected enum `Ty`, found struct `Box`
|
= note: expected enum `Ty`
found struct `Box<Ty>`
help: try dereferencing the `Box`
|
9 | Ty::List(elem) => foo(*elem),
| +
help: try using a variant of the expected enum
|
9 | Ty::List(elem) => foo(Ty::List(elem)),
| ~~~~~~~~~~~~~~
r? ``@davidtwco``
|
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.