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ebfac4ecaf
Using an error type instead of `()` avoids the duplicated errors
on `struct SUnsizedField` in `deriving-from-wrong-target.rs`. It also
improves the expanded output from this:
```
struct S2(u32, u32);
impl ::core::convert::From<()> for S2 {
#[inline]
fn from(value: ()) -> S2 { (/*ERROR*/) }
}
```
to this:
```
struct S2(u32, u32);
impl ::core::convert::From<(/*ERROR*/)> for S2 {
#[inline]
fn from(value: (/*ERROR*/)) -> S2 { (/*ERROR*/) }
}
```
The new code also only matchs on `item.kind` once.
78 lines
2.1 KiB
Plaintext
78 lines
2.1 KiB
Plaintext
error: `#[derive(From)]` used on a struct with no fields
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--> $DIR/deriving-from-wrong-target.rs:8:10
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LL | #[derive(From)]
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| ^^^^
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LL |
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LL | struct S1;
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| ^^
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= note: `#[derive(From)]` can only be used on structs with exactly one field
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error: `#[derive(From)]` used on a struct with no fields
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--> $DIR/deriving-from-wrong-target.rs:12:10
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LL | #[derive(From)]
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| ^^^^
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LL |
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LL | struct S2 {}
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| ^^
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= note: `#[derive(From)]` can only be used on structs with exactly one field
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error: `#[derive(From)]` used on a struct with multiple fields
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--> $DIR/deriving-from-wrong-target.rs:16:10
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LL | #[derive(From)]
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| ^^^^
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LL |
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LL | struct S3(u32, bool);
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| ^^
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= note: `#[derive(From)]` can only be used on structs with exactly one field
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error: `#[derive(From)]` used on a struct with multiple fields
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--> $DIR/deriving-from-wrong-target.rs:20:10
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LL | #[derive(From)]
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| ^^^^
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LL |
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LL | struct S4 {
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| ^^
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= note: `#[derive(From)]` can only be used on structs with exactly one field
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error: `#[derive(From)]` used on an enum
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--> $DIR/deriving-from-wrong-target.rs:27:10
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LL | #[derive(From)]
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| ^^^^
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LL |
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LL | enum E1 {}
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| ^^
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= note: `#[derive(From)]` can only be used on structs with exactly one field
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error[E0277]: the size for values of type `T` cannot be known at compilation time
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--> $DIR/deriving-from-wrong-target.rs:33:11
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LL | struct SUnsizedField<T: ?Sized> {
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| - this type parameter needs to be `Sized`
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LL | last: T,
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| ^ doesn't have a size known at compile-time
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= help: unsized fn params are gated as an unstable feature
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help: consider removing the `?Sized` bound to make the type parameter `Sized`
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LL - struct SUnsizedField<T: ?Sized> {
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LL + struct SUnsizedField<T> {
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help: function arguments must have a statically known size, borrowed types always have a known size
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LL | last: &T,
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| +
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error: aborting due to 6 previous errors
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For more information about this error, try `rustc --explain E0277`.
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