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Add sample fix for E0749 #75360

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Merged
merged 4 commits into from
Aug 11, 2020
Merged

Add sample fix for E0749 #75360

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ec23f4e
Add sample fix for E0749
pickfire Aug 10, 2020
a2d7c33
Split fix into another section for E0749
pickfire Aug 10, 2020
8cb1a2f
Use : rather than . in example description
pickfire Aug 10, 2020
a7f61bf
Remove empty fn main from E0749
pickfire Aug 10, 2020
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12 changes: 11 additions & 1 deletion src/librustc_error_codes/error_codes/E0749.md
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Expand Up @@ -11,9 +11,19 @@ trait MyTrait {
impl !MyTrait for u32 {
type Foo = i32; // error!
}
# fn main() {}
```

Negative impls are not allowed to have any items. Negative impls declare that a
trait is **not** implemented (and never will be) and hence there is no need to
specify the values for trait methods or other items.

One way to fix this is to remove the items in negative impls:

```
# #![feature(negative_impls)]
trait MyTrait {
type Foo;
}
impl !MyTrait for u32 {}
```