Subtraits ignored when they specify associated types of supertraits
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Description
We must specify the associated types of supertraits in trait objects, even if the actual trait fixes that associated type. In this example, we cannot write &mut Rng but must instead write &mut Rng<Error=!> where the traits consist of :
trait CryptoRng {
type Error;
...
}
trait Rng: CryptoRng<Error=!> {
...
}
Is this a bug?
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Research direction
Start by reproducing the linked playground example with the CryptoRng and Rng traits. Read the trait-object and associated-type handling relevant to this behavior, then determine whether the supertrait’s fixed associated type can be inferred. Done means the example can use &mut Rng without explicitly specifying Error=! or the issue is documented as expected behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100