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trait SuperTrait {
    type Raw;
 
    fn raw(&self) -> Self::Raw;
}
 
trait SubTrait: SuperTrait<Raw=i32> {}
 
// compiler suggests changing 'B' to 'B: SuperTrait'
// while correct solution is 'B: SubTrait'
fn generic_method<A: SubTrait, B>(a: A, b: B) -> A::Raw {
    a.raw() + b.raw()
}
 
fn main() {}
 

error: no method named `raw` found for type `B` in the current scope
  --> prog.rs:12:17
   |
12 |     a.raw() + b.raw()
   |                 ^^^
   |
   = help: items from traits can only be used if the trait is implemented and in scope; the following trait defines an item `raw`, perhaps you need to implement it:
   = help: candidate #1: `SuperTrait`

error: aborting due to previous error

Standard output is empty