error[E0119]: conflicting implementations of trait `AnotherTrait` for type `OpaqueType`
  --> $DIR/issue-83613.rs:10:1
   |
LL | impl<T: Send> AnotherTrait for T {}
   | -------------------------------- first implementation here
LL | impl AnotherTrait for OpaqueType {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `OpaqueType`

error: cannot implement trait on type alias impl trait
  --> $DIR/issue-83613.rs:10:23
   |
LL | impl AnotherTrait for OpaqueType {}
   |                       ^^^^^^^^^^
   |
note: type alias impl trait defined here
  --> $DIR/issue-83613.rs:4:19
   |
LL | type OpaqueType = impl OpaqueTrait;
   |                   ^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0119`.