Under experimental.modularity, cannot extend a class inheriting a deferred given

[rjolly]

Compiler version

3.5.0-RC3 with -source:future -language:experimental.modularity

Minimized code

trait Ord[T]

trait Sorted[T]:
  given Ord[T] as ord = compiletime.deferred

class SortedSet[T : Ord] extends Sorted[T]

class SortedSet2[T : Ord] extends SortedSet[T]

Output

^
error overriding given instance ord in class SortedSet of type Ord[T];
  given instance ord of type Ord[T] cannot override final member given instance ord in class SortedSet

Workaround

class SortedSet[T : Ord] extends Sorted[T]:
  override given ord: Ord[T] = summon

[bishabosha]

I can't reproduce the error, it compiles fine for me in 3.5.0-RC3 - maybe you oversimplified the code?

I tried to make the given final but still no error

[rjolly]

Yes, sorry, you have to actually have several source files:
Ord.scala

trait Ord[T]

Sorted.scala

trait Sorted[T]:
  given Ord[T] as ord = compiletime.deferred

SortedSet.scala

class SortedSet[T : Ord] extends Sorted[T]

And (as unbelievable as it is) this last one needs to not contain the above as prefix : MySortedSet.scala

class MySortedSet[T : Ord] extends SortedSet[T]

(MySortedSet instead of SortedSet2)

[KacperFKorban]

I managed to minimize it into a single file, but the order of declarations is important. Or at least it's important for MySortedSet to be declared before SortedSet.

//> using scala 3.nightly
//> using options -source:future -language:experimental.modularity

class MySortedSet[T : Ord] extends SortedSet[T]

trait Ord[T]

trait Sorted[T]:
  given Ord[T] as ord = compiletime.deferred

open class SortedSet[T : Ord] extends Sorted[T]