Generated given instances' names are the same for different types

[nikololiahim]

Compiler version

3.1.2

Minimized code

//> using scala "3.1.2"

trait Thing[A]
trait Box[A]

given Thing[Box[Int]] = new Thing[Box[Int]] {}
given Thing[Box[String]] = new Thing[Box[String]] {}

Output

Double definition:
final lazy given val given_Thing_Box: Thing[Box[Int]] in package object bug$package at line 6 and
final lazy given val given_Thing_Box: Thing[Box[String]] in package object bug$package at line 7
bloop

Expectation

The code should compile and the instances of Thing for both Box[String] and Box[Int] should be available.

[som-snytt]

It specifies "top-level argument type constructors" at https://dotty.epfl.ch/docs/reference/contextual/relationship-implicits.html#anonymous-given-instances

which is linked from https://dotty.epfl.ch/docs/reference/contextual/givens.html#anonymous-givens

where it says the generated names are not conflict-free.

The only problem in computer science harder than naming is automatic name generation.

[bishabosha]

as mentioned above, this problem is documented and as specified, so I will close.

I'm not sure of your original code but could something like the following work?

given [T](using Box[T]): Thing[Box[T]] = ...

you can also use a type alias:

type BoxInt = Box[Int]
type BoxString = Box[String]
given Thing[BoxInt] = new Thing[BoxInt] {}
given Thing[BoxString] = new Thing[BoxString] {}

[nikololiahim]

@bishabosha @som-snytt The workarounds do work. Thank you for the pointers to docs!