How to disambiguates the call to `f`?

Consider the following code:

trait A: ...
trait B: ...

@value
struct S(A, B):
  ...

fn f[ty: A](s: ty): ...
fn f[ty: B](s: ty): ...

fn test():
  let s = S()
  f(s)

trait A: ...
trait B: ...

@value
struct S(A, B):
  ...

fn f[ty: A](s: ty): ...
fn f[ty: B](s: ty): ...

fn test():
  let s = S()
  f(s)

What do I pass to

as the parameter? Named trait instance can be helpful here.

How to disambiguates the call to `f`? - Modular