Inconsistency in type inference from function parameters about scala3 HOT 2 OPEN

#18558 is likely related

from scala3.

Minimisation:

def foo(v: Int): Any = v
def bar[B](f: B => Any): B = ???

val infersInt = bar(x => foo(x))
val infersNothing = bar(foo)

In the first case, we have an explicit parameter which unifies the two constraints B <: x and x <: Int.
Whereas in the second case, the parameter from the expansion (say v) gets a separate type variable (say C). We then have the constraints B <: C, C <: v and v <: Int, but B is instantiated later and hence from below.

from scala3.