Compilation error with context bounds

Hello there!

Compilation of the following code will fail

import monocle.Lens
import monocle.macros.GenLens

trait Foo[T]
trait Bar[T]

case class A[T: Foo](s: A.S[T]) {
  private val lens: Lens[A.S[T], Bar[T]] = GenLens[A.S[T]](_.bar)
}

object A {
  case class S[T: Foo](bar: Bar[T])
}

in Scala 3 with the following error

[error] 8 |  private val lens: Lens[A.S[T], Bar[T]] = GenLens[A.S[T]](_.bar)
[error]   |                                           ^^^^^^^^^^^^^^^^^^^^^^
[error]   |Exception occurred while executing macro expansion.
[error]   |java.lang.Exception: Expected an expression. This is a partially applied Term. Try eta-expanding the term first.

and in Scala 2.13 with

[error] could not find implicit value for evidence parameter of type Foo[T]
[error]   private val lens: Lens[A.S[T], Bar[T]] = GenLens[A.S[T]](_.bar)
[error]                                                           ^

Interestingly, the last version that appears to work is 1.5.1-cats on Scala 2.11 (but not on Scala 2.12.)

Start by reproducing the minimal example around GenLensA.S[T] on the reported Scala versions, comparing the Scala 2.11, 2.12, 2.13, and Scala 3 results. Inspect how the macro handles the context bounds on A and A.S. Done means the example compiles on the supported affected versions and has a regression test covering the case.