False unused import with -Wunused:imports

[joan38]

import cats.derived.auto.semigroup.given is reported used but if removed it was actually used.
import cats.derived.auto.semigroup.given Semigroup[?] same issue.
import cats.derived.auto.semigroup.given_Semigroup_A works fine.

Identified in kittens 3.3.0 but works with kittens 3.2.0 typelevel/kittens#655
I believe this is related to the transparent implementation for givens.

Compiler version

Reproducable in 3.3.3 and 3.4.0

Minimized code

https://scastie.scala-lang.org/Po0uhQLgSjyzEdnffZLi1g

[Gedochao]

Looks similar to #18564 and #19657
@szymon-rd is this a duplicate?

[som-snytt]

The PR improves how derived and inline are handled, but without a minimization, I probably won't get to testing this.

scala-cli doesn't honor -Ylog-classpath FSR.

//> using dep org.typelevel::kittens:3.4.0
//> using options -Wunused:imports
//> using options -Xmax-inlines:64
//> abusing options "-Vprint:typer,inlining"
//> using options -color:never
//> using options -Yplain-printer
//> using options -verbose
//> using options -Ylog-classpath
//> using scala 3.6.2

import cats.Monoid
import cats.Semigroup
import cats.derived.auto.monoid.given//_Monoid_A
import cats.derived.auto.semigroup.given//_Semigroup_A
import cats.syntax.all.*

case class Rebuffers(
    total: Rebuffers.Metrics,
    network: Rebuffers.Stats,
    media: Rebuffers.Stats,
    network_media_overlap: Rebuffers.Stats,
    timedtext: Rebuffers.Stats
)

object Rebuffers:
  given Semigroup[Rebuffers] with
    def combine(x: Rebuffers, y: Rebuffers): Rebuffers = Rebuffers(
      total = x.total.combine(y.total),
      network = x.network.combine(y.network),
      media = x.media.combine(y.media),
      network_media_overlap = x.network_media_overlap.combine(y.network_media_overlap),
      timedtext = x.timedtext.combine(y.timedtext)
    )

  case class Metrics(count: Int, duration_ms: Long)
  case class Stats(total: Metrics, segment: EarlyLate, session: EarlyLate)
  case class EarlyLate(early: Metrics, late: Metrics)

@main def test() = println:
  val rebuffers: Rebuffers = Monoid[Rebuffers].empty
  rebuffers.combine(rebuffers)

[som-snytt]

Actually it "just worked" with local compiler.

//> using scala 3.6.4-RC1-bin-SNAPSHOT

➜  snips scala-cli compile --server=false i19912.scala
-- [E205] Potential Issue Warning: /home/amarki/snips/i19912.scala:32:25 -------
 32 |      network = x.network.combine(y.network),
    |                         ^
    |Given search preference for cats.kernel.Semigroup[Rebuffers.Metrics] between alternatives
    |  (cats.derived.auto.monoid.given_Monoid_A :
    |  [A]
    |    (using evidence$1: scala.util.NotGiven[cats.kernel.Monoid[A]]):
    |      cats.kernel.Monoid[A]
    |)
    |and
    |  (cats.derived.auto.semigroup.given_Semigroup_A :
    |  [A]
    |    (using evidence$1: scala.util.NotGiven[cats.kernel.Semigroup[A]]):
    |      cats.kernel.Semigroup[A]
    |)
    |will change in the future release.
    |Current choice        : the first alternative
    |Choice from Scala 3.7 : the second alternative
    |
    |Suppress this warning by choosing -source 3.5, -source 3.7, or
    |by using @annotation.nowarn("id=205")
    |---------------------------------------------------------------------------
    |Inline stack trace
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
    |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    |This location contains code that was inlined from Derived.scala:37
     ---------------------------------------------------------------------------
1 warning found

Closing this ticket as duplicate. I would add a minimized test if one comes to light.