Regression for typer in `sageserpent-open/kineticmerge` with implicit conversions

[WojciechMazur]

Based on the OpenCB failure in sageserpent-open/kineticmerge

Compiler version

Last good release: 3.7.3-RC1-bin-20250717-fb66af2-NIGHTLY
First bad release: 3.7.3-RC1-bin-20250718-42fdd76-NIGHTLY
Bisect points to 45f7ef6 / #23532

Minimized code

// https://github.com/scala/scala-collection-contrib/blob/main/src/main/scala/scala/collection/decorators/package.scala
object decorators {
  import scala.collection.generic.IsMap
  class MapDecorator[C, M <: IsMap[C]](coll: C)(implicit val map: M)
  implicit def mapDecorator[C](coll: C)(implicit map: IsMap[C]): MapDecorator[C, map.type] = ???
}
import decorators.mapDecorator // unused, required to reprouce


trait Eq[T]
trait Applicative[F[_]]
given Applicative[Option] = ???

trait Traverse[F[_]]:
  // context bound required to reproduce
  def traverse[G[_]: Applicative, A, B](fa: F[A])(f: A => G[B]): G[F[B]] 

object Traverse:
  def apply[F[_]]: Traverse[F] = ???

trait Segment[Element: Eq]:
  def fuseWith(another: Segment[Element])(
      elementFusion: (Element, Element) => Option[Element]
  ): Option[Segment[Element]] = ???

case class MergeResult[Element: Eq] private (segments: Seq[Segment[Element]]):
  def fuseWith(another: MergeResult[Element])(
      elementFusion: (Element, Element) => Option[Element]
  ): Option[MergeResult[Element]] =
    if segments.size != another.segments.size then None
    else
      Traverse[Seq]
        .traverse(segments.zip(another.segments))(_.fuseWith(_)(elementFusion))
        .map(MergeResult.apply) // error

Output

[error] No given instance of type Eq[Any] was found for a context parameter of method apply in object MergeResult
[error]         .map(MergeResult.apply) // error
[error]                               ^

Expectation

Should compile