Tweak scalac options

cache/js/src/main/scala/coursier/Platform.scala

@@ -4,7 +4,6 @@ import coursier.util.EitherT
 import org.scalajs.dom.raw.{Event, XMLHttpRequest}
 
 import scala.concurrent.{ExecutionContext, Future, Promise}
-import scala.language.implicitConversions
 import scala.scalajs.js
 import js.Dynamic.{global => g}
 import scala.scalajs.js.timers._

cache/jvm/src/main/scala/coursier/util/Schedulable.scala

@@ -2,8 +2,6 @@ package coursier.util
 
 import java.util.concurrent.{ExecutorService, Executors, ThreadFactory}
 
-import scala.language.higherKinds
-
 trait Schedulable[F[_]] extends Gather[F] {
   def schedule[A](pool: ExecutorService)(f: => A): F[A]
 }

cli/src/main/scala-2.12/coursier/cli/Fetch.scala

@@ -6,8 +6,6 @@ import java.io.File
 import caseapp._
 import coursier.cli.options.FetchOptions
 
-import scala.language.reflectiveCalls
-
 final class Fetch(options: FetchOptions, args: RemainingArgs) {
 
   val helper = new Helper(options.common, args.all, ignoreErrors = options.artifactOptions.force)

cli/src/main/scala-2.12/coursier/cli/scaladex/Scaladex.scala

@@ -11,8 +11,6 @@ import coursier.util.{EitherT, Gather}
 import coursier.{Fetch, Module}
 import scalaz.concurrent.Task
 
-import scala.language.higherKinds
-
 object Scaladex {
 
   case class SearchResult(

core/shared/src/main/scala/coursier/Fetch.scala

@@ -2,8 +2,6 @@ package coursier
 
 import coursier.util.{EitherT, Gather, Monad}
 
-import scala.language.higherKinds
-
 object Fetch {
 
   type Content[F[_]] = Artifact => EitherT[F, String, String]

core/shared/src/main/scala/coursier/core/Repository.scala

@@ -2,7 +2,6 @@ package coursier.core
 
 import coursier.Fetch
 
-import scala.language.higherKinds
 import coursier.core.compatibility.encodeURIComponent
 import coursier.util.{EitherT, Monad}
 

core/shared/src/main/scala/coursier/core/ResolutionProcess.scala

@@ -4,7 +4,6 @@ package core
 import coursier.util.Monad
 
 import scala.annotation.tailrec
-import scala.language.higherKinds
 
 
 sealed abstract class ResolutionProcess {

core/shared/src/main/scala/coursier/ivy/IvyRepository.scala

@@ -4,8 +4,6 @@ import coursier.Fetch
 import coursier.core._
 import coursier.util.{EitherT, Monad, WebPage}
 
-import scala.language.higherKinds
-
 final case class IvyRepository(
   pattern: Pattern,
   metadataPatternOpt: Option[Pattern],

core/shared/src/main/scala/coursier/ivy/Pattern.scala

@@ -4,8 +4,6 @@ import coursier.util.Traverse.TraverseOps
 import coursier.util.ValidationNel
 import fastparse.all._
 
-import scala.language.implicitConversions
-
 final case class PropertiesPattern(chunks: Seq[PropertiesPattern.ChunkOrProperty]) {
 
   def string: String = chunks.map(_.string).mkString

core/shared/src/main/scala/coursier/maven/MavenRepository.scala

@@ -5,8 +5,6 @@ import coursier.core._
 import coursier.core.compatibility.encodeURIComponent
 import coursier.util.{EitherT, Monad, WebPage}
 
-import scala.language.higherKinds
-
 object MavenRepository {
   val SnapshotTimestamp = "(.*-)?[0-9]{8}\\.[0-9]{6}-[0-9]+".r
 

core/shared/src/main/scala/coursier/util/EitherT.scala

@@ -1,7 +1,5 @@
 package coursier.util
 
-import scala.language.higherKinds
-
 final case class EitherT[F[_], L, R](run: F[Either[L, R]]) {
 
   def map[S](f: R => S)(implicit M: Monad[F]): EitherT[F, L, S] =

core/shared/src/main/scala/coursier/util/Gather.scala

@@ -1,7 +1,5 @@
 package coursier.util
 
-import scala.language.higherKinds
-
 trait Gather[F[_]] extends Monad[F] {
   def gather[A](elems: Seq[F[A]]): F[Seq[A]]
 }

core/shared/src/main/scala/coursier/util/Monad.scala

@@ -1,7 +1,5 @@
 package coursier.util
 
-import scala.language.higherKinds
-
 trait Monad[F[_]] {
   def point[A](a: A): F[A]
   def bind[A, B](elem: F[A])(f: A => F[B]): F[B]

extra/src/main/scala/coursier/FallbackDependenciesRepository.scala

@@ -5,8 +5,6 @@ import java.net.{HttpURLConnection, URL, URLConnection}
 
 import coursier.util.{EitherT, Monad}
 
-import scala.language.higherKinds
-
 object FallbackDependenciesRepository {
 
   def exists(url: URL): Boolean = {

project/Settings.scala

@@ -39,7 +39,12 @@ object Settings {
           Seq()
       }
   
-      targetJvm ++ Seq("-feature", "-deprecation")
+      targetJvm ++ Seq(
+        "-feature",
+        "-deprecation",
+        "-language:higherKinds",
+        "-language:implicitConversions"
+      )
     },
     javacOptions ++= {
       scalaBinaryVersion.value match {

sbt-coursier/src/main/scala/coursier/InterProjectRepository.scala

@@ -2,8 +2,6 @@ package coursier
 
 import coursier.util.{EitherT, Monad}
 
-import scala.language.higherKinds
-
 final case class InterProjectRepository(projects: Seq[Project]) extends Repository {
 
   private val map = projects

sbt-coursier/src/main/scala/coursier/Structure.scala

@@ -2,8 +2,6 @@ package coursier
 
 import sbt._
 
-import scala.language.implicitConversions
-
 // things from sbt-structure
 object Structure {
 

scalaz/shared/src/main/scala/coursier/interop/scalaz.scala

@@ -2,8 +2,6 @@ package coursier.interop
 
 import coursier.util.{Gather, Monad}
 
-import scala.language.higherKinds
-
 object scalaz extends LowPriorityScalazImplicits {
 
   implicit def coursierMonadFromScalaz[F[_]](implicit M: _root_.scalaz.Monad[F]): Monad[F] =

tests/jvm/src/test/scala/coursier/Platform.scala

@@ -6,7 +6,6 @@ import java.nio.charset.Charset
 import coursier.interop.scalaz._
 import coursier.util.EitherT
 
-import scala.language.implicitConversions
 import scala.util.{Failure, Success, Try}
 import scalaz.concurrent.Task
 

tests/shared/src/test/scala/coursier/test/TestRepository.scala

@@ -4,8 +4,6 @@ package test
 import coursier.core._
 import coursier.util.{EitherT, Monad}
 
-import scala.language.higherKinds
-
 final case class TestRepository(projects: Map[(Module, String), Project]) extends Repository {
   val source = new core.Artifact.Source {
     def artifacts(