Backports typelevel#3133 to scala_2.11

* Adds scala version specific src directories
* Backports PR typelevel#3133 to add scala 2.11 support
* Brings scalafmt plugin and configs utd with master

.scalafmt.conf

@@ -1,9 +1,9 @@
-version=2.0.1
+version=2.1.0
 align.openParenCallSite = true
 align.openParenDefnSite = true
 maxColumn = 120
 continuationIndent.defnSite = 2
 assumeStandardLibraryStripMargin = true
 danglingParentheses = true
 rewrite.rules = [AvoidInfix, SortImports, RedundantBraces, RedundantParens, SortModifiers]
-docstrings = JavaDoc
+docstrings = JavaDoc

core/src/main/scala-2.11/cats/data/ScalaVersionSpecificNonEmptyChainImpl.scala

@@ -0,0 +1,6 @@
+package cats.data
+
+private[data] trait ScalaVersionSpecificNonEmptyChainImpl {
+  def fromSeq[A](as: scala.collection.Seq[A]): Option[NonEmptyChain[A]] =
+    if (as.nonEmpty) Option(NonEmptyChainImpl.create(Chain.fromSeq(as))) else None
+}

core/src/main/scala-2.12/cats/data/ScalaVersionSpecificNonEmptyChainImpl.scala

@@ -0,0 +1,6 @@
+package cats.data
+
+private[data] trait ScalaVersionSpecificNonEmptyChainImpl {
+  def fromSeq[A](as: scala.collection.Seq[A]): Option[NonEmptyChain[A]] =
+    if (as.nonEmpty) Option(NonEmptyChainImpl.create(Chain.fromSeq(as))) else None
+}

core/src/main/scala-2.13+/cats/data/ScalaVersionSpecificNonEmptyChainImpl.scala

@@ -0,0 +1,3 @@
+package cats.data
+
+private[data] trait ScalaVersionSpecificNonEmptyChainImpl

core/src/main/scala/cats/data/NonEmptyChain.scala

@@ -21,9 +21,7 @@ import NonEmptyChainImpl.create
 import cats.{Order, Semigroup}
 import cats.kernel._
 
-import scala.collection.immutable._
-
-private[data] object NonEmptyChainImpl extends NonEmptyChainInstances {
+private[data] object NonEmptyChainImpl extends NonEmptyChainInstances with ScalaVersionSpecificNonEmptyChainImpl {
   // The following 3 types are components of a technique to
   // create a no-boxing newtype. It's coped from the
   // newtypes lib by @alexknvl
@@ -52,7 +50,7 @@ private[data] object NonEmptyChainImpl extends NonEmptyChainInstances {
   def fromNonEmptyVector[A](as: NonEmptyVector[A]): NonEmptyChain[A] =
     create(Chain.fromSeq(as.toVector))
 
-  def fromSeq[A](as: Seq[A]): Option[NonEmptyChain[A]] =
+  def fromSeq[A](as: scala.collection.immutable.Seq[A]): Option[NonEmptyChain[A]] =
     if (as.nonEmpty) Option(create(Chain.fromSeq(as))) else None
 
   def fromChainPrepend[A](a: A, ca: Chain[A]): NonEmptyChain[A] =

core/src/main/scala/cats/data/NonEmptyList.scala

@@ -511,8 +511,10 @@ sealed abstract private[data] class NonEmptyListInstances extends NonEmptyListIn
 
   implicit val catsDataInstancesForNonEmptyList
     : SemigroupK[NonEmptyList] with Bimonad[NonEmptyList] with NonEmptyTraverse[NonEmptyList] =
-    new NonEmptyReducible[NonEmptyList, List] with SemigroupK[NonEmptyList] with Bimonad[NonEmptyList]
-    with NonEmptyTraverse[NonEmptyList] {
+    new NonEmptyReducible[NonEmptyList, List]
+      with SemigroupK[NonEmptyList]
+      with Bimonad[NonEmptyList]
+      with NonEmptyTraverse[NonEmptyList] {
 
       def combineK[A](a: NonEmptyList[A], b: NonEmptyList[A]): NonEmptyList[A] =
         a.concatNel(b)

core/src/main/scala/cats/data/NonEmptyVector.scala

@@ -240,8 +240,10 @@ sealed abstract private[data] class NonEmptyVectorInstances {
 
   implicit val catsDataInstancesForNonEmptyVector
     : SemigroupK[NonEmptyVector] with Bimonad[NonEmptyVector] with NonEmptyTraverse[NonEmptyVector] =
-    new NonEmptyReducible[NonEmptyVector, Vector] with SemigroupK[NonEmptyVector] with Bimonad[NonEmptyVector]
-    with NonEmptyTraverse[NonEmptyVector] {
+    new NonEmptyReducible[NonEmptyVector, Vector]
+      with SemigroupK[NonEmptyVector]
+      with Bimonad[NonEmptyVector]
+      with NonEmptyTraverse[NonEmptyVector] {
 
       def combineK[A](a: NonEmptyVector[A], b: NonEmptyVector[A]): NonEmptyVector[A] =
         a.concatNev(b)

core/src/main/scala/cats/instances/option.scala

@@ -10,8 +10,11 @@ trait OptionInstances extends cats.kernel.instances.OptionInstances {
     with Alternative[Option]
     with CommutativeMonad[Option]
     with CoflatMap[Option] =
-    new Traverse[Option] with MonadError[Option, Unit] with Alternative[Option] with CommutativeMonad[Option]
-    with CoflatMap[Option] {
+    new Traverse[Option]
+      with MonadError[Option, Unit]
+      with Alternative[Option]
+      with CommutativeMonad[Option]
+      with CoflatMap[Option] {
 
       def empty[A]: Option[A] = None
 

laws/src/main/scala/cats/laws/discipline/MiniInt.scala

@@ -51,12 +51,12 @@ object MiniInt {
 
   val allValues: List[MiniInt] = (minIntValue to maxIntValue).map(unsafeFromInt).toList
 
-  implicit val catsLawsEqInstancesForMiniInt: Order[MiniInt] with Hash[MiniInt] = new Order[MiniInt]
-  with Hash[MiniInt] {
-    def hash(x: MiniInt): Int = Hash[Int].hash(x.intBits)
+  implicit val catsLawsEqInstancesForMiniInt: Order[MiniInt] with Hash[MiniInt] =
+    new Order[MiniInt] with Hash[MiniInt] {
+      def hash(x: MiniInt): Int = Hash[Int].hash(x.intBits)
 
-    def compare(x: MiniInt, y: MiniInt): Int = Order[Int].compare(x.toInt, y.toInt)
-  }
+      def compare(x: MiniInt, y: MiniInt): Int = Order[Int].compare(x.toInt, y.toInt)
+    }
 
   implicit val catsLawsExhaustiveCheckForMiniInt: ExhaustiveCheck[MiniInt] =
     ExhaustiveCheck.instance(allValues)

project/plugins.sbt

@@ -15,7 +15,7 @@ addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "0.6.1")
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "0.6.1")
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.28")
 addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.3.9")
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.0.4")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.2.1")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.9.0")
 
 /* Temporarily disabling sbt-hydra, see #2870.

tests/src/test/scala/cats/tests/NonEmptyChainSuite.scala

@@ -106,7 +106,7 @@ class NonEmptyChainSuite extends CatsSuite {
 
   test("fromSeq . toList . iterator is id") {
     forAll { (ci: NonEmptyChain[Int]) =>
-      NonEmptyChain.fromSeq(ci.iterator.toList) should ===(Option(ci))
+      NonEmptyChain.fromSeq(ci.iterator.toSeq) should ===(Option(ci))
     }
   }