Update to Scala 3.1.2-RC3 and fix outstanding issues (#455)

.github/workflows/ci.yml

@@ -28,7 +28,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [2.12.15, 2.13.8, 3.1.1]
+        scala: [2.12.15, 2.13.8, 3.1.2-RC3]
         java: [temurin@8]
         project: [rootJS, rootJVM]
     runs-on: ${{ matrix.os }}
@@ -100,7 +100,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [3.1.1]
+        scala: [3.1.2-RC3]
         java: [temurin@8]
     runs-on: ${{ matrix.os }}
     steps:
@@ -168,22 +168,22 @@ jobs:
           tar xf targets.tar
           rm targets.tar
 
-      - name: Download target directories (3.1.1, rootJS)
+      - name: Download target directories (3.1.2-RC3, rootJS)
         uses: actions/download-artifact@v2
         with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-3.1.1-rootJS
+          name: target-${{ matrix.os }}-${{ matrix.java }}-3.1.2-RC3-rootJS
 
-      - name: Inflate target directories (3.1.1, rootJS)
+      - name: Inflate target directories (3.1.2-RC3, rootJS)
         run: |
           tar xf targets.tar
           rm targets.tar
 
-      - name: Download target directories (3.1.1, rootJVM)
+      - name: Download target directories (3.1.2-RC3, rootJVM)
         uses: actions/download-artifact@v2
         with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-3.1.1-rootJVM
+          name: target-${{ matrix.os }}-${{ matrix.java }}-3.1.2-RC3-rootJVM
 
-      - name: Inflate target directories (3.1.1, rootJVM)
+      - name: Inflate target directories (3.1.2-RC3, rootJVM)
         run: |
           tar xf targets.tar
           rm targets.tar

build.sbt

@@ -2,7 +2,7 @@ import sbt._
 
 val scala212 = "2.12.15"
 val scala213 = "2.13.8"
-val scala3 = "3.1.1"
+val scala3 = "3.1.2-RC3"
 
 ThisBuild / crossScalaVersions := Seq(scala212, scala213, scala3)
 ThisBuild / scalaVersion := scala3

core/src/main/scala-3/cats/derived/DerivedCommutativeMonoid.scala

@@ -12,7 +12,7 @@ object DerivedCommutativeMonoid:
     import DerivedCommutativeMonoid.given
     summonInline[DerivedCommutativeMonoid[A]].instance
 
-  given [A](using inst: K0.ProductInstances[Or, A]): DerivedCommutativeMonoid[A] =
+  given [A](using inst: => K0.ProductInstances[Or, A]): DerivedCommutativeMonoid[A] =
     given K0.ProductInstances[CommutativeMonoid, A] = inst.unify
     new Product[CommutativeMonoid, A] {}
 

core/src/main/scala-3/cats/derived/DerivedCommutativeSemigroup.scala

@@ -12,7 +12,7 @@ object DerivedCommutativeSemigroup:
     import DerivedCommutativeSemigroup.given
     summonInline[DerivedCommutativeSemigroup[A]].instance
 
-  given [A](using inst: K0.ProductInstances[Or, A]): DerivedCommutativeSemigroup[A] =
+  given [A](using inst: => K0.ProductInstances[Or, A]): DerivedCommutativeSemigroup[A] =
     given K0.ProductInstances[CommutativeSemigroup, A] = inst.unify
     new Product[CommutativeSemigroup, A] {}
 

core/src/main/scala-3/cats/derived/DerivedEq.scala

@@ -12,11 +12,11 @@ object DerivedEq:
     import DerivedEq.given
     summonInline[DerivedEq[A]].instance
 
-  given [A](using inst: K0.ProductInstances[Or, A]): DerivedEq[A] =
+  given product[A](using inst: => K0.ProductInstances[Or, A]): DerivedEq[A] =
     given K0.ProductInstances[Eq, A] = inst.unify
     new Product[Eq, A] {}
 
-  given [A](using inst: => K0.CoproductInstances[Or, A]): DerivedEq[A] =
+  given coproduct[A](using inst: => K0.CoproductInstances[Or, A]): DerivedEq[A] =
     given K0.CoproductInstances[Eq, A] = inst.unify
     new Coproduct[Eq, A] {}
 

core/src/main/scala-3/cats/derived/DerivedHash.scala

@@ -13,11 +13,11 @@ object DerivedHash:
     import DerivedHash.given
     summonInline[DerivedHash[A]].instance
 
-  given [A <: scala.Product](using inst: K0.ProductInstances[Or, A]): DerivedHash[A] =
+  given product[A <: scala.Product](using inst: => K0.ProductInstances[Or, A]): DerivedHash[A] =
     given K0.ProductInstances[Hash, A] = inst.unify
     new Product[Hash, A] {}
 
-  given [A](using inst: => K0.CoproductInstances[Or, A]): DerivedHash[A] =
+  given coproduct[A](using inst: => K0.CoproductInstances[Or, A]): DerivedHash[A] =
     given K0.CoproductInstances[Hash, A] = inst.unify
     new Coproduct[Hash, A] {}
 

core/src/main/scala-3/cats/derived/DerivedMonoid.scala

@@ -12,11 +12,12 @@ object DerivedMonoid:
     import DerivedMonoid.given
     summonInline[DerivedMonoid[A]].instance
 
-  given [A](using inst: K0.ProductInstances[Or, A]): DerivedMonoid[A] =
+  given [A](using inst: => K0.ProductInstances[Or, A]): DerivedMonoid[A] =
     given K0.ProductInstances[Monoid, A] = inst.unify
     new Product[Monoid, A] {}
 
   trait Product[F[x] <: Monoid[x], A](using inst: K0.ProductInstances[F, A])
       extends DerivedSemigroup.Product[F, A],
         Monoid[A]:
-    final override val empty: A = inst.construct([A] => (F: F[A]) => F.empty)
+    final override lazy val empty: A =
+      inst.construct([A] => (F: F[A]) => F.empty)

core/src/main/scala-3/cats/derived/DerivedSemigroup.scala

@@ -12,7 +12,7 @@ object DerivedSemigroup:
     import DerivedSemigroup.given
     summonInline[DerivedSemigroup[A]].instance
 
-  given [A](using inst: K0.ProductInstances[Or, A]): DerivedSemigroup[A] =
+  given [A](using inst: => K0.ProductInstances[Or, A]): DerivedSemigroup[A] =
     given K0.ProductInstances[Semigroup, A] = inst.unify
     new Product[Semigroup, A] {}
 

core/src/test/scala-3/cats/derived/CommutativeMonoidSuite.scala

@@ -32,8 +32,7 @@ class CommutativeMonoidSuite extends KittensSuite:
 
   inline def testCommutativeMonoid(inline context: String): Unit =
     checkAll(s"$context.CommutativeMonoid[Foo]", commutativeMonoidTests[CommutativeFoo].commutativeMonoid)
-    // FIXME: Doesn't work
-    // checkAll(s"$context.CommutativeMonoid[Recursive]", commutativeMonoidTests[Recursive].commutativeMonoid)
+    checkAll(s"$context.CommutativeMonoid[Recursive]", commutativeMonoidTests[Recursive].commutativeMonoid)
     checkAll(s"$context.CommutativeMonoid[Box[Mul]]", commutativeMonoidTests[Box[Mul]].commutativeMonoid)
     checkAll(
       s"$context.CommutativeMonoid is Serializable",

core/src/test/scala-3/cats/derived/CommutativeSemigroupSuite.scala

@@ -35,8 +35,7 @@ class CommutativeSemigroupSuite extends KittensSuite:
       s"$context.CommutativeSemigroup[CommutativeFoo]",
       commutativeSemigroupTests[CommutativeFoo].commutativeSemigroup
     )
-    // FIXME: Doesn't work
-    // checkAll(s"$context.CommutativeSemigroup[Recursive]", commutativeSemigroupTests[Recursive].commutativeSemigroup)
+    checkAll(s"$context.CommutativeSemigroup[Recursive]", commutativeSemigroupTests[Recursive].commutativeSemigroup)
     checkAll(s"$context.CommutativeSemigroup[Box[Mul]]", commutativeSemigroupTests[Box[Mul]].commutativeSemigroup)
     checkAll(
       s"$context.CommutativeSemigroup is Serializable",

core/src/test/scala-3/cats/derived/EqSuite.scala

@@ -35,8 +35,7 @@ class EqSuite extends KittensSuite.WithoutEq:
     checkAll(s"$context.Eq[Outer]", eqTests[Outer].eqv)
     checkAll(s"$context.Eq[Interleaved[Int]]", eqTests[Interleaved[Int]].eqv)
     checkAll(s"$context.Eq[Tree[Int]]", eqTests[Tree[Int]].eqv)
-    // FIXME: Doesn't work for recursive case classes.
-    // checkAll(s"$context.Eq[Recursive]", eqTests[Recursive].eqv)
+    checkAll(s"$context.Eq[Recursive]", eqTests[Recursive].eqv)
     checkAll(s"$context.Eq is Serializable", SerializableTests.serializable(summonInline[Eq[Foo]]))
 
   locally {

core/src/test/scala-3/cats/derived/FunctorSuite.scala

@@ -37,8 +37,7 @@ class FunctorSuite extends KittensSuite:
     checkAll(s"$context.Functor[GenericAdt]", functorTests[GenericAdt].functor[Int, String, Long])
     checkAll(s"$context.Functor[OptList]", functorTests[OptList].functor[Int, String, Long])
     checkAll(s"$context.Functor[ListSnoc]", functorTests[ListSnoc].functor[Int, String, Long])
-    // FIXME: Testing `functorTests[AndChar].functor[Int, String, Long]` causes a ClassCastException
-    checkAll(s"$context.Functor[AndChar]", functorTests[AndChar].functor[Int, String, Int])
+    checkAll(s"$context.Functor[AndChar]", functorTests[AndChar].functor[Int, String, Long])
     checkAll(s"$context.Functor[Interleaved]", functorTests[Interleaved].functor[Int, String, Long])
     checkAll(s"$context.Functor[NestedPred]", functorTests[NestedPred].functor[Boolean, Int, Boolean])
     checkAll(s"$context.Functor is Serializable", SerializableTests.serializable(summonInline[Functor[Tree]]))

core/src/test/scala-3/cats/derived/HashSuite.scala

@@ -20,8 +20,7 @@ class HashSuite extends KittensSuite:
     // FIXME: typelevel/cats#2878
     // checkAll(s"$context.Hash[Interleaved[Int]]", hashTests[Interleaved[Int]].hash)
     checkAll(s"$context.Hash[Tree[Int]]", hashTests[Tree[Int]].hash)
-    // FIXME: Doesn't work for recursive case classes.
-    // checkAll(s"$context.Hash[Recursive]", hashTests[Recursive].hash)
+    checkAll(s"$context.Hash[Recursive]", hashTests[Recursive].hash)
     checkAll(s"$context.Hash is Serializable", SerializableTests.serializable(summonInline[Hash[Inner]]))
 
   locally {

core/src/test/scala-3/cats/derived/MonoidSuite.scala

@@ -33,8 +33,7 @@ class MonoidSuite extends KittensSuite:
     checkAll(s"$context.Monoid[Foo]", monoidTests[Foo].monoid)
     checkAll(s"$context.Monoid[Interleaved[Int]]", monoidTests[Interleaved[Int]].monoid)
     checkAll(s"$context.Monoid[Box[Mul]]", monoidTests[Box[Mul]].monoid)
-    // FIXME: Doesn't work
-    // checkAll(s"$context.Monoid[Recursive]", monoidTests[Recursive].monoid)
+    checkAll(s"$context.Monoid[Recursive]", monoidTests[Recursive].monoid)
     checkAll(s"$context.Monoid is Serializable", SerializableTests.serializable(summonInline[Monoid[Foo]]))
     test(s"$context.Monoid respects existing instances") {
       val box = summonInline[Monoid[Box[Mul]]]

core/src/test/scala-3/cats/derived/NonEmptyTraverseSuite.scala

@@ -41,15 +41,14 @@ class NonEmptyTraverseSuite extends KittensSuite:
       s"$context.NonEmptyTraverse[Tree]",
       nonEmptyTraverseTests[Tree].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
     )
-    // FIXME: Those don't work
-//    checkAll(
-//      s"$context.NonEmptyTraverse[NelSCons]",
-//      nonEmptyTraverseTests[NelSCons].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
-//    )
-//    checkAll(
-//      s"$context.NonEmptyTraverse[NelAndOne]",
-//      nonEmptyTraverseTests[NelAndOne].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
-//    )
+    checkAll(
+      s"$context.NonEmptyTraverse[NelSCons]",
+      nonEmptyTraverseTests[NelSCons].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
+    )
+    checkAll(
+      s"$context.NonEmptyTraverse[NelAndOne]",
+      nonEmptyTraverseTests[NelAndOne].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
+    )
     checkAll(
       s"$context.NonEmptyTraverse[VecAndNel]",
       nonEmptyTraverseTests[VecAndNel].nonEmptyTraverse[Option, Int, Int, Int, Int, Option, Option]
@@ -79,19 +78,8 @@ object NonEmptyTraverseSuite:
   import TestDefns.*
 
   type NelSCons[A] = NonEmptyList[SCons[A]]
-  type NelAndOne[A] = NonEmptyList[OneAnd[List, A]]
-
-  // FIXME: Doesn't work if we define `ListAndNel` as a type alias
-  final case class VecAndNel[A](vec: Vector[A], nel: NonEmptyList[A])
-  object VecAndNel:
-    given [A: Eq]: Eq[VecAndNel[A]] =
-      (x, y) => x.vec === y.vec && x.nel === y.nel
-
-    given [A: Arbitrary]: Arbitrary[VecAndNel[A]] =
-      Arbitrary(for
-        vec <- Arbitrary.arbitrary[Vector[A]]
-        nel <- Arbitrary.arbitrary[NonEmptyList[A]]
-      yield VecAndNel(vec, nel))
+  type NelAndOne[A] = NonEmptyList[OneAnd[Vector, A]]
+  type VecAndNel[A] = (Vector[A], NonEmptyList[A])
 
   object semiInstances:
     given NonEmptyTraverse[ICons] = semiauto.nonEmptyTraverse

core/src/test/scala-3/cats/derived/ReducibleSuite.scala

@@ -34,9 +34,8 @@ class ReducibleSuite extends KittensSuite:
   inline def testReducible(context: String): Unit =
     checkAll(s"$context.Reducible[ICons]", reducibleTests[ICons].reducible[Option, Int, Long])
     checkAll(s"$context.Reducible[Tree]", reducibleTests[Tree].reducible[Option, Int, Long])
-    // FIXME: Those don't work
-//    checkAll(s"$context.Reducible[NelSCons]", reducibleTests[NelSCons].reducible[Option, Int, Long])
-//    checkAll(s"$context.Reducible[NelAndOne]", reducibleTests[NelAndOne].reducible[Option, Int, Long])
+    checkAll(s"$context.Reducible[NelSCons]", reducibleTests[NelSCons].reducible[Option, Int, Long])
+    checkAll(s"$context.Reducible[NelAndOne]", reducibleTests[NelAndOne].reducible[Option, Int, Long])
     checkAll(s"$context.Reducible[VecAndNel]", reducibleTests[VecAndNel].reducible[Option, Int, Long])
     checkAll(s"$context.Reducible[Interleaved]", reducibleTests[Interleaved].reducible[Option, Int, Long])
     checkAll(s"$context.Reducible[BoxZipper]", reducibleTests[BoxZipper].reducible[Option, Int, Long])
@@ -58,7 +57,8 @@ object ReducibleSuite:
   import TestDefns.*
 
   type NelSCons[A] = NonEmptyList[SCons[A]]
-  type NelAndOne[A] = NonEmptyList[OneAnd[List, A]]
+  type NelAndOne[A] = NonEmptyList[OneAnd[Vector, A]]
+  type VecAndNel[A] = (Vector[A], NonEmptyList[A])
   type BoxZipper[A] = Box[Zipper[A]]
 
   object semiInstances:
@@ -70,18 +70,6 @@ object ReducibleSuite:
     given Reducible[Interleaved] = semiauto.reducible
     given Reducible[BoxZipper] = semiauto.reducible
 
-  // FIXME: Doesn't work if we define `VecAndNel` as a type alias
-  final case class VecAndNel[A](vec: Vector[A], nel: NonEmptyList[A])
-  object VecAndNel:
-    given [A: Eq]: Eq[VecAndNel[A]] =
-      (x, y) => x.vec === y.vec && x.nel === y.nel
-
-    given [A: Arbitrary]: Arbitrary[VecAndNel[A]] =
-      Arbitrary(for
-        vec <- Arbitrary.arbitrary[Vector[A]]
-        nel <- Arbitrary.arbitrary[NonEmptyList[A]]
-      yield VecAndNel(vec, nel))
-
   final case class Zipper[+A](left: List[A], focus: A, right: List[A])
   object Zipper:
     given [A: Eq]: Eq[Zipper[A]] =

core/src/test/scala-3/cats/derived/SemigroupSuite.scala

@@ -33,8 +33,7 @@ class SemigroupSuite extends KittensSuite:
     checkAll(s"$context.Semigroup[Foo]", semigroupTests[Foo].semigroup)
     checkAll(s"$context.Semigroup[Interleaved[Int]]", semigroupTests[Interleaved[Int]].semigroup)
     checkAll(s"$context.Semigroup[Box[Mul]]", semigroupTests[Box[Mul]].semigroup)
-    // FIXME: Doesn't work
-    // checkAll(s"$context.Semigroup[Recursive]", semigroupTests[Recursive].semigroup)
+    checkAll(s"$context.Semigroup[Recursive]", semigroupTests[Recursive].semigroup)
     checkAll(s"$context.Semigroup is Serializable", SerializableTests.serializable(summonInline[Semigroup[Foo]]))
     test(s"$context.Semigroup respects existing instances") {
       val box = summonInline[Semigroup[Box[Mul]]]

core/src/test/scala-3/cats/derived/TraverseSuite.scala

@@ -49,14 +49,7 @@ object TraverseSuite:
 
   type OptList[A] = Option[List[A]]
   type ListSnoc[A] = List[Snoc[A]]
-
-  // FIXME: Doesn't work if we define `ListAndNel` as a type alias
-  case class AndChar[A](value: A, letter: Char)
-  object AndChar:
-    given [A: Eq]: Eq[AndChar[A]] =
-      Eq.by(ac => (ac.value, ac.letter))
-    given [A: Arbitrary]: Arbitrary[AndChar[A]] =
-      Arbitrary(Arbitrary.arbitrary[(A, Char)].map(apply[A].tupled))
+  type AndChar[A] = (A, Char)
 
   object semiInstances:
     given Traverse[IList] = semiauto.traverse