Various improvements

- ImplicitNotFound error for SemigroupK/MonoidK
- Replace given priority via traits with NotGiven

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

@@ -3,10 +3,19 @@ package cats.derived
 import cats.*
 import shapeless3.deriving.{Const, K1}
 
+import scala.annotation.implicitNotFound
 import scala.compiletime.*
-
+import scala.util.NotGiven
+
+@implicitNotFound("""Could not derive an instance of MonoidK[F] where F = ${F}.
+Make sure that F[_] satisfies one of the following conditions:
+  * it is a constant type [x] =>> T where T: Monoid
+  * it is a nested type [x] =>> G[H[x]] where G: MonoidK
+  * it is a nested type [x] =>> G[H[x]] where G: Applicative and H: MonoidK
+  * it is a generic case class where all fields have a MonoidK instance
+""")
 type DerivedMonoidK[F[_]] = Derived[MonoidK[F]]
-object DerivedMonoidK extends DerivedMonoidKInstances1:
+object DerivedMonoidK:
   type Or[F[_]] = Derived.Or[MonoidK[F]]
   inline def apply[F[_]]: MonoidK[F] =
     import DerivedMonoidK.given
@@ -20,6 +29,19 @@ object DerivedMonoidK extends DerivedMonoidKInstances1:
   given [F[_], G[_]](using F: Or[F]): DerivedMonoidK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
+  given [F[_], G[_]](using
+      N: NotGiven[Or[F]],
+      F0: DerivedApplicative.Or[F],
+      G0: Or[G]
+  ): DerivedMonoidK[[x] =>> F[G[x]]] =
+    new MonoidK[[x] =>> F[G[x]]]:
+      val F: Applicative[F] = F0.unify
+      val G: MonoidK[G] = G0.unify
+
+      final override def empty[A]: F[G[A]] = F.pure(G.empty[A])
+
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.map2(x, y)(G.combineK(_, _))
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedMonoidK[F] =
     given K1.ProductInstances[MonoidK, F] = inst.unify
     new Product[MonoidK, F] {}
@@ -28,15 +50,3 @@ object DerivedMonoidK extends DerivedMonoidKInstances1:
       extends MonoidK[F],
         DerivedSemigroupK.Product[T, F]:
     final override def empty[A]: F[A] = inst.construct([t[_]] => (emp: T[t]) => emp.empty[A])
-
-trait DerivedMonoidKInstances1:
-  import DerivedMonoidK.Or
-
-  given [F[_], G[_]](using F0: DerivedApplicative.Or[F], G0: Or[G]): DerivedMonoidK[[x] =>> F[G[x]]] =
-    new MonoidK[[x] =>> F[G[x]]]:
-      val F: Applicative[F] = F0.unify
-      val G: MonoidK[G] = G0.unify
-
-      final override def empty[A]: F[G[A]] = F.pure(G.empty[A])
-
-      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.map2(x, y)(G.combineK(_, _))

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

@@ -3,10 +3,19 @@ package cats.derived
 import cats.{Semigroup, SemigroupK}
 import shapeless3.deriving.{Const, K1}
 
+import scala.annotation.implicitNotFound
 import scala.compiletime.*
-
+import scala.util.NotGiven
+
+@implicitNotFound("""Could not derive an instance of SemigroupK[F] where F = ${F}.
+Make sure that F[_] satisfies one of the following conditions:
+  * it is a constant type [x] =>> T where T: Semigroup
+  * it is a nested type [x] =>> G[H[x]] where G: SemigroupK
+  * it is a nested type [x] =>> G[H[x]] where G: Apply and H: SemigroupK
+  * it is a generic case class where all fields have a SemigroupK instance
+""")
 type DerivedSemigroupK[F[_]] = Derived[SemigroupK[F]]
-object DerivedSemigroupK extends DerivedSemigroupKInstances1:
+object DerivedSemigroupK:
   type Or[F[_]] = Derived.Or[SemigroupK[F]]
   inline def apply[F[_]]: SemigroupK[F] =
     import DerivedSemigroupK.given
@@ -18,17 +27,14 @@ object DerivedSemigroupK extends DerivedSemigroupKInstances1:
   given [F[_], G[_]](using F: Or[F]): DerivedSemigroupK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
+  given [F[_], G[_]](using N: NotGiven[Or[F]], F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
+    new SemigroupK[[x] =>> F[G[x]]]:
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
     given K1.ProductInstances[SemigroupK, F] = inst.unify
     new Product[SemigroupK, F] {}
 
   trait Product[T[x[_]] <: SemigroupK[x], F[_]](using inst: K1.ProductInstances[T, F]) extends SemigroupK[F]:
     final override def combineK[A](x: F[A], y: F[A]): F[A] =
       inst.map2[A, A, A](x, y)([t[_]] => (smgrpk: T[t], x: t[A], y: t[A]) => smgrpk.combineK(x, y))
-
-trait DerivedSemigroupKInstances1:
-  import DerivedSemigroupK.Or
-
-  given [F[_], G[_]](using F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
-    new SemigroupK[[x] =>> F[G[x]]]:
-      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))

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

@@ -32,7 +32,7 @@ class MonoidKSuite extends KittensSuite {
   }
 
   {
-    import semiInstances.given
+    import monInstances.given
     testMonoidK("semi")
   }
 }
@@ -42,7 +42,7 @@ object MonoidKSuite {
 
   type BoxMul[A] = Box[Mul[A]]
 
-  object semiInstances {
+  object monInstances {
     implicit val complexProduct: MonoidK[ComplexProduct] = semiauto.monoidK
     implicit val caseClassWOption: MonoidK[CaseClassWOption] = semiauto.monoidK
     implicit val boxMul: MonoidK[BoxMul] = semiauto.monoidK

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

@@ -25,7 +25,6 @@ class SemigroupKSuite extends KittensSuite {
 
   locally {
     import auto.semigroupK.given
-    summon[SemigroupK[[a] =>> Eval[Option[a]]]]
     testSemigroupK("auto")
   }