Changed precedence of tupled instances for Hash and PartialOrder (#3105)

typelevel · Oct 16, 2019 · 6e7ff8f · 6e7ff8f
1 parent eb52c0b
commit 6e7ff8f
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Showing 3 changed files with 29 additions and 7 deletions.
diff --git a/PULL_REQUEST_TEMPLATE.md b/PULL_REQUEST_TEMPLATE.md
@@ -1,5 +1,5 @@
 Thank you for contributing to Cats!
 
-This is a kind reminder to run `sbt prePR` and commit the changed files, if any, before submitting. 
+This is a kind reminder to run `sbt +prePR` and commit the changed files, if any, before submitting. 
 
 
diff --git a/project/KernelBoiler.scala b/project/KernelBoiler.scala
@@ -201,12 +201,6 @@ object KernelBoiler {
                   .mkString(s"$tupleNHeader(", ", ", ")")}.hashCode()
                     def eqv(x: ${`(A..N)`}, y: ${`(A..N)`}): Boolean = ${binMethod("eqv").mkString(" && ")}
                   }
-
-                implicit def catsKernelStdPartialOrderForTuple${arity}[${`A..N`}](implicit ${constraints("PartialOrder")}): PartialOrder[${`(A..N)`}] =
-                  new PartialOrder[${`(A..N)`}] {
-                    def partialCompare(x: ${`(A..N)`}, y: ${`(A..N)`}): Double =
-                      ${binMethod("partialCompare").mkString("Array(", ", ", ")")}.find(_ != 0.0).getOrElse(0.0)
-                }
         """
             }
         ),
@@ -217,6 +211,12 @@ object KernelBoiler {
               import tv._
               def content =
                 block"""
+                implicit def catsKernelStdPartialOrderForTuple${arity}[${`A..N`}](implicit ${constraints("PartialOrder")}): PartialOrder[${`(A..N)`}] =
+                  new PartialOrder[${`(A..N)`}] {
+                    def partialCompare(x: ${`(A..N)`}, y: ${`(A..N)`}): Double =
+                      ${binMethod("partialCompare").mkString("Array(", ", ", ")")}.find(_ != 0.0).getOrElse(0.0)
+                }
+
                 implicit def catsKernelStdBandForTuple${arity}[${`A..N`}](implicit ${constraints("Band")}): Band[${`(A..N)`}] =
                   new Band[${`(A..N)`}] {
                     def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}

diff --git a/tests/src/test/scala/cats/tests/EqSuite.scala b/tests/src/test/scala/cats/tests/EqSuite.scala
@@ -6,6 +6,8 @@ import cats.laws.discipline.{ContravariantMonoidalTests, MiniInt}
 import cats.laws.discipline.arbitrary._
 import cats.laws.discipline.eq._
 
+import scala.collection.immutable.Queue
+
 class EqSuite extends CatsSuite {
   Invariant[Eq]
   Contravariant[Eq]
@@ -15,4 +17,24 @@ class EqSuite extends CatsSuite {
   checkAll("Eq", ContravariantMonoidalTests[Eq].contravariantMonoidal[MiniInt, Boolean, Boolean])
   checkAll("ContravariantMonoidal[Eq]", SerializableTests.serializable(ContravariantMonoidal[Eq]))
 
+  test("The Eq instance for tuples of A is not ambiguous when A has a Hash and a PartialOrder") {
+
+    import cats.kernel.{Hash, PartialOrder}
+
+    trait A
+    implicit def po: PartialOrder[A] = ???
+    implicit def ho: Hash[A] = ???
+
+    lazy val a2 = implicitly[Eq[(A, A)]]
+    lazy val b2 = implicitly[Eq[(List[A], List[A])]]
+    lazy val c2 = implicitly[Eq[(Set[A], Set[A])]]
+    lazy val d2 = implicitly[Eq[(Vector[A], Vector[A])]]
+    lazy val e2 = implicitly[Eq[(Queue[A], Queue[A])]]
+
+    lazy val a3 = implicitly[Eq[(A, A, A)]]
+    lazy val b3 = implicitly[Eq[(List[A], List[A], List[A])]]
+    lazy val c3 = implicitly[Eq[(Set[A], Set[A], Set[A])]]
+    lazy val d3 = implicitly[Eq[(Vector[A], Vector[A], Vector[A])]]
+    lazy val e3 = implicitly[Eq[(Queue[A], Queue[A], Queue[A])]]
+  }
 }