Add an Ordering given instance for named tuples (#23379)

Author: odersky

library/src/scala/NamedTuple.scala

@@ -128,6 +128,10 @@ object NamedTuple:
   /** The empty named tuple */
   val Empty: Empty = EmptyTuple
 
+  /** The ordering instance for named tuples */
+  given namedTupleOrdering: [N <: Tuple, V <: Tuple] => (ord: Ordering[V]) => Ordering[NamedTuple[N, V]]:
+    def compare(x: NamedTuple[N, V], y: NamedTuple[N, V]): Int =
+      ord.compare(x.toTuple, y.toTuple)
 end NamedTuple
 
 /** Separate from NamedTuple object so that we can match on the opaque type NamedTuple. */

project/MiMaFilters.scala

@@ -8,25 +8,26 @@ object MiMaFilters {
     val ForwardsBreakingChanges: Map[String, Seq[ProblemFilter]] = Map(
       // Additions that require a new minor version of the library
       Build.mimaPreviousDottyVersion -> Seq(
-        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.readOnlyCapability"),
-        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.onlyCapability"),
-
         // Scala.js-only class
         ProblemFilters.exclude[FinalClassProblem]("scala.scalajs.runtime.AnonFunctionXXL"),
         ProblemFilters.exclude[DirectMissingMethodProblem]("scala.scalajs.runtime.AnonFunctionXXL.this"),
 
         ProblemFilters.exclude[MissingFieldProblem]("scala.runtime.stdLibPatches.language.2.13"),
         ProblemFilters.exclude[MissingClassProblem]("scala.runtime.stdLibPatches.language$2$u002E13$"),
-        ProblemFilters.exclude[MissingFieldProblem]("scala.runtime.stdLibPatches.language#experimental.separationChecking"),
-        ProblemFilters.exclude[MissingClassProblem]("scala.runtime.stdLibPatches.language$experimental$separationChecking$"),
 
         ProblemFilters.exclude[DirectMissingMethodProblem]("scala.Conversion.underlying"),
         ProblemFilters.exclude[MissingClassProblem]("scala.Conversion$"),
-        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.RuntimeChecked"),
-        
+        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.RuntimeChecked"),        
         ProblemFilters.exclude[MissingClassProblem]("scala.annotation.stableNull"),
 
-        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ValDefModule.let"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.NamedTuple.namedTupleOrdering"),
+        ProblemFilters.exclude[MissingClassProblem]("scala.NamedTuple$namedTupleOrdering"),
+
+		// cc related
+        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.readOnlyCapability"),
+        ProblemFilters.exclude[MissingClassProblem]("scala.annotation.internal.onlyCapability"),
+        ProblemFilters.exclude[MissingFieldProblem]("scala.runtime.stdLibPatches.language#experimental.separationChecking"),
+        ProblemFilters.exclude[MissingClassProblem]("scala.runtime.stdLibPatches.language$experimental$separationChecking$"),
       ),
 
       // Additions since last LTS

tests/run/named-tuple-ordering.check

@@ -0,0 +1 @@
+List((Alice,29), (Alice,30), (Bob,25), (Charlie,35))

tests/run/named-tuple-ordering.scala

@@ -0,0 +1,13 @@
+type Person = (name: String, age: Int)
+
+val so = summon[Ordering[Person]]
+
+val people: List[Person] = List(
+  (name = "Charlie", age = 35),
+  (name = "Alice", age = 30),
+  (name = "Alice", age = 29),
+  (name = "Bob", age = 25),
+)
+val sortedPeople = people.sorted
+
+@main def Test = println(s"$sortedPeople")