PR comments

Author: eejbyfeldt

compiler/src/dotty/tools/dotc/core/StdNames.scala

@@ -394,6 +394,7 @@ object StdNames {
     val This: N                 = "This"
     val ThisType: N             = "ThisType"
     val Tuple2: N               = "Tuple2"
+    val Tuple: N                = "Tuple"
     val TYPE_ : N               = "TYPE"
     val TypeApply: N            = "TypeApply"
     val TypeRef: N              = "TypeRef"

compiler/src/dotty/tools/dotc/typer/Synthesizer.scala

@@ -438,13 +438,13 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
 
     def makeTupleProductMirror(tps: List[Type]): TreeWithErrors =
       val arity = tps.size
-      if arity < Definitions.MaxTupleArity then
+      if arity <= Definitions.MaxTupleArity then
         val tupleCls = defn.TupleType(arity).nn.classSymbol
         makeClassProductMirror(tupleCls.owner.reachableThisType, tupleCls, Some(tps))
       else
         val elemLabels = (for i <- 1 to arity yield ConstantType(Constant(s"_$i"))).toList
         val mirrorRef: Type => Tree = _ => newTupleMirror(arity)
-        makeProductMirror(tps, elemLabels, s"Tuple$arity".toTermName, mirrorRef)
+        makeProductMirror(tps, elemLabels, tpnme.Tuple, mirrorRef)
     end makeTupleProductMirror
 
     def makeClassProductMirror(pre: Type, cls: Symbol, tps: Option[List[Type]]) =

tests/pos/i15398.scala

@@ -3,7 +3,7 @@ object i15398 {
 
   summon[Tuple.Size[Tuple23] =:= 23]
   val m = summon[scala.deriving.Mirror.Of[Tuple23]]
-  summon[m.MirroredLabel =:= "Tuple23"]
+  summon[m.MirroredLabel =:= "Tuple"]
   summon[m.MirroredElemTypes =:= Tuple23]
   summon[m.MirroredElemLabels =:= ("_1", "_2", "_3", "_4", "_5", "_6", "_7", "_8", "_9", "_10", "_11", "_12", "_13", "_14", "_15", "_16", "_17", "_18", "_19", "_20", "_21", "_22", "_23")]
 }