Call dealias after stripping type variables for tupleElementTypesUpTo

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

@@ -68,7 +68,7 @@ class TypeUtils:
     def tupleElementTypesUpTo(bound: Int, normalize: Boolean = true)(using Context): Option[List[Type]] =
       def recur(tp: Type, bound: Int): Option[List[Type]] =
         if bound < 0 then Some(Nil)
-        else (if normalize then tp.normalized else tp).dealias match
+        else (if normalize then tp.dealias.normalized else tp).dealias match
           case AppliedType(tycon, hd :: tl :: Nil) if tycon.isRef(defn.PairClass) =>
             recur(tl, bound - 1).map(hd :: _)
           case tp: AppliedType if defn.isTupleNType(tp) && normalize =>

compiler/test/dotc/pos-test-pickling.excludelist

@@ -71,6 +71,7 @@ i18211.scala
 named-tuples1.scala
 i20897.scala
 i20512.scala
+i22645b.scala
 
 # Opaque type
 i5720.scala

tests/pos/i22643.scala

@@ -0,0 +1,48 @@
+import language.experimental.namedTuples
+
+
+
+object ExhibitB:
+
+  trait JoinB[A <: Tuple, B <: Tuple]:
+    type NTB = NamedTuple.NamedTuple[Tuple.Concat[A, B], (String, Int)]
+    val ntB: NTB = ???
+
+  val joinB: JoinB[Tuple1["nameB"], Tuple1["ageB"]] = ???
+
+  joinB.ntB.nameB    // works
+
+
+object ExhibitC:
+
+  type A = Tuple1["nameC"]
+  type B = Tuple1["ageC"]
+
+  type NamesC = Tuple.Concat[A, B]
+  type NTC = NamedTuple.NamedTuple[NamesC, (String, Int)]
+  val ntC: NTC = ???
+
+  ntC.nameC   // works
+
+
+object ExhibitD:
+
+  trait JoinD[A, B]:
+    type NamesD = (A, B)
+    type NTD = NamedTuple.NamedTuple[NamesD, (String, Int)]
+    val ntD: NTD = ???
+
+  val joinD: JoinD["nameD", "ageD"] = ???
+
+  joinD.ntD.nameD    // works
+
+object ExhibitA:
+
+  trait JoinA[A <: Tuple, B <: Tuple]:
+    type NamesA = Tuple.Concat[A, B]
+    type NTA = NamedTuple.NamedTuple[NamesA, (String, Int)]
+    val ntA: NTA = ???
+
+  val joinA: JoinA[Tuple1["nameA"], Tuple1["ageA"]] = ???
+
+  joinA.ntA.nameA    // fixed

tests/pos/i22645a.scala

@@ -0,0 +1,44 @@
+import language.experimental.namedTuples
+object ExhibitA:  //  fails
+
+  class SelectableNT[N <: Tuple] extends Selectable:
+    def selectDynamic(name: String) = ???
+    type Names = Tuple.Map[N, [X] =>> X]
+    type Fields = NamedTuple.NamedTuple[Names, (String, Int)]
+
+  val x = new SelectableNT[("name", "age")]
+  x.name  // fails
+
+
+object ExhibitB:  //  works
+
+  class SelectableNT[N <: Tuple] extends Selectable:
+    def selectDynamic(name: String) = ???
+    type Fields = NamedTuple.NamedTuple[N, (String, Int)]
+
+  val x = new SelectableNT[("name", "age")]
+  x.name
+
+
+object ExhibitC:  // works
+
+  class SelectableNT[N <: Tuple] extends Selectable:
+    def selectDynamic(name: String) = ???
+    type Fields = NamedTuple.NamedTuple[N, (String, Int)]
+
+  type N = ("name", "age")
+  val x = new SelectableNT[N]
+  x.name
+
+
+object ExhibitD:  // works
+
+  class SelectableNT[N <: Tuple] extends Selectable:
+    def selectDynamic(name: String) = ???
+    type Fields = NamedTuple.NamedTuple[N, (String, Int)]
+
+  type N = ("name", "age")
+  type Names = Tuple.Map[N, [X] =>> X]
+  val x = new SelectableNT[Names]
+  x.name
+

tests/pos/i22645b.scala

@@ -0,0 +1,12 @@
+import language.experimental.namedTuples
+object ExhibitE:  // works
+
+  type N = ("name", "age")
+  type Names = Tuple.Map[N, [X] =>> X]
+
+  class SelectableNT extends Selectable:
+    def selectDynamic(name: String) = ???
+    type Fields = NamedTuple.NamedTuple[Names, (String, Int)]
+
+  val x = new SelectableNT
+  x.name