Fix #17115: Try to normalize while computing typeSize.

Author: sjrd

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

@@ -6459,7 +6459,9 @@ object Types {
         seen += tp
         tp match {
           case tp: AppliedType =>
-            foldOver(n + 1, tp)
+            val tpNorm = tp.tryNormalize
+            if tpNorm.exists then apply(n, tpNorm)
+            else foldOver(n + 1, tp)
           case tp: RefinedType =>
             foldOver(n + 1, tp)
           case tp: TypeRef if tp.info.isTypeAlias =>

tests/pos/i17115.scala

@@ -0,0 +1,9 @@
+trait A[T <: Tuple] { val x: Int }
+given empty: A[EmptyTuple] with { val x = 1 }
+given inductive[Tup <: NonEmptyTuple](using A[Tuple.Tail[Tup]]): A[Tup] with { val x = summon[A[Tuple.Tail[Tup]]].x + 1 }
+
+object Test:
+  def main(args: Array[String]): Unit =
+    println(summon[A[(String, String, String)]].x) //this line is fine
+    println(summon[A[(String, String, String, String)]].x) //this line gives error
+end Test