Unused check of secondary constructor param

[Cherry-picked aef0a25]

Author: som-snytt

compiler/src/dotty/tools/dotc/transform/CheckUnused.scala

@@ -606,7 +606,7 @@ object CheckUnused:
 
     // does the param have an alias in a default arg method that is used?
     def usedByDefaultGetter(param: Symbol, meth: Symbol): Boolean =
-      val cls = if meth.isPrimaryConstructor then meth.enclosingClass.companionModule else meth.enclosingClass
+      val cls = if meth.isConstructor then meth.enclosingClass.companionModule else meth.enclosingClass
       val MethName = meth.name
       cls.info.decls.exists: d =>
         d.name match

tests/warn/i23349.scala

@@ -24,3 +24,7 @@ class K(k: Int)(s: String = "*"*k):
 
 class KU(using k: Int)(s: String = "*"*k):
   override val toString = s
+
+class KK(s: String):
+  def this(k: Int)(s: String = "*"*k) = this(s)
+  override val toString = s