Fix scala#16438: Ignore erroneous parent call in init check

compiler/src/dotty/tools/dotc/transform/init/Semantic.scala

@@ -1663,9 +1663,13 @@ object Semantic:
           // term arguments to B. That can only be done in a concrete class.
           val tref = typeRefOf(klass.typeRef.baseType(mixin).typeConstructor)
           val ctor = tref.classSymbol.primaryConstructor
-          if ctor.exists then extendTrace(superParent) {
-            superCall(tref, ctor, Nil, tasks)
-          }
+          if ctor.exists && ctor.paramSymss.isEmpty then
+            // The parameter check of traits comes late in the mixin phase.
+            // To avoid crash we ignore the initialization check for erroneous
+            // parent call code. See tests/neg/i16438.scala.
+            extendTrace(superParent) {
+              superCall(tref, ctor, args = Nil, tasks)
+            }
       }
 
       // initialize super classes after outers are set

tests/neg/i16438.scala

@@ -0,0 +1,4 @@
+// scalac: -Ysafe-init
+trait ATrait(val string: String, val int: Int)
+trait AnotherTrait( override val string: String, override val int: Int) extends ATrait
+case class ACaseClass(override val string: String) extends AnotherTrait(string, 3) // error