Add test

Author: liufengyun

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

@@ -36,8 +36,8 @@ class Checker extends Phase {
     units.foreach { unit => traverser.traverse(unit.tpdTree) }
     val classes = traverser.getConcreteClasses()
 
-    Semantic.checkClasses(classes)(using checkCtx)
     ParamOverridingCheck.checkClasses(classes)(using checkCtx)
+    Semantic.checkClasses(classes)(using checkCtx)
 
     units
 

tests/init/neg/class-param.check

@@ -0,0 +1,4 @@
+-- Error: tests/init/neg/class-param.scala:7:15 ------------------------------------------------------------------------
+7 |  override val y: Int = 20  // error: overriding parameter with non-parameter
+  |  ^^^^^^^^^^^^^^^^^^^^^^^^
+  |  Overriding parameter value y in class B as non-parameter in class C

tests/init/neg/class-param.scala

@@ -0,0 +1,7 @@
+class A(x: Int)
+
+class B(val y: Int) extends A(y):
+  println(y)   // no warning, parameter access
+
+class C extends B(10):
+  override val y: Int = 20  // error: overriding parameter with non-parameter