Handle overrides in abstract class correctly

Author: liufengyun

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

@@ -135,7 +135,7 @@ object ParamOverridingCheck:
             thisV.callConstructor(ref.symbol, args)
 
           case _ =>
-            report.error("Unexpected rhs = " + ddef.rhs.show, ddef.rhs)
+            report.error("Unexpected rhs = " + ddef.rhs.show + " in " + cls.show, ddef.rhs)
 
     }
   end extension
@@ -146,7 +146,7 @@ object ParamOverridingCheck:
    * Check the specified concrete classes
    */
   def checkClasses(concreteClasses: List[ClassSymbol])(using Context): Unit =
-    for classSym <- concreteClasses if overrideClassParams(classSym) do
+    for classSym <- concreteClasses do
       val thisRef = ThisRef(classSym, fields = mutable.Map.empty)
       val tpl = classSym.defTree.asInstanceOf[TypeDef].rhs.asInstanceOf[Template]
       for param <- tpl.constr.termParamss.flatten yield
@@ -331,33 +331,18 @@ object ParamOverridingCheck:
     // check parameter access semantics
     for
       paramSym <- klass.paramGetters
-      overridingSym = paramSym.overridingSymbol(thisV.klass)
-      if overridingSym.exists
+      overridingSym = paramSym.matchingMember(thisV.klass.thisType)
+      if overridingSym.exists && overridingSym != paramSym && overridingSym.is(Flags.Override)
     do
       // println(paramSym.show + " is overridden in " + thisV.klass)
       if !overridingSym.is(Flags.ParamAccessor) then
-        report.warning("Overriding parameter " + paramSym.show + " in " + klass.show + " as non-parameter in " + thisV.klass.show, overridingSym.defTree)
+        report.warning("Overriding parameter " + paramSym.show + " in " + klass.show + " as non-parameter in " + overridingSym.owner.show, overridingSym.defTree)
       else
         val overridingValue = thisV.field(overridingSym)
         // println(overridingSym.show + " in " + thisV.klass + " = " + overridingValue)
         // println(paramSym.show + " in " + klass + " = " + thisV.field(paramSym))
         if thisV.field(paramSym) != overridingValue then
-          report.warning("Incorrect overriding: " + paramSym.show + " in " + klass.show + " has a different value from " + overridingSym.show + " in " + thisV.klass.show, overridingValue.source)
+          report.warning("Incorrect overriding: " + paramSym.show + " in " + klass.show + " has a different value from " + overridingSym.show + " in " + overridingSym.owner.show, overridingSym.defTree)
 
     thisV
   }
-
-  // ------------------------- Helper methods ----------------------------------
-
-  /** Does the given class override any class parameter? */
-  def overrideClassParams(classSym: ClassSymbol)(using Context): Boolean =
-    classSym.info.baseClasses match
-      case _ :: inherited =>
-        inherited.exists(superCls => anyClassParameterOverridenBy(superCls, by = classSym))
-
-      case Nil =>
-        false
-
-  /** Does the class `classSym` have any class parameter overridden by the class `by`? */
-  def anyClassParameterOverridenBy(classSym: ClassSymbol, by: ClassSymbol)(using Context): Boolean =
-    classSym.paramGetters.exists(_.overridingSymbol(by).exists)

tests/init/neg/i15764d.scala

@@ -0,0 +1,5 @@
+class A(val y: Int)
+
+abstract class B(override val y: Int) extends A(10) // error
+
+class C extends B(7)