Fix implcit use check and override check on repeared

Author: noti0na1

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

@@ -33,6 +33,8 @@ object NullOpsDecorator {
             if (tp1s ne tp1) && (tp2s ne tp2) then
               tp.derivedAndType(tp1s, tp2s)
             else tp
+          case tp @ TypeBounds(lo, hi) =>
+            tp.derivedTypeBounds(strip(lo), strip(hi))
           case tp => tp
         }
         if tpStriped ne tpWiden then tpStriped else tp

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

@@ -11,6 +11,7 @@ import transform.ValueClasses._
 import transform.TypeUtils._
 import transform.ContextFunctionResults._
 import Decorators._
+import NullOpsDecorator._
 import Definitions.MaxImplementedFunctionArity
 import scala.annotation.tailrec
 
@@ -514,8 +515,11 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
   private def eraseArray(tp: Type)(using Context) = {
     val defn.ArrayOf(elemtp) = tp
     if (classify(elemtp).derivesFrom(defn.NullClass)) JavaArrayType(defn.ObjectType)
-    else if (isUnboundedGeneric(elemtp) && !isJava) defn.ObjectType
-    else JavaArrayType(erasureFn(isJava, semiEraseVCs = false, isConstructor, wildcardOK)(elemtp))
+    else {
+      val elemtp1 = if (ctx.explicitNulls) elemtp.stripNull else elemtp
+      if (isUnboundedGeneric(elemtp1) && !isJava) defn.ObjectType
+      else JavaArrayType(erasureFn(isJava, semiEraseVCs = false, isConstructor, wildcardOK)(elemtp1))
+    }
   }
 
   private def erasePair(tp: Type)(using Context): Type = {

compiler/src/dotty/tools/dotc/typer/Checking.scala

@@ -15,6 +15,7 @@ import TreeInfo._
 import ProtoTypes._
 import Scopes._
 import CheckRealizable._
+import NullOpsDecorator._
 import ErrorReporting.errorTree
 import rewrites.Rewrites.patch
 import util.Spans.Span
@@ -776,17 +777,18 @@ trait Checking {
    *    - it is defined in Predef
    *    - it is the scala.reflect.Selectable.reflectiveSelectable conversion
    */
-  def checkImplicitConversionUseOK(sym: Symbol, posd: Positioned)(using Context): Unit =
+  def checkImplicitConversionUseOK(sym: Symbol, tpe: Type, posd: Positioned)(using Context): Unit =
     if (sym.exists) {
       val conv =
         if (sym.isOneOf(GivenOrImplicit) || sym.info.isErroneous) sym
         else {
           assert(sym.name == nme.apply || ctx.reporter.errorsReported)
           sym.owner
         }
+      val tpe1 = if ctx.explicitNulls then tpe.stripNull else tpe
       val conversionOK =
         conv.is(Synthetic) ||
-        sym.info.finalResultType.classSymbols.exists(_.isLinkedWith(conv.owner)) ||
+        tpe1.classSymbols.exists(_.isLinkedWith(conv.owner)) ||
         defn.isPredefClass(conv.owner) ||
         conv.name == nme.reflectiveSelectable && conv.maybeOwner.maybeOwner.maybeOwner == defn.ScalaPackageClass
       if (!conversionOK)
@@ -1219,7 +1221,7 @@ trait NoChecking extends ReChecking {
   override def checkStable(tp: Type, pos: SourcePosition, kind: String)(using Context): Unit = ()
   override def checkClassType(tp: Type, pos: SourcePosition, traitReq: Boolean, stablePrefixReq: Boolean)(using Context): Type = tp
   override def checkImplicitConversionDefOK(sym: Symbol)(using Context): Unit = ()
-  override def checkImplicitConversionUseOK(sym: Symbol, posd: Positioned)(using Context): Unit = ()
+  override def checkImplicitConversionUseOK(sym: Symbol, tpe: Type, posd: Positioned)(using Context): Unit = ()
   override def checkFeasibleParent(tp: Type, pos: SourcePosition, where: => String = "")(using Context): Type = tp
   override def checkInlineConformant(tpt: Tree, tree: Tree, sym: Symbol)(using Context): Unit = ()
   override def checkNoAlphaConflict(stats: List[Tree])(using Context): Unit = ()

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -3463,7 +3463,7 @@ class Typer extends Namer
           case SearchSuccess(found: ExtMethodApply, _, _) =>
             found // nothing to check or adapt for extension method applications
           case SearchSuccess(found, ref, _) =>
-            checkImplicitConversionUseOK(ref.symbol, t.posd)
+            checkImplicitConversionUseOK(ref.symbol, found.typeOpt, t.posd)
             readapt(found)(using ctx.retractMode(Mode.ImplicitsEnabled))
           case failure: SearchFailure =>
             fail(failure)

tests/explicit-nulls/pos/override-java-varargs/S.scala

@@ -1,9 +1,7 @@
-// TODO: currently, OverridingParis cannot find bar in S1
-//
-// class S1 extends J {
-//   override def foo(x: (String | Null)*): Unit = ???
-//   override def bar(x: String | Null, y: (String | Null)*): Unit = ???
-// }
+class S1 extends J {
+  override def foo(x: (String | Null)*): Unit = ???
+  override def bar(x: String | Null, y: (String | Null)*): Unit = ???
+}
 
 class S2 extends J {
   override def foo(x: String*): Unit = ???