Exclude exported symbols

[Cherry-picked 77dae85]

Author: noti0na1

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

@@ -2961,7 +2961,7 @@ object SymDenotations {
       dependent = null
     }
 
-    protected def addDependent(dep: InheritedCache) = {
+    protected def addDependent(dep: InheritedCache): Unit = {
       if (dependent == null) dependent = new WeakHashMap
       dependent.nn.put(dep, ())
     }

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

@@ -1189,7 +1189,7 @@ object RefChecks {
   def checkPublicFlexibleTypes(sym: Symbol)(using Context): Unit =
     if ctx.explicitNulls && !ctx.isJava
         && sym.exists && !sym.is(Private) && sym.owner.isClass
-        && !sym.isOneOf(Synthetic | InlineProxy | Param) then
+        && !sym.isOneOf(Synthetic | InlineProxy | Param | Exported) then
       val resTp = sym.info.finalResultType
       if resTp.existsPart(_.isInstanceOf[FlexibleType], StopAt.Static) then
         report.warning(

compiler/src/dotty/tools/repl/AbstractFileClassLoader.scala

@@ -26,7 +26,7 @@ class AbstractFileClassLoader(val root: AbstractFile, parent: ClassLoader) exten
   // on JDK 20 the URL constructor we're using is deprecated,
   // but the recommended replacement, URL.of, doesn't exist on JDK 8
   @annotation.nowarn("cat=deprecation")
-  override protected def findResource(name: String) =
+  override protected def findResource(name: String): URL | Null =
     findAbstractFile(name) match
       case null => null
       case file => new URL(null, s"memory:${file.path}", new URLStreamHandler {
@@ -35,13 +35,13 @@ class AbstractFileClassLoader(val root: AbstractFile, parent: ClassLoader) exten
           override def getInputStream = file.input
         }
       })
-  override protected def findResources(name: String) =
+  override protected def findResources(name: String): java.util.Enumeration[URL] =
     findResource(name) match
       case null => Collections.enumeration(Collections.emptyList[URL])  //Collections.emptyEnumeration[URL]
       case url  => Collections.enumeration(Collections.singleton(url))
 
   override def findClass(name: String): Class[?] = {
-    var file: AbstractFile = root
+    var file: AbstractFile | Null = root
     val pathParts = name.split("[./]").toList
     for (dirPart <- pathParts.init) {
       file = file.lookupName(dirPart, true)