Filter out static forwarders for Java package private methods

Co-authored-by: Guillaume Martres <smarter@ubuntu.com>

Author: vasilmkd

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

@@ -1388,7 +1388,7 @@ object SymDenotations {
     final def accessBoundary(base: Symbol)(using Context): Symbol =
       if (this.is(Private)) owner
       else if (this.isAllOf(StaticProtected)) defn.RootClass
-      else if (privateWithin.exists && !ctx.phase.erasedTypes) privateWithin
+      else if (privateWithin.exists && (!ctx.phase.erasedTypes || this.is(JavaDefined))) privateWithin
       else if (this.is(Protected)) base
       else defn.RootClass
 

tests/run/forwarder-java-package-private.check

@@ -0,0 +1 @@
+public static java.lang.String scalapackage.Foo.publicMethod()

tests/run/forwarder-java-package-private/Base_1.java

@@ -0,0 +1,11 @@
+package javapackage;
+
+public class Base_1 {
+    int packagePrivateMethod() {
+        return 42;
+    }
+
+    public String publicMethod() {
+        return "foo";
+    }
+}

tests/run/forwarder-java-package-private/Test_2.scala

@@ -0,0 +1,12 @@
+package scalapackage:
+  object Foo extends javapackage.Base_1
+end scalapackage
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    println(
+      Class.forName("scalapackage.Foo").getMethods
+        .filter(m => (m.getModifiers & java.lang.reflect.Modifier.STATIC) != 0)
+        .mkString("\n"))
+  }
+}