don't try to override members that are privateWithin anything

jvm/src/test/java/com/paulbutcher/test/JavaClassWithDefaultAccess.java

@@ -0,0 +1,26 @@
+// Copyright (c) ScalaMock Contributors (https://github.com/paulbutcher/ScalaMock/graphs/contributors)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package com.paulbutcher.test;
+
+public class JavaClassWithDefaultAccess {
+  public JavaClassWithDefaultAccess(){}
+  int getSomeInt(){ return 1;}
+}

jvm/src/test/scala/org/scalamock/test/scalatest/DefaultAccessMockTest.scala

@@ -0,0 +1,33 @@
+// Copyright (c) ScalaMock Contributors (https://github.com/paulbutcher/ScalaMock/graphs/contributors)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package org.scalamock.test.scalatest
+
+import com.paulbutcher.test.JavaClassWithDefaultAccess
+import org.scalamock.scalatest.MockFactory
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+class DefaultAccessMockTest extends AnyFlatSpec with MockFactory with Matchers {
+  "mockign classes with members with JMV default access" should "work" in {
+    class DefaultExtended extends JavaClassWithDefaultAccess()
+    val m = mock[DefaultExtended]
+  }
+}

shared/src/main/scala-3/org/scalamock/clazz/Utils.scala

@@ -172,6 +172,7 @@ private[clazz] class Utils(using val quotes: Quotes):
           !sym.flags.is(Flags.Private) &&
           !sym.flags.is(Flags.Final) &&
           !sym.flags.is(Flags.Mutable) &&
+          sym.privateWithin.isEmpty &&
           !sym.name.contains("$default$")
         )
         .zipWithIndex