Kapt3: Nested class inside an interface should always be public and static (KT-15145)

plugins/kapt3/src/org/jetbrains/kotlin/kapt3/stubs/ClassFileToSourceStubConverter.kt

@@ -135,9 +135,18 @@ class ClassFileToSourceStubConverter(
         val isNested = (descriptor as? ClassDescriptor)?.isNested ?: false
         val isInner = isNested && (descriptor as? ClassDescriptor)?.isInner ?: false
 
-        val modifiers = convertModifiers(
-                if (!isInner && isNested) (clazz.access or Opcodes.ACC_STATIC) else clazz.access,
-                ElementKind.CLASS, packageFqName, clazz.visibleAnnotations, clazz.invisibleAnnotations)
+        val flags = when {
+            (descriptor.containingDeclaration as? ClassDescriptor)?.kind == ClassKind.INTERFACE -> {
+                // Classes inside interfaces should always be public and static.
+                // See com.sun.tools.javac.comp.Enter.visitClassDef for more information.
+                (clazz.access or Opcodes.ACC_PUBLIC or Opcodes.ACC_STATIC) and
+                        Opcodes.ACC_PRIVATE.inv() and Opcodes.ACC_PROTECTED.inv() // Remove private and protected modifiers
+            }
+            !isInner && isNested -> clazz.access or Opcodes.ACC_STATIC
+            else -> clazz.access
+        }
+
+        val modifiers = convertModifiers(flags, ElementKind.CLASS, packageFqName, clazz.visibleAnnotations, clazz.invisibleAnnotations)
 
         val isEnum = clazz.isEnum()
         val isAnnotation = clazz.isAnnotation()

plugins/kapt3/test/org/jetbrains/kotlin/kapt3/test/ClassFileToSourceStubConverterTestGenerated.java

@@ -144,6 +144,12 @@ public class ClassFileToSourceStubConverterTestGenerated extends AbstractClassFi
         doTest(fileName);
     }
 
+    @TestMetadata("kt15145.kt")
+    public void testKt15145() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("plugins/kapt3/testData/converter/kt15145.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("mapEntry.kt")
     public void testMapEntry() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("plugins/kapt3/testData/converter/mapEntry.kt");

plugins/kapt3/testData/converter/kt15145.kt

@@ -0,0 +1,4 @@
+interface MyInterface {
+    fun someFun()
+    private class MyDefaultInferface()
+}

plugins/kapt3/testData/converter/kt15145.txt

@@ -0,0 +1,11 @@
+public abstract interface MyInterface {
+
+    public abstract void someFun();
+
+    public static final class MyDefaultInferface {
+
+        public MyDefaultInferface() {
+            super();
+        }
+    }
+}