private inner class can't be used in top class signature ( IDEA-57751)

java/java-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightClassUtil.java

@@ -654,7 +654,7 @@ public class HighlightClassUtil {
    * @param extendRef points to the class in the extends list
    * @param resolved  extendRef resolved
    */
-  public static HighlightInfo checkClassExtendsForeignInnerClass(PsiJavaCodeReferenceElement extendRef, PsiElement resolved) {
+  public static HighlightInfo checkClassExtendsForeignInnerClass(final PsiJavaCodeReferenceElement extendRef, PsiElement resolved) {
     PsiElement parent = extendRef.getParent();
     if (!(parent instanceof PsiReferenceList)) {
       return null;
@@ -663,7 +663,7 @@ public class HighlightClassUtil {
     if (!(grand instanceof PsiClass)) {
       return null;
     }
-    PsiClass aClass = (PsiClass)grand;
+    final PsiClass aClass = (PsiClass)grand;
     if (aClass instanceof PsiTypeParameter) {
       return null;
     }
@@ -673,17 +673,41 @@ public class HighlightClassUtil {
     if (!(resolved instanceof PsiClass)) {
       return HighlightInfo.createHighlightInfo(HighlightInfoType.ERROR, extendRef, JavaErrorMessages.message("class.name.expected"));
     }
-    PsiClass base = (PsiClass)resolved;
-    // must be inner class
-    if (!PsiUtil.isInnerClass(base)) return null;
-    PsiClass baseClass = base.getContainingClass();
+    final HighlightInfo[] infos = new HighlightInfo[1];
+    extendRef.accept(new JavaRecursiveElementWalkingVisitor() {
+      @Override
+      public void visitElement(PsiElement element) {
+        if (infos[0] != null) return;
+        super.visitElement(element);
+      }
 
-    if (!hasEnclosingInstanceInScope(baseClass, extendRef, true) && !qualifiedNewCalledInConstructors(aClass, baseClass)) {
-      String description = JavaErrorMessages.message("no.enclosing.instance.in.scope", HighlightUtil.formatClass(baseClass));
-      return HighlightInfo.createHighlightInfo(HighlightInfoType.ERROR, extendRef, description);
-    }
+      @Override
+      public void visitReferenceElement(PsiJavaCodeReferenceElement reference) {
+        super.visitReferenceElement(reference);
+        final PsiElement resolve = reference.resolve();
+        if (resolve instanceof PsiClass) {
+          final PsiClass base = (PsiClass)resolve;
+          final PsiClass baseClass = base.getContainingClass();
+          if (baseClass != null && base.hasModifierProperty(PsiModifier.PRIVATE) && !PsiTreeUtil.isAncestor(baseClass, aClass, true)) {
+            String description = JavaErrorMessages.message("private.symbol",
+                                                           HighlightUtil.formatClass(base),
+                                                           HighlightUtil.formatClass(baseClass));
+            infos[0] = HighlightInfo.createHighlightInfo(HighlightInfoType.ERROR, extendRef, description);
+            return;
+          }
 
-    return null;
+          // must be inner class
+          if (!PsiUtil.isInnerClass(base)) return;
+
+          if (!hasEnclosingInstanceInScope(baseClass, extendRef, true) && !qualifiedNewCalledInConstructors(aClass, baseClass)) {
+            String description = JavaErrorMessages.message("no.enclosing.instance.in.scope", HighlightUtil.formatClass(baseClass));
+            infos[0] = HighlightInfo.createHighlightInfo(HighlightInfoType.ERROR, extendRef, description);
+          }
+        }
+      }
+    });
+
+    return infos[0];
   }
 
   private static boolean qualifiedNewCalledInConstructors(final PsiClass aClass, final PsiClass baseClass) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting/PrivateInnerClassRef.java

@@ -0,0 +1,14 @@
+import java.util.Comparator;
+
+public abstract class A implements <error descr="'A.B' has private access in 'A'">Comparator<A.B></error> {
+
+  private static class B {
+  }
+
+  private interface I extends Comparator<I>{}
+  private interface I1 extends Comparator<I>{}
+}
+
+//abstract class C implements error descr="'C.D' has private access in 'C'">C.D error {
+//  private static class D {}
+//}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/GenericsHighlightingTest.java

@@ -102,6 +102,7 @@ public class GenericsHighlightingTest extends LightDaemonAnalyzerTestCase {
   public void testTypeWithinItsWildcardBound() throws Exception { doTest(false); }
   public void testMethodSignatureEquality() throws Exception { doTest(false); }
   public void testInnerClassRef() throws Exception { doTest(false); }
+  public void testPrivateInnerClassRef() throws Exception { doTest(false); }
 
   public void testJavaUtilCollections() throws Exception {
     PsiClass collectionsClass = getJavaFacade().findClass("java.util.Collections", GlobalSearchScope.moduleWithLibrariesScope(getModule()));