check for abstract method implemented optimized: don't go through hierarchy if superClass is not abstract and there is no interfaces, would also fix asm implementations with 'broken' erasures inside

java/java-psi-api/src/com/intellij/codeInsight/ClassUtil.java

@@ -20,6 +20,7 @@
 package com.intellij.codeInsight;
 
 import com.intellij.psi.*;
+import com.intellij.psi.util.PsiUtil;
 import gnu.trove.THashSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -46,6 +47,10 @@ public class ClassUtil {
 
   @Nullable
   public static PsiMethod getAnyMethodToImplement(@NotNull PsiClass aClass) {
+    final PsiClass superClass = aClass instanceof PsiAnonymousClass ? PsiUtil.resolveClassInClassTypeOnly(((PsiAnonymousClass)aClass).getBaseClassType()) : aClass.getSuperClass();
+    if (superClass != null && !superClass.hasModifierProperty(PsiModifier.ABSTRACT) && aClass.getImplementsListTypes().length == 0) {
+      return null;
+    }
     Set<PsiMethod> alreadyImplemented = new THashSet<PsiMethod>();
     for (HierarchicalMethodSignature signatureHierarchical : aClass.getVisibleSignatures()) {
       for (PsiMethod superS : signatureHierarchical.getMethod().findSuperMethods()) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting6/SkipAbstractMethodsIfTheyMustBeDeclaredInNonAbstractSuperclass.java

@@ -0,0 +1,14 @@
+interface I {
+  void m();
+}
+
+<error descr="Class 'A' must either be declared abstract or implement abstract method 'm()' in 'I'">class A implements I</error> {}
+
+class B extends A {}
+
+class U {
+  {
+    new B() {};
+    B b = new B();
+  }
+}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/LightAdvHighlightingJdk6Test.java

@@ -69,4 +69,7 @@ public class LightAdvHighlightingJdk6Test extends LightDaemonAnalyzerTestCase {
   public void testUnhandledErrorsFromEnumConstructors() {
     doTest(true, false);
   }
+  public void testSkipAbstractMethodsIfTheyMustBeDeclaredInNonAbstractSuperclass() {
+    doTest(false, false);
+  }
 }