lambda: functional interface can contain multiple default methods

java/java-psi-api/src/com/intellij/psi/LambdaUtil.java

@@ -216,12 +216,12 @@ public class LambdaUtil {
   private static List<MethodSignature> findFunctionCandidates(PsiClass psiClass) {
     if (psiClass.isInterface()) {
       final List<MethodSignature> methods = new ArrayList<MethodSignature>();
-      final PsiMethod[] psiClassMethods = psiClass.getAllMethods();
-      for (PsiMethod psiMethod : psiClassMethods) {
+      final Collection<HierarchicalMethodSignature> visibleSignatures = psiClass.getVisibleSignatures();
+      for (HierarchicalMethodSignature signature : visibleSignatures) {
+        final PsiMethod psiMethod = signature.getMethod();
         if (!psiMethod.hasModifierProperty(PsiModifier.ABSTRACT)) continue;
-        final PsiClass methodContainingClass = psiMethod.getContainingClass();
-        if (!overridesPublicObjectMethod(psiMethod)) {
-          methods.add(getMethodSignature(psiMethod, psiClass, methodContainingClass));
+        if (!overridesPublicObjectMethod(psiMethod) && !PsiUtil.isExtensionMethod(psiMethod)) {
+          methods.add(signature);
         }
       }
 

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/highlighting/DefaultMethod.java

@@ -0,0 +1,17 @@
+class Test {
+  public static final BinaryOperator<Integer> rPlus = (x, y) -> x + y;
+  interface BinaryOperator<T> extends Combiner<T,T,T> {
+    public T operate(T left, T right);
+
+    @Override
+    T combine(T t1, T t2) default {
+      return operate(t1, t2);
+    }
+  }
+
+  interface Combiner<T, U, V> {
+    V combine(T t, U u);
+  }
+}
+
+

java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/LambdaHighlightingTest.java

@@ -85,7 +85,9 @@ public class LambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
   
- 
+  public void testDefaultMethod() throws Exception {
+    doTest();
+  }
   
   public void testNoInferenceResult() throws Exception {
     doTest();