From 7d74b9dcf182efc1ad16636270ae38c2c16d761a Mon Sep 17 00:00:00 2001
From: Anna Kozlova <anna.kozlova@jetbrains.com>
Date: Tue, 22 Apr 2014 15:20:33 +0200
Subject: [PATCH] NPE

---
 .../source/tree/java/MethodReferenceResolver.java   |  2 +-
 .../tree/java/PsiMethodReferenceExpressionImpl.java |  4 +---
 .../MissedFunctionalInterfaceMethodReturnType.java  | 13 +++++++++++++
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/MethodReferenceResolver.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/MethodReferenceResolver.java
index cf25710008bc..fb6f831fe6b6 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/MethodReferenceResolver.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/MethodReferenceResolver.java
@@ -175,7 +175,7 @@ class MethodReferenceResolver implements ResolveCache.PolyVariantResolver<PsiMet
                     return substitutor;
                   }
 
-                  if (interfaceMethodReturnType != PsiType.VOID) {
+                  if (interfaceMethodReturnType != PsiType.VOID && interfaceMethodReturnType != null) {
                     final PsiType returnType = method.isConstructor() ? composeReturnType(containingClass, substitutor) : method.getReturnType();
                     if (returnType != null) {
                       session.registerConstraints(returnType, interfaceMethodReturnType);
diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java
index 7a82b2437a90..5ddab8e6e2f8 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java
@@ -421,9 +421,7 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
     if (interfaceMethod != null) {
       final PsiType interfaceReturnType = LambdaUtil.getFunctionalInterfaceReturnType(left);
 
-      LOG.assertTrue(interfaceReturnType != null);
-
-      if (interfaceReturnType == PsiType.VOID) {
+      if (interfaceReturnType == PsiType.VOID || interfaceReturnType == null) {
         return true;
       }
 
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/incomplete/MissedFunctionalInterfaceMethodReturnType.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/incomplete/MissedFunctionalInterfaceMethodReturnType.java
index ed1ab55f7fa2..574268764010 100644
--- a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/incomplete/MissedFunctionalInterfaceMethodReturnType.java
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/incomplete/MissedFunctionalInterfaceMethodReturnType.java
@@ -20,3 +20,16 @@ class Test {
   <T> void foo(T t1, I<T> t3) {}
 
 }
+
+class Test2 {
+
+  interface F {
+    <X>  <error descr="Invalid method declaration; return type required">m</error>();
+  }
+
+  void g() {}
+
+  {
+    F f = this::g;
+  }
+}