new overload resolution: reject explicitly typed lambda to be pertinent to applicability if any of its return expressions is not

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java

@@ -174,7 +174,6 @@ public class InferenceSession {
           }
         }
       }
-      return true;
     }
     if (expr instanceof PsiLambdaExpression) {
       if (!((PsiLambdaExpression)expr).hasFormalParameterTypes()) {

java/java-psi-impl/src/com/intellij/psi/scope/conflictResolvers/JavaMethodsConflictResolver.java

@@ -158,7 +158,8 @@ public class JavaMethodsConflictResolver implements PsiConflictResolver{
       // A lambda expression or a method reference expression is potentially compatible with a type variable if the type variable is a type parameter of the candidate method.
       final PsiClass paramClass = PsiUtil.resolveClassInType(paramType);
       if (paramClass instanceof PsiTypeParameter && ((PsiTypeParameter)paramClass).getOwner() == method) continue;
-      if (!lambdaExpression.isAcceptable(((MethodCandidateInfo)conflict).getSubstitutor(false).substitute(paramType), lambdaExpression.hasFormalParameterTypes())) {
+      if (!lambdaExpression.isAcceptable(((MethodCandidateInfo)conflict).getSubstitutor(false).substitute(paramType),
+                                         InferenceSession.isPertinentToApplicability(lambdaExpression, method))) {
         iterator.remove();
       }
     }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/overloadResolution/PertinentToApplicabilityOfExplicitlyTypedLambda.java

@@ -0,0 +1,17 @@
+abstract class PertinentToApplicabilityOfExplicitlyTypedLambdaTest {
+
+  interface A {
+    B m(int a);
+  }
+
+  interface B {
+    int m(int b);
+  }
+
+  abstract void foo(A a);
+  abstract void foo(B b);
+
+  {
+    foo<error descr="Ambiguous method call: both 'PertinentToApplicabilityOfExplicitlyTypedLambdaTest.foo(A)' and 'PertinentToApplicabilityOfExplicitlyTypedLambdaTest.foo(B)' match">(x -> y -> 42)</error>;
+  }
+}

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

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.codeInsight.daemon.lambda;
+
+import com.intellij.codeInsight.daemon.LightDaemonAnalyzerTestCase;
+import com.intellij.codeInspection.LocalInspectionTool;
+import com.intellij.codeInspection.unusedSymbol.UnusedSymbolLocalInspection;
+import com.intellij.openapi.projectRoots.JavaSdkVersion;
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.testFramework.IdeaTestUtil;
+import org.jetbrains.annotations.NonNls;
+import org.jetbrains.annotations.NotNull;
+
+public class OverloadResolutionTest extends LightDaemonAnalyzerTestCase {
+  @NonNls static final String BASE_PATH = "/codeInsight/daemonCodeAnalyzer/lambda/overloadResolution";
+
+  @NotNull
+  @Override
+  protected LocalInspectionTool[] configureLocalInspectionTools() {
+    return new LocalInspectionTool[]{
+      new UnusedSymbolLocalInspection(),
+    };
+  }
+
+  public void testPertinentToApplicabilityOfExplicitlyTypedLambda() throws Exception {
+    doTest();
+  }
+
+
+  private void doTest() {
+    doTest(true);
+  }
+
+  private void doTest(boolean warnings) {
+    IdeaTestUtil.setTestVersion(JavaSdkVersion.JDK_1_8, getModule(), getTestRootDisposable());
+    doTestNewInference(BASE_PATH + "/" + getTestName(false) + ".java", warnings, false);
+  }
+
+  @Override
+  protected Sdk getProjectJDK() {
+    return IdeaTestUtil.getMockJdk18();
+  }
+}