new inference: lambda compatibility: ground type constraint added

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

@@ -45,6 +45,7 @@ public class LambdaExpressionCompatibilityConstraint implements ConstraintFormul
       for (int i = 0; i < lambdaParameters.length; i++) {
         constraints.add(new TypeEqualityConstraint(lambdaParameters[i].getType(), substitutor.substitute(parameters[i].getType())));
       }
+      constraints.add(new StrictSubtypingConstraint(myT, groundTargetType));
     } else {
       for (PsiParameter parameter : parameters) {
         if (!session.isProperType(substitutor.substitute(parameter.getType()))) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/constraints/LambdaGroundTest.java

@@ -0,0 +1,13 @@
+import java.util.List;
+
+public class Sample {
+  interface Fun<A extends List <String>, B> {
+    B f(A a);
+  }
+
+  <T, R> void foo(Fun<? super T , R> f) {}
+
+  {
+    foo((List<String> ls) -> ls.size());
+  }
+}

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

@@ -50,6 +50,10 @@ public class ConstraintsInferenceMiscTest extends LightDaemonAnalyzerTestCase {
     doTest(false);
   }
 
+  public void testLambdaGroundTest() throws Exception {
+    doTest(false);
+  }
+
   private void doTest(final boolean checkWarnings) {
     doTestNewInference(BASE_PATH + "/" + getTestName(false) + ".java", checkWarnings, false);
   }