lambda: get info for return types from type arguments

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

@@ -289,6 +289,11 @@ public class LambdaUtil {
   public static boolean isFreeFromTypeInferenceArgs(final PsiParameter[] methodParameters,
                                                     final PsiLambdaExpression lambdaExpression,
                                                     final PsiExpression expression) {
+    if (expression instanceof PsiCallExpression && ((PsiCallExpression)expression).getTypeArguments().length > 0) return true;
+    if (expression instanceof PsiNewExpression) {
+      final PsiJavaCodeReferenceElement classReference = ((PsiNewExpression)expression).getClassOrAnonymousClassReference();
+      if (classReference != null && classReference.getTypeParameters().length > 0) return true;
+    }
     final PsiParameter[] lambdaParams = lambdaExpression.getParameterList().getParameters(); 
     if (lambdaParams.length != methodParameters.length) return false;
     final boolean [] independent = new boolean[]{true};

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/PsiResolveHelperImpl.java

@@ -629,7 +629,7 @@ public class PsiResolveHelperImpl implements PsiResolveHelper {
           }
 
           final Pair<PsiType, ConstraintType> returnExprConstraint =
-            getSubstitutionForTypeParameterConstraint(typeParam, returnType, exprType, false, PsiUtil.getLanguageLevel(method));
+            getSubstitutionForTypeParameterConstraint(typeParam, returnType, exprType, true, PsiUtil.getLanguageLevel(method));
           if (returnExprConstraint != null) {
             if (returnExprConstraint == FAILED_INFERENCE) return returnExprConstraint;
             if (constraint != null) {

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

@@ -0,0 +1,16 @@
+import java.util.*;
+public class BugReportLambdaSquiggles<T> {
+
+  private T t;
+  public <V> List<V> flatMap(Mapper<T, List<V>> mapper) {
+    return mapper.map(t);
+  }
+
+  static void bar( BugReportLambdaSquiggles<Integer> x) {
+    x.flatMap(t1 -> new ArrayList<String>(t1));
+  }
+
+  interface Mapper<T, U> {
+    U map(T t);
+  }
+}

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

@@ -68,6 +68,10 @@ public class LambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
   public void testInferenceOnMethodCallSite() throws Exception {
     doTest();
   }
+
+  public void testInferFromTypeArgs() throws Exception {
+    doTest();
+  }
   
   public void testAmbiguity1() throws Exception {
     doTest();