new inference: skip parenthesized expressions during additional constrains collection

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

@@ -266,21 +266,22 @@ public class InferenceSession {
                                             Set<ConstraintFormula> additionalConstraints,
                                             boolean varargs, boolean toplevel) {
     for (int i = 0; i < args.length; i++) {
-      if (args[i] != null) {
-        final InferenceSession nestedCallSession = findNestedCallSession(args[i]);
+      final PsiExpression arg = PsiUtil.skipParenthesizedExprDown(args[i]);
+      if (arg != null) {
+        final InferenceSession nestedCallSession = findNestedCallSession(arg);
         final PsiType parameterType =
           nestedCallSession.substituteWithInferenceVariables(getParameterType(parameters, i, siteSubstitutor, varargs));
-        if (!isPertinentToApplicability(args[i], parentMethod)) {
-          additionalConstraints.add(new ExpressionCompatibilityConstraint(args[i], parameterType));
+        if (!isPertinentToApplicability(arg, parentMethod)) {
+          additionalConstraints.add(new ExpressionCompatibilityConstraint(arg, parameterType));
         }
-        additionalConstraints.add(new CheckedExceptionCompatibilityConstraint(args[i], parameterType));
-        if (args[i] instanceof PsiCallExpression && PsiPolyExpressionUtil.isPolyExpression(args[i])) {
+        additionalConstraints.add(new CheckedExceptionCompatibilityConstraint(arg, parameterType));
+        if (arg instanceof PsiCallExpression && PsiPolyExpressionUtil.isPolyExpression(arg)) {
           //If the expression is a poly class instance creation expression (15.9) or a poly method invocation expression (15.12), 
           //the set contains all constraint formulas that would appear in the set C when determining the poly expression's invocation type.
-          final PsiCallExpression callExpression = (PsiCallExpression)args[i];
+          final PsiCallExpression callExpression = (PsiCallExpression)arg;
           collectAdditionalConstraints(additionalConstraints, callExpression);
-        } else if (args[i] instanceof PsiLambdaExpression && toplevel) {
-          collectLambdaReturnExpression(additionalConstraints, (PsiLambdaExpression)args[i], parameterType);
+        } else if (arg instanceof PsiLambdaExpression && toplevel) {
+          collectLambdaReturnExpression(additionalConstraints, (PsiLambdaExpression)arg, parameterType);
         }
       }
     }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/ParenthesizedExpressionsDuringConstrainsCollection.java

@@ -0,0 +1,13 @@
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+abstract class Test {
+  public List<Integer> gerFirstTriangles() {
+    return flatMap((y -> (map((z1 -> (1)))))).collect(Collectors.toList());
+  }
+
+  abstract <R> R         flatMap(Function<Integer, R> mapper);
+  abstract <R> Stream<R> map    (Function<Integer, R> mapper);
+}

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

@@ -117,6 +117,10 @@ public class NewLambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testParenthesizedExpressionsDuringConstrainsCollection() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }