method refs: check first parameter if it could be a receiver for varargs methods (IDEA-127506)

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

@@ -970,7 +970,8 @@ public class InferenceSession {
         addConstraint(new TypeCompatibilityConstraint(getParameterType(parameters, i, PsiSubstitutor.EMPTY, varargs), pType));
       }
     }
-    else if (parameters.length + 1 == functionalMethodParameters.length && !varargs || !isStatic && varargs && functionalMethodParameters.length > 0) { //instance methods
+    else if (parameters.length + 1 == functionalMethodParameters.length && !varargs || 
+             !isStatic && varargs && functionalMethodParameters.length > 0 && PsiMethodReferenceUtil.hasReceiver(reference, method)) { //instance methods
       initBounds(containingClass.getTypeParameters());
 
       final PsiType pType = signature.getParameterTypes()[0];

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newMethodRef/IDEA127506.java

@@ -0,0 +1,24 @@
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Stream;
+
+class Validator {
+  static boolean thereAreConstraintViolationsIn1(final Stream<Object> objectStream, Validator validator) {
+    Stream<Set<List<Object>>> rStream = objectStream
+      .map(validator::validate);
+    return rStream
+      .flatMap(set -> set.stream())
+      .findAny()
+      .isPresent();
+  }
+
+  static void thereAreConstraintViolationsIn(final Stream<Object> objectStream, Validator validator) {
+    Stream<Set<List<Object>>> rStream = objectStream.map(validator ::validate);
+
+    Stream<Set<List<Object>>> lStream = objectStream.map((a) -> validator.validate(a));
+  }
+
+  <T> Set<List<T>> validate(T var1, Class<?> ... var2) {
+    return null;
+  }
+}

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

@@ -277,6 +277,10 @@ public class NewMethodRefHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testIDEA127506() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }