find of constructor with one vararg parameter should assume implicit usages (IDEA-158585)

java/java-indexing-impl/src/com/intellij/psi/impl/search/ConstructorReferencesSearchHelper.java

@@ -64,6 +64,9 @@ class ConstructorReferencesSearchHelper {
       @Override
       public Void compute() {
         constructorCanBeCalledImplicitly[0] = constructor.getParameterList().getParametersCount() == 0;
+        if (!constructorCanBeCalledImplicitly[0]) {
+          constructorCanBeCalledImplicitly[0] = hasDefaultConstructorWithVarargParameter(containingClass);
+        }
         isEnum[0] = containingClass.isEnum();
         isUnder18[0] = PsiUtil.getLanguageLevel(containingClass).isAtLeast(LanguageLevel.JDK_1_8);
         return null;
@@ -124,6 +127,17 @@ class ConstructorReferencesSearchHelper {
     return ClassInheritorsSearch.search(containingClass, searchScope, false).forEach(processor2);
   }
 
+  private static boolean hasDefaultConstructorWithVarargParameter(@NotNull PsiClass containingClass) {
+    final PsiMethod[] constructors = containingClass.getConstructors();
+    for (PsiMethod ctr : constructors) {
+      final PsiParameter[] parameters = ctr.getParameterList().getParameters();
+      if (parameters.length == 1 && parameters[0].isVarArgs()) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   private static boolean processEnumReferences(@NotNull final Processor<PsiReference> processor,
                                                @NotNull final PsiMethod constructor,
                                                @NotNull final Project project,

java/java-tests/testSrc/com/intellij/psi/search/FindFixtureBasedTest.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2000-2016 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.psi.search
+
+import com.intellij.psi.search.searches.MethodReferencesSearch
+import com.intellij.testFramework.fixtures.LightCodeInsightFixtureTestCase
+
+class FindFixtureBasedTest : LightCodeInsightFixtureTestCase() {
+  fun testDefaultConstructorWithVarargsParameters() {
+    val aClass = myFixture.addClass("public class Foo {public Foo(int... a) {}}")
+    myFixture.addClass("public class Bar extends Foo {}")
+
+    val constructors = aClass.constructors
+    assertSize(1, constructors)
+    val references = MethodReferencesSearch.search(constructors[0]).findAll()
+    assertSize(1, references)
+  }
+}