java completion: suggest AbstractClass::new[] (IDEA-188431)

java/java-impl/src/com/intellij/codeInsight/completion/FunctionalExpressionCompletionProvider.java

@@ -154,9 +154,11 @@ public class FunctionalExpressionCompletionProvider extends CompletionProvider<C
 
     Consumer<PsiType> consumer = eachReturnType -> {
       PsiClass psiClass = PsiUtil.resolveClassInType(eachReturnType);
-      if (psiClass == null || !MethodReferenceResolver.canBeConstructed(psiClass)) return;
+      if (psiClass == null) return;
 
       if (eachReturnType.getArrayDimensions() == 0) {
+        if (!MethodReferenceResolver.canBeConstructed(psiClass)) return;
+        
         PsiMethod[] constructors = psiClass.getConstructors();
         for (PsiMethod psiMethod : constructors) {
           if (isSignatureAppropriate(psiMethod, params, substitutor, 0, originalPosition)) {

java/java-tests/testData/codeInsight/completion/smartType/AbstractArrayConstructorRef-out.java

@@ -0,0 +1,9 @@
+import java.util.stream.Stream;
+public class Outer {
+
+  Abstract[] foo(Stream<Abstract> s) {
+    return s.toArray(Abstract[]::new)<caret>;
+  }
+}
+
+abstract class Abstract {}

java/java-tests/testData/codeInsight/completion/smartType/AbstractArrayConstructorRef.java

@@ -0,0 +1,9 @@
+import java.util.stream.Stream;
+public class Outer {
+
+  Abstract[] foo(Stream<Abstract> s) {
+    return s.toArray(Ab<caret>);
+  }
+}
+
+abstract class Abstract {}

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/SmartType18CompletionTest.java

@@ -88,6 +88,7 @@ public class SmartType18CompletionTest extends LightFixtureCompletionTestCase {
   }
 
   public void testInnerArrayConstructorRef() { doTest(true); }
+  public void testAbstractArrayConstructorRef() { doTest(true); }
 
   public void testNoConstraintsWildcard() {
     doTest();