IDEA-CR-12743, IDEA-157088 The autocomplete to offer not only the implementation of the interface, but the interface itself (when Object arrays are expected)

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

@@ -84,7 +84,8 @@ public class JavaInheritorsGetter extends CompletionProvider<CompletionParameter
     addArrayTypes(parameters.getPosition(), infos, consumer);
 
     List<PsiClassType> classTypes = extractClassTypes(infos);
-    boolean arraysWelcome = classTypes.stream().anyMatch(t -> t.equalsToText(CommonClassNames.JAVA_LANG_OBJECT));
+    boolean arraysWelcome = ContainerUtil.exists(ExpectedTypesGetter.extractTypes(infos, true),
+                                                 t -> t.getDeepComponentType().equalsToText(CommonClassNames.JAVA_LANG_OBJECT));
     processInheritors(parameters, classTypes, prefixMatcher, type -> {
       final LookupElement element = addExpectedType(type, parameters);
       if (element != null) {

java/java-tests/testData/codeInsight/completion/normal/SuggestInterfaceArrayWhenObjectArrayIsExpected.java

@@ -0,0 +1,8 @@
+interface MyIntf {}
+
+    void foo(MyIntf i){}
+    void foo(Object[] array){}
+
+    void test() {
+        foo(new MyIntf<caret>)
+    }

java/java-tests/testSrc/com/intellij/codeInsight/completion/NormalCompletionTest.groovy

@@ -1603,4 +1603,10 @@ class Bar {
     assert LookupElementPresentation.renderElement(myFixture.lookup.items[0]).tailText.contains('{...}')
     assert LookupElementPresentation.renderElement(myFixture.lookup.items[1]).tailText.contains('[]')
   }
+
+  public void testSuggestInterfaceArrayWhenObjectArrayIsExpected() {
+    configure()
+    assert LookupElementPresentation.renderElement(myFixture.lookup.items[0]).tailText.contains('{...}')
+    assert LookupElementPresentation.renderElement(myFixture.lookup.items[1]).tailText.contains('[]')
+  }
 }