prefer local variables over NULL_PSI_ELEMENT in smart completion

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

@@ -75,12 +75,14 @@ public class JavaCompletionSorting {
       sorter = ((CompletionSorterImpl)sorter).withClassifier("liftShorterClasses", true, new LiftShorterClasses(position));
     }
     if (smart) {
-      sorter = sorter.weighAfter("priority", new PreferDefaultTypeWeigher(expectedTypes, parameters));
+      sorter = sorter.weighAfter("priority", new PreferDefaultTypeWeigher(expectedTypes, parameters, false));
     }
 
     List<LookupElementWeigher> afterStats = ContainerUtil.newArrayList();
     afterStats.add(new PreferByKindWeigher(type, position, expectedTypes));
-    if (!smart) {
+    if (smart) {
+      afterStats.add(new PreferDefaultTypeWeigher(expectedTypes, parameters, true));
+    } else {
       if (preferMostUsedWeigher == null) {
         ContainerUtil.addIfNotNull(afterStats, preferStatics(position, expectedTypes));
       }
@@ -298,10 +300,11 @@ public class JavaCompletionSorting {
     private final PsiTypeParameter myTypeParameter;
     private final ExpectedTypeInfo[] myExpectedTypes;
     private final CompletionParameters myParameters;
+    private final boolean myPreferExact;
     private final CompletionLocation myLocation;
 
-    public PreferDefaultTypeWeigher(@NotNull ExpectedTypeInfo[] expectedTypes, CompletionParameters parameters) {
-      super("defaultType");
+    PreferDefaultTypeWeigher(@NotNull ExpectedTypeInfo[] expectedTypes, CompletionParameters parameters, boolean preferExact) {
+      super("defaultType" + (preferExact ? "Exact" : ""));
       myExpectedTypes = ContainerUtil.map2Array(expectedTypes, ExpectedTypeInfo.class, info -> {
         PsiType type = removeClassWildcard(info.getType());
         PsiType defaultType = removeClassWildcard(info.getDefaultType());
@@ -311,6 +314,7 @@ public class JavaCompletionSorting {
         return new ExpectedTypeInfoImpl(type, info.getKind(), defaultType, info.getTailType(), null, ExpectedTypeInfoImpl.NULL);
       });
       myParameters = parameters;
+      myPreferExact = preferExact;
 
       final Pair<PsiTypeParameterListOwner,Integer> pair = TypeArgumentCompletionProvider.getTypeParameterInfo(parameters.getPosition());
       myTypeParameter = pair == null ? null : pair.first.getTypeParameters()[pair.second.intValue()];
@@ -333,7 +337,7 @@ public class JavaCompletionSorting {
       if (returnsUnboundType(item)) return MyResult.normal;
 
       PsiType itemType = JavaCompletionUtil.getLookupElementType(item);
-      if (isExactlyExpected(item, itemType)) {
+      if ((myPreferExact || object instanceof PsiClass) && isExactlyExpected(item, itemType)) {
         return AbstractExpectedTypeSkipper.skips(item, myLocation) ? MyResult.expectedNoSelect : MyResult.exactlyExpected;
       }
 
@@ -344,7 +348,7 @@ public class JavaCompletionSorting {
         final PsiType expectedType = expectedInfo.getType();
 
         if (defaultType != expectedType) {
-          if (defaultType.equals(itemType)) {
+          if (myPreferExact && defaultType.equals(itemType)) {
             return MyResult.exactlyDefault;
           }
 

java/java-tests/testData/codeInsight/completion/smartTypeSorting/PreferExpectedLocalOverExactlyDefaultMember.java

@@ -0,0 +1,14 @@
+class Usage {
+  void foo(PsiMethod method) {
+    PsiUtil.ensureValid(<caret>);
+  }
+}
+
+class PsiUtil {
+  static final PsiElement NULL_PSI_ELEMENT;
+
+  static void ensureValid(PsiElement e) {}
+}
+
+interface PsiElement {}
+interface PsiMethod extends PsiElement {}

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

@@ -324,7 +324,7 @@ class SmartTypeCompletionOrderingTest extends CompletionSortingTestCase {
   }
 
   void testPreferLocalOverThis() {
-    checkPreferredItems 0, 'value', 'hashCode', 'this'
+    checkPreferredItems 0, 'value', 'this', 'hashCode'
   }
 
   void testGetLogger() {
@@ -340,7 +340,7 @@ class SmartTypeCompletionOrderingTest extends CompletionSortingTestCase {
   }
 
   void testPreferLocalWildcardClassOverObject() {
-    checkPreferredItems 0, 'type', 'forName', 'forName', 'Object.class'
+    checkPreferredItems 0, 'type', 'Object.class', 'forName', 'forName'
   }
 
   void testPreferStringsInStringConcatenation() {
@@ -369,6 +369,10 @@ class SmartTypeCompletionOrderingTest extends CompletionSortingTestCase {
     assert LookupElementPresentation.renderElement(items[1]).itemText == 'BiMap.builder'
   }
 
+  void testPreferExpectedLocalOverExactlyDefaultMember() {
+    checkPreferredItems 0, 'method', 'PsiUtil.NULL_PSI_ELEMENT'
+  }
+
   @Override
   protected String getBasePath() {
     return JavaTestUtil.getRelativeJavaTestDataPath() + BASE_PATH

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

@@ -833,7 +833,7 @@ public class SmartTypeCompletionTest extends LightFixtureCompletionTestCase {
   }
   public void testNoClassLiteral() throws Exception {
     doActionTest();
-    assertStringItems("forName", "forName", "Object.class", "getClass");
+    assertStringItems("Object.class", "getClass", "forName", "forName");
   }
 
   public void testClassLiteralInAnno2() throws Throwable {