resolve member/type annotation nullable/notnull conflict (IDEA-174042)

java/java-psi-api/src/com/intellij/codeInsight/NullableNotNullManager.java

@@ -245,11 +245,35 @@ public abstract class NullableNotNullManager {
   private PsiAnnotation findPlainNullabilityAnnotation(@NotNull PsiModifierListOwner owner, boolean checkBases) {
     Set<String> qNames = ContainerUtil.newHashSet(getNullablesWithNickNames());
     qNames.addAll(getNotNullsWithNickNames());
-    return checkBases && owner instanceof PsiMethod
-           ? AnnotationUtil.findAnnotationInHierarchy(owner, qNames)
-           : AnnotationUtil.findAnnotation(owner, qNames);
+    PsiAnnotation memberAnno = checkBases && owner instanceof PsiMethod
+                               ? AnnotationUtil.findAnnotationInHierarchy(owner, qNames)
+                               : AnnotationUtil.findAnnotation(owner, qNames);
+    if (memberAnno != null) {
+      if (owner instanceof PsiMethod) {
+        return preferTypeAnnotation(memberAnno, ((PsiMethod)owner).getReturnType());
+      }
+      if (owner instanceof PsiVariable) {
+        return preferTypeAnnotation(memberAnno, ((PsiVariable)owner).getType());
+      }
+    }
+    return memberAnno;
   }
 
+  private static PsiAnnotation preferTypeAnnotation(@NotNull PsiAnnotation memberAnno, @Nullable PsiType type) {
+    if (type != null) {
+      for (PsiAnnotation typeAnno : type.getApplicableAnnotations()) {
+        if (areDifferentNullityAnnotations(memberAnno, typeAnno)) {
+          return typeAnno;
+        }
+      }
+    }
+    return memberAnno;
+  }
+
+  private static boolean areDifferentNullityAnnotations(@NotNull PsiAnnotation memberAnno, PsiAnnotation typeAnno) {
+    return isNullableAnnotation(typeAnno) && isNotNullAnnotation(memberAnno) ||
+        isNullableAnnotation(memberAnno) && isNotNullAnnotation(typeAnno);
+  }
 
   @NotNull
   protected List<String> getNullablesWithNickNames() {

java/java-tests/testData/inspection/dataFlow/fixture/ArrayComponentAndMethodAnnotationConflict.java

@@ -0,0 +1,25 @@
+import withTypeUse.NotNull;
+import withTypeUse.Nullable;
+
+interface Foo {
+  @Nullable Object @NotNull [] getNotNullArrayOfNullableObjects();
+  @NotNull Object @Nullable [] getNullableArrayOfNotNullObjects();
+}
+
+class FooImpl implements Foo {
+
+  @Override
+  public @Nullable Object @NotNull [] getNotNullArrayOfNullableObjects() {
+    return <warning descr="'null' is returned by the method declared as @NotNull">null</warning>;
+  }
+
+  @Override
+  public @NotNull Object @Nullable [] getNullableArrayOfNotNullObjects() {
+    if (Math.random() > 0.5) {
+      return null;
+    }
+    else {
+      return new Object[]{null, new Object()};
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java

@@ -133,8 +133,12 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   }
 
   static void setupTypeUseAnnotations(String pkg, JavaCodeInsightTestFixture fixture) {
-    fixture.addClass("package " + pkg + ";\n\nimport java.lang.annotation.*;\n\n@Target({ElementType.TYPE_USE}) public @interface Nullable { }");
-    fixture.addClass("package " + pkg + ";\n\nimport java.lang.annotation.*;\n\n@Target({ElementType.TYPE_USE}) public @interface NotNull { }");
+    setupCustomAnnotations(pkg, "{ElementType.TYPE_USE}", fixture);
+  }
+
+  private static void setupCustomAnnotations(String pkg, String target, JavaCodeInsightTestFixture fixture) {
+    fixture.addClass("package " + pkg + ";\n\nimport java.lang.annotation.*;\n\n@Target(" + target + ") public @interface Nullable { }");
+    fixture.addClass("package " + pkg + ";\n\nimport java.lang.annotation.*;\n\n@Target(" + target + ") public @interface NotNull { }");
     setCustomAnnotations(fixture.getProject(), fixture.getTestRootDisposable(), pkg + ".NotNull", pkg + ".Nullable");
   }
 
@@ -151,4 +155,9 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   public void testCapturedWildcardNotNull() { doTest(); }
   public void testVarargNotNull() { doTestWithCustomAnnotations(); }
 
+  public void testArrayComponentAndMethodAnnotationConflict() {
+    setupCustomAnnotations("withTypeUse", "{ElementType.METHOD, ElementType.TYPE_USE}", myFixture);
+    doTest();
+  }
+
 }