safe delete: more precise check for safe delete top level classes (IDEA-150276)

java/java-impl/src/com/intellij/refactoring/safeDelete/JavaSafeDeleteProcessor.java

@@ -519,9 +519,13 @@ public class JavaSafeDeleteProcessor extends SafeDeleteProcessorDelegateBase {
           }
           LOG.assertTrue(element.getTextRange() != null);
           final PsiFile containingFile = psiClass.getContainingFile();
-          final boolean sameFileWithSingleClass = containingFile instanceof PsiClassOwner &&
-                                                  ((PsiClassOwner)containingFile).getClasses().length == 1 &&
-                                                  element.getContainingFile() == containingFile;
+          boolean sameFileWithSingleClass = false;
+          if (containingFile instanceof PsiClassOwner) {
+            final PsiClass[] classes = ((PsiClassOwner)containingFile).getClasses();
+            sameFileWithSingleClass = classes.length == 1 && 
+                                      classes[0] == psiClass && 
+                                      element.getContainingFile() == containingFile;
+          }
           usages.add(new SafeDeleteReferenceJavaDeleteUsageInfo(element, psiClass, sameFileWithSingleClass || isInNonStaticImport(element)));
         }
         return true;

java/java-tests/testData/refactoring/safeDelete/InnerClassUsedInTheSameFile.java

@@ -0,0 +1,5 @@
+class Test {
+  public void method(Foo p) {}
+
+  static class F<caret>oo {}
+}

java/java-tests/testSrc/com/intellij/refactoring/SafeDeleteTest.java

@@ -289,6 +289,17 @@ public class SafeDeleteTest extends MultiFileTestCase {
     doTest("ClassWithInnerStaticImport");
   }
 
+  public void testInnerClassUsedInTheSameFile() throws Exception {
+    try {
+      doSingleFileTest();
+      fail("Side effect was ignored");
+    }
+    catch (BaseRefactoringProcessor.ConflictsInTestsException e) {
+      String message = e.getMessage();
+      assertEquals("class <b><code>Test.Foo</code></b> has 1 usage that is not safe to delete.", message);
+    }
+  }
+
   private void doTest(@NonNls final String qClassName) throws Exception {
     doTest((rootDir, rootAfter) -> {
       SafeDeleteTest.this.performAction(qClassName);