8278612: [macos] test/jdk/java/awt/dnd/RemoveDropTargetCrashTest crashes with VoiceOver on macOS

Reviewed-by: serb, kizune

Author: Anton Tarasov

src/java.desktop/macosx/native/libawt_lwawt/awt/a11y/CommonComponentAccessibility.h

@@ -83,6 +83,7 @@
 - (NSView* _Nonnull)view;
 - (NSWindow* _Nonnull)window;
 - (id _Nonnull)parent;
+- (CommonComponentAccessibility* _Nullable)typeSafeParent;
 - (NSString* _Nonnull)javaRole;
 
 - (BOOL)isMenu;

src/java.desktop/macosx/native/libawt_lwawt/awt/a11y/CommonComponentAccessibility.m

@@ -95,7 +95,11 @@ - (BOOL)isSelected:(JNIEnv *)env
         return NO;
     }
 
-    return isChildSelected(env, ((CommonComponentAccessibility *)[self parent])->fAccessible, fIndex, fComponent);
+    CommonComponentAccessibility* parent = [self typeSafeParent];
+    if (parent != nil) {
+        return isChildSelected(env, parent->fAccessible, fIndex, fComponent);
+    }
+    return NO;
 }
 
 - (BOOL)isSelectable:(JNIEnv *)env
@@ -708,6 +712,15 @@ - (id)parent
     return fParent;
 }
 
+- (CommonComponentAccessibility *)typeSafeParent
+{
+    id parent = [self parent];
+    if ([parent isKindOfClass:[CommonComponentAccessibility class]]) {
+        return (CommonComponentAccessibility*)parent;
+    }
+    return nil;
+}
+
 - (NSString *)javaRole
 {
     if(fJavaRole == nil) {
@@ -824,11 +837,13 @@ - (NSAccessibilityRole)accessibilityRole
     if (fNSRole == nil) {
         NSString *javaRole = [self javaRole];
         fNSRole = [sRoles objectForKey:javaRole];
+        CommonComponentAccessibility* parent = [self typeSafeParent];
         // The sRoles NSMutableDictionary maps popupmenu to Mac's popup button.
         // JComboBox behavior currently relies on this.  However this is not the
         // proper mapping for a JPopupMenu so fix that.
         if ( [javaRole isEqualToString:@"popupmenu"] &&
-             ![[[self parent] javaRole] isEqualToString:@"combobox"] ) {
+             parent != nil &&
+             ![[parent javaRole] isEqualToString:@"combobox"] ) {
              fNSRole = NSAccessibilityMenuRole;
         }
         if (fNSRole == nil) {
@@ -1025,8 +1040,9 @@ - (id)accessibilityValue
     // This may change when later fixing issues which currently
     // exist for combo boxes, but for now the following is only
     // for JPopupMenus, not for combobox menus.
-    id parent = [self parent];
+    id parent = [self typeSafeParent];
     if ( [[self javaRole] isEqualToString:@"popupmenu"] &&
+         parent != nil &&
          ![[parent javaRole] isEqualToString:@"combobox"] ) {
         NSArray *children =
             [CommonComponentAccessibility childrenOfParent:self

src/java.desktop/macosx/native/libawt_lwawt/awt/a11y/TabButtonAccessibility.m

@@ -59,11 +59,14 @@ - (void)dealloc
 - (jobject)tabGroup
 {
     if (fTabGroupAxContext == NULL) {
-        JNIEnv* env = [ThreadUtilities getJNIEnv];
-        jobject tabGroupAxContext = [(CommonComponentAccessibility *)[self parent] axContextWithEnv:env];
-        fTabGroupAxContext = (*env)->NewWeakGlobalRef(env, tabGroupAxContext);
-        CHECK_EXCEPTION();
-        (*env)->DeleteLocalRef(env, tabGroupAxContext);
+        CommonComponentAccessibility* parent = [self typeSafeParent];
+        if (parent != nil) {
+            JNIEnv *env = [ThreadUtilities getJNIEnv];
+            jobject tabGroupAxContext = [parent axContextWithEnv:env];
+            fTabGroupAxContext = (*env)->NewWeakGlobalRef(env, tabGroupAxContext);
+            CHECK_EXCEPTION();
+            (*env)->DeleteLocalRef(env, tabGroupAxContext);
+        }
     }
     return fTabGroupAxContext;
 }