Fix panic dragging tabs multiple positions to the right (#32305)

Closes https://github.com/zed-industries/zed/issues/32303

Release Notes:

- Fixed a panic that occurred when dragging tabs multiple positions to
the right (preview only)

crates/workspace/src/pane.rs

@@ -2924,12 +2924,9 @@ impl Pane {
                             let moved_right = ix > from_ix;
                             let ix = if moved_right { ix - 1 } else { ix };
                             let is_pinned_in_to_pane = this.is_tab_pinned(ix);
-                            let is_at_same_position = ix == from_ix;
 
-                            if is_at_same_position
+                            if (was_pinned_in_from_pane && is_pinned_in_to_pane)
-                                || (moved_right && is_pinned_in_to_pane)
+                                || (!was_pinned_in_from_pane && !is_pinned_in_to_pane)
-                                || (!moved_right && !is_pinned_in_to_pane)
-                                || (!moved_right && was_pinned_in_from_pane)
                             {
                                 return;
                             }
@@ -4981,6 +4978,70 @@ mod tests {
         assert_item_labels(&pane_a, ["A*!", "B!", "C!"], cx);
     }
 
+    #[gpui::test]
+    async fn test_drag_first_tab_to_last_position(cx: &mut TestAppContext) {
+        init_test(cx);
+        let fs = FakeFs::new(cx.executor());
+
+        let project = Project::test(fs, None, cx).await;
+        let (workspace, cx) =
+            cx.add_window_view(|window, cx| Workspace::test_new(project.clone(), window, cx));
+        let pane_a = workspace.read_with(cx, |workspace, _| workspace.active_pane().clone());
+
+        // Add A, B, C
+        let item_a = add_labeled_item(&pane_a, "A", false, cx);
+        add_labeled_item(&pane_a, "B", false, cx);
+        add_labeled_item(&pane_a, "C", false, cx);
+        assert_item_labels(&pane_a, ["A", "B", "C*"], cx);
+
+        // Move A to the end
+        pane_a.update_in(cx, |pane, window, cx| {
+            let dragged_tab = DraggedTab {
+                pane: pane_a.clone(),
+                item: item_a.boxed_clone(),
+                ix: 0,
+                detail: 0,
+                is_active: true,
+            };
+            pane.handle_tab_drop(&dragged_tab, 2, window, cx);
+        });
+
+        // A should be at the end
+        assert_item_labels(&pane_a, ["B", "C", "A*"], cx);
+    }
+
+    #[gpui::test]
+    async fn test_drag_last_tab_to_first_position(cx: &mut TestAppContext) {
+        init_test(cx);
+        let fs = FakeFs::new(cx.executor());
+
+        let project = Project::test(fs, None, cx).await;
+        let (workspace, cx) =
+            cx.add_window_view(|window, cx| Workspace::test_new(project.clone(), window, cx));
+        let pane_a = workspace.read_with(cx, |workspace, _| workspace.active_pane().clone());
+
+        // Add A, B, C
+        add_labeled_item(&pane_a, "A", false, cx);
+        add_labeled_item(&pane_a, "B", false, cx);
+        let item_c = add_labeled_item(&pane_a, "C", false, cx);
+        assert_item_labels(&pane_a, ["A", "B", "C*"], cx);
+
+        // Move C to the beginning
+        pane_a.update_in(cx, |pane, window, cx| {
+            let dragged_tab = DraggedTab {
+                pane: pane_a.clone(),
+                item: item_c.boxed_clone(),
+                ix: 2,
+                detail: 0,
+                is_active: true,
+            };
+            pane.handle_tab_drop(&dragged_tab, 0, window, cx);
+        });
+
+        // C should be at the beginning
+        assert_item_labels(&pane_a, ["C*", "A", "B"], cx);
+    }
+
     #[gpui::test]
     async fn test_add_item_with_new_item(cx: &mut TestAppContext) {
         init_test(cx);