Fix completion menu intrinsic width measurement

crates/ui/src/list/list.rs

@@ -510,6 +510,9 @@ where
         let rows_cache = self.rows_cache.clone();
         let scrollbar_visible = self.options.scrollbar_visible;
         let scroll_handle = self.scroll_handle.clone();
+        let item_to_measure_index = rows_cache
+            .position_of(&self.item_to_measure_index)
+            .unwrap_or(0);
 
         v_flex()
             .flex_grow_1()
@@ -563,6 +566,7 @@ where
                                     .collect::<Vec<_>>()
                             },
                         )
+                        .with_item_to_measure_index(item_to_measure_index)
                         .paddings(self.options.paddings.clone())
                         .when(self.options.max_height.is_some(), |this| {
                             this.with_sizing_behavior(ListSizingBehavior::Infer)

crates/ui/src/virtual_list.rs

@@ -124,8 +124,9 @@ impl VirtualListScrollHandle {
 ///
 /// This is like `uniform_list` in GPUI, but support two axis.
 ///
-/// The `item_sizes` is the size of each column,
-/// only the `height` is used, `width` is ignored and VirtualList will measure the first item width.
+/// The `item_sizes` is the size of each row. Only the `height` is used; `width` is inferred
+/// by measuring the item selected with [`VirtualList::with_item_to_measure_index`], defaulting
+/// to the first item.
 ///
 /// See also [`h_virtual_list`]
 #[inline]
@@ -197,6 +198,7 @@ where
         item_sizes,
         render_items: Box::new(render_range),
         sizing_behavior: ListSizingBehavior::default(),
+        item_to_measure_index: 0,
     }
 }
 
@@ -212,6 +214,7 @@ pub struct VirtualList {
         dyn for<'a> Fn(Range<usize>, &'a mut Window, &'a mut App) -> SmallVec<[AnyElement; 64]>,
     >,
     sizing_behavior: ListSizingBehavior,
+    item_to_measure_index: usize,
 }
 
 impl Styled for VirtualList {
@@ -233,6 +236,12 @@ impl VirtualList {
         self
     }
 
+    /// Set the item index used to infer the list's cross-axis size.
+    pub fn with_item_to_measure_index(mut self, index: usize) -> Self {
+        self.item_to_measure_index = index;
+        self
+    }
+
     /// Specify for table.
     ///
     /// Table is special, because the `scroll_handle` is based on Table head (That is not a virtual list).
@@ -301,7 +310,7 @@ impl VirtualList {
             return Size::default();
         }
 
-        let item_ix = 0;
+        let item_ix = self.item_to_measure_index.min(self.items_count - 1);
         let mut items = (self.render_items)(item_ix..item_ix + 1, window, cx);
         let Some(mut item_to_measure) = items.pop() else {
             return Size::default();